EP-EPP-P7-S1 Technical Specifications for the Connection of Solar PV Systems to Network PDF

EP-EPP-P7-S1 Technical Specifications for the Connection of PV Systems to the Network Public Page 1 of 50  Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 Table of Contents Contents...

EP-EPP-P7-S1 Technical Specifications for the Connection of PV Systems to the Network Public Page 1 of 50  Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 Table of Contents Contents Page Title Page 1 Document Control & Issue Record Page 2 Table of Contents 3 1 Purpose 4 2 Scope 4 2.1 Notice to Users 5 2.2 Kahramaa Limitation of Liability and Customer’s undertaking 5 3 Abbreviations, Definitions of Terms & Key References 6 4 Applicable Standards for Solar PV Systems Components 11 5 Technical Requirements 14 5.1 General Requirements 14 5.2 Connection Schemes 14 5.3 Circuit Breakers Selection 17 5.4 Protection against Faults 19 5.5 Operating Ranges 20 5.6 Immunity to Disturbances 21 5.6.1 Low Voltage Ride Through (LVRT) Capability 21 5.6.2 ROCOF Withstand Capability 22 5.7 Requirements for the Frequency Stability of the Power System 22 5.7.1 Active Power Response to Frequency Variations 22 5.7.2 Active power delivery at under-frequencies 23 Public Page 2 of 50  Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 5.7.3 Remote Limitation of Active Power 24 5.8 Requirements for the Voltage Stability of the Power System 24 5.8.1 Reactive Power Capability 24 5.8.2 Reactive Power Control Modes 26 5.8.3 Power Reduction at Increasing Voltage 29 5.9 Requirements for the Management of the Power System 30 5.9.1 Connection Conditions after Programmed Disconnection 29 5.9.2 Remote Disconnection 29 5.9.3 Automatic Reconnection after Tripping 29 5.9.4 Interface Protection 30 5.9.5 Protection and Control Ranking Priority 32 5.9.6 Monitoring, Remote Control and Information Exchange 33 5.9.7 Power Factor 34 5.9.8 Power Quality 34 5.10 Metering System 35 5.11 Earthing and Lightning Systems 36 6 Particular Requirements for LV Photovoltaic Systems 37 6.1 LV System Characteristics 37 6.2 DC Injection 37 6.3 Clusters of Single-phase PV Units 37 7 Compliance with the Standards 38 ANNEX A. Connection Schemes 39 ANNEX B. Default Settings of Interface Protection 49 ANNEX C. Configuration of LV Distribution Systems of Kahramaa 49 ANNEX D. Service and Environmental Conditions 49 Public Page 3 of 50 Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 1 Purpose This document provides a common set of requirements specific for grid-connected Solar PV (Photovoltaic) Systems that operates in parallel with the LV & MV distribution networks of Kahramaa, Qatar. The maximum capacity of a Solar PV System considered in this document is 25 MW for connection to up to 33 kV voltage level and the capacity of Solar PV system should not exceed Contracted demand as defined and approved in the building permit. These requirements shall be fulfilled regardless of the presence of loads in the Customer’s installation. In case of standalone PV systems not connected to Kahramaa’s grid, the document “Standalone Solar PV Systems” shall be used. 2 Scope The current Technical Standards for grid-connected PV Systems define: a) Requirements for the equipment used to interconnect a solar PV System with the distribution network. b) Requirements to support the frequency and voltage stability of the power system when it is subject to disturbances. c) Requirements for the start-up, operation and disconnection of the solar PV Systems. d) Requirements to prevent the solar PV Systems from causing disturbances and damages, either to the distribution network or to other Customers connected to the same distribution network. e) Requirements to prevent the solar PV Systems from operating in parallel with an island or portion of the distribution network which has been disconnected on purpose from the main power system. The present document is not contradicting additional requirements set out by other national & international standards, network codes or specific technical requirements of Kahramaa, and which may apply to the connection of a solar PV System, including, but not limited to the following: The Qatar Transmission Grid Code – Issue ES-M4 – Revision 0.0 – March 2020 and amendments in force (hereinafter “Transmission Code”) CS-CSI-P1/C1 – Kahramaa’s Low Voltage Electricity Wiring Code 2016 CS-CSI-P1 E_W – Building Permit Issuance CS-CSI-P1-C1 – Design - Water Management Code 2016 Qatar Construction Specifications latest edition All the Contractors and Consultants should follow the Qatari regulations in their latest edition. Specifically, the Consultants and Contractors shall follow the Qatar Construction Specifications document in its last edition for all the non-solar components of the PV Systems required in the electrical design, installation and connection of a PV System. The Transmission Code here above indicated is also applicable to all users of the distribution system. The present Technical Standards shall apply in case the new installation (or the modified one) includes a solar PV System and shall be intended as an extension of the Transmission Code for what is not directly ruled by the code itself. For all the aspects not covered by the present document, reference shall be made to the Transmission Code. This information can be found in other companion documents, as listed in part. 0. Public Page 4 of 50 Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 Finally, it is not under the purpose of these standards to define technical rules for the off-grid operation of networks in isolated (e.g., rural) areas where no part of Kahramaa distribution network is involved. Unless otherwise explicitly specified, the requirements set forth by the present standards apply to new solar PV Systems, i.e., to those solar PV Systems which do have not already been approved by Kahramaa at the date of publication of the standards. 2.1 Notice to Users This document is for the use of employees of Kahramaa, Customers, Consultants, Contractors and Manufacturers. Users of this guideline should be aware of the applicable laws and regulations. Users are responsible for observing or referring to the applicable regulatory requirements. Kahramaa, by the publication of its standards, does not intend to urge action that is not in compliance with applicable laws, and these documents may not be construed as doing so. Users should be aware that this document may be superseded at any time by the issuance of new editions or may be amended from time to time through the issuance of amendments, corrigenda, or errata. At any point in time, these Technical Standards consist of the current edition of the document together with any amendments, corrigenda, or errata in effect. All users should ensure that they have the latest edition of this document uploaded on Kahramaa website. Finally, unless otherwise specified, the User shall refer to all applicable Kahramaa Standards, Qatar Standards, or International Standards mentioned in this document. DISCLAIMER These Technical Standards are provided without a consolidated Framework Regulation by Kahramaa; therefore, the content of the present document may be subject to change in the next revisions of the Technical Standards. 2.2 Kahramaa Limitation of Liability and Customer’s undertaking Kahramaa disclaims liability for any personal injury, property or other damage of any nature whatsoever, whether special, indirect, consequential, or compensatory, directly or indirectly resulting from the connection point. Customers are responsible for observing or referring to the applicable laws and regulatory requirements. It is the Customer’s responsibility through their Consultant/Contractor to determine the interconnection equipment’s specifications and confirmed performance to satisfy the technical needs of the Kahramaa network and be compatible with the present and any other applicable Kahramaa standards. Kahramaa standards are indispensable for solar PV applications. All equipment in an installation connected to Kahramaa network shall be designed, manufactured, tested and installed following all applicable statutory obligations and shall conform to the relevant Kahramaa standards current at the time of the connection of the installation to Kahramaa network. The Customer shall undertake to comply with the following: a) Arrange all necessary requirements and systems to connect his solar PV System to Kahramaa network, including compliance with security and safety requirements by providing necessary equipment. b) Comply with the terms and conditions for the PV System connection, such as the Connection Agreement, connection conditions, and any other relevant requirement adopted by Kahramaa. Public Page 5 of 50 Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 c) Do not exceed the authorised Maximum Connected Capacity for exporting to the Kahramaa network. d) Cooperate with Kahramaa staff in all matters related to exporting electricity to Kahramaa network. e) To bear all the costs associated with the connection of his solar PV System to Kahramaa network. f) To export to Kahramaa network any excess electricity generated by his solar PV System to Kahramaa network in accordance with the provisions of the Connection Agreement. g) To let Kahramaa disconnect or perform an immediate disconnection of his solar PV System under Kahramaa request if it was identified risk for the safety or the security of the system and the Kahramaa public electricity network. h) Ensure the development of a Maintenance manual which guarantees the correct operation and performance of the PV system during its entire lifetime. 3 Abbreviations, Definitions of Terms & Key References Abbreviations cos  : Power factor IP : Interface Protection LOM : Loss of Mains LV : Low Voltage LVRT : Low Voltage Ride Through MV : Medium Voltage (namely 11 kV or 22 kV) NCC : National Control Centre P : Active power Pnom : Nominal active power of equipment pu : per unit PV : (Solar) Photovoltaic Q : Reactive Power ROCOF : Rate of Change of Frequency S : Apparent Power expressed in Hz/s Sn : Nominal Apparent Power V : Voltage Vnom Nominal Voltage EP : Electricity Planning Dept Term Description Active Power Active Power is the real component of the apparent power, expressed in watts or multiples thereof, e.g. kilowatts (kW) or megawatts (MW). In the text, this will be generically referred as P or Pnom in case of the nominal active power of equipment Apparent Power The product of voltage and current at the fundamental frequency, and the square root of three in the case of three-phase systems, usually expressed in kilovolt-amperes (kVA) or megavolt-amperes (MVA). It consists of a real component (Active Power) and the reactive component (Reactive Power). This will be generically referred to S or Sn in case of the rated apparent power of equipment Apparent power of The rated apparent power of an Inverter is the product of the rms voltage an Inverter and current and is expressed in kVA or MVA. Auxiliary Supply Electricity supply for supporting auxiliary systems and services such as Power Interface Protection or circuit breaker and contactor opening coils. Circuit Breaker (CB) As per the Kahramaa Electricity and Wiring Code definition Public Page 6 of 50 Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 Term Description Connection Point Also referred to as Point of Connection, is the interface point at which a PV System of the Customer is connected. Consultant A qualified consultant for the design of grid-connected solar PV Systems. Customer Any Person supplied with electricity services for his own consumption. In this context, this term will also be used to refer to a User owning a solar PV System. Contractor A certified contractor for the installation of grid-connected solar PV Systems. Delay time (of a Indicates the minimum duration of a fault detected by the protection relay protection relay) before the output of the protection relay is triggered. Delivery Point The interface point at which electrical energy is delivered by Kahramaa to a Demand Facility or Generating Unit or by a Demand Facility or Generating Unit to Kahramaa. Distribution System Qatar electrical infrastructure (lines, cables, substations, etc.) at 33 kV and / Distribution below, operated by Kahramaa. The Distribution network can be either a Network Medium or Low Voltage system for the scope of the present document and in accordance with international standards: A Low Voltage (LV) Distribution System is a network with a nominal voltage lower than 1 kV AC or 1.5 kV DC. The LV network in the State of Qatar is 240/415 V ± 6%, 3 Phase, 4 Wire. A Medium Voltage (MV) Distribution System is a network with nominal voltage included in the range from 1 kV AC up to 33 kV. The MV Distribution System nominal voltages in Qatar are 11, 22 and 33 kV. Electrical network voltages equal to or higher than 33 kV are not considered in this document. According to the Transmission Grid Code, the 33 kV is considered a sub-transmission network. To avoid doubt, the term Distribution Network will be preferred in this document in place of Distribution System. Electricity Qatar electrical infrastructure (lines, cables, substations, etc.) from above 33 Transmission kV up to 400 kV operated by Kahramaa. Network (ETN) Interface protection Electrical protection part of the solar PV System that ensures the PV System (IP) is disconnected from the network in case of an event that compromises the integrity of Kahramaa’s distribution network. Irradiation Irradiance integrated over a given time interval and measured in energy units (e.g. kWh/m2/day). Islanding Situation where a portion of the distribution network containing generating plants becomes physically disconnected from the rest of the distribution network. One or more generating plants maintain electricity supply to such isolated parts of the distribution network. Load Flow It is a numerical analysis of the electric power flow in a transmission and/or distribution systems. A power-flow study usually uses simplified notations such as a one-line diagram and per-unit system, and focuses on various parameters, such as voltages, voltage angles, real power and reactive power. It analyses the power systems in normal steady-state operation. Loss Of Mains Represents an operating condition in which a distribution network, or part of (LOM) it, is separated from the main power system (on purpose or in case of a fault) with the final aim of de-energisation. The protection that detects this condition is known as anti-islanding protection. Public Page 7 of 50 Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 Term Description Main Meter It is the bidirectional smart meter installed at the Connection Point which measures the amount of electric energy actually exchanged (import or export) by the Customer with the distribution network. Maximum Available This is the Active Power Output based on the primary resource (for example, Active Power Output sun irradiance) and the maximum steady-state efficiency of the Solar PV System for this operating point. Maximum Capacity It is the maximum continuous active power which a Generating Unit can (Pmax) produce, less any auxiliary consumption associated used to facilitate the operation of that Generating Unit. The Maximum Capacity shall not be fed into the distribution network as specified in the Connection Agreement. In this document, this term is also referred to as Maximum Connected Capacity. Peak Power (Wp) The output power achieved by a Photovoltaic Module under Standard Test Conditions (STC). It is measured in Wp (W peak). The sum of the peak power of the photovoltaic modules of either a string or an array determines the peak power of the string and the array, respectively (usually measured in kWp). The peak power of a photovoltaic array at STC is conventionally assumed as the rated power of the array. Solar PV System This term also has the same meaning as Power Plant or User’s System or Grid User, defined in the Transmission Grid Code. It is a solar PV installation of not more than 25 MW and not less than 1 kW capacity installed in one Premise and connected in parallel to Kahramaa’s Distribution Network. This document aims to be considered a power plant with one or more Solar PV Units. Besides, circuits and auxiliary services are also part of a solar PV System. To avoid doubt, in this document, the generic term Solar PV System is considered equivalent to solar PV System. This PV System includes the PV array, controllers, inverters, batteries (if used), wiring, junction boxes, circuit breakers, and electrical safety equipment. Solar PV System It is the smart metering installed at the output point of the solar PV System Meter and measures the total energy produced from the Solar PV Units. Solar PV Unit A group of devices that collects the sun’s irradiance in a Solar PV System, together with all plant and apparatus and any step-up transformer which relates exclusively to the operation of that part of the same Solar PV System. Only units that are Inverter based (i.e. Asynchronously connected to the Distribution Network through power electronics devices) are considered in this document. For these Technical Standards, this definition will be equivalent to that of the Power Park Module as given in the Transmission Code. For the avoidance of doubt, in this document, the generic term Solar PV Unit will be considered equivalent to a solar PV Unit. National Control Main Kahramaa’s facility used to operate and control/maintain the Electric Centre (NCC) Power System. Photovoltaic (PV) The most elementary device that exhibits the photovoltaic effect, i.e. the cell direct non-thermal conversion of radiant energy into electrical energy Power Factor Is the ratio of Active Power to Apparent Power. Power Park Module A unit or ensemble of units generating electricity, which is either non- (PPM) synchronously connected to the network or connected through power electronics, and that also has a single Connection Point to the ETN. PV Array Assembly of electrically interconnected PV modules, PV strings or PV sub- arrays. For the purposes of these Technical Standards, a PV Array comprises all components up to the DC input terminals of the Inverter. PV String A set of series-connected PV modules. Public Page 8 of 50 Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 Term Description PV String Combiner A box where PV strings are connected, which may also include circuit Box breaker, monitoring equipment, and electrical protection devices. Rated Active Power Represents the sum of the nominal active power of all the Solar PV Units which compose the Solar PV System; it is generally referred to as Pnom of the Solar PV System. Reactive Power Represents a component of the apparent power at the fundamental frequency, usually expressed in kilovar (kVAr) or Megavar (MVAr). Reactive Power Defines the reserves of inductive/capacitive reactive power which can be Capability provided by a generating system/unit. The reactive power capability usually varies with the active power and the voltage of the generating system/unit. Residual Current A sensitive switch that disconnects a circuit when the residual current Device (RCD) exceeds the operating value of the circuit, referred as RCD in this document. Switch As per the Kahramaa Electricity and Wiring Code definition. Time Current Curve The time current curve plots the interrupting time of an overcurrent device (TCC) based on a given current level. These curves are used for the protection coordination, and are provided by the manufacturers of electrical overcurrent interrupting devices such as fuses and circuit breakers. THD (Total Concerning an alternating quantity, it represents the ratio of the r.m.s. value Harmonic Distortion) of the harmonic content to the r.m.s. value of the fundamental component or the reference fundamental component. Key References The Qatar Transmission Grid Code – Issue ES-M4 – Revision 0.0 – March 2020 and amendments in force until 02/2022 (in this document referred to as “Transmission Code”) CS-CSI-P1/C1 Kahramaa’s Low Voltage Electricity Wiring Code 2016 Safety Rules for the Control, Operation and Maintenance of Electricity Transmission & Distribution System of Qatar General Electricity & Water Corporation. System Operation Memorandum (SOM). Kahramaa interlocking document, (Qatar Power Transmission System Expansion – Latest phase – Substations). Qatar Construction Specifications, Latest edition ET-P26-G1 Guidelines for Protection Requirements. ES–EST-P1-G1 Guidelines for System Control Requirements for Power Supply to Bulk Customers. ET-P20-S1 Transmission Protection Standards for TA and ET Projects. ES-M2 Qatar Power System Restoration Plan; and ES-M3 System Emergency, Categorization, Communication & Restoration Responsibility. QCDD (Qatar Civil Defence Department) regulations CS-CSI-P2 E_W – Infrastructure Preparation for Service Connection Purpose v3 CS-CSI-P3 E_W – Services Inspection v5 CS-CSI-P4 – Low Voltage Electrical Contractor Licensing v3 CS-CSI-P5 – Handling of Contractors Violations Procedure v2 CS-JCU-P1 – Illegal Connections Reconnections v3 CS-CSM-P2 E_W – Supply Connection and Disconnection CS-AMI-P1 – AMI operations CS-MAS-P2 E_W – Meter Installation v4 Public Page 9 of 50 Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 CS-MAS-P3 – Maintenance of Electricity and Water Meter v2 CS-MAS-P5 – Materials Submittal Review _ Approval Procedure v2 Energy and Water Conservation Code 2016 EP-EPD-P1 – Electricity Supply Approval v3 EP-EPD-P4 – Processing Service Notes v2 EP-EPD-P6 11kV – Load Flow Study v2 EP-EPP-C1 – Electricity Planning Regulations for Supply EP-EPP-P3 – Early Arrangement for Supply Connection EP-EPP-P5 – Electricity Supply Application EP-EPT-P2 – Basic Concept Report-Direct Connection Notification EP-EPT-P3 – Peak Demand Forecast EP-EPT-P4 – Power System Studies and Five Years Development Plan ES-ESN-P3 – Dispatching Procedure ES-ESN-P4 – Bulk Industrial Consumers Energy Meter Readings Collection v2 ES-ESP-P1 – Creating Operational Load Forecast ES-ESP-P2 – Long Term Operation Planning ES-ESP-P3 – Develop Monitor Energy Purchase Schedules and Allocation Plans ES-ESP-P4 – Operation Studies ES-ESP-P7 – Develop Surplus Available Capacity Plan for Marketing ES-M4 – Qatar Transmission Grid Code 2020 ET-P26 ETD – Responsibilities for Bulk Consumer’s Request for Supply of Electricity CS-CSB-P1– Bulk Supply of Electricity and Water PW-PWP-P1 E_W – Demand Forecasting PW-PWP-P2 – Additional Capacity Planning PW-PWP-PL1 – Planning _ Procurement Policy PW-PWR-P2 – Renewable Energy Standards Development DISCLAIMER The latest editions of the Distribution/Transmission Grid Code, the Electricity Wiring Code, Qatar Construction Specifications, as well as all the documents indicated in the above list in force at the time of the contract, shall prevail and be complied with. The Customer shall also comply with the requirements of any standards issued by Qatar Authorities at the time of the Connection Purchase Agreement. Companion Documents The documents listed hereinafter have to be considered a compendium of the current document. Therefore, they should be carefully read in addition to this. a) EP-EPP-P7 Electricity Supply Approval for REG connection b) EP-EPP-P7-G2 Guidelines for Information in Basic and Final Design c) CS-CSI-P3-G2 Inspection and Testing Guidelines for Solar PV Systems Connected to LV and MV Network, last revision d) PW-PWR-G2 Safety related to the installation of Solar PV Systems, last revision e) KM-PW-PL01-Kahramaa policy for Renewable Energy systems connected to the distribution network Public Page 10 of 50 Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 4 Applicable Standards for Solar PV Systems Components Along with the Technical Standards for the Connection described in the current document, all the components of solar PV Systems shall comply with the applicable International and Qatar standards listed here below, according to the component they apply to. This ensures that the components and equipment used in solar PV Systems in Qatar fit with a minimum set of technical characteristics that give the necessary quality avoiding using unfit or unreliable materials and equipment in Solar PV projects. However, standards may be subject to future revisions, amendments or extensions, and it will be the User’s care to find the latest published versions and utilise them. PV MODULES 1) IEC 61215-1 – Terrestrial photovoltaic (PV) modules - Design qualification and type approval - Part 1: Test requirements. 2) IEC 61215-1-1 – Terrestrial photovoltaic (PV) modules - Design qualification and type approval - Part 1-1: Special requirements for testing of crystalline silicon photovoltaic (PV) modules. 3) IEC 61215-1-2 – Terrestrial photovoltaic (PV) modules - Design qualification and type approval - Part 1-2: Special requirements for testing of thin-film Cadmium Telluride (CdTe) based photovoltaic (PV) modules. 4) IEC 61215-1-3 – Terrestrial photovoltaic (PV) modules - Design qualification and type approval - Part 1-3: Special requirements for testing of thin-film amorphous silicon-based photovoltaic (PV) modules. 5) IEC 61215-1-4 – Terrestrial photovoltaic (PV) modules - Design qualification and type approval - Part 1-4: Special requirements for testing of thin-film Cu (In, GA) (S,Se)2 based photovoltaic (PV) modules. 6) IEC 61215-2 – Terrestrial photovoltaic (PV) modules - Design qualification and type approval - Part 2: Test procedures. 7) IEC 61345- UV test for photovoltaic (PV) modules- PV modules subject to a greater UV exposure 8) IEC 61730-1 – Photovoltaic (PV) module safety qualification - Part 1: Requirements for construction. 9) IEC 61730-2 – Photovoltaic (PV) module safety qualification - Part 2: Requirements for testing. 10) IEC 61701 – Salt mist corrosion testing of photovoltaic (PV) modules. 11) IEC TS 62804-1 – Photovoltaic (PV) modules - Test methods for the detection of potential-induced degradation - Part 1: Crystalline silicon. 12) IEC 62716 – Photovoltaic (PV) modules - Ammonia corrosion testing. 13) IEC 62759-1 – Photovoltaic (PV) modules - Transportation testing - Part 1: Transportation and shipping of module package units. 14) IEC 62790 – Junction boxes for photovoltaic modules - Safety requirements and tests. 15) IEC 62852 – Connectors for DC-application in photovoltaic systems - Safety requirements and tests. 16) IEC 62979 – Photovoltaic modules - Bypass diode - Thermal runaway test. 17) IEC TS 62941 – Terrestrial photovoltaic (PV) modules - Guideline for increased confidence in PV module design qualification and type approval. 18) IEC TS 62782 – Photovoltaic (PV) modules - Cyclic (dynamic) mechanical load testing. Public Page 11 of 50 Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 19) IEC 60068-2-68 – Environmental testing - Part 2-68: Tests - Test L: Dust and sand. 20) IEC TS 63126 – Guidelines for qualifying PV modules, components and materials for operation at high temperatures. 21) IEC 61853 (series) – Photovoltaic (PV) module performance testing and energy rating. 22) IEC TS 61836 - Solar Photovoltaic Energy System Terms, definitions and Symbols. 23) IEC 61853-2 - PV Module performance Testing and Energy rating-Part 2: Special responsivity, incidence angle and module operating temperature measurements. INVERTERS 1) IEC 62109-1 – Safety of power converters for use in photovoltaic power systems - Part 1: General requirements. 2) IEC 62109-2 – Safety of power converters for use in photovoltaic power systems - Part 2: Particular requirements for inverters. 3) EN 50530 – Overall efficiency of grid connected photovoltaic inverters. 4) EN 50524 – Data sheet and name plate for photovoltaic inverters. 5) IEC 62116 – Utility-interconnected photovoltaic inverters - Test procedure of islanding prevention measures. 6) IEC TS 62910 – Utility-interconnected photovoltaic inverters - Test procedure for low voltage ride-through measurements. 7) IEC 62920 – Photovoltaic power generating systems - EMC requirements and test methods for power conversion equipment. 8) IEC 61000-3-2 – Electromagnetic compatibility (EMC) - Part 3-2: Limits - Limits for harmonic current emissions (equipment input current ≤ 16 A per phase). 9) IEC-61000-3-7: The limits of flicker severity of a solar PV system connected to Distribution Network. 10) IEC 61000-3-12 – Electromagnetic compatibility (EMC) - Part 3-12: Limits - Limits for harmonic currents produced by equipment connected to public low-voltage systems with input current >16 A and ≤ 75 A per phase. 11) IEC/TR 61000-3-15 – Assessment of low frequency electromagnetic immunity and emission requirements for dispersed generation systems in LV network INTERFACE PROTECTION 1) IEC 62116 – Utility-interconnected photovoltaic inverters – Test procedure of islanding prevention measures 2) IEC 61727 – Photovoltaic (PV) systems - Characteristics of the utility interface SOLAR CABLES AND CONNECTORS 1) EN 50618 – Electric cables for photovoltaic systems. 2) IEC 62930 – Electric cables for photovoltaic systems with a voltage rating of 1.5 kV DC 3) EN 50521- Connectors for photovoltaic systems – Safety requirements and tests 4) CEI 20-91- Fire retardant and halogen free electric cable with elastomeric insulation and sheath for rated voltages not exceeding 1 000 V a.c and 1 500 V d.c for use in photovoltaic system (PV) PV STRING COMBINER BOXES 1) EN 50178 – Electronic equipment for use in power installations. 2) IEC 62477-1 – Safety requirements for power electronic converter systems and equipment - Part 1: General. Public Page 12 of 50 Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 3) IEC 62477-2 – Safety requirements for power electronic converter systems and equipment - Part 2: Power electronic converters from 1 000 V AC or 1 500 V DC up to 36 kV AC or 54 kV DC 4) IEC 62093 – Balance-of-system components for photovoltaic systems - Design qualification natural environments. SYSTEM INSTALLATION 1) IEC 60364-1 & IEC 60364-7-712: Low voltage electrical installations – Part 1: Fundamental principles, assessment of general characteristics, definitions, and Part 7-712: Requirements for special installations or locations - Solar photovoltaic (PV) power supply systems 2) UL 1741: Standard for Inverters, Converters, Controllers and Interconnection System Equipment for Use with Distributed Energy Resources 3) UL 2703: Mounting Systems, Mounting Devices, Clamping/Retention Devices, and Ground Lugs for Use with Flat-Plate Photovoltaic Modules and Panels 4) IEC 61439-1– Low-voltage switchgear and control gear assemblies – General Rules 5) IEC 61439-2– Low-voltage switchgear and control gear assemblies - Part 2: Power switchgear and control gear assemblies. 6) IEC 62548 – Photovoltaic (PV) arrays - Design requirements 7) IEC 62817 – Photovoltaic systems - Design qualification of solar trackers 8) IEC TR 63149 – Land usage photovoltaic (PV) farms – Mathematical models and calculation examples EARTHING 1) IEC 60364-5-54 for all LV installations; 2) IEC 60364-7-712 and IEC 62548 specifically for PV Systems; LIGHTNING 1) IEC 62305 - Lightning protection standard COMMUNICATION 1) IEEE-2030; Communication standard for Integrating Solar PV system to Distribution Network. SAFETY 1) NEC-Article 690: Safety standard for Installation of PV Systems. DISCLAIMER The listed standards are related only to the major solar PV equipment. Standards for other electrical components, such as transformers, switches, circuit breakers, switchgears, etc., shall follow the standards accepted and approved by Kahramaa in their regulations. Public Page 13 of 50 Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 5 Technical Requirements 5.1 General Requirements A solar PV System can be connected to Kahramaa Distribution Network, either LV or MV, at an appropriate point called Connection Point. It is the responsibility of Kahramaa to determine the appropriate Connection Point and assess the integration capacity of his network to host the connecting solar PV System at that point whilst maintaining a stable and reliable operation of the distribution network for all operating conditions. According to the Transmission Code, if the results of such process highlight that the connecting solar PV System is likely to cause the network to possibly operate outside of Kahramaa statutory performance standards, Kahramaa has the right to reject the connection application or to propose modifications (for example in terms of Connection Point and/or characteristics of the solar PV System) or alternative solutions (for example in terms of network reinforcements) to enable the connection. The Maximum Connected Capacity of the solar PV System to be proposed by the Customer will be determined in agreement with the specific clauses of Power and Water Purchase Agreement (PWPA) and Qatar Transmission Grid Code. 5.2 Connection Schemes A solar PV System shall comply with the connection requirements of Kahramaa, and especially shall meet the following requirements: The synchronisation, operation, and disconnection of the System under normal network operating conditions, i.e., in the absence of faults or malfunctions, shall bear no consequences to the power quality of the network as established in Section D2.6 of the Qatar Transmission Grid Code. The protection schemes and settings needed for the Solar PV System shall be coordinated with the distribution network protection. Kahramaa and the Customer (though his Consultant/Contractor) shall define the protection settings coordination with the following purpose: o Faults and malfunctions within the Solar PV System shall not impair the normal operation of Kahramaa distribution network. In particular, any faults that include earth faults with leakage current internal to the Customer’s installation will be detected and cleared below or at the connection point before any Kahramaa protection operates. o The protection schemes and settings for electrical faults within the Customer’s installation must not affect the performance of the Solar PV System. o The protection schemes of the Solar PV System shall be coordinated with those of the distribution network in order to operate properly in case of faults either within the Solar PV System or within the distribution network. To satisfy the above requirements, Figure 1 and Figure 2 present the typical equipment which shall be at least installed for a safe and reliable interconnection of a solar PV System to the LV and MV distribution network. Public Page 14 of 50 Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 Figure 1: Schematic representation for the connection of a Solar System to LV Distribution Network Public Page 15 of 50 Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 Figure 2: Schematic representation for the connection of a Solar PV System to MV Distribution Network The typical equipment in Figure 1 and Figure 2 are the following: The Main Circuit Breaker shall be installed as close as possible to the Connection Point and operated by a protection system in case of internal faults. If agreed with Kahramaa, it is possible to install more than one main circuit breaker in order, for example, to have two separate circuits, one dedicated to the Customer’s loads and one dedicated to the solar PV System. An example of this is given in Figure 13 in ANNEX A. Public Page 16 of 50 Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 The Interface Circuit Breaker, operated by an Interface Protection, shall be envisaged in the Customer installation to separate the portion of it containing one or more Solar PV Units from both the remaining part of the Customer’s installation containing only loads and Kahramaa distribution network. For Solar PV Systems whose power exceeds 20 kW, a Backup Circuit Breaker is necessary in case of failure on this circuit breaker opening. The Solar PV Unit Circuit Breaker shall be installed as electrically close as possible to the terminals of each Solar PV Unit for the protection and the connection/disconnection of that unit. For the protection issues, the recommendations and requirements of the manufacturer of the equipment shall apply. ANNEX A presents typical connection schemes that can be adopted to connect a Solar PV System to Kahramaa Distribution Network. Different arrangements may be used if previously agreed with Kahramaa. DISCLAIMER In case the nominal voltage of the inverters does not match the nominal voltage of the distribution Network, a transformer shall be necessary to connect either to the solar PV System or to each single Solar PV Unit. The cost of this transformer shall not for any reason be ascribed to Kahramaa and shall be entirely borne by the Customer. 5.3 Circuit Breakers Selection DISCLAIMER In this document and the Single Line Diagrams, the nomenclature, and symbols of the Kahramaa Electricity Wiring Code were used for the protection/disconnection (under normal and fault conditions) and insulation of the PV Systems. These circuit breakers are just indicative and, for that reason, shall be carefully considered by the Consultants during their design according to the specific case and need. These circuit breakers cannot be directly applied or copied by the Consultant without conducting a technical assessment for the specific PV System they are designing. They have to be replaced by the proper symbol and disconnection device following what is established in Kahramaa’s Electricity Wiring Code. This circuit breaker and its corresponding symbol, shall be replaced by the proper device as per the Electricity Wiring Code, depending on choices made by the PV System designer (Consultant / Contractor). For each of the circuit breakers mentioned above, the choice of the type to be installed shall be based on: The functions the circuit breaker shall carry out. The characteristics of the Customer’s installation. The characteristics of Kahramaa Distribution Network at the Customer’s Connection Point. Especially, the following criteria shall be adopted: The circuit breakers, panels and switchgear shall be compliant with the requirements of the Transmission Code, The circuit breaker(s) of the Solar PV Unit(s) shall be compliant with the Manufacturer's requirements, Public Page 17 of 50 Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 Electronic switches shall not be used for protective (overcurrent & Earth) functions. For Solar PV Systems connected to the MV Distribution Network and with the Interface Circuit Breaker on the MV side of the plant (see Figure 17 in ANNEX A), the Interface Circuit Breaker shall be a three-pole automatic circuit breaker operated by an undervoltage release along with an isolator (either upstream or downstream of the circuit breaker). The above requirement shall be incorporated into the standard type of panels for MV applications approved by Kahramaa. o Considering the requirement for solar/distributed generation, a new standard type of Switchgear panel shall be designed. In the case of MV panels, a dedicated panel type shall be proposed by the Consultant/Contractor with the required protection & control functions to use for such applications. The consensus to the reclosure of the Interface Circuit Breaker shall be given by the Interface Protection itself, which has then to sense the voltages on the network side (as represented in the Connection Schemes, Figure 16 and Figure 17) and not on the Solar PV System side of the Interface Circuit Breaker. For Solar PV Systems connected to the MV Distribution Network and with the Interface Circuit Breaker on the LV side of the plant (see Figure 16 in ANNEX A) or for Solar PV Systems connected to the LV distribution network (see schemes from Figure 11 to Figure 15 in ANNEX A), the Interface Circuit Breaker shall consist of motorised automatic switch to allow automatic reclosure once the network disturbances that have led to the trip of the Interface Protection have been cleared. The consensus to reclosure of the Interface Circuit Breaker shall be given by the Interface Protection itself, which has then to sense the voltages on the network side (as represented in the Connection Schemes, from Figure 11 to Figure 15) and not on the Solar PV System side of the Interface Circuit Breaker. Any circuit breaker shall have a breaking and making capacity coordinated with the rated values of the Customer’s installation, considering both the generating plant and the contribution to the short circuit from the Distribution Network. The short time withstand-current of the switching devices shall be coordinated with the maximum short circuit current/power at the Connection Point1. In case of loss of auxiliary supply power to the switchgear, a secure disconnection of the Interface Circuit Breaker is required immediately. The function of the Interface Circuit Breaker can be combined with either the Main Circuit Breaker or the Solar PV Unit Circuit Breaker in a single switching device2. In case of a combination of these, the single combined switching device shall be compliant with both the requirements of the Interface Circuit Breaker and of either the Main Circuit Breaker or PV Unit Circuit Breaker, according to the combination chosen. Consequently, at least two circuit breakers in series shall always be present between a solar PV Unit and the Connection Point. For further details, please refer to the indicative Connection Schemes in ANNEX A. 1Kahramaa shall deliver to the Demand Facility Owner an estimate of the minimum and maximum short-circuit currents to be expected at the Delivery Point as an equivalent of the network. 2For connection schemes using a single main switch, the combination of the interface switch with the main switch will lead to the disconnection of the overall Customer’s facility when the interface switch is opened, that is a lack of supply will also affect the Customer load. Public Page 18 of 50 Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 5.4 Protection against Faults The electrical protections required for connecting a Solar PV System to Kahramaa Distribution Network are also of concern in the present document. These additional protections shall be checked and approved by Kahramaa. Other protections shall also be installed to protect the Customer’s electrical assets as per Kahramaa protection policy. All protections shall be graded and coordinated with Kahramaa upstream protections and downstream protections within the solar installation. Any faults down to the Connection Point shall be cleared at the same point or below without impacting Kahramaa distribution network. Where overcurrent and earth protection is required for the safety of the equipment, whether this be part of the Solar PV System or not, automatic disconnection of the faulted circuit shall be accomplished. The Customer shall comply with the relevant Kahramaa material standards & specifications and the applicable requirements and specifications of the latest issue of Kahramaa Protection Guidelines/Standard ET-P26-G1 (Guidelines for Protection/Energy meter requirements for Power supply to Bulk Customers). Deviation (if any) from the standard shall notify Kahramaa for reviewing and approval at the initial stage of the project itself. The Customer shall provide required new protection or modify existing protection of the Kahramaa interfacing bays. The Customer shall agree with Kahramaa on protection schemes and settings relevant to the Demand Facility. Kahramaa will review the Connection Equipment protection scheme and settings. The protection and settings of all other equipment and circuits in the Demand Facility are under the responsibility of Demand Facility Owners. Protection schemes and devices shall cover the following events and equipment: 1. External and internal short-circuits 2. Over- and under-voltage at the Delivery Point to the ETN 3. Over- and under-frequency 4. Demand circuit (cable/line) 5. Transformer 6. Switchgear malfunction 7. Circuit Breaker failure 8. Busbar Customer shall provide Protections as mandatory for interfacing bay at both ends and the required modifications to match the local end of Kahramaa Substations’ remote end. The protection document required by Kahramaa at each stage of the project shall be submitted to Kahramaa for review/approval/record. Electrical protection of the Customer’s Facility shall take precedence over operational controls while respecting system Security, health and safety of the staff and public. Kahramaa and the Customer shall agree on any changes to the agreed protection schemes. The maintenance of all protection equipment at the premises of the Demand Facility, including those of Connection equipment, is the Customer’s responsibility in coordination with Kahramaa, as applicable. Public Page 19 of 50 Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 The Customer shall comply with Kahramaa Interlocking requirements and test such interlocking in Kahramaa’s engineer presence. 5.5 Operating Ranges A Solar PV System shall be capable of remaining connected to the Distribution Network and operating stably, as specified in this document. The frequency and voltage ranges for the time periods specified in the tables below should be as per Qatar Transmission Grid Code, paragraphs E.4.1 and E.4.2, regardless of the type and settings of the protection systems. Table 1: Frequency operating range Time periods for Frequency ranges operation 47.5 Hz – 49.5 Hz Maximum 30 min 49.5 Hz – 50.5 Hz Unlimited 50.5 Hz – 51.5 Hz Maximum 30 min After 30 minutes of over frequency, the Generating Facility operator must consult the NCC to continue operation. Table 2: Voltage operating range Time period for Voltage Level (1 pu) Voltage range operation 11 kV – 33kV (limited to 0.85 pu - 0.90 pu Maximum 30 min 33 kV as per this 0.9 pu – 1.1 pu Unlimited document scope) 1.1 pu - 1.15 pu Maximum 30 min The following figure defines the profiles of the periods of time for limited and unlimited operation according to the above tables. The Generating Units shall be capable of remaining connected to the Distribution Network in the event of simultaneous overvoltage and under-frequency or simultaneous under-voltage and over-frequency. In case of deviation of the Voltage at the Connection Point from its nominal voltage, the PV Unit shall be disconnected from the network with a delay consistent with settings indicated in Annex B. The voltage values for points A and B shall be agreed upon between the Generating Facility Owner and Kahramaa: Public Page 20 of 50 Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 Figure 3: Simultaneous UF profile 5.6 Immunity to Disturbances 5.6.1 Low Voltage Ride Through (LVRT) Capability Solar PV Systems shall contribute to the stability of the overall power system by providing immunity toward dynamic voltage changes, especially those due to faults on the higher voltage level networks. The requirements below apply to all kinds of disturbances (1ph, 2ph and 3ph faults) and are independent of the Interface Protection settings (see 5.9.4), which overrule the technical capabilities of a Solar PV System. Therefore, whether the Solar PV System will stay connected or not will also depend on the settings of the Interface Protection. A Solar PV System with a Maximum Connected Capacity greater than 11 kW shall be capable of staying connected to the distribution network as long as the voltage at the Connection Point remains above the voltage-time diagram in Figure 4. The minimum voltage during the fault shall be 5% of the rated voltage. The p.u. voltage shall be calculated with respect to the nominal voltage at the Connection Point. For three-phase generating systems, the smallest phase-to-phase voltage shall be evaluated. The compliance to such LVRT requirements shall apply to all equipment that might cause the disconnection of the solar PV System, i.e., Inverters and Interface Protection. After the fault is cleared and the voltage returned within the normal operating range (see 7.5), the pre-disturbance operating conditions (active & reactive power) shall be recovered as fast as possible with a tolerance of ±10% of the solar PV System rated power. Public Page 21 of 50 Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 Figure 4: LVRT characteristic for solar PV System > 11 kW 5.6.2 ROCOF Withstand Capability The solar PV Systems, when generating power, shall be able to go through frequency transients with frequency within the normal operating range (see 5.5) and with ROCOF value up to 2.5 Hz/s 3. In the case that the Loss of Mains (LOM) protection implements a ROCOF-based method (as described in 5.9.4), the threshold of the LOM function shall not cause the intervention of the protection within the immunity ranges as specified in this paragraph. 5.7 Requirements for the Frequency Stability of the Power System 5.7.1 Active Power Response to Frequency Variations A solar PV System shall be capable of activating the provision of active power response to over-frequency transients according to the curve of Figure 5, with frequency threshold and droop settings adjustable and specified by Kahramaa. The frequency threshold shall be settable at least between 50 Hz and 52 Hz inclusive; if not differently specified by Kahramaa, the threshold shall be set to 50.5 Hz. In case of deviation of the network frequency above 51.5 Hz, the Solar PV System shall disconnect from the Transmission Network. In case of deviation of the Network frequency from its nominal value below 47.5Hz, the PV System shall be disconnected from the network. The generated active power Pgen shall be referred to as the actual active power value Pact when the threshold is reached, and the active power response is activated. The Generating Units shall be capable of activating the provision of active power frequency response according to Figure D.2-2 of the Transmission Grid Code at a 3 It is recommended to measure the ROCOF over a sliding 500ms time period. Public Page 22 of 50 Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 frequency threshold between 50.2 Hz and 50.5 Hz inclusive and Droop settings between 2 % and 12 % specified by Kahramaa. The settings of the disconnection protection (threshold, time delay of the tripping) shall be agreed upon with Kahramaa. The Slope of the decreasing ramp and the frequency where the power shall decrease may be modified by Kahramaa. The resolution of the frequency measurement shall be ±10mHz or less. The active power response shall be activated as fast as possible and delivered with an accuracy of ±10% of the nominal power. Figure 5: Active power frequency response for solar PV System 5.7.2 Active power delivery at under-frequencies When a solar PV System works in under-frequency operating conditions due to the Distribution Network, the reduction of the maximum active power shall be kept as low as technically feasible; in any case, any decrease of the maximum reachable active power output shall be kept above the curve of Figure 6. Public Page 23 of 50 Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 Figure 6: Maximum permissible output power reduction at under- frequencies 5.7.3 Remote Limitation of Active Power A solar PV System with a Maximum Connected Capacity greater than 11 kW shall be equipped with an interface (input port) that is able to receive, from a remote-control centre, an instruction requiring the reduction of the active power output. The reduction of active power shall be carried out as fast as possible and with an accuracy greater than 5% of the nominal active power of the Solar PV System. Kahramaa shall have the right to specify further requirements in terms of equipment, communication protocol, information to be exchanged and/or time of execution, which allow integration of such features into the control systems of its Distribution Network and which allow to remotely limit the active power output of the solar PV Units connected to its network. 5.8 Requirements for the Voltage Stability of the Power System Requirements as per Transmission Grid Code, par. D.3.4 shall apply. 5.8.1 Reactive Power Capability When voltage and frequency at the Connection Point are within their normal operating ranges, a solar PV System shall be able to provide reactive power in any operating point within the boundaries of the reactive power capability curves defined in Figure 74. 4 The active power 1 p.u. shall refer to the nominal active power value of the Solar PV System: at 1 p.u. of active power, the reactive power capability of a Solar PV System corresponds to a power factor varying between 0.95 leading (inductive reactive power absorbed) to 0.95 lagging (inductive reactive power generated). Public Page 24 of 50 Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 According to this capability, the inverters will either generate or absorb inductive reactive power from the Distribution Network to participate in voltage support at the Connection Point for any of the values of active power generated by the Solar PV System. Three areas are visible in Figure 7: - Triangular area, required for inverters included in Solar PV Systems whose Maximum Connected Capacity is smaller than or equal to 11 kW: for an active power ranging from zero to the nominal power of the Solar PV System (i.e., 1 p.u.), the Inverter shall be capable of either generating or absorbing inductive reactive power Q at a power factor cos of 0.95 (boundary points of the triangular curve in the chart); - Rectangular area required for inverters included in Solar PV Systems whose Maximum Connected Capacity is greater than 11 kW: these shall be capable of either generating or absorbing inductive reactive power Q within the area. For a value of 1 p.u. of active power, that is, when the generated power is equal to nominal power, this corresponds to a power factor cos of 0.95 (apex points of the rectangular area for P = 1 p.u.); - Design free area which can be optionally exploited by the Inverter Manufacturers. Concerning Figure 7 and Figure 8, when the solar PV System operates in the design- free area (i.e., above its nominal active power because of favourable environmental conditions), it is allowed to reduce the reactive power capability according to the widest possible technical capability of the Solar PV Units. When the solar PV System operates above a threshold of 10 % of its nominal apparent power Sn, the required reactive power Q shall be provided with an accuracy of ±2% Sn. Below the threshold of 10% of Sn, deviations above 2% of accuracy are permissible; nevertheless, the accuracy shall always be as good as technically feasible and shall not exceed 10% of Sn. Figure 7: Reactive power capability For LV connection Public Page 25 of 50 Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 Figure 8: Reactive power capability For MV connection 5.8.2 Reactive Power Control Modes A solar PV System shall be capable of operating in the control modes stated below, within the limits of its reactive power capability as expressed in 5.8.1: fixed Q: the reactive power is controlled to obtain a fixed value. fixed cos φ: the reactive power is controlled to obtain a fixed power factor. cos φ (P): the reactive power is controlled to obtain a power factor that is a function of the actual active power delivery. Q = f(V): the reactive power is controlled as a function of the local voltage, according to a characteristic curve. The above control modes are exclusive; only one mode may be active at a time. The control modes’ activation, deactivation, and configuration shall be field adjustable. It is the responsibility of Kahramaa to communicate to the Solar PV System’s owner which of the above-mentioned reactive power control mode shall be activated. 5.8.2.1 Fixed Control Modes When operated with fixed Q or fixed cos φ control mode, the solar PV Unit shall control the reactive power or the cos φ of its output according to a set point set in the control system of the solar PV System. If not explicitly specified by Kahramaa, the default setpoint values shall be 0 for fixed Q control mode and 1 for fixed cos φ control mode. For a solar PV System with a Maximum Connected Capacity greater than 11 kW, the Solar PV System shall also be able to receive remotely from Kahramaa control centre, the set-point following the provisions set forth in 5.9.5. 5.8.2.2 Power Related Control Mode The Power Related Control Mode cos φ (P) controls the cos φ of the output as a function of the active power output. A characteristic with a minimum and maximum Public Page 26 of 50 Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 value and three connected lines, according to Figure 9, shall be configurable within the control systems of the solar PV System; a change in active power output results in a new cos φ set point according to the characteristic. The parameters A, B, C and D shall be field adjustable, and their settings are the responsibility of Kahramaa. If not explicitly specified by Kahramaa, these parameters shall be set as indicated below: A P = 0 Pnom cos  = 1 B P = 0.5 Pnom cos  = 1 C P = Pnom cos  = 0.95 Lag (with the solar PV System absorbing reactive power from the Distribution Network) D P = Pnom cos  = 0.95 Lead (with the solar PV System injecting reactive power towards the Distribution Network) where Pnom is the active nominal power of the Solar PV Unit. The response to a new cos φ set point value shall be as fast as technically feasible after the new value of the active power is reached. The accuracy of the control to each set point shall be in accordance with the requirements of 5.8.1. Figure 9: Characteristic for Cos  (P) control mode The implementation of lock-in and lock-out voltage levels shall be configurable, each in the range of 90% to 110% of the nominal voltage at the Connection Point. The contribution is activated when the voltage at the Connection Point exceeds the lock-in voltage and is deactivated when the voltage drops below the lock-out voltage. When the contribution is not activated, the solar PV System shall be controlled with a unity power factor (cos  = 1). 5.8.2.3 Reactive Power Support as a Function of the Voltage Q(V) For solar PV Systems with a Maximum Connected Capacity greater than 11 kW, for such control mode, a characteristic with a minimum and maximum reactive power value and three connecting lines, according to Figure 10: shall be configurable. Public Page 27 of 50 Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 It is Kahramaa's responsibility to communicate the parameters to be configured in case this support is required from Solar PV Systems. The values shall be assigned with the following criteria; therefore, the parameter ranges available in the Inverter shall not limit this setting: Qmax and –Qmax correspond to the capability curve boundaries as per Figure 10 (e.g., 0.33 Pnom, where Pnom is the nominal power of the Solar PV Unit) V1 > threshold of Interface Protection V2 < Vnom < V3 Possible default values can be the following unless differently agreed with Kahramaa: V1 = 0.9 Vnom V4 = 1.1 Vnom V2 = 0.95 Vnom, V3 = 1.05 Vnom where Vnom is the nominal Voltage at the Connection Point. Figure 10: Characteristic for Q(V) control mode 5.8.3 Power Reduction at Increasing Voltage In order to avoid disconnection due to overvoltage protection, a solar PV System is allowed to reduce its power output (active and/or reactive power) as a function of the rising voltage at the Connection Point. The implemented logic can be chosen by the Manufacturer/Customer. Nevertheless, the implemented logic shall not cause steps or oscillations in the system's power output. Public Page 28 of 50 Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 5.9 Requirements for the Management of the Power System 5.9.1 Connection Conditions after Programmed Disconnection A solar PV System is allowed to be connected to the network and to start to generate electrical power due to normal operational start-up when the voltage and frequency are within the following range for at least the observation time: Frequency range 49.5 Hz ≤ Frequency ≤ 50.05 Hz. Voltage range 90% Vnom ≤ Voltage ≤ 110% Vnom (Vnom= nominal voltage at the Connection Point). Minimum observation time 30s. Synchronising a solar PV System with the distribution network shall be fully automatic. It shall not be possible to manually close the circuit breaker between the two systems to carry out the synchronisation5. The synchronisation of a Solar PV System to the distribution network shall not create a transient voltage variation at the Connection Point of more than 4% of nominal voltage. After the connection, a Solar PV System shall follow its target active power value with a variable rate not greater than 10% Pnom/min, where Pnom is the nominal active power of the Solar PV System. The active power target shall be the maximum available active power output that the Solar PV System can generate, taking into account the environmental conditions (irradiation, temperature), except for the operating conditions when the power output shall follow changes due to the provision of some of the services specified in this document (see sections 5.7.1, 5.7.3 and 5.8.3). 5.9.2 Remote Disconnection A solar PV System with a Maximum Connected Capacity greater than 100 kW shall be equipped with a logic interface (input port) in order to perform remote disconnection. According to the provisions set forth in 5.9.5, Kahramaa shall have the right to specify further requirements in terms of equipment, time of execution, communication protocol and/or data to be exchanged to integrate such features into the control systems of its distribution network and to allow the remote disconnection of the solar PV Systems connected to its network. 5.9.3 Automatic Reconnection after Tripping After the trip of the Interface Protection, a solar PV System is allowed to reconnect to the network only if the voltage and frequency are within the following range for at least the observation time: Frequency range 49.5 Hz ≤ Frequency ≤ 50.05 Hz. Voltage range 90% Vnom ≤ Voltage ≤ 110% Vnom (Vnom= nominal voltage at the Connection Point). Minimum observation time 300s. 5 It means that the switch used for the synchronization with the network cannot be a manual switch. Public Page 29 of 50 Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 After reconnection, the solar PV System shall return to its target active power value with a variation rate not greater than 10% Pnom/min, where Pnom is the nominal active power of the Solar PV System. 5.9.4 Interface Protection The purpose of the Interface Protection is to: Disconnect the solar PV System from the Distribution Network in the following cases: o When the Distribution Network (or the feeder) where the Solar PV System is connected has to de-energise from the main supply source, the de- energisation can happen automatically due to protection system operation or manual/electrical disconnection. Electrical/manual disconnection in the Distribution Network can happen remotely by Kahramaa SCADA system or by local switching. o The voltage and/or frequency values at the Connection Point are out of the normal operating ranges as defined in 5.5. Prevent the solar PV System, when generating power, from causing over- voltages in the distribution network it is connected to. The voltage and nominal frequency of the power grid to be considered as a reference for all the protection functions are: - Rated Voltage: (240-415) V in LV side - Rated Frequency: 50 Hz It is not the purpose of the Interface Protection to: Disconnect the Solar PV System from the Distribution Network in case of faults within the Customer’s installation. For such issues, the requirements for the connection of passive Customers shall apply (refer to Transmission Code). Prevent damages to the Customer’s equipment (generating units or loads) due to faults/incidents (e.g., short circuits) in the Distribution Network or on the Customer’s installation. For such issues, the recommendations and requirements of the equipment manufacturers shall apply. The Interface Protection shall be a dedicated device that acts on the Interface Circuit Breaker. For a solar PV System with a Maximum Connected Capacity smaller than or equal to 11 kW, it is permitted to integrate both the Interface Protection and the Interface Circuit Breaker into the Inverter (see, for example, Figure 11 in ANNEX A). The use of inverter-integrated Interface Protection for capacities above 11 kW can be decided by Kahramaa on a case-by-case basis. The Interface Protection shall command the Interface Circuit Breaker. For a solar PV System with a Maximum Connected Capacity greater than 11 kW, unless explicitly agreed by Kahramaa, only one Interface Protection and one Interface Circuit Breaker shall be used. For a solar PV System with a Maximum Connected Capacity greater than 20 kW, the Interface Protection shall additionally act on another circuit breaker (Backup Circuit Breaker) with a proper delay in case the Interface Circuit Breaker fails to operate (see, for example, Figure 15 in ANNEX A). The Backup Circuit Breaker may consist of a Public Page 30 of 50 Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 dedicated circuit breaker or an already existing one6. Only manual reclosure shall be possible when the Backup Circuit Breaker is triggered because the Interface Circuit Breaker has failed to open7. For a solar PV System with a Maximum Connected Capacity greater than 11 kW, the power supply of the Interface Protection shall include an uninterruptible power supply. The loss of the auxiliary voltage on either the Interface Protection or on the Solar PV System’s control system shall trigger the Interface Circuit Breaker without delay. The protection functions required in the Interface Protection are the following: Undervoltage o One threshold in the range [100%; 130%] of the nominal voltage at the Connection Point adjustable by steps of 1%, and delay time in the range [0.1s; 5s] adjustable in steps of 0.05s. Over frequency [81>] o One threshold [81>] in the range [50Hz; 53Hz] adjustable by steps of 0.1Hz, and delay time in the range [0.1s; 100s] adjustable in steps of 0.1s. o One threshold [81>>] in the range [50Hz; 53Hz] adjustable by steps of 0.1Hz, and delay time in the range [0.1s;5s] adjustable in steps of 0.05s. Underfrequency [81 11 kW and ≤ 20 kW Multiple Solar PV Units with external and unique Interface Protection Figure 15 LV > 20 kW and ≤ 1.6 MW Multiple Solar PV Units with external and unique Interface Protection. Backup Circuit Breaker is required. Solar PV System Meter required if Maximum Connected Capacity of the Solar PV System > 100 kW Figure 16 MV ≥ 100 kW and ≤ 1.6 MW Multiple Solar PV Units with external and unique Interface Protection. Interface Protection on the LV side. Backup Circuit Breaker is required. Solar PV System Meter required if Maximum Connected Capacity of the Solar PV System > 100 kW Figure 17 MV ≥ 100 kW and ≤ 25 MW Multiple Solar PV Units with external and unique Interface Protection. Interface Protection on the MV side. Backup Circuit Breaker required. Public Page 39 of 50 Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 Distribution Maximum Connected Figure Network Capacity of the solar Notes (LV/MV) PV System Solar PV System Meter required if Maximum Connected Capacity of the Solar PV System > 100 kW The meaning of the symbols and codes used in the single line diagrams is explained hereinafter: ANSI CODES FOR PROTECTIONS 27 UNDERVOLTAGE PROTECTION 59 OVERVOLTAGE PROTECTION UNDERFREQUENCY (81) PROTECTION LOM LOSS OF MAINS PROTECTION INSTANTANEOUS OVERCURRENT 50 PROTECTION 51 IDMTL OVERCURRENT PROTECTION 50N/51N EARTH FAULT CURRENT PROTECTION Public Page 40 of 50 Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 NOTES: (1) Automatic Circuit Breaker (2) Automatic Circuit Breaker with: Overload Protection Short Circuit Protection Protection against electric shock (RCD) Figure 11: Indicative Scheme for LV Connection– Solar PV System with Maximum Connected Capacity  11 kW Public Page 41 of 50 Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 NOTES: (1) Automatic Circuit Breaker (2) Motorized Automatic Circuit Breaker (3) LOM protection is not required if it is integrated into the Inverter (4) Auxiliary power supply from a UPS Figure 12: Indicative Scheme for LV Connection– solar PV System with Maximum Connected Capacity > 11 kW and  20 kW – External Interface Protection Public Page 42 of 50 Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 NOTES: (1) Automatic Circuit Breaker with: Overload Protection Short Circuit Protection Protection against electric shock (RCD) (2) Motorized Automatic Circuit Breaker (3) LOM protection is not required if it is integrated into the Inverter (4) Auxiliary power supply from a UPS Figure 13: Indicative Scheme for LV Connection– Case of Two (or more) Main Circuit Breakers in absence of one general Main Circuit Breaker in the incomer from Kahramaa (case as per Figure 11 shown, but this applies to both schemes of Figure 11 and Figure 12) Public Page 43 of 50 Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 NOTES: (1) Automatic Circuit Breaker (2) Motorized Automatic Circuit Breaker with: Overload Protection Short Circuit Protection Protection against electric shock (RCD) (3) LOM protection is not required if it is integrated into the Inverter (4) Auxiliary power supply from a UPS (5) Automatic Circuit Breaker Figure 14: Indicative Scheme for LV Connection– solar PV System with Maximum Connected Capacity > 11 kW and  20 kW – Multiple Solar PV Units with external and unique Interface Protection Public Page 44 of 50 Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 NOTES: (1) Automatic Circuit Breaker with: Overload Protection, Short Circuit Protection against electric shock (RCD) (2) Motorized Automatic Circuit Breaker (3) LOM protection is not required if integrated into the Inverter (4) Auxiliary power supply from a UPS (5) Automatic Circuit Breaker (6) Second meter to be supplied by Kahramaa for Pnom > 100 kW Figure 15: Indicative Scheme for LV Connection– solar PV System with Maximum Connected Capacity > 20 kW and ≤ 1.6 MW – Multiple Solar PV Units with external and unique Interface Protection; Backup Circuit Breaker; Solar PV System Meter (only if Nominal Power of the Solar PV System > 100 kW) Public Page 45 of 50 Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 Figure 16: Indicative Scheme for MV Connection - Interface Protection on the LV side solar PV System with Maximum Connected Capacity > 100 kW – Multiple Solar PV Units with external and unique Interface Protection on the LV side; Backup Circuit Breaker; Solar PV System Meter (only if Nominal Power of the Solar PV System > 100 kW) Public Page 46 of 50 Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 NOTES: (1) Motorized Automatic Circuit Breaker with Overload Protection (51), Phase Protection (50), Earth Protection (51N) (2) Automatic Circuit Breaker with Overload Protection, Short Circuit Protection against electric shock (RCD) (3) LOM is not required if integrated into the Inverter (4) Auxiliary power supply from a UPS (5) Automatic Circuit Breaker (6) Second meter to be supplied by Kahramaa for Pnom > 100 kW Figure 17: Indicative Scheme for MV Connection– Interface Protection on the MV side solar PV System with Maximum Connected Capacity > 100 kW – Multiple Solar PV Units with external and unique Interface Protection on the MV side; Backup Circuit Breaker; Solar PV System Meter (only if Maximum Connected Capacity of the Solar PV System > 100 kW) Public Page 47 of 50 Technical Specification for the Connection of PV System to Network EP-EPP-P7-S1 ANNEX B. Default Settings of Interface Protection The following table reports the default settings to be implemented in the Interface Protection of solar PV Systems when Kahramaa has communicated no other settings. Table 5: Default settings for the protection functions of the IP Protection Settings function Threshold Time delay 27< 90% Nominal Voltage 3s 27 110% Nominal Voltage 3s 59>> 120% Nominal Voltage 0.2 s 81>> 52.5 Hz 0.1 s 81< 47.5 Hz 4s 81