EP-EPP-P7-S1 Technical Specifications for PV Systems Connection PDF

# EP-EPP-P7-S1 Technical Specifications for the Connection of PV Systems to the Network ## 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 K...

# EP-EPP-P7-S1 Technical Specifications for the Connection of PV Systems to the Network ## 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 | | 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 | | 5.9.8.1 Voltage Deviation | 34 | | 5.9.8.2 Rapid Voltage Changes | 34 | | 5.9.8.3 Harmonic and Interharmonic Voltages | 34 | | 5.9.8.4 DC Injection | 35 | | 5.9.8.5 Clusters of Single-phase / Two-phase Solar PV Generating Units | 35 | | 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 | ## 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: - Requirements for the equipment used to interconnect a solar PV System with the distribution network. - Requirements to support the frequency and voltage stability of the power system when it is subject to disturbances. - Requirements for the start-up, operation and disconnection of the solar PV Systems. - 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. - 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. 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: - 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. - 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. - Do not exceed the authorised Maximum Connected Capacity for exporting to the Kahramaa network. - Cooperate with Kahramaa staff in all matters related to exporting electricity to Kahramaa network. - To bear all the costs associated with the connection of his solar PV System to Kahramaa network. - 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. - 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. - 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** | Abbreviation | Description | |---|---| | cos p | Power factor | | LOM | Loss of Mains | | LVRT | Low Voltage Ride Through | | NCC | National Control Centre | | Pnom | Nominal active power of equipment | | PV | (Solar) Photovoltaic | | ROCOF | Rate of Change of Frequency expressed in Hz/s | | Sn | Nominal Apparent Power | | Vnom | Nominal Voltage | | IP | Interface Protection | | LV | Low Voltage | | MV | Medium Voltage (namely 11 kV or 22 kV) | | P | Active power | | pu | per unit | | Q | Reactive Power | | S | Apparent Power | | V | 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 Por 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 an Inverter | The rated apparent power of an Inverter is the product of the rms voltage and current and is expressed in kVA or MVA. | | Auxiliary Supply Power | Electricity supply for supporting auxiliary systems and services such as Interface Protection or circuit breaker and contactor opening coils. | | Circuit Breaker (CB) | As per the Kahramaa Electricity and Wiring Code definition | | 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 protection relay) | Indicates the minimum duration of a fault detected by the 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 / Distribution Network | Qatar electrical infrastructure (lines, cables, substations, etc.) at 33 kV and below, operated by Kahramaa. The Distribution network can be either a 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 Transmission Network (ETN) | Qatar electrical infrastructure (lines, cables, substations, etc.) from above 33 kV up to 400 kV operated by Kahramaa. | | Interface protection (IP) | Electrical protection part of the solar PV System that ensures the PV System 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 (LOM) | Represents an operating condition in which a distribution network, or part of 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. | ## 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. 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. 3. IEC 62477-2 – Safety requirements for power electronic converter systems and equipment - Part 2: Power electronic converters from 1000 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. ## 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: - 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. - The protection schemes and settings for electrical faults within the Customer's installation must not affect the performance of the Solar PV System. - 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. - 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. - 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, - 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. - 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. 1 Kahramaa 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. 2 For 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. ### 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 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. 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. | Frequency ranges | Time periods for 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. | Voltage Level (1 pu) | Voltage range | Time period for operation | |---|---|---| | 11 kV-33kV (limited to 33 kV as per this document scope) | 0.85 pu - 0.90 pu | Maximum 30 min | | | 0.9 pu 1.1 pu | Unlimited | | | 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