Introduction-Operation and Control of Power Systems PDF

Operation and Control of Power Systems INTRODUCTION Dr Zayed Huneiti  Textbooks Allen J. Wood, Bruce F. Wollenberg, Gerald B. Sheblé, Power Generation Operation and Control, John Wiley and Sons, 3rd edition, 2013. S. Sivanagaraju, G. Sreenivasan, Po...

Operation and Control of Power Systems INTRODUCTION Dr Zayed Huneiti  Textbooks Allen J. Wood, Bruce F. Wollenberg, Gerald B. Sheblé, Power Generation Operation and Control, John Wiley and Sons, 3rd edition, 2013. S. Sivanagaraju, G. Sreenivasan, Power System Operation and Control, Pearson Education, 2010.  Course Instructions The objective is to provide you with a learning environment in which you will learn the essential theories and principles of the operation and control of power systems. The approach is to encourage each student to learn how to learn. To take possession of the learning process: Initiative, involvement, interactive participation are the keys to an effective learning experience. I expect you to inform me if I have not been successful in achieving this goal. Do not wait until exam time to express your frustrations. I am ready to listen to your concerns or difficulties with the material, and am always available to help inside and outside the lecture. Please do not expect me to pass you or give marks for nothing.  Introduction What is a power system?  A Power System: A Power System is the interconnection/network or combination of all components that are used in the generation, transmission and distribution of electricity to consumers. A Power System  Overview of power systems Consists of three major subsystems Generation subsystem Transmission subsystem Electrical Power System Consume r Distributio n Transmissio Generation n Electrical Power Generation  Power Systems Power systems are responsible for generating electrical power, transmitting this power and then distributing it to customers at voltage levels and reliability that are appropriate to various users.  Simple Power System Every large-scale power system has three major components: – generation: source of power, ideally with a specified voltage and frequency – load or demand: consumes power; ideally with a constant resistive value – transmission system: transmits power; ideally as a perfect conductor Additional components include: 11 – distribution system: local reticulation of power (may be in place of transmission system in case of  System Layout Different Technologies Generation Extra High Voltage Transmission Distribution Medium and Low voltage Customer Service Different Requirements  Complications No ideal voltage sources exist. Loads are seldom constant and are typically not entirely resistive. Transmission system has resistance, inductance, capacitance and flow limitations. Simple system has no redundancy so power system will not work if any component fails. 13  An overview of electrical supply and services from power generation to its distribution and consumption  Overview What is a Power System? Power system includes all parts of an electric system power sources and customers. What is the function of the system? The Function of the system is to generate power , transmit this power and to distribute it to customers at voltage levels and reliability that are appropriate to various users.  System Components What are the main component of a power system? Generation plants HV Substations Transmission Lines Bulk power Substations Distribution system  Voltage levels Generation: 1kV-30 kV EHV Transmission: 500kV-765kV HV Transmission: 230kV-345kV Sub-transmission system: 69kV-169kV Distribution system: 120V-35kV  Overview Power plants convert the energy stored in the fuel or hydro into electric energy. The energy is supplied through step-up transformers to the electric network. Power systems are comprised of 3 basic electrical subsystems. Generation subsystem Transmission subsystem Distribution subsystem High Voltage Network  High Voltage Network High-voltage networks, consist of transmission lines, connects the power plants and high-voltage substations in parallel. This network permits load sharing among power plants The typical voltage of the network is between 240 and 700 kV. The high-voltage substations are located near the load centers. High Voltage Network  Sub-transmission Network The sub-transmission system connects the high- voltage substations to the distribution substations. The typical voltage of the sub-transmission system is between 138 and 69 kV. In high load density areas, the sub-transmission system uses a network configuration that is similar to the high voltage network. In medium and low load density areas, the loop or radial connection is used.  Distribution Network The distribution system has two parts, primary and secondary. The primary distribution system consists of overhead lines or underground cables, which are called feeders. The feeders supply the distribution transformers that step the voltage down to the secondary level. The secondary distribution system contains overhead lines or underground cables supplying the consumers directly by single- or three-phase power.  Today’s Electrical Power System Today’s electric power systems are large and complex networks of interconnected electrical equipment and circuits, stretching over thousands of kilometers and deliver electricity to hundreds of millions of consumers. In any power system generators are located at few selected points and loads are distributed throughout the network. The electrical load keeps changing from time to time. Properly designed power system should have the following characteristics:  Characteristics of a Properly Designed Power System A Properly designed power system should have the following characteristics: 1. It must supply power, wherever and whenever the customer demands. 2. It must be able to supply the ever changing load demand. 3. The power supplied should be of good quality and high reliability. 4. The power supplied should be most economical.  Quality of the power supply The delivered power must meet certain minimum requirements with regards to the quality of the supply. The following determine the quality of the power supply. i. The system frequency must be kept around the specified 50 Hz with a variation of ± 0.05 Hz. ii. The magnitude of bus voltages are maintained within narrow prescribed limits around the normal value. Generally voltage variation should be limited to ± 5%. Voltage and frequency controls are necessary for the effective operation of power systems. The frequency is a common parameter throughout the power system Frequency Balancing of Power System Frequency Balancing of Power System Frequency Balancing of Power System Frequency Balancing of Power System  Frequency Fluctuations Frequency fluctuations are detrimental to electrical appliances. The following are some reasons why frequency deviations should be kept strictly limited. Three phase AC motors run at speeds that are directly proportional to the frequency. Variation of system frequency will affect the motor performance. The blades of steam and water turbines are designed to operate at a particular speed. Frequency variations will cause change in speed. This will result in excessive vibration  Effect of Over and Under Voltage Both over voltage and under voltage are detrimental to electrical appliances. Electric motors will tend to run on over speed when they are fed with higher voltages. Over voltage may cause insulation failure, vibration and mechanical damage. For a specified power rating, when the supply voltage is less, the current drawn is more and it will give rise to heating problems. Therefore it is essential to keep the system frequency constant and the voltage variation  Traditional Electric Power systems Traditional Power Systems have a hierachical vertical control and operation: INFORMATION ENERGY FLOW FLOW GENERATORS TRANSMISSION POWER SYSTEMS DISTRIBUTION POWER SYSTEMS COSTUMERS  Operation and Control of power systems Power systems require a level of centralized planning and operation to ensure system reliability. System operators at control centers carry out many of these centralized functions in support of operations, including short-term monitoring, analysis, and control. A single electrical interconnect contains many system operators. Operation and Control of power systems Operation and Control of power systems Operation of Power System  Bulk Operation Within the setting of power systems, "bulk operation" normally refers to the large-scale generation, and transmission of electrical power. It includes the planning, management, and control of electric power at a system-wide level, often involving high-voltage transmission lines, substations, and power plants. Bulk operation is vital for maintaining the reliability and efficiency of the power system, as it ensures that power is reliably delivered to consumers while minimizing losses and ensuring the system's resilience. It also involves long-term  Distribution Operations In the context of power systems, "distribution operations" refer to the activities and processes involved in delivering electrical power from the high-voltage transmission system to the end-users, which can include residential, commercial, and industrial customers. Distribution operations are the final stage of the electricity supply chain and play a critical role in ensuring reliable and safe delivery of electricity to consumers. Distribution operations are essential for maintaining the quality and reliability of electricity supply to consumers, as they directly  Operational Objectives of Power Systems What are the operational objectives of a power system? Operational Objectives of Power Systems The power system operations are required to meet multiple objectives, namely minimizing the total costs, minimizing the total emissions, and maximizing the generating system reliability (minimizing the loss of load expectation). That is the power system operation must be safe, reliable and economical  Electric Power System Operation. Operational objectives of a power system have been to provide a continuous quality service with minimum cost to the user. These objectives are: First Objective: Supplying the energy user with quality service, i.e., at acceptable voltage and frequency Second Objective: Meeting the first objective with acceptable impact upon the environment. Third Objective: Meeting the first and second objectives continuously, i.e., with adequate security and reliability. Fourth Objective: Meeting the first, second, and third objectives with optimum economy, i.e., minimum cost to the energy user. The term “continuous service” can be translated to mean “secure and reliable service”  Integrated Objectives Interrelated objectives of operation of a power system The direction of the arrows indicates the priority in which the objectives are implemented The dotted line indicates that if the operation of the system violates the environmental constraints, then the operation of the system may have to be changed or reduced. Economically constrained operation of a power system.  Goals of Power System Operation Supply load (users) with electricity at – specified voltage (120/240 AC volts common for residential), – specified frequency, – at minimum cost consistent with operating constraints, safety, etc.  Major Impediments Load is constantly changing: Electricity is not storable (stored by conversion to other forms of energy), Power system is subject to disturbances, such as lightning strikes. Engineering tradeoffs between reliability and cost. 49  Power System Control Power system control is concerned with optimal power-frequency and voltage control. These two basic control problems differ in many respects. The main objective of Power System Control is to generate and transfer energy from source to load in the most cost and energy-efficient manner. This must be carried out within the constraints of the system in order that it remains both steady-state and dynamically stable. Power system control methods are primarily focused in response to the classification of power Power System Control Objectives  Main Objective of Power System Operation and Control The main objective of power system operation and control is to maintain continuous supply of power with an acceptable quality and reliability, to all the consumers in the system. The system will be in equilibrium, when there is a balance between the power demand and the power generated.  Power System Operation and Control To summarise; the operation and control of power system should ultimately maintain the following: System stability System security System reliability Evolution of Electric Grid  Modern Power Systems 57  Modern Power Systems Smarter, more Distributed, Intelligent, Interactive and Integrated Power System The Existing Grid vs the Smart Grid A Brief Comparison between the Existing Grid and the Smart Grid Existing Grid Smart Grid Electromechanical Digital One-way communication Two-way communication Centralized generation Distributed generation Few sensors Distributed Sensors throughout Manual and discrete monitoring Self-real time monitoring Manual restoration Self-healing Failures and blackouts Adaptive and islanding Limited control Pervasive control Evolution of the Electrical System  Smart Grid Defined The Smart Grid is an advanced digital two-way power flow power system capable of self-healing, adaptive, resilient and sustainable with foresight for prediction under different uncertainties. The smart grid uses digital technology to improve reliability, security, and efficiency of the electric system: from large generation, through the delivery systems to electricity consumers and a growing number of distributed-generation and storage resources. The information networks that are transforming our economy in other areas are also being applied to applications for dynamic optimization of electric system operations, maintenance, and planning.  Smart Grid Vision Bring digital intelligence & real-time communications to transform grid operations Demand-side resources participate with distribution equipment in system operation – Consumers engage to mitigate peak demand and price spikes – More throughput with existing assets reduces need for new assets – Enhances reliability by reducing disturbance impacts, local resources self-organize in response to contingencies – Provide demand-side ancillary services – supports wind integration The transmission and bulk generation resources get smarter too – Improve the timeliness, quality, and geographic scope of the operators’ situational awareness and control – Better coordinate generation, balancing, reliability, and emergencies – Utilize high-performance computing, sophisticated sensors, and advanced coordination strategies Making the electricity system less vulnerable to “all hazard” disruptions The smart grid will Enhance situational awareness – Improves visibility of the overall systems – Easier detection of deviations – Decreases time to distinguish attacks/events – Better information enables better decisions Facilitate increased distributed generation and redundancy – Less reliance on central generation and T&D Enable intermittent generation – Integration of renewable resources (minimize reliance on oil) Reduce outage propagation 64 – Self healing characteristics  Restoring electricity system integrity subsequent to disruptions (i.e. event management) The smart grid will Allow compartmentalization of disturbances – Through reconfiguration, adaptive islanding, use of microgrids, and failsafe design strategies Facilitates informed decision making and response – Through rapid data visualization from sensors – Faster and more precise identification of event root cause Enable faster response time responding to multiple (or evolving) events – Restoring stakeholder confidence in the system Enhance prioritized power restoration – Based on criticality of loads (i.e., public safety, emergency response, national security) Smart Grid Components Communication and Information Technology will be Central to Smart Grid Deployment Communication and Information Technology will be Central to Smart Grid Deployment The overall smart grid concept. It is capable of providing electrical power from multiple and widely distributed sources, such as from wind turbines, solar power systems, and plug-in hybrid electric vehicles. It uses digital automation technology for monitoring, control, and analysis through the supply chain.  Data in Smart Grids The flow of data management in smart grids is sequentially organized, as depicted in the figure. However, the data collection phase is the first step in the data management process, where the information is collected from the data centers. Data Collection and Flow in Smart The ultimate source of Grids data is the so-called advanced metering infrastructure (AMI) that retrieves the information from end-users’ premises. The AMI measures and collects the data every 10– 15 min. The data are prone to an escalation in size, depending on the population of a given location. Data Management In Smart Grid Systems Smart grids come with their strange advantages and changes that involve the information and communication technologies systems sector. These new changes include: New forms of information flow coming from the electricity grid. New players like decentralized producers of renewable energies, prosumers and involved consumers New uses linked with DERs such as electric vehicles and connected houses. New communicating equipment such as smart  Big Data in Smart Grid In smart grid, data are collected and transmitted with help of smart meters which provide energy related information to both the utility company and customers. The grid collects data from different sources and stores it as a huge quantity of dataset that should be easily consumable for analytics. Analytics has a critical role to make the grid more intelligent, efficient and gainful.  Smart Grid Cyber Security The same information and communication technologies that enhance the resilience of the power system may also present a new set of vulnerabilities relating to communications and information technologies associated with the control layer of the physical infrastructure If there are common modes of failure present in these control layers, there will necessarily be challenges to achieving full degrees of resilience in future smart grid deployments Because smart grid technologies transcend the scope of traditional normal boundaries associated with the bulk electricity system, we cannot rely on existing mandatory cyber security standards and Example of interdependent sectors vulnerable under Cyber Physical attacks on the smart grid Smart Grid Security Threats Security Life Cycle Categories of Cybersecurity Vulnerabilities  Mitigation Strategies in both the network layer and the application layer have been developed to mitigate the threat of attacks. When signs of an attack have been confirmed, mitigation efforts are made by the system operator to minimise the potential disruptions and damages. If the attack has been cleared from the system, existing mitigation and restoration mechanisms can effectively resume the secure and reliable power system operations. However, if the attack threat has not been resolved, the operator needs to consider persisting malicious attempts in the system. Cybersecurity Incident Management 79 The 5 Key Elements of Cybersecurity Incident Management The five phases of cybersecurity incident management, outlined in the figure above, are: 1. The first phase involves Planning and Preparing for a cybersecurity incident, so that the organization is prepared for a cybersecurity incident when one arises. 2. The Detect and Report phase involves the continuous monitoring of information sources, the detection of a cybersecurity event, and the collection and recording of information associated with the event. 80 3. The Assess and Decide phase involves  Smart Grid A smart grid is an electricity network that uses digital and other advanced technologies to monitor and manage the transport of electricity from all generation sources to meet the varying electricity demands of end-users. Smart grids co-ordinate the needs and capabilities of all generators, grid operators, end- users and electricity market stakeholders to operate all parts of the system as efficiently as possible, minimising costs and environmental impacts while maximising system reliability, Recent Advances in Smart Grid  Smart Grid Functions The principal smart grid functional characteristics are: Self-healing from power disturbance events Enabling active participation by consumers in demand response Operating resiliently against physical and cyber attack Providing power quality for 21st century needs Accommodating all generation and storage Smart Grid Characteristics and applications of SG  Remarks The power grid is exceptionally complex, and extraordinarily reliable – Most customer outages are due to issues with radial distribution feeders vs. the networked transmission grid Blackouts provide an opportunity to study and apply lessons learned to further enhance reliability As advanced technology is being considered for deployment, need to consider unintended consequences (e.g., cyber security) Robustness and resiliency are enhanced by considering all threats to the power system – An “all-hazards” approach Facility managers should build relationships with their suppliers to better understand their electrical reliability issues Implement best practice designs to minimize impacts of disruptive events, including redundancy and backup equipment Communication enabled smart grid applications  Smart Grid Success Requirements For Smart Grid (SG) to succeed, numerous requirements and technologies must be made available. SG require an effective deployment to the information and communication technology to have a successful implementation of this concept. Upgrading the conventional power grid toward an active network of a two-way communication capability is one of the main barriers in smart grids. The following figures shows some of the smart grid success requirements.  Ten Keys to Successful Smart Grid 1. Set a high bar: Require a grid design that significantly reduces the total environmental footprint of the current electric generation and delivery system. 2. Use assets more efficiently: A smarter grid can make fuller use of capital assets while minimizing operating and maintenance costs. Optimized power flows reduce energy waste and maximize use of existing infrastructure. Make realizing these efficiencies a priority. 3. Empower consumers: Provide information and price incentives to help them make smarter choices about when, where, and how to use The Do’s and Don’ts of Smart Grid Deployment  Modern Grid The application of a modernized network would: Improve the reliability and quality of the power grid. Optimize the operation of existed assets to avert the future expansion of backup plants. Enhance the overall system efficiency. Improve system resiliency. Facilitate the incorporation of Distributed Resources. Enable predictive maintenance and self-healing  Smarter Grid A smarter grid applies technologies, tools and techniques available now to bring knowledge to power – knowledge capable of making the grid work far more efficiently... Ensuring its reliability to degrees never before possible. Maintaining its affordability. Reinforcing global competitiveness. Fully accommodating renewable and traditional energy sources. Potentially reducing carbon footprint. Introducing advancements and efficiencies yet to be envisioned. A smarter grid works as an enabling engine for the economy, the environment and the future.  THE OVERALL VISION OF The Intelligent – capable of sensing system overloads and rerouting power to prevent or minimize Smart Grid a potential outage; of working autonomously when conditions require resolution faster than humans can respond…and cooperatively in aligning the goals of utilities, consumers and regulators. Efficient – capable of meeting increased consumer demand without adding infrastructure. Accommodating – accepting energy from virtually any fuel source including solar and wind as easily and transparently as coal and natural gas; capable of integrating any and all better ideas and technologies – energy storage technologies, for example – as they are market- proven and ready to come online. Motivating – enabling real-time communication between the consumer and utility so consumers can tailor their energy consumption based on individual preferences, like price and/or environmental concerns. Opportunistic – creating new opportunities and markets by means of its ability to capitalize on plug-and-play innovation wherever and whenever appropriate. Quality-focused – capable of delivering the power quality necessary – free of sags, spikes, disturbances and interruptions – to power our increasingly digital economy and the data centers, computers and electronics necessary to make it run. Resilient – increasingly resistant to attack and natural disasters as it becomes more decentralized and reinforced with Smart Grid security protocols. “Green” – slowing the advance of global climate change and offering a genuine path toward significant environmental improvement. TODAY’s GRID AND TOMORROW’s Example of Future Power Distribution Future Challenges to Power Systems