Automatic Generation Control

Abstract: In this paper, the idea of operating an inverter to mimic a synchronous generator (SG) is motivated and developed. We call the inverters that are operated in this way synchronverters. Using synchronverters, the well-established theory/algorithms used to control SGs can still be used in power systems where a significant proportion of the generating capacity is inverter-based. We describe the dynamics, implementation, and operation of synchronverters. The real and reactive power delivered by synchronverters connected in parallel and operated as generators can be automatically shared using the well-known frequency- and voltage-drooping mechanisms. Synchronverters can be easily operated also in island mode, and hence, they provide an ideal solution for microgrids or smart grids. Both simulation and experimental results are given to verify the idea.

Abstract: About The Authors. Preface. Acknowledgements. List of Symbols. PART I: INTRODUCTION TO POWER SYSTEMS. 1 Introduction . 1.1 Stability and Control of a Dynamic System. 1.2 Classification of Power System Dynamics. 1.3 Two Pairs of Important Quantities: Reactive Power/Voltage and Real Power/Frequency. 1.4 Stability of Power System. 1.5 Security of Power System. 1.6 Brief Historical Overview. 2. Power System Components. 2.1 Structure of the Electrical Power System. 2.2 Generating Units. 2.3 Substations. 2.4 Transmission and Distribution Network. 2.5 Protection. 2.6 Wide Area Measurement Systems. 3. The Power System in the Steady-State. 3.1. Transmission Lines. 3.2. Transformers. 3.3. Synchronous Generators. 3.4. Power System Loads. 3.5. Network Equations. 3.6. Power Flows in Transmission Networks. PART II: INTRODUCTION TO POWER SYSTEM DYNAMICS. 4. Electromagnetic Phenomena. 4.1. Fundamentals. 4.2. Three-Phase Short-Circuit on a Synchronous Generator. 4.3. Phase-to-Phase Short-Circuit. 4.4. Synchronization. 4.5. Short Circuit in a Network and its Clearing. 5. Electromechanical Dynamics - Small Disturbances. 5.1. Swing Equation. 5.2. Damping Power. 5.3. Equilibrium Points. 5.4. Steady-State Stability of Unregulated System. 5.5. Steady-State Stability of the Regulated System. 6. Electromechanical Dynamics - Large Disturbances. 6.1. Transient Stability. 6.2. Swings in Multi-Machine Systems. 6.3. Direct Method for Stability Assessment. 6.4. Synchronization. 6.5. Asynchronous Operation and Resynchronization. 6.6 Out-Of-Step Protection Systems. 6.7. Torsional Oscillations in the Drive Shaft. 7. Wind Power. 7.1 Wind Turbines. 7.2 Induction Machine Equivalent Circuit. 7.3 Induction Generator Coupled to the Grid. 7.4 Induction Generators with Slightly Increased Speed Range Via External Rotor Resistance. 7.5 Induction Generators with Significantly Increased Speed Range: DFIGs. 7.6 Fully Rated Converter Systems: Wide Speed Control. 7.7 Peak Power Tracking Of Variable Speed Wind Turbines. 7.8 Connections of Wind Farms. 7.9 Fault Behaviour of Induction Generators. 7.10 Influence of Wind Generators on Power System Stability. 8. Voltage Stability. 8.1. Network Feasibility. 8.2. Stability Criteria. 8.3. Critical Load Demand and Voltage Collapse. 8.4. Static Analysis. 8.5. Dynamic Analysis. 8.6. Prevention of Voltage Collapse. 8.7. Self-Excitation of a Generator Operating on a Capacitive Load. 9. Frequency Stability and Control. 9.1. Automatic Generation Control. 9.2. Stage I - Rotor Swings in the Generators. 9.3. Stage II - Frequency Drop. 9.4. Stage III - Primary Control. 9.5. STAGE IV - Secondary Control. 9.6. FACTS Devices in Tie-Lines. 10. Stability Enhancement. 10.1. Power System Stabilizers. 10.2. Fast Valving. 10.3. Braking Resistors. 10.4. Generator Tripping. 10.5. Shunt FACTS Devices. 10.6. Series Compensators. 10.7. Unified Power Flow Controller . PART III: ADVANCED TOPICS IN POWER SYSTEM DYNAMICS. 11. Advanced Power System Modelling. 11.1 Synchronous Generator. 11.2. Excitation Systems. 11.3. Turbines and Turbine Governors. 11.4. FACTS Devices. 12. Steady-State Stability of Multi-Machine System. 12.1. Mathematical Background. 12.2. Steady-State Stability of Unregulated System. 12.3. Steady-State Stability of The Regulated System. 13. Power System Dynamic Simulation. 13.1. Numerical Integration Methods. 13.2. The Partitioned-Solution. 13.3. The Simultaneous Solution Methods. 13.4. Comparison Between the Methods. 14. Power System Model Reduction - Equivalents. 14.1. Types of Equivalents. 14.2. Network Transformation. 14.3. Aggregation of Generating Units. 14.4. Equivalent Model of External Subsystem. 14.5. Coherency Recognition. 14.6. Properties of Coherency-Based Equivalents. Appendix. References. Index.

Abstract: Summary form only given, as follows. This paper presents a particle swarm optimization (PSO) for reactive power and voltage control (volt/VAr control: VVC) considering voltage security assessment (VSA). VVC can be formulated as a mixed-integer nonlinear optimization problem (MINLP). The proposed method expands the original PSO to handle a MINLP and determines an online VVC strategy with continuous and discrete control variables such as automatic voltage regulator (AVR) operating values of generators, tap positions of on-load tap changer (OLTC) of transformers, and the number of reactive power compensation equipment. The method considers voltage security using a continuation power now and a contingency analysis technique. The feasibility of the proposed method is demonstrated and compared with reactive tabu search (RTS) and the enumeration method on practical power system models with promising results.

Abstract: Frequency control as a major function of automatic generation control is one of the important control problems in electric power system design and operation, and is becoming more significant today due to the increasing size, changing structure, emerging new uncertainties, environmental constraints, and the complexity of power systems. Robust Power System Frequency Control uses the recent development of linear robust control theory to provide practical, systematic, fast, and flexible algorithms for the tuning of power system load-frequency controllers. The physical constraints and important challenges related to the frequency regulation issue in a deregulated environment are emphasized, and most results are supplemented by real-time simulations. The developed control strategies attempt to bridge the existing gap between the advantages of robust/optimal control and traditional power system frequency control design. The material summarizes the long term research outcomes and contributions of the author’s experience with power system frequency regulation. It provides a thorough understanding of the basic principles of power system frequency behavior over a wide range of operating conditions. It uses simple frequency response models, control structures and mathematical algorithms to adapt modern robust control theorems with frequency control issues as well as conceptual explanations. The engineering aspects of frequency regulation have been considered, and practical methods for computer analysis and design are also discussed. Robust Power System Frequency Control provides a comprehensive coverage of frequency control understanding, simulation and design. The material develops an appropriate intuition relative to the robust load frequency regulation problem in real-world power systems, rather than to describe sophisticated mathematical analytical methods.