The Coordinated Control Of FACTS On Voltage Stability Based On Fuzzy Theory And Expert System

Voltage stability is an important factor to ensure the security and effective operation of power system. Low voltage or high voltage can not meet the requirements of the system, seriously, the devices will be damage and occurs voltage collapse. With the rapid development of power electronics, FACTS devices have been widely used in power system to control voltage and reactive power, while the interactive effects have not been effectively resolved. The thesis proposed a rule-based coordinated control strategy of voltage stability, so as to meet the actual needs of voltage stability.The voltage stability of SVC and TCSC is analyzed under constant power factor of load or motor load. Firstly, the thesis introduces principles and models of FACTS, and analyzes the voltage stability of SVC and TCSC under different loads cases. Analysis indicates more reactive compensation is more beneficial for voltage stability in simple system, and the capacity of parallel device and series device can be interchangeable when maintain a certain voltage value.According to the different voltage stability problems, the medium and long-term voltage stability adopts proportional control mode while the transient voltage stability applies switching control method. Then the thesis elaborates the expert rules to improve the voltage stability, and design the controllers of FACTS for simulation.In addition, the thesis improves the traditional reactive power optimization model and optimizes the critical parameters of FACTS based on genetic algorithm. The results show that increasing compensation capacity can improve voltage stability within a reasonable range, but play negative roles beyond the limit.Based on the control rules on voltage stability of FACTS, the thesis analyzes the SVC and TCSC control logics, and poses coordinated control strategy based on fuzzy control and expert rules. First of all, introduces the fuzzy control theory and sets up the coordinated control strategy based on fuzzy control and expert rules, then the thesis designs fuzzy controller of SVC and TCSC in Matlab toolbox. The simulation results indicate that the fuzzy controller can operate correctly to compensate reactive power and improve voltage stability effectively.