A Coordinated Control Strategy Of Demand Response And Unified Power Flow Controller To Suppress Low-frequency Oscillations Of Power Systems

With the increasing complex of power system,more and more regional power grids are connected with each other.Hence,how to improve the stability and reliability of power system is in urgent need solved.Low frequency oscillation,generated from the connection of different grids,brings high challenge to the safe and stable operation of power grids.Demand response means to make the loads from the supply side to engage in power system through the economic and technical methods,so as to control the low frequency oscillation of the system.The united UPFC can improve the damping of the system,suppress the low frequency oscillation and promote the overall stability.This paper will make a demand response and UPFC coordinated control strategy to achieve the highest controlling efficiency.The main contents are as follows.Through linear differential equation of synchronous generator system,this paper analyzes the added damping from demand response loads,as well as its influence to the whole system,and illustrates the controlling feasibility and effectiveness of the demand response loads.Then,this paper provides a demand response and UPFC coordinated control strategy.At the very beginning,the structure and the operational principle are illustrated;then this paper points a normally connected strategy with demand response and UPFC,and analyzes some elements that will affect the damping considering the characteristic of the added damping;lastly,this research finds the best controlling parameter of the system through genetic algorithm.Finally,this paper checks the feasibility and effectiveness of the coordinated strategy.The functional equations are majorly focused on two aspects:the stand-alone infinity system and the four-machine-two-district system.This experiment can be divided into two parts.The first part checks the feasibility and effectiveness of the system and the second part verifies the efficiency of the optimum controlling parameter.