A New Method Of Tracking Power System’s Oscillation Center Based On Wide Area Information

With the development of smart grid and increasing connection of power grid,maintaining the power system operating safely and stable is more essential than before.As a usual form of unstable,power system oscillation may cause power flow changing,voltage fluctuation or even power system collapse.Therefore,we need to further study on power system oscillation in order to find out an efficient scheme including oscillation distinguishing,oscillation center determining and out-of-step islanding control.Almost existing schemes only using local electric quantities and they cannot meet the safety and stability requirement of complex power grid.The using of WAMS has make it possible to synthesize and conduct wide area data.Through providing wide area electric quantities,WAMS can improve the accuracy of oscillation recognizing and oscillation center determine.The location of out-of-step centre and mechanism of oscillation centre migrating are studied considering impedance irregularity and potential amplitude inequality based on a two-machine equivalent system model,then the position of oscillation centre is detected in real time.In the paper it concludes that the position of out-of-step centre can be determined by the relationship between the function of node location defined in this paper and the potential amplitude’s proportion of both sides,and derives the rules whether the lines between both power systems contain out-of-step centre.After that,migrating range of oscillation centre is analyzed accurately and four types of migrating state are found,and the locating criteria for oscillation centre are present by measuring of the phase angle of impedance on the bus line of power system.Finally,the simulation results verify the correctness of the analysis.