Research On The Factors And Control Strategy To The Dynamic Stability Of AC-DC Power Systems

With the national grid connection and the DC line construction，Large areas of ACand DC power systems are becoming more and more common，the connection of windpower、PV and FACTS devices to the grid etc. intensify the complexity of the modernnetwork,and pose a challenge to the stability of the grid,also make the study of the lowfrequency oscillation become even more important.This paper utilized the schedulingunit output and DC active power as a method，and proposed control strategy fromDamping ratio sensitivity and Participation respectively.Introduce the damping ratio sensitivity to the active power to AC and DC powersystems,and use this index to formulate control strategy to suppress the area modeoscillation.Firstly,on the basis of classical mathematical mode,derivate of the dampingratio sensitivity formula of the generator nodes and DC converter stationnodes;Then,with damping ratio sensitivity as a guide,with the least adjustment amount ofsystem contribute as the objective function,propose the control strategy through adjustingunits active output and DC active power.Finally, optimize the strategy by geneticalgorithm.To reduce the dependent of control strategy to the mathematical model,pose thecontrol strategy based on the line identification to suppress the oscillation of AC-DCpower system.Based on the line identification,pose the control strategy with the generatorparticipation and clustering results as the indicator.Based on the information of unitsparticipation and clustering results，propose the strategy in principle of”Units in sendinggroup reduce active power and units in accepted group reduce increase power’.Build the Eight-Machine AC-DC power system in DIgSILENT and simulation,thesimulation results proof the rationality and effectiveness of this strategy.