Study On The Influence Of Generator Excitation Control On Low Frequency Oscillation In Power System

Generator excitation system plays an important role in the safe and stable operation of power system,The operation status of the generator can be controlled effectively by controlling the excitation regulator,Which ensures the stable operation of power system.So improving the excitation regulator and the stability of the system has become the main research direction of the excitation control mode.Although the control mode of the excitation regulator has been more mature,low frequency oscillation still occurs in the long distance and high voltage transmission process,it can make great harm to the power system.The research based on traditional single closed-loop control is quite mature,but the analysis on the introduction of current measurement unit is insufficient.In this paper,from the angle of compensation current in the excitation regulation system,we will study the effect of low frequency oscillation of the system.Firstly,describe the function of the generator excitation control system and the connection mode of each unit in the excitation regulator.At the same time,it is pointed out that when the generator and the system oscillation,the excitation regulator will have a certain effect on the performance of the generator excitation control system after the introduction of compensation current.Secondly,describe the power system low frequency oscillation mechanism and suppression strategies,and establish two simulation models of generator operation and parallel operation,obtained under two different operating conditions of excitation adjuster to adjust characteristics,and the Thewenin's equivalent circuit of excitation regulation device in the current analysis.Simulation results show that the excitation regulator in the generators stand-alone and grid connected operation failure after resection of the adjustment characteristic is different,and when the system is oscillating,the compensation current of the excitation adjustment unit is an alternating current of amplitude oscillation.The approximate value is the ratio of open circuit voltage and loop reactance,and its oscillation characteristics are the same as power angle oscillation.Finally,in the simulation environment of Matlab/Simulink,established.the simulation model of three different excitation control systems.Simulation results show that when the generator adopts negative adjustment,the compensation current will aggravate the oscillation;when the generator adopts positive adjustment,the compensation current will weaken the oscillation.