Study On The Influence Of Low Frequency Disturbance Of Excitation And Speed Regulation System On Generator Output

With the diversification of power production,interconnection of power grids and grid connection,low frequency oscillation caused by small interferences occurs from time to time,which makes the data in wide area measurement system contain low frequency disturbance components.Low frequency oscillation has gradually become an important factor endangering the safe and stable operation of power grids,stable output of generators and accurate analysis and calculation of data.Analyzing the influence of low frequency disturbance on generator output is of great significance for improving power system stability,locating disturbance sources timely and accurately,and compensating for the harm caused by low frequency disturbance.However,at present,the related research results mostly focus on single-point and multi-point disturbance sources locating by voltage and power identification,ignoring the impact of low-frequency disturbance on the output voltage,current and speed of the generator itself.Based on this,this paper analyses the different influence characteristics of low frequency disturbance on generator output voltage,current and speed in amplitude and phase,and then accurately locates low frequency disturbance in excitation regulation system or speed control system.The correctness of the influence of low frequency disturbance on generator output is verified by theoretical analysis,simulation and experimental data analysis.The main contents and achievements of this paper are as follows:(1)According to the PMU voltage,current and speed data,the different effects of low frequency disturbance on the output voltage,current and speed of the generator are theoretically analyzed,and the disturbance signal is accurately located in the excitation control system or speed control system of the generator.(2)Two kinds of low-frequency oscillation simulation models of generator are established by using MATLAB simulation software.They are single-machine infinite low-frequency oscillation simulation system and ring structure Five-Machine with load low-frequency oscillation simulation system.The comparison of simulation results and theoretical analysis verifies the correctness of the ratio constant and phase relationship between voltage and speed proposed in this paper.(3)Taking the measured data of a power plant as an example,PMU data in acertain period of time are selected.The amplitude and phase characteristics of generator output voltage,current and speed are analyzed first,and then the low frequency disturbance signal is located accurately in the excitation regulation system or speed control system.The measured data verify the correctness and practicability of the influence of low frequency disturbance on generator output.The analysis and experimental results show that the proposed method can accurately locate the low-frequency disturbance signal located in the generator,and can give the influence of low-frequency disturbance on the output voltage,current and speed of the generator in terms of amplitude and phase.Different characteristics provide a basis for quickly eliminating the influence of low frequency disturbance,and lay a foundation for quickly formulating corresponding control measures to ensure the safe and stable operation of the power grid.