A Typical Cascading Failure Analysis And Optimization Of Generator Excitation Performance

In recent years,a large blackout is mostly caused by a cascading failure caused by a single system failure,which has caused great losses to the stability and economy of the power grid in our country.The generator excitation control system is one of the important measures to improve the stability of power system.The research on the limitation of excitation auxiliary has an important influence on the stability of power system.It is of great significance to study the performance optimization of generator excitation regulator and its auxiliary limits.This paper relies on the science and technology project of "Research on Simulation and Evaluation of Performance of Generator Excitation Regulator Network and Function Specification".Based on an accident,the simulation software is used to customize the model to analyze the impact of the accident on the power plant.The dynamic performance optimization of the stator current limiter has been studied.At first,the basic introduction to DIgSILENT/PowerFactory is given,and the methods and steps of DIgSILENT software custom modeling are expounded.The modeling of self-excitation main ring of magnetic system is taken as an example to carry on the custom modeling.The simulation results of the customized model are compared with those of real time digital simulator(RTDS)to verify the validity of the modeling of the main loop of the self-defined excitation system.The follow-up simulation analysis and research laid the foundation.Secondly,according to a certain accident,this paper introduces the causes of the accident and the main causes of the accident.Fault wave recording curves were processed by Wuhan Zhongyuan wave recording Software.The accident curve was drawn based on the processed data in MATLAB,and the impact of the accident on neighboring power plants was analyzed through the curve.A single-machine infinite-bus system and a custom structural framework that matches the actual exciter system are built in DIgSILENT/PowerFactory.The synchronous generator,excitation system,governor,power system stabilizer,stator current limiter,under excitation limiter and the minimum excitation current limiter were used to build the model.According to the actual data of the accident and the fault waveform,the waveform of the accident was reproduced through the simulation,and the reason of system instability was analyzed through the waveform curve of the simulation.Finally,this paper analyzes the accident and analyzes the influence of the secondary force excitation of the stator current limit on the stability of the system.By analyzing the influence of the existing typical stator current limiter on the voltage stability of the system,it is pointed out that not only is it unable to protect the safety of the generating set equipment but also it will aggravate the collapse of voltage.Based on the analysis of the characteristic of the V-curve of the single machine infinite bus system,the criterion that the power factor angle of generator terminal is smaller than the external power angle of the system to identify the minimum point of the stator current is proposed by the specific case.The validity of this method is verified and the stator current limit is optimized.