Research On The Fuzzy Control Strategy Of Asynchronous Generator Voltage Stability

Compared with synchronous generators,Self-excited Induction Generators(SEIG)have the advantages of ruggedness,simple structure and easy manufacture.They have become one of the research and application hotspots of independent power supplies and mobile power stations..As an independent power supply system,the asynchronous power supply system is susceptible to load changes during operation,so it is necessary to input a reactive power compensation device to improve its load capacity and restore its voltage to the rated value.Static Synchronous Compensator(STATCOM)is an important reactive power compensation device.It consists of a self-commutated inverter composed of fully-controlled switching devices and an optional energy storage device.The working principle is based on instantaneous reactive power.The theory has the advantages of rapid dynamic response and smoothing of reactive power.Fuzzy control is an intelligent control that does not require an accurate mathematical model of the controlled object.It has the advantages of strong adaptability,precise control and easy design.Fuzzy control has become one of the most widely used control methods in the control field.This paper mainly studies the STATCOM system using fuzzy PI control strategy and uses it to compensate the terminal voltage of the squirrel-cage rotor asynchronous generator.Based on the working principle of SEIG,the paper analyzes the relationship between current and voltage between stator and rotor based on dq coordinate transformation.Based on the saturation of magnetizing inductance,an accurate motor transient model is established and the model is simulated with no-load pressure.By analyzing the STATCOM topology,a time domain mathematical model is built.The stability of the STATCOM system is analyzed by using the Rolls criterion,and the response time of the device is estimated.The fuzzy control strategy is adopted on the basis of the traditional PI controller,so that the PI control parameters can be automatically adjusted,and the precise control of the STATCOM system in the dq coordinate system is realized.A dual dq coordinate system self-decoupling phase-locked loop tracking system is designed to obtain the load voltage phase angle and positive and negative sequence vectors.The main idea of the self-decoupled phase-locked loop tracking system is the two sets of Parker transformation results with opposite rotation directions.Cross-decoupling is adopted,and a negative sequence voltage feedforward control strategy is adopted to realize positive-sequence phase tracking of three-phase voltage and current fundamental waves.The STATCOM system adopts the double closed-loop direct voltage control method under the fuzzy control strategy,and designs the voltage loop and the current loop separately,and establishes the Simulink model for simulation verification.Based on the STATCOM and SEIG experimental systems,the relevant software is used for programming,and the feasibility of the control strategy is verified through experiments.It can be seen from the comparison between the simulation results and the experimental results that the STATCOM based on the fuzzy control strategy can be effectively applied to the reactive power compensation of the asynchronous generator on-load operation system,and can smoothly adjust the terminal voltage better than the traditional PI control.There by improving the stable operation capability of the asynchronous power generation independent system.