Research On Control Of A Three-stage Synchronous Generator

Three-stage synchronous generator is a kind of electric excitation generator without brush structure,which has the advantages of high reliability and low maintenance cost.It is suitable for application in aviation power system.This system needs achieve the purpose of voltage regulation by controlling the excitation current.However,there are still some problems.First,the frequency fluctuation will have a negative impact on the calculation of RMS voltage;second,as a complex nonlinear system,the dynamic performance of the AC power generation system is difficult to be guaranteed.Based on the above situation,this paper studies the generation control of three-stage synchronous generator.First of all,this paper describes the working principle of three-stage synchronous generator,and establishes a mathematical model in Matlab/Simulink software.Then the simulation of this model is carried out.The simulation results are compared with the finite element simulation and experimental results of the generator,and the accuracy of the model is verified.Finally,the generation control principle of AC power generation system is introduced and the model of voltage regulation system is built.Secondly,the influence of frequency fluctuation on the calculation of RMS voltage is studied.This paper introduces three kinds of effective value calculation methods——constant frequency sampling algorithm,zero crossing algorithm and quasi synchronous sampling algorithm.Through the comparition of simulation,the quasi synchronous sampling algorithm is selected because of the least error.Due to the long response time of quasi synchronous sampling algorithm,semi periodic integration optimization is carried out and the number of calculation iterations is appropriately reduced.The simulation results show that,compared with the constant frequency sampling algorithm,the error of the quasi synchronous sampling algorithm is greatly reduced;compared with the pre optimized quasi synchronous sampling algorithm,the delay time of the optimized algorithm is much shorter.Thirdly,in order to optimize the dynamic performance of AC power generation system,a variable universe fuzzy PID control strategy is proposed.In the system,the conventional double loop PID control strategy,the fuzzy PID control strategy and the variable universe fuzzy PID control strategy are used to simulate under transient condition.The simulation results prove that the variable universe fuzzy PID control strategy has better dynamic regulation performance than the others two.Finally,a set of digital voltage regulator is designed for 10 k VA three-stage synchronous generator.The design flow of software and hardware is introduced,and the experiment of the controller on the 10 k VA generator is carried out.The experimental results show that the quasi synchronous sampling algorithm and the variable universe fuzzy PID control strategy proposed in this paper are both correct and feasible.