Parameter Optimization Of Control System For Back To Back Converter Station Based On Genetic Algorithm

Interconnect of power system has became a major trend in development of thegrid for coordinating the power resources optimal allocation and improving thereliability of power supply. Because the back to back converter station has lowoverall costs, fast-controled speed and low loss, it is widely applied innon-synchronous interconnect. parameters of control method is much importantsince back to back converter station has no direct line, especially in the case that thepower system were in faults or disturbances.Genetic Algorithm has highly probability to get global optimal solution andgood robust performance that can be easily used for complex nonlinear problems tosolve the difficult traditional methods. This thesis presents a method based onGenetic Algorithm for optimization parameters for the control system of back toback converter station. This thesis analyzes the basis of control system structure ofback to back converter station, derived the mathematical model for the constantcurrent, constant voltage, constant extinction angle and constant power control modeof back to back converter station system. In this thesis，objective function andconstraints for genetic algorithm parameter optimization has determined，usingMatlab genetic algorithm parameter optimization program has made and the basiccontrol parameter optimization program has set. By running of the program, we canget the final optimal parameters and fitness function of genetic algorithmconvergence curve.The effect of Genetic Algorithm parameters optimization verification is carriedout based on PSCAD simulation software. First, using fault in AC side of converterstation as an example, after parameter optimization transient process of back toback converter station has been significantly improved. The objective function valueof the parameter created in the optimum run from PSCAD is the same as GeneticAlgorithms objective function. Then comparing two optimization methods, get thedescription of the Genetic Algorithm parameters optimization for back to back converter station is effective and feasible.Parameters before and after the control system optimization basing on GeneticAlgorithm both are met the transient performance requirements. After the controlsystem parameter optimization, back to back converter station transient performanceimproved significantly, reducing the impact on DC system from AC side in fault,improved transient performance of the entire system.