Research On Multi-objective Optimization Of Railway Power Quality Manage System

For China in the new era,"high-speed railway" has become a shining business card of our country in the international community.With the arrival of high-speed electrified railway,the capacity design of the compensation device is of great significance to the popularization and application of the device,especially for high power compensation device.The smaller the compensation capacity of the device is,the less the installation cost is and the higher the economic benefit is.In this paper,a multi-objective optimization scheme of power quality control system for electrified railway is proposed,On the premise of satisfying various power quality indexes,in order to minimize the capacity of compensation device and the negative sequence current of three-phase public power network of traction power supply system.The specific work is as follows:First of all,in this paper,the research background and significance of the topic is introduced,the current situation of electrified railway and a series of methods of power quality control at home and abroad are compared.the traction power supply system is introduced,and the causes and hazards of power quality is elaborated.the compensation device of traction power supply system of electrified railway is introduced.and the basic structure and main characteristics of power quality compensation device are analyzed.Secondly,by establishing the electrification model of the railway power quality manage system(RPQMS),the compensation principle of RPQMS is analyzed and deduced in detail.In this paper,the principle of complete compensation and optimal compensation is analyzed,the mathematical relationship between compensation parameters and compensation capacity and negative sequence current of three-phase public power grid is studied.The multi-objective optimization mathematical model of RPQMS with the objective of minimum compensation capacity and minimum negative sequence current is established under the constraints of various power quality conditions,based on the compensation power factor angle and active power transfer degree as variables.Then,in order to improve the convergence speed and accuracy of the multi-objective particle swarm optimization algorithm,the particle swarm optimization algorithm is improved adaptively.In order to improve the uniformity of Pareto frontier solution set,a Pareto frontier knowledge base updating mechanismbased on density distance is proposed.Through the analysis of examples and MATLAB simulation,it is verified that the multi-objective optimization of RPQMS can effectively reduce the compensation capacity of the device and the negative sequence current of the three-phase public power grid on the premise of meeting the power quality indicators.At last,the GUI is designed for the multi-objective optimization of the railway power quality manage system.Through the GUI interface,it is convenient to compare the compensation effects under various compensation methods.The theoretical support for the application of the optimization scheme in engineering practice is provided.