Research On Control Strategy Of Three-Level Unified Power Flow Controller

With the rapid development of global energy interconnection and market economy,the demand for electricity is also increasing,the stability of power supply and distribution flexibility of distribution networks are increasingly valued.The Distribution Unified Power Flow Controller,which apply to power distribution systems,is a full-featured,flexible configuration of power distribution equipment,it can control the power,phase angle and impedance of the system.The paper do a research about control strategy of the three-level D-UPFC.The main work of the paper as follows:(1)First,the research background,research significance and research progress of D-UPFC are introduced,the related knowledge of its topological structure and working principle is analyzed.(2)PWM converter is the core of D-UPFC.Three-level PWM converter has the advantages of low voltage stress,good output waveform quality,and low harmonic content,the paper applies a diode-clamped three-level converter topology to D-UPFC devices and introduces a dynamic modeling method for three-level D-UPFC.(3)Based on the introduction of D-UPFC control strategy,this paper discusses the realization method of cross-coupling and cross-coupling control strategy based on PI regulator,and the difference and connection between the two methods.In order to improve the system performance,a control algorithm based on model current prediction and its two improved algorithms are presented,the working principles and implementation flow of the three types of model prediction algorithms are discussed,Infect,the algorithm can improve the system's immunity and stability effectively.(4)Finally,a simulation model of three-level D-UPFC was-built.The above research methods were simulated and compared.The accuracy and feasibility of the algorithm were verified by comparison.