Research On Distributed Power Flow Controller Based On Multi-objective Optimization

In order to meeting the demand of power supply from the user and ensuring the power quality,The requirement for the power flow control of China's power system is more and more higher with the modern power grid structure and operation mode becoming more and more complex.Technology about flexible alternative current transmission systems(FACTS)can improve the capability of power flow control in power system,and ensure the power system stability,safety,reliability.and distributed power flow controller(DPFC)is a new FACTS device.This paper studies Multi-objective optimization problem of DPFC,and the process which puts intelligence algorithms into the parameter optimization of DPFC,and makes the control of the line power flow more quick and stable.Firstly,this paper introduces the research status of FACTS technology and DPFC.In order to fully understand the function and characteristics of distributed power flow controller,the topology structure of DPFC is analyzed in detail,and then its working theory based on Non-sinusoidal periodic power theory is expounded.Based on these work,the mathematical model of the fundamental and the third harmonic is established,and deriving the power control features of DPFC.Then,based on the different working modes of DPFC,analyses the working theory of the shunt side and the series side when working alone,and carefully analyzing the working mode of the coordinated operation between the shunt side and the series side.The equivalent mathematical model of DPFC is established,and putting forward the control strategy based on PI for multiple different targets of DPFC.The shunt side is mainly responsible for sending out the controllable third harmonic current,the series side absorbs the third harmonic and then injects the fundamental wave into the system,realizing the power regulation of the lineThe point of DPFC coordinate control about multiple targets can often be transformed into a multi-objective optimization problem,so the improved multi-objective particle swarm optimization algorithm is used for the multi-objective controller optimization.The paper firstly introduces the related concepts on the particle swarm optimization algorithm which is verified,putting forward the problem of multi-objective optimization.In the design of multi-objective algorithm,considering the limitation of which seriously depending on engineering experience in the coefficient of variation method when weighting coefficient,the multi-objective particle swarm optimization algorithm is implemented by the selective ranking method.And optimizes the controller parameters for specific objective functions such as active power,multi-objective optimization design of distributed power flow controller is carried out,using the optimal compromise solution based on membership function to select the optimal parameter solution.Finally,the system with DPFC is modeled and simulated in PSCAD/EMTDC,and the simulation waveform through the controller based on traditional PI theory is obtained.Then the multi-objective particle swarm optimization algorithm is used to optimize the control parameters of the controller,which includes the capacitor voltage controller and the line power flow controller of the series side,and the control effect of the system was significantly improved.The simulation result verifies the correctness and feasibility of the controller designed to multiobjective optimization by the multi-objective particle swarm algorithm.