Optimal Power Flow Of AC/DC Hybrid Power Grid With DCPFC Based On Particle Swarm Optimization

Compared with the traditional AC transmission system,HVDC transmission system has great advantages in long-distance transmission and new energy grid connection.However,there is a problem of insufficient power flow control in DC transmission system.Adding DC power flow controller(DCPFC)can improve the power flow distribution.This paper studies the power flow optimization of AC / DC hybrid system with DC power flow controller,which has certain application significance.First of all,this paper deduces the DC Newton-Raphson(NR)method for DC power flow calculation by analogy with the power flow calculation method of AC transmission system;then compares the advantages and disadvantages of the two types of DCPFC after analyzing the principle of the two types of DCPFC,selects the change voltage type DCPFC to control the power flow of DC system,and puts forward the πtype equivalent circuit of the change voltage type DCPFC;based on the equivalent model of DC NR method and DCPFC,this paper establishes the power flow calculation model with DC NR method The power flow calculation model of DCPFC DC power grid and the sensitivity model of each state quantity are analyzed,and the influence of DCPFC on network loss is emphatically analyzed.The effectiveness of the DC NR method and the sensitivity analysis method is proved by an example.Then,combined with the model of voltage source converter(VSC),the power distribution and active power loss of AC and DC sides of VSC converter station are analyzed.The traditional alternating iteration method of AC / DC power flow is studied,and its shortcomings are pointed out.By re selecting the dividing point of AC / DC system,the decoupling power flow calculation of AC / DC system is obtained.By comparing the alternating iteration method with the decoupled power flow algorithm,it is proved that the alternating iteration method has the advantages of simple switching control mode and better convergence.Finally,considering the economy and stability of AC / DC system,this paper optimizes the network loss of AC / DC system by particle swarm optimization algorithm,and improves the convergence of traditional particle swarm optimization algorithm.Taking the modified IEEE14 node as the optimization object,the two algorithms are compared.The results show that the improved algorithm has better effect in reducing network loss.