Multi-objective Optimal Power Flow Of AC/DC Hybrid System With DCPFC

The AC/DC hybrid power grid has great technical advantages in terms of centralized grid connection and long-distance transmission of new energy power generation.However,there are many ring networks in the DC power grid,and the system has insufficient freedom of power flow control,which leads to an unbalanced power flow distribution and even leads to line overload.DC power flow controller(DCPFC)can realize reasonable distribution of line power flow and promote safe and stable operation of AC and DC hybrid systems.Therefore,in this paper,the in-depth study of the multi-objective optimal power flow problem of the AC-DC hybrid system with DCPFC has certain theoretical significance and engineering application value.This article first classifies the existing DCPFC,and introduces the working principles and advantages and disadvantages of various types of DCPFC in detail.The external characteristic equivalent model of the voltage source DCPFC is deduced,and a method for solving the DC power flow based on equivalent resistance is proposed.The calculation error of the DC power flow including the DCPFC is greatly reduced while ensuring the calculation efficiency.Secondly,for the AC/DC hybrid system with DCPFC,a multi-objective optimal power flow mathematical model considering system economics and static safety is constructed,and a hybrid of interior point method and fast non-dominated genetic algorithm(Non-dominated Sorting Genetic Algorithm-?,NSGA-?)is proposed.The optimization algorithm calculates the optimal power flow and obtains an effective compromise solution that meets the requirements of the operating personnel.Finally,fully taking into account the fluctuation and randomness of new energy output,expressing uncertainties such as fan output as interval variables,propose a DCPFC configuration method based on the sensitivity of the system's performance index(Performance Index,PI),constructing an interval optimal flow mathematical model of an AC/DC hybrid system with DCPFC based on interval and affine arithmetic.the NSGA-? was used to solve the model to obtain a Pareto optimal solution set evenly distributed in space.Simulations are performed using a 5-node and 39-node system with a DC network,and it is verified that the method can optimize the system's network loss and static safety index while taking into account wind fan output fluctuation.