OPF Analysis On AC/hybrid DC Combined System

With the continuous improvement of high-voltage power electronics technology,high-voltage DC transmission composed of high-voltage converter devices get popularly attention.At the same time,the full-controlled power electronic devices as the main body of the voltage source converter developed successfully,because of its flexible operating mode,easy parallel operation,change the form of high-voltage DC transmission from point to point DC transmission into multi-terminal DC transmission.Today,with the successful development of DC circuit breakers,DC transmission form change toward a flexible,high-redundancy high-voltage DC power grid.Based on the detailed analysis of voltage source converter and current source converter composition and working principle,a steady-state calculation model of current source and voltage source converter including converter loss is established.Combined with the control mode on two kinds of converter,the study of mixed DC power system operation mode and mutual conversion methods and voltage regulation strategy.In this paper,the power flow model of AC / hybrid DC combined power system is established,the unified iterative method of the model is studied,the formula of Jacobi matrix element is deduced,and the C language is used to simulate the code on the CodeBlocks platform.The feasibility of the algorithm are verified.In this paper,the state variables of the hybrid DC system and the selection method of the control variables are studied.The equations and inequality constraints of the two converters and the DC power grid are established.On this basis,the AC / hybrid DC combined system optimal power flow method is given.This paper studies the method and process of solving the model by using the interior point method,deduces the calculation formula of all the elements needed in the calculation,and simulates the feasibility and correctness of the algorithm by programming the simulation on the CodeBlocks platform.In order to control the trend of the line effectively,the DCPFC optimization method is studied,and the DCPFC ratio is used as the control variable to construct the system to consider the whole system coal consumption and the whole system power flow.In this paper,The optimal power flow model of AC / hybrid DC system with DC power balance is obtained.The DCPFC ratio is obtained by analyzing the optimal power flow.