Hybrid Transient Simulation And Parallel Computing Of Large-scale AC/DC Power System

With the continuous construction of UHVAC and UHVDC projects,China has gradually formed a complex network with UHV as the main grid and AC and DC hybrid connection.The formation of large-scale AC-DC grids puts higher requirements on the speed and accuracy of power system simulation.At the same time,the problems of multi-infeed DC interference and commutation failure are also prominent.In this paper,the electromechanical-electromagnetic hybrid simulation of AC-DC grid,the parallel computing of large-scale power grid and the interaction of multi-infeed DC are studied.Firstly,aiming at the shortcomings of the HVDC quasi-steady-state model in electromechanical transient simulation,the HVDC electromagnetic transient simulation model is used to construct the electromechanical-electromagnetic hybrid simulation platform of AC/DC grid.At the same time,the method of controlling the step size is adopted to solve the non-convergence problem that may occur in the simulation of large-scale AC-DC power grid.In order to improve the speed of simulation,this paper uses parallel computing technology.Based on the classic bordered blocked diagonal form(BBDF)method,the calculation of the cut-node network and the calculation of the subnets are parallelized,and a new fully parallel BBDF method is proposed.The execution time of the new method is the larger one of the subnets solution time and the cut-node network solution time(including the communication overhead),and is no longer the sum of the two in the classic method.The test results show that the new method requires less computing time than the classic method and can increase the speedup of the parallel computing.Finally,in order to solve the problem of multi-infeed HVDC interaction,this paper adjusts the electrical distance through the installation of series reactors,thus achieving the purpose of limiting the multi-infeed interaction factor(MIIF),At the same time,by taking the local reactive power compensation measures at some point,the influence of reactors on the system voltage drop and the power flow distribution is controlled.Finally,a mathematical model for the configuration of reactors and reactive power compensation is established,and the particle swarm optimization algorithm is used to realize the optimal configuration.The configuration scheme limits the MIIF,and suppresses the problem of simultaneous multi-infeed HVDC commutation failure.