AC/DC System Reliability Rapid Evaluation Method Research

AC/DC interconnected power grid can transmit electricity over a long distance and it can make the development of electricity and the configuration is more efficient. China will form a large-scale "west to east, north to south" power flow the future, the pattern of AC/DC interconnected power grid will be basically in place.So, it has a great significance to assess the reliability of ac/dc power system fast.In this paper, combined with the actual situation of China's power grid space truss structure, we do a research of the AC/DC hybrid transmission system reliability evaluation method. First of all, based on the theory of Markov process,according to the method of frequency and duration of DC transmission system is divided into several smaller subsystems. To establish each subsystem state space transfer diagram, and then merge the same capacity. Finally, integrate the subsystems of state space graph, establish a complete transfer of DC transmission system state space. DC transmission system reliability evaluation model is presented in this paper, and the results were analyzed and calculated.By analyzing the connection mode and characteristics of the DC system, using sequential Monte Carlo simulation, power flow calculation of ac/dc system model and active optimization adjustment model are established. In the traditional bulk power system reliability assessment, in order to meet the precision of the assessment, it often takes a lot of calculation and the time-consuming is very long.To this end, this paper proposes a power system reliability evaluation methods based on decoupling ring power grid and radial power grid.By building the initial network topology, then based on the analysis of the entire network topology,decompose the grid into the ring power grid and radial power grid. Using the method of minimum-cut sets on the evaluation of radial network reliability, and consider the maintenance plan and component capacity constraints. Then, amend the border nodes of ring network and radiation network. Finally calculate the reliability index of the whole system. Finally established the system of the AC/DC hybrid transmission system reliability evaluation method. Through the simulation and calculation of the RTS-79 test system, the effectiveness of the reliability evaluation method was verified.