Research On Selection Of UHVDC Location At AC Termination And Its Influence On AC System

With the implementation of power grid interconnection and the Power transmission from west to east, a national hybrid UHVAC/DC grid will be formed in the future. According to plans of State Grid, Jiangxi Grid will receive7500MW active power from Northwest Grid through Gansu-Jiangxi UHVDC system. Then Jiangxi Grid will become a receiving end and turn into hybrid AC/DC operation state. Therefore, research conducted around interaction between AC and DC system has great significance.In this paper, focusing on interaction of AC-DC system, is based on PSD-BPA, the selection of DC location at AC termination and security and stability of receiving end are two aspects studied.First, a new method is proposed in this paper to select the stable and economic location of DC links. The main factors are found out for planning DC links terminating at AC locations from the point of interactions between AC and DC systems. Based on the linear weighted summation method for multi-objective decision-making problems, the objective function is established to select the optimal placement of a commutation bus. After calculated each index of object function corresponding to all500kV buses in Jiangxi Grid according to2016BPA data, weight coefficients of each index are determined and object function values of each500kV node are calculated. Finally, the optimal UHVDC location at Jiangxi Grid is identified by comparing all object function of each node.Then Jiangxi AC network rotor angle and voltage stability problems and related problems are analyzed after Gansu-Jiangxi UHVDC accessing Jiangxi Grid in the year2016. Research data with a core of Jiangxi Grid contains UHV grids as their backbones. The security and stability in high-water period are analyzed in condition that power flow meets demand. The research contains typical AC or DC fault, including three-phase short-circuit and synonym single-phase-to-ground fault of AC system and unipolar/bipolar block of UHVDC system. According to simulation results after fault, stability of rotor angle and voltage is determined and propose necessary control strategies.