The Research On HVDC Commutation Failure Solution

As China’s "west to east, north and south, a nationwide network of development strategy implemented, the development of the power system more quickly. In the era of large power grids, HVDC transmission distance has a large transmission capacity, Transmission flexible benefits, HVDC as a strong complement to the AC transmission. Thus in the large-capacity long-distance power transmission applied more widely. With HVDC power transmission capacity in the proportion is growing, HVDC systems provide electricity for the receiving end of the AC systems, Converter station consumes reactive power is40%to60%of the dc system active power transmission. Because the converter station reactive power consumption, AC bus voltage fluctuations will have a major impact on the stable operation of the system. Therefore, this dissertation focuses on fluctuations of AC bus voltage of converter station, studied the solutions of DC latching fault of HVDC system. The details are as follows:Firstly, this dissertation aimed at the primary and secondary constitution of converter station of the HVDC system, analysis the basic structure of HVDC control system and working principle, the common faults for HVDC transmission system are summarized. Specially, analyzing commutation failure mechanism and influence, gives the commutation failure prevention and control measures.Secondly, aiming at the problem of ac bus voltage fluctuations, used the criterion of converter station in the AC bus voltage stability, analysis of the role of the different control method to converter station. In view of the perturbed problems while HVDC system running, rectifier and inverter select different control strategies, inverter side which mainly uses the constant voltage control, to maintain the ac bus voltage stability; For reactive power consumption on the problem, analysis the necessity of converter station for reactive power compensation, In view of the inverter side AC bus voltage fluctuation problem, the reactive power compensation device to select the constant voltage control, can adjust the output of the controller admittance value in real time, rapid adjustment of the thyristor trigger Angle, it can quickly control the reactive power output of the controller, Achieve the goal of a stable voltage.Finally, to build a simulation platform in PSCAD/EMTDC, the constant voltage control of the inverter side and on the reactive power compensation for simulation, simulation results show the effectiveness and feasibility of the control method and reactive power compensation.