Influence Of HVDC Control And Protection Characteristics On Inner Overvoltage

West to east, the regional network is an important strategy for China's energy development. The adjustment of HVDC power is quick and flexible, the transmission distance is limitation from the stability of synchronous operation, so it is an ideal way of high-power long-distance transmission. Insulation coordination is one of the basic problems encountered in construction of HVDC system. The central problem of insulation coordination is to determine the insulation level, specifically, is to determine the voltage level of various insulation structure taken from various pressure test, and to solve the problem of insulation coordination, we must fully grasp the generation and the distribution of over-voltage. DC transmission system is also the same as all other power system, it produce a variety of over-voltage waveform since being struck by lightning, operation, failure or other reasons. The problem of over-voltage is always be concerned in HVDC field.DC transmission system must be running under the automatic control, to reduce the influence of AC system voltage fluctuations, and to improve the operating performance. Properly designed the control and protection system in DC system, is one of the effective way to reduce the over-voltage in DC system. However, the internal research of over-voltage control and protection system is still relatively small, so the study of this article is based on the standard model of HVDC transmission system proposed by CIGRE, using electromagnetic transient simulation software PSCAD/EMTDC, aiming at five fault (AC earth fault cleared,inverter side AC source failure lost,full-voltage starting fault,failure load rejection,converter transformer input) which will cause over-voltage, researching the influence of over-voltage by VDCOL current setting and the bypass control strategy of rectifier side. The author designed a simulation experiment and done a lot of simulation, further more, the author use matlab to deal with the simulation results and make some analysis. The simulation results shows that the best value of VDCOL current setting for reducing over-voltage is 0.55.The influence of over-voltage by bypass strategy is complex, specific issues need to adopt different control strategies. In this paper several sets of experimental data for the bypass of the control strategy can be used a certain reference.In summary, this paper studied the influence of over-voltage by HVDC control and protection features. The result will definitely help to reduce the cost of HVDC insulation design and provides a new approach of the High-voltage DC transmission voltage analysis.