The research on reactive power and DC bias compensation

High voltage DC transmission (HVDC) used in the way of single cycle operation will make the transformer produce serious DC magnetic bias. Besides that, still with distortion of the transformer excitation current, temperature rises and noise increases, then will cause a lot of accidentally harmonic pollution for the grid. The use of inductive appliances, high-power motor and electric arc furnace, will make grid current lag the voltage and reactive power rise, then impact the grid. For DC magnetic bias of the transformer and reactive power compensation problems in the grid, this paper proposes a solution of comprehensive compensation DC magnetic bias and grid reactive power. In this scheme, the instantaneous reactive power theory detects the meritorious and reactive current, then compares with the triangle wave, with the trigger pulses produces, it´s the switching devices needed. Second, after three-phase bridge type inverter circuits producing required compensation current, a chopper is paralleled on the inverter circuit´s support capacitance then the partial magnetic compensation current generates that the transformer needed. At last, the scheme can realize results of supplement the reactive power and DC magnetic bias at the same time.