Research of Comprehensive Compensation of Harmonics, Reactive current and DC Bias in UHV Power Grid

Abstract

A comprehensive compensation device with paralleled decoupling for suppressing harmonics current, reactive power, and DC Bias of power transformer is proposed. Harmonics current and reactive current are detected by instantaneous reactive power theory. In this way, the fundamental active power is converted to be compensated reactive power and harmonics by controlling the converter. Compared to the ASVG with IGBT, the capacity and withstanding voltage level of ASVG with GTO are improved. The voltage across the devices of APF with multi-level inverter is reduced because of the paralleled decoupling connection. The harmonics compensation with multi-stage inverter can also reduce the voltage across the devices effectively. The reactive power compensator can work as a controllable rectifier and output controllable current by changing control algorithm. This current injects neutral point of transformer and suppresses its DC Bias, which has obvious effect on a power transformer. As a part of intelligent power grid, this compensator plays an important role for the development of smart grid automation.