Application analysis of three-phase four-wire system combining adjustable reactance and zero-sequence filter

This paper presents the design of a power quality governor combining adjustable reactance and zero sequence filter, including a zero-sequence filter module, an adjustable reactance module, a zero-blocker module, a current sampling module and an MCU intelligent control system. The zigzag transformer module is designed to reduce the current in the neutral line through its own electromagnetic effect in order to achieve power savings. The adjustable reactor is introduced for non-linear loads and works by sampling the current of each phase of the three-phase circuit, calculating its unbalance through the MCU module to output the corresponding three-phase PWM waveform to adjust the adjustable reactor winding, thus adjusting the three-phase reactor winding connected in series in the three-phase circuit to achieve the purpose of balancing the three-phase load. To address the problem of unbalanced three-phase voltages, a zero resistor is connected in series with the three-phase circuit to produce a large zero-sequence impedance, which reduces the three-phase unbalance current caused by the three-phase unbalance voltage. This paper achieves the goal of reducing the zero sequence harmonic components in the three-phase circuit and reducing the current on the neutral line to achieve power saving.