A DC side soft start protection circuit for APF or SVG

To solve the problem of excessive instantaneous current during direct current (DC) side startup of Active power filters (APF) or static var generators (SVG), this paper proposes a DC side soft start protection circuit for APF or SVG. In the soft start circuit, a relay driven by the driving circuit is connected in parallel at both ends of the current limiting resistor, effectively reducing the instantaneous current on the DC side and better protecting the components in the circuit. Moreover, this article uses Simulink simulation software to compare and verify the DC side soft start circuit designed in this article with traditional soft start methods. It is found that the DC side soft start circuit can greatly reduce the alternating current (AC) and DC side surge currents, and better protect the components in the circuit.