The rectifier and inverter are using three-level Neutral Point Clamped (NPC) converter with VSC converters

Abstract

In this paper forced-commutated Voltage-Sourced Converter (VSC) interconnection is used to transmit power from a 230 kV, 2000 MVA, 50 Hz system to another identical AC system. The rectifier and the inverter are three-level Neutral Point Clamped (NPC) VSC converters using close IGBT/Diodes. The Sinusoidal Pulse Width Modulation (SPWM) switching uses a single-phase triangular carrier wave with a frequency of fundamental frequency. Along with the converters, the station includes on the AC side,the step down Yg-D transformer, the AC filters, the converter reactor and on the DC side the capacitors, the DC filtersThe discrete control system generates the three sinusoidal modulating signals that are the reference value of the bridge phase voltages. The amplitude and phase of the modulating signals can be calculated to control either: the reactive and real AC power flow at the PCC, or the reactive power flow at the PCC and the pole to pole DC voltage.