System analysis of component outage in electrical LNG plant with voltage source inverters

This paper presents a system analysis of the adjustable speed drive system (ASDS) employing a voltage source inverter (VSI) under fault conditions such as tripping of a gas turbine generator. Investigated system includes four 80 MW VSI-ASDSs, four 105 MW gas turbine generators and two 90 MW steam turbine generators, all connecting to the 132 kV common bus. Proposed VSI-ASDS converts AC power from the generators to DC by the diode rectifier then drives a compressor motor by the five-level gate commutated turn-off thyristors (GCT) inverter. The simulation results show that the frequency and the voltage at the 132 kV bus can be maintained when one of the gas turbine generators or compressors is tripped. Continuous operation of the ASDS during a short circuit fault at a transformer for a base load is also investigated.