Study of an Electrical LNG Plant with Active Front End Drive Systems for Power Unbalance Failure

Electrical drives for large capacity compressors in a liquefied natural gas (LNG) plant have been investigated. When the LNG plant is located in a remote location, the power supply system may be an independent power source consists of gas turbine generators. In such power generation and distribution system, supplied grid voltage may be perturbated during an event of an equipment failure such as an equipment tripping or a short circuit in the distribution system. There is a configuration in which an active front end electrical drive is combined with a compressor driven by a gas turbine drive, and an operation mode in which the electric drive supplies electric power to the distribution system is also conceivable. In the case of tripping a generator in the distribution system, power balance should be maintained by remaining generators and load control including electrical drives to keep the frequency of the system. In this paper, system of four compressor drives and two gas turbine generators is studied by evaluating transient characteristics of the grid voltages and frequency during the above event. Simulation results show that the active front end drive system is effective for stabilization of the system.