Increasing the Robustness of Large Electric Driven Compressor Systems During Voltage Dips

Grid voltage disturbances pose serious problems to gas compression stations powered by drives such as load commutated inverters (LCI). Until recently, drive control systems used in industrial practice were not capable of handling reduced grid voltage situations appropriately, and instead interrupted the supply of drive torque. Without drive torque, compressors may quickly enter surge conditions, under which the gas flows rapidly back and forth, causing wear and risking damage to the equipment. In this paper, experimental evidence is provided showing that a combination of a revised control scheme for LCIs based on model predictive control and an advanced protection scheme for compressors, the so-called dynamic time to surge improves robustness of the system during voltage dips. We share successful voltage dip ride-throughs of two 41.2 MW LCI-fed synchronous machines, each powering a gas compressor at a large industrial site in Norway. We further analyze the impact of partial torque during voltage dips on the availability and safety of the gas compression station.