Design and Implementation of Generation Control System for an Offshore Platform

An offshore complex with five production platforms is powered by two gas turbine generators, three gas engine generators, and one diesel engine generator operating in parallel. An automatic generation control system (GCS) controls the six generators and maintains system voltage, frequency, and generator kW/kVAR load sharing. System development and commissioning was complicated because of the multiple inertia models imposed by dissimilar generators. The primary controls (governor and automatic voltage regulators) are set to frequency-droop and voltage-droop modes under normal operating conditions. However, isochronous load sharing lines are also present between the turbine- and engine-driven generators as a manufacturer backup control strategy in the event of GCS control loss. The GCS needed to be adaptive to operate in parallel with a second control system for the turbine-driven generator. Another challenge was simultaneous regulation of bus voltage and kVAR load sharing between the generators. This paper presents a tested GCS that was designed and implemented to adapt to a generation system with multiple inertias, islands, control modes, and voltage levels that will tolerate system contingencies.