Droop regulated VSCs for island operation of future offshore systems

This paper proposes a control strategy for island operation of a future offshore system dominated by large wind turbines with full back to back converters run in parallel with traditional gas/diesel generators. The control strategy aims to a balanced sharing of the power between the generation units with a decentralized architecture based on modified droop regulators whose gains are adapted according to the available power. The control structure requires no intercommunication between the units while the wind turbines can be operated to supply the entire power that is available locally. With this control scheme the gas/diesel generator will produce only a minimum of power. Furthermore the wind turbines will manage the voltage and frequency control also when the gas/diesel generators are disconnected.. These characteristics produce a very reliable and reconfigurable system with major benefits for an offshore application. The algorithm was validated by numerical simulations on a sample notional system using PSCAD. Island operation, voltage source converters, droop regulator, offshore wind.