Inertial Response from Remote Offshore Wind Farms Connected Through VSC-HVDC Links: A Communication-less Scheme

A communication-less scheme that allows remote offshore wind farms connected through HVDC links to participate in primary frequency control and contribute to system inertia is discussed in this paper. As a HVDC link decouples the offshore system from the onshore side, real-time communication of onshore frequency is normally required for the primary frequency control loop of the wind farms. Dependance on remote communication which could be unreliable at times is a problem. To obviate the need for communication, appropriate droop control on the offshore and onshore converters is used in this paper to translate the variation in onshore frequency to an equivalent variation on the offshore end. Thus the need for communicating onshore frequency to the offshore side is mitigated which ensures reliable operation. Such a communication-less scheme is compared against the conventional approach involving remote communication of onshore grid frequency to the wind farm site. Along side physical and analytical justification, a case study is presented to demonstrate that the communication-less scheme performs similar to the conventional one in terms of reducing grid frequency variations.