Inertial response from remote offshore wind farms connected through VSC-HVDC links: A Communication-less scheme

Abstract

Abstract-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 obviated 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.

A receding horizon approach to incorporate frequency support into the AC/DC converters of a multi-terminal DC grid

“…A number of publications are devoted to control strategies enabling primary and inertia emulation response by offshore wind farms connected to the main onshore grid through an MTDC grid [8,9,10,11]. In this application, the main idea is to enable the offshore converters to change the frequency (or the AC voltage magnitude) they impose to the offshore grid [12].…”

A review of control methods for providing frequency response in VSC-HVDC transmission systems

“…Two control schemes for remote offshore wind turbines connected to the main grid via VSC-HVC have been introduced in [33]. One of the schemes is to make the wind turbine adjust its output active power to the rectifier VSC according to the measured frequency on the main grid side, while maintaining constant dc voltage on the inverter VSC.…”

Frequency Regulation Strategies in Grid Integrated Offshore Wind Turbines via VSC-HVDC Technology: A Review

“…As a result of this, the frequency regulation response in the offshore wind farm is slow and is unable to provide it with an appropriate quantity of active power to the rectifier-VSC. Various approaches have been proposed in [46,[69][70][71][72] to address this problem.…”