Decentralized model predictive control of voltage source converters for AC frequency containment

This paper presents a novel control scheme for exchange of frequency support between asynchronous AC systems through a High Voltage Direct Current link or grid. The proposed controller bears the spirit of an emergency scheme. Using only locally available measurements, each converter can identify emergency situations that could potentially lead to unacceptable frequency values. Then appropriate control actions are taken to restrain the frequency decline and prevent it from reaching the thresholds of load shedding relays. Inspired of Model Predictive Control, the method uses simplified models of the AC and DC sides of the converter, and can incorporate various constraints. The effectiveness of the method is demonstrated on a test system consisting of two asynchronous AC areas interconnected through a five-terminal HVDC grid.