DC and AC Microgrids for Standalone Applications

The commitment of mining industry to reduction of greenhouse gas emissions necessitates enhancements in operational efficiency, electrification, and renewable-energy use. An effective way to integrate renewable resources into a mining electrical system is to utilize microgrids. This article reviews DC and AC microgrid technologies, with a focus on coordination mechanisms for power sharing in islanded mode. The article then concentrates on a cost-effective decentralized control strategy, initially formulated for DC microgrids, which uses no communication and no droop. The article shows that, by using only an extra current sensor, this “current-driven control” strategy can achieve coordination of distributed generators (DG), their equitable power sharing, synchronized dynamic responses and stability in the presence of any loads. The article extends this attractive current-driven sharing concept to AC microgrids and studies their operation under a range of scenarios relevant to mining and other industries. A special form of secure Power Line Communication (PLC), compatible with the current-driven control, is then added to achieve reconfiguration flexibility and fault tolerance. Findings of the article are supported by simulation and experiment.