Advanced sensorless power control strategy of renewable microgrids for reliability enhancement

Microgrids are able to reduce fossil fuel emissions by integrating renewable energy resources, and to improve reliability and resilience of electrical grid. This paper presents a sensorless droop control strategy to enhance reliability and reduce operation cost of microgrids, where virtual flux-based voltage reconstruction and current reconstruction strategies are proposed to estimate three-phase voltage and current signals according to DC-link current instead of direct measurement. Combined reconstruction strategy of three-phase voltages and currents is first developed, and the implementation procedure of sensorless droop control is given. Furthermore, small signal model of microgrid equipped with the proposed droop control strategy is established. And closed-loop stability and dynamic performance of sensorless droop control strategy are investigated. Simulation and experiments are implemented to validate the proposed sensorless droop control strategy. The verification results show that the proposed method is able to perform accurate three-phase voltages and currents reconstruction of inverters, and achieve desirable power sharing control performance. The proposed droop control strategy is able to improve fault-tolerant capability of microgrid in the presence of sensors faults due to sensorless operation. It thus provides a cost-effective and high reliability solution for practical application of microgrids.