Active and Frequency Control Strategy of Improved Droop Control in Islanded Microgrid The traditional droop control will reduce the frequency of the system, and will seriously affect the power quality in an independent microgrid consisting of a variety of distributed power sources. However, if the frequency recovery time is too long, the frequency does not return to the power frequency and will drop seriously and deviate from the rated value when the next load disturbance occurs. In order to solve these problems, this paper proposes a fuzzy PI active and frequency control strategy based on the traditional droop control. The degree of frequency offset is taken as the reference amount, and its control parameters are dynamically adjusted to quickly restore the frequency to the stable value. In addition, the first function term of the power and droop coefficient is established to replace the fixed droop coefficient to prevent the frequency from crossing the boundary. Finally, the effectiveness of the proposed strategy is verified by MatlabSimulink simulation. The improved control strategy can make the system frequency stable in power frequency and improve the dynamic performance of the system.

A Control Strategy for Voltage Unbalance Mitigation in an Islanded Microgrid Considering Demand Side Management Capability Inverterbased distributed generators (DGs) have been customarily used for voltage unbalance (VU) mitigation in microgrids. The sole dependency on DGs for VU mitigation may not be justified, particularly in islanded microgrids. Demand side management (DSM) can be a potential candidate for VU mitigation in microgrids. Therefore, this paper presents a new VU mitigation scheme for an islanded microgrid by coordinating photovoltaic (PV) gridtied inverters, and thermostatically controlled loads (TCLs). A negative sequence compensation loop working in parallel with a positive sequence compensation loop is designed for PV inverters for VU mitigation. Also, a voltage dependent model of TCLs, unlike the conventional one, along with the control strategy for VU mitigation is presented. The proposed control of TCLs not only minimizes VU, and hence increases the dynamic reactive power reserve of the inverter based DGs, but also effectively maintains the customersu0027 thermal comfort. The proposed VU mitigation scheme is studied with comprehensive simulations in PSCADEMTDC, and is verified using a realtime digital simulator, OPALRT. Simulations and realtime results of the proposed scheme demonstrated the regulation of voltage unbalance factor (VUF) within the permissible range defined by IEC and CIGRE Working Group 36.07.