Cooperative management of microgrids systems with distributed energy resources

Abstract

With high penetration of distributed energy resources (DERs) into power system, microgrid has showed great advantages of enabling efficient and reliable grid operation of distribution grids with high flexibilities. However, due to the intermittent characteristics of the DERs, the traditional control strategy is no longer the best choice for the distribution system like microgrid/ smart grid. In order to maintain the optimal operation of the microgrid system no matter in grid connected mood or the islanded mood, and to coordinate the feature of the DERs, various control strategies have been put forward to settle the microgrid operation problems. A cooperative distributed voltage optimization is proposed to tackle the problem of active and reactive power sharing in microgrids. Different from other control strategies available so far, the control strategy presented does provide a desired active and reactive power distribution to mitigate the voltage fluctuations while only requiring distributed communication among inverters without central controller. The subgradient method makes the control strategy feasible even with some information is lost or unknown. The compatibility of the proposed distributed voltage control with the usual voltage droop control for inverters is shown and the performance of the proposed strategy is compared with centralized power dispatch control method via simulation of a microgrid based on the IEEE 399-1997 standard. Simulation results illustrate superior performance of the proposed technique. Chapter 1 introduced the research background and motivation. Chapter 2 summarizes overview of the recent advancements of microgrid development. Different control and optimization schemes applied in the microgrid operations are researched and analyzed in Chapter 3. Based on a comprehensive review on microgrid control strategies, a cooperative distributed control scheme to optimally mitigate the system voltage, which dispatches the active and reactive power simultaneously is proposed in Chapter 4. Conclusions and future scope are reached in Chapter 5.