Reliability Evaluation Of Grid-Connected Microgrids Considering Demand Response

With the emergence of energy crisis in the late twentieth century, renewable energies are paid more and more attention in our world. Distributed generations in microgrids are becoming an effective way of connecting renewable energies into power grids, but the randomness and intermittence of renewable energies increase the difficulty of controlling microgrids. Traditional dispatching strategies for power grids are only focused on considering the impact of power sources on power systems, however, demand response strategies based on the consumer psychology can be used to optimize power system operations from the demand point of view. Reliability evaluation of microgrids is complicated due to the connection of renewable energies and considering demand response strategies. Therefore, this thesis focuses on the research of the impacts of demand response strategies on the reliability of microgrids.Peak load has a significant influence on the reliability and economy of power systems. Therefore, a load demand response model is built with the aim of shaving peak load and filling valley load. The hourly loads in a day are classified into three periods, i.e. peak loads, flat loads and valley loads, based on the fuzzy classes of peak and valley periods by using the F equivalent matrix. A load demand response model is built considering the constraints of customer satisfaction, total consumed load energy being unchanged and electricity price, of which the objective functions are the minimizations of peak load and the gap between peak load and valley load. PSO algorithm is used to solve the proposed model to obtain a new load curve. The proposed method is applied to the IEEE-RBTS(Roy Billinton Test System), and case studies show that the proposed method can be used to effectively shave the peak load and fill the valley load. In addition, influences of customer satisfaction and electricity price of valley load on load curve are also analyzed.Coordination between new energy of microgrids and load will affect the reliability of microgrids and the use ratio of new energy. Therefore, a load demand response model is built based on load satisfaction from new energy of microgrids. Load satisfaction from new energy of microgrids index is defined, and load demand response model of which the objective function is the maximum of load satisfaction from new energy of microgrids, based on period effect of PV output and time-of-use strategy. PSO algorithm is used to solve the proposed model. The method is applied to IEEE-RBTS load curve, and case studies show that: load satisfaction from new energy of microgrids can be effectively improved using the demand response strategy, and use ratio of PV is increased with the limit of microgrid power releasing.Few researches have studied the impact of demand response strategies on microgrid reliability. Therefore, a reliability evaluation method of grid-connected microgrids is proposed considering load demand response, which incorporates the load demand response strategies, structure of microgrid and ESS output strategies. Solve the load demand response models to obtain new load curves; using sequential Monte Carlo method to evaluate the reliability of grid-connected microgrids considering ESS output and microgrid load shedding strategies. The proposed method is used in RBTS-BUS6 system. The case studies show that the reliability of microgrid is effectively improved using the load demand response measure based on load satisfaction from new energy of microgrids; while the reliability of microgrid is deteriorated using load demand response measure aming at clipping peak load and filling valley load for some conditions.