Research On Optimization Configuration Strategy Of Operating Reserve Capacity In Microgrid

The existence of the uncontrollability of renewable distributed generation output, the randomness of load and the failure outage of power generators leads larger operational risk to isolated microgrid. It is important to set aside a certain amount of operating reserve capability for the stable operation of microgrid. Based on day-ahead time-scales, this paper describes the uncontrollability of renewable distributed generation output as the uncertainty of forecast error, and describes the randomness of load as the uncertainty of forecast error, a model of optimal operating reserve capacity in microgrid is established to coordinate the reserve capacity between the generation side and the demand side under uncertain environment.Firstly, considering the impacts of time-of-use price (TOU), the model of purchasing reserve capacity of the generation side and the demand side are established respectively. The reserve capacity of generation side in microgrid is provided by the generator which the power output is controllable, such as non-renewable distributed generation and energy storage system. In electricity market environment, the demand response can be implemented in many ways, the interaction of those various ways will influence the optimal configuration of operating reserve capacity in microgrid. TOU and interruptible load are considered in this paper, and the interruptible load is regarded as reserve of the demand side.Secondly, a way of optimal configuration of operating reserve capacity based on chance-constrained programming is proposed on condition that the renewable distributed generation output and load in microgrid have sufficient history data. Under the framework of chance-constrained programming, a mathematical model of optimal operating reserve capacity is established. The objective is minimizing the purchase cost of operating reserve, and the constraint is the secure requirement of microgrid met at a certain confidence level. In the model, the short-term prediction errors of renewable distributed generation output and load is described as isolated random variables, and the probability statistics of those errors is determined through statistical analysis. Then the probability statistics of the total prediction error is further determined. Hierarchical genetic algorithm based on Monte-Carlo simulation is adopted to solve the constructed model. The simulation results showed that there has a game relationship between the reliability and economy of microgrid operation. It also points out the effect that different forms of demand response have on total cost of configuration.Thirdly, as the represent stochastic variable characteristics can not be accurately described due to lack of historical data, a mathematical model of optimization configuration of operating reserve capacity based on fuzzy random chance-constrained programming has been put forward. In the model, the prediction errors of renewable distributed generation output is described as fuzzy variable, and the short-term prediction errors of load is described as fuzzy random variable, according to the fuzzy random theory, the total prediction error can be further described as fuzzy random variable. By finding the relevant deterministic equivalent formulation of the fuzzy random chance-constraint, the original mathematical model was translated into mixed-integer nonlinear programming (MINP), the validity of the established model is verified by simulation results.Finally, the work of this paper is summarized, and the two modeling ideas are compared in different aspects, such as the scope of application, the solution methods and the complexity of decision-making. In addition, further research problems are put forward to provide a reference for future research of optimal configuration of operating reserve capacity in microgrid.