Optimal day-ahead and intra-day scheduling of energy and operating reserve considering fluctuating wind power

Abstract

High penetration of wind power increases the complexities in system planning and operation. How to determine the required amount of operating reserve becomes a major problem due to the uncertainty and fast fluctuation of wind generation. Most of existing schedule methods determine the amount of operating reserve in day-ahead optimal scheduling considering economic costs and reliability indexes. However, they are not completely accurate due to the day-ahead forecast error of wind power and loads. It is well known that the forecast error of wind power and loads decreases from long-term timescale to short-term timescale. Therefore, it is important to develop an optimal schedule of energy and operating reserve in both day-ahead and intra-day to minimize total system cost considering ever-changing forecasted wind power. The spinning reserve is solved by day-ahead schedule to deal with contingencies like outages of units and other instantaneous failures. It will not change in intra-day schedule. Regulating reserve is pre-scheduled in day-ahead schedule and later adjusted in intra-day schedule due to the reduction of forecast errors of loads and wind energy. Both of the reserves can be provided by generators and demand response. We illustrate our methods in a modified 4-bus 9-generator system. Analysis shows that the proposed methods can provide a useful reference for system operators to schedule day-ahead, intra-day plan of energy and operating reserve. The system fluctuation induced by accessing wind energy is restrained by progressively utilizing a series of optimal allocations of energy and operating reserve in thermal power plants to enhance the secure and economical system operation.