Research Of Short-term Optimal Operation For Hydropower Plant In Electricity Market

The current mature electricity markets overseas generally include long-term contract market and short-term market, which composing multistage markets. The short-term market is often composed of energy market and ancillary service market and so on. The optimization dispatch problem for hydropower plants turns into the coordinative dispatch problem in the multi-markets in the electricity market. The AGC market is the most important part of the ancillary service market. Because of excellent performance at start and stop as well as adjustment for hydro unit, it is extremely suitable for participates in the AGC adjustment. This paper studies the combination optimization dispatch problem for hydropower plants in the day-ahead energy market and AGC market and obtains some valuable research results.This paper first introduces the current worldwide electricity markets, pointing out the market environment for hydropower plants. Then the market risk faced by hydropower plants and the methods of risk assessment, which are widely used in current financial domain, have been analyzed. These are the foundations of making coordinative schedule in the following parts of this paper.Solving the coordinate dispatch problem is the most important part of this paper. As the doubt of using variance for risk assessment, it takes the value at risk (VaR) as the risk measurement index. The VaR and expected revenue constitute different utility functions to describe market behavior of different power producer. A model for short-term coordinative dispatch in energy and AGC markets is established for hydropower plants, which is based on the forecasted MCPs for energy market and AGC market. In the model, the constrain of water using, which is obtained by the medium or long-term dispatch plan, is considered as a weak constrain, which is proven to be effective to revise the longer plan. In consideration of the difficulty of choosing appropriate risk factor in utility function for different power producer, Monte-Carlo Method is used for combined risk assessment of power price and inflow. The result can help power producer choose more appropriate risk factor (weight factor), thereby improving the generate schedule.A case study is given in the end of this paper, which is based on the Three Gorges plant and the historic price data of New England in American.