Long-Term Risk Dispatching of Cascaded Hydropower Stations in Electricity Market

In the first-stage of power market, hydroelectricity still participates in electricity market with long-term or short-term electricity contracts. So, there may be risk for hydroelectricity due to forecasted error of reservoir runoff or other uncertain factors. For cascaded hydropower stations, short-term risk can be avoid by utilization of flow in regulation reservoirs. But, how to reduce long-term risk is still a hard work by recent technologies. In this paper, long-term risk dispatching of cascaded hydropower stations in electricity market is developed. Risks are analyzed in detail. And two risk sources are identified, which are forecasted error of reservoir runoff and uncertain human factors. Their random simulation strategies are also proposed. Then long-term risk dispatching model is constructed with its solving approach. The objective function contains three parts: minimum possibility of surplus water, minimum possibility of default and maximum generation profit. Finally, with Three-gorges and Gezhouba cascaded hydropower station as a real case, suggestions for long-term dispatching of cascaded hydropower stations in electricity market with risk considered are proposed by analysis to the simulation results of 27 typical working conditions.