水情变化条件下梯级水电站实时负荷调整方法

Real-time load-adjusting method of cascade hydropower plants considering hydrological regime-changing conditions

当来水预报不准确或流域上游及区间来水变化时,水电站实际入流可产生的出力与电网基于确定性来水制定的计划负荷不匹配,若电站仍按原计划负荷运行,易导致水位约束破坏或大量弃水。针对这一问题,本文构思了一种实时负荷调整方法,在来水增大时,以减少弃水为原则增加水电出力,通过降低火电出力以充分吸纳水电;在来水减少时,结合梯级水电站蓄能效应对站间负荷合理分配,并在水电发电能力不足时及时调整火电以满足电网下达计划要求。以华中电网辖下沅水流域三板溪、白市、托口和五强溪四级直调水电站为对象进行实时调度仿真模拟,实例计算表明,所提方法能有效降低水情变化对梯级水电站未来时段调度产生的不利影响,制定出的梯级水电站出力调整计划满足水电站运行要求和电网安全稳定运行约束,其建模思路能为类似工程提供参考。

The changing of runoff in the fiver basin or upstream or the inaccuracy of inflow forecasts may result in a mismatch between the hydropower generation based on actual inflow and the planned load of the grid based on deterministic inflow forecasts. In such circumstances, if the hydropower plants still follow their original plan in operation, they will be likely to violate water level constraint or bring about a mass of surplus water. To solve these problems, a real-time load-adjusting method of cascade hydropower plants considering inflow-changing conditions is presented herein. Under inflow increasing, this method can guide the plants to generate more electricity by reducing surplus water release and be able to adjust thermal power output to absorb the spare hydroelectric power; under inflow decreasing, it can reasonably redistribute the load among plants considering the effect of energy storage in the cascade reservoirs and redeploy the thermal power to offset the deficit in hydropower generation by the grid load demands. Its feasibility and effectiveness was demonstrated in a case study of a hydroplant cascade on the Central China Power Grid, including the plants at Sanbanxi, Baishi, Tuokou and Wuqiangxi. The results show that our new method can effectively reduce the adverse impact of hydrological regime changing on the dispatches for upcoming periods. And the method can work out a plan adjustment that meets the requirements of hydropower plant operation and ensures the safety and stability of power grids.