The Influence Of Inflow Forecasting Error To Cascade Hydrostation Generation Compensating Operation

With the construction and operation of cascade hydrostations in our major basin, the cascade hydrostations have gradually transformed from construction oriented to management and operation oriented. Generation compensating operation of cascade hydrostations in the basin is one of the key contents of the coordinated operation of cascade hydrostations. It means that under certain inflow conditions, meeting the electricity and hydraulic safety constraints, in the specified period by runoff compensating adjustment of each cascade reservoir and hydrostation, this operating strategy can obtain the maximum overall power generation benefit of cascade hydrostations. Research on cascade hydrostation generation compensating operation is of great significance to increase the efficiency of cascade power generation, improve the security of power generation, and improve the structure of energy grid.The generation compensating operation of cascade hydrostations is achieved mainly through the flow compensation adjustment of each stations. And it will be affected by inflow error. This paper focus on the flow compensation scheme selection of cascade hydrostation generation compensating operation under certain conditions, the influence of principal reservoir water level to storage risk and cascade overall power generation benefit which are led by inflow error. This paper studies the issues as follow:(1) Explains the significance of cascade hydrostation generation compensating operation. Analyses the precondition of cascade hydrostation generation compensating operation, and divides compensating operation period into the flow compensation period and the water level return period. When the full-time cascade total power generation benefit is maximum, this is our scheduling target. Under the constraint conditions, according to the technical route of compensation adjustment, this paper calculates the resulting flow compensation schemes and filters out the best solution.(2) According to the stage characteristics of generation compensating operation, uses matrix method to analyze inflow forecasting error and probability of two stage. After calculating the final water level of two stage period by period, we can obtain the principal reservoir water level at the end of water level return period and the corresponding probability. By further analysis, we obtain the risk of principal reservoir water return under different flow compensation schemes.(3) Analyses the influence of cascade hydrostation inflow forecasting error on the power generation gain in the flow compensation period, considers the power loss caused by the risk of principal reservoir water level return at the end of back to storage period, and build the full-time scheduling model. By solving water return risk and total power generation gain expected value of different flow, theoretical and data support are provided for decision makers to choose the optimal generation compensating operation scheme. Finally, we use the historical data of Qing river cascade hydrostation to simulate generation compensating operation. The results show that the proposed method is reasonable and feasible, and it has certain engineering significance.