Influence Of Hydro-PV Complementary System On Short-term Optimal Operation Of Cascade Hydropower Stations

With the development of society and economy,the energy problems of China have become increasingly prominent.Developing renewable clean energy is an important means to alleviate the energy shortage and reduce the proportion of fossil energy consumption.However,the application of a single new energy is not conducive to the stable and safe operation of the power grid.The development of multi-energy complementary projects will help promote the integration of new energy into the grid,improve the stability of the energy system,and play a strong role in improving the energy industry structure.In this paper,the cascade hydropower station on the upper reaches of the Yellow River is taken as the research object,and the short-term adaptive operation strategy research of the cascade hydropower station is carried out considering Hydro-photovoltaic(PV)complementarity.First,the changing characteristics of the outflow flow process of Longyangxia Reservoir after Hydro-PV complementary is explored.Then,based on this characteristic,a short-term optimized operation strategy for the Laxiwa-Lijiaxia Cascade Hydropower Station is proposed.At last,the adaptive scheduling strategy of Longyangxia Hydropower Station is proposed under the consideration of smooth photovoltaic power fluctuation,in view of the frequent adjustment of units.The main research results are as follows:(1)Based on the measured data during the historical operation period of Longyangxia reservoir and combined with the weather characteristics,the daily output characteristics of Longyangxia Reservoir after the Hydro-PV complementation are summarized.The differences of the daily output process before and after the Hydro-PV project are analyzed from the aspects of the fluctuation of output,the daily output and the time characteristics of output.And six kinds of curve eigenvalues are proposed.Five typical daily discharge processes of Longyangxia Hydropower Station are obtained by K-means clustering model.The influence degree and mechanism of Hydro-PV project on daily discharge of Longyangxia reservoir are revealed by typical eigenvalues.(2)Research on adaptive operation of cascade hydropower stations downstream of Longyangxia under the conditions of Hydro-PV complementary.The short-term optimal dispatching model of the cascade hydropower station is constructed,and the model is solved to obtain the optimal dispatching scheme of the Laxiwa-Lijiaxia cascade hydropower station.The output characteristics,peak regulation capacity,and outflow capacity,the operating water level and the plant’s units operation and other indicators of the Laxiwa-Lijiaxia hydropower station before and after complementary were compared and analyzed.Finally,the adaptive dispatching strategy of the Laxiwa-Lijiaxia cascade hydropower station downstream after Longyangxia Hydro-PV complementarity is summarized and proposed.(3)Combining the research of the first two parts,the research on the adaptive operation of Longyangxia considering the stabilization of PV power fluctuations is carried out.Taking into account the differences in the fluctuation of photovoltaic output,a short-term optimal dispatching model of Longyangxia was constructed.The principles of PV power plant MPPT power generation and two smoothing PV power fluctuation methods to reduce the fluctuation of photovoltaic power are described.Aiming at the characteristics of PV output under 4 types of weather,considering the impact of different PV smoothing target values,a short-term optimal scheduling model of Longyangxia with target of minimum water consumption was established,and the operation of Longyangxia Hydropower Station after smoothing PV power fluctuations was optimized.Finally,the adaptive operation strategy of Longyangxia to suppress the fluctuation of PV power is proposed.