Research On Medium To Long-Term Multi-Objective Cooperative Operation Of Hydro-Wind-Photovoltaic Power In Water Scarcity Area

With the continuous emission of greenhouse gases worldwide and the announcement of domestic dual carbon targets,the importance of renewable energy is becoming increasingly prominent,especially for wind and solar power,which are experiencing a new period of rapid growth.The Yellow River Basin is a relatively rich area of wind and solar resources in the country and can provide strong support for the construction of a multi-energy complementary system proposed in the "Yellow River Basin Ecological Protection and High-Quality Development Plan".Wind and solar power have characteristics such as fluctuation,randomness,and intermittency,and their grid connection and absorption require flexible power sources to compensate and regulate them.Hydroelectric power is a well-performing renewable energy source that can complement wind and solar power generation.Currently,research in the field of hydropower,wind power,and solar power complementarity is mainly concentrated on short-term optimization of operation,and the results of short-term optimization still have room for improvement in a longer time range due to the lack of guidance in the medium and long term.The medium to long term time range is broader and involves many operational tasks,such as flood control,power generation,irrigation,ecology,etc.There are generally no simultaneous optimal solutions for multiple objectives,and there are also competitive relationships between some objectives,especially in water-scarce areas,where the aforementioned competitive relationships are more complex.In order to explore the operational rules and competition among multiple objectives in the medium to long-term coordinated operation of water,wind,and solar power in waterscarce areas,this paper takes six cascade reservoirs,including Longyangxia,Laxiwa,Lijiagou,Gongboxia,Jishixia,and Liujiagou,as the research objects of hydropower,and complementary wind and solar power outputs of five northwestern provinces in China as complementary objects,to construct a medium to long-term multi-objective optimization model for water,wind,and solar power and carry out research on longterm coordinated operation with multiple objectives in water-scarce areas.The main research results of the paper are as follows:(1)Aiming at the multi-objective decision-making problem of how to obtain better comprehensive benefits in the medium to long-term coordinated operation of water,wind,and wind,a medium to long-term multi-objective optimization model for water,wind,and wind is constructed.The NSGAⅡalgorithm was used to solve the model,and the TOPSIS method was used to comprehensively evaluate the non-inferior frontier.The results showed that the model had the advantage of comprehensively considering multiple objectives,which was helpful to improve the utilization rate of water resources to a certain extent.(2)In terms of the characteristics of the competitive relationship,the competitive relationship is the most complicated in the dry year with a high proportion of scenery,and the competitive relationship between the safety of snow prevention and flood control appears in the year of high water.Power generation in wet years,irrigation water shortage,and flow fluctuations in ice flood seasons are all sensitive to changes in the proportion of wind and rain,and irrigation water shortages are most sensitive to changes in the proportion of wind and solar.The sensitivity of flow fluctuations to changes in the proportion of wind and rain during the ice-flood season in normal water years is poor.(3)In terms of changing trends,the smaller the proportion of scenery in different typical years,the better the optimization effect of the non-inferior frontier.When the hydropower generation is similar,the irrigation water shortage in the entire dispatch period increases with the increase of the wind and solar proportion;when the irrigation water shortage is similar,the total hydropower generation decreases with the increase of the wind and wind proportion.Under the same water,wind,and solar power scene,the irrigation water shortage increases with the increase of the total hydropower generation.The order of complexity of competition relationship in different typical years is dry year > wet year > normal year.The order of risk in the ice flood season is the scene with a high proportion of wind and photovoltaic power scenes > medium proportion of wind and photovoltaic power scenes > low proportion of wind and photovoltaic power scenes.