Multi-scale Operation Of Hydropower Stations In The Upper Yellow River Considering The Large-scale New Energy Integration Into Power Systems

To deal with climate change and energy crisis,the energy structure transformation has become an irreversible trend of energy system,thus promoting the development of renewable energy.Wind power and photovoltaic power,as relatively mature clean renewable energy sources,have got booming expansion and high penetration in the power systems,which has played an important role in energy conservation and emission reduction.However,due to the inherent stochastic,intermittent and volatility of wind and photovoltaic power,the operation process of these new energy sources shows significant reverse peak regulation characteristics.The increasing integration of new energy into the power system has brought new challenges to the operation of the power systems and increased the operation difficulty of peak shaving plants.Under this background,the serious curtailment of wind and photovoltaic power issues has emerged,which severely impedes the utilization of renewable energy.This paper aims to mitigate the new energy curtailment problem of power system by exploring the reasonable dispatching modes of multi-hydropower stations in different time scales.For this purpose,first,the supporting capacity of hydropower to the new energy consumption was analyzed.Second,the short-term hydro-thermal-wind-photovoltaic complementary operations of provincial power systems and multi-provincial interconnected power systems were studied considering the comprehensive utilization of reservoirs and the new demand of power system on hydropower.Finally,based on the quantitative relationship between the key factors of hydropower and new energy consumption,the long-term operation of hydropower stations was studied considering the comprehensive demand of hydraulic systems and electrical power systems.The main research work and achievements of this thesis are as follows:(1)The main influence factors of hydropower on the new energy consumption was analyzed based on the power generation characteristics of different types of energy and new energy consumption theory.The results show that the installed capacity of hydropower station determines the maximum support capacity for new energy consumption,while the water availability determined by the comprehensive utilization of reservoirs restricts its capacity on new energy consumption.In addition,the regulation capacity and operating condition of hydropower stations also affects the new energy consumption.(2)The short-term hydro-thermal-wind-photovoltaic complementary operation model of provincial power systems was proposed to increase the new energy consumption.Moreover,the adaptive simultaneous peak regulation strategy of hydropower plants was proposed to obtain reasonable and feasible hydropower generation plan together with a comparison model.The proposed model and strategy were performed in Qinghai grids of China to make the day-ahead scheduling plan of power systems in different scenarios.The results show that the hydropower can share most of the peak regulation task and decrease the thermal peak regulation demand by taking advantage of the flexible regulation capacity of hydropower plants based on the multi-energy complementary operation.Furthermore,the water availability for power generation of hydropower plants has great influence on the new energy consumption.There is a distinct difference of new energy consumption and power surplus or deficient in different water availability scenarios.(3)The short-term hydro-thermal-wind-photovoltaic complementary operation model of multi-provincial interconnected power systems combining with adaptive simultaneous peak regulation strategy was proposed to increase the new energy consumption.The proposed model and strategy were applied to the Qinghai-Gansu interconnected grids of China to verify the effectiveness together with actual operation data and a comparison model.The results show that the proposed model can increase the new energy consumption effectively by using the peak regulation capacity and power transmission capacity.Furthermore,there is a distinct difference of the hydropower operation modes between the Qinghai-Gansu interconnected power systems and Qinghai power grids.The results further illustrate that the power sources structure and the new energy output characteristics can affect the operation mode of hydropower stations in multi-energy complementary power system.(4)The hydro-thermal-wind-photovoltaic complementary operation model on ten-day scale was established.The model was used to explore the relationship among the water availability,the operating condition of hydropower stations and the new energy consumption by setting different scenarios.The Qinghai-Gansu interconnected power systems was selected a case study.The results show that the new energy consumption capacity of power system are various in different seasons.Under current installed capacity of new energy and load demand,some new energy power is inevitably curtailed.This curtailment issue is more serious in winter and summer compared with spring and autumn.Moreover,the relationship between the water availability and the new energy consumption are not exactly the same in different seasons.More importantly,the appropriate average daily outflow of hydropower plants is 500m3/s-800m3/s for Qinghai-Gansu interconnected power systems.The results further demonstrate that there is a maximum point of hydropower for promoting the consumption of new energy.In addition,too large or too small water availability is adverse to new energy consumption.(5)The long-term hydropower operation model was proposed by using the relationship between the key factors of hydropower and the new energy consumption.An improved optimization method based on individual constraints and group constraints was proposed to solve the model.The model and method were performed in the long-term optimization operation of cascade hydropower stations in the Upper Yellow River.The results show that the long-term hydropower operation considering the new energy consumption has a slight negative impact on the hydropower generation(decreased by 0.59%)compared to the conventional hydropower operation with the goal of maximizing the hydropower generation.Nonetheless,the improved model can increase the new energy consumption effectively(increased by 12.1%).Moreover,given the new energy consumption demand,Longyangxia reservoir should change the original operating rules and reserve a certain amount of storage capacity to undertake the new energy consumption task.Compared with the upper limit of guaranteeing zone for power generation,the water level of Longyangxia reservoir decreases during the whole operation period in the case of 10%or 15%new energy curtailment.