| In recent years,with the continuous adjustment of China's power supply side structure,the proportion of renewable energy in the power grid is getting higher and higher.However,the renewable energy power generation represented by wind and solar energy has the characteristics of intermittence and randomness,which leads to the large-scale grid connection and the load peak valley difference.Under the condition of insufficient peak load regulation resources,the peak load regulation pressure of the system is increasing.In order to alleviate the difficulty of peak load regulation,various power grids have launched deep peak load regulation of thermal power units,but deep peak load regulation will increase the operating cost.This means that it is necessary to solve how to balance the economy and performance of thermal power peak regulation,and how to mine and optimize the use of new peak regulation resources.Energy storage can not only smooth the randomness of renewable energy generation on the supply side,make immediately response according to the dynamic changes of load on the demand side,but also makes the "rigid" power system of real-time power balance more "flexible"by storing and releasing electric energy,which is conducive to large-scale grid connection of energy storage.However,the National Development and Reform Commission and National Energy Administration's Notice on "Measures for the Supervision and Examination of Transmission and Distribution Pricing Costs"(FAB Price Regulation[2019]No.897)clearly states that pumped storage power stations,electricity storage facilities,and power grids cost of a power plant that independently determines the on-grid price are not included in the cost of transmission and distribution,which means that how to establish a market-based mechanism will become a key issue affecting the application and promotion of energy storage in the power system and the realization of its commercial value.The main research contents of this article are as follows:(1)The development status,relevant policies and application prospects in power system of energy storage technology at home and abroad are analyzed.First of all,from the development and application of energy storage technology.the paper compares the development and application scale of energy storage technology in the world and China,and forecasts the development trend of energy storage technology in the future.Then,the development prospects of different energy storage technologies are compared and analyzed,and the relevant policies and existing problems of energy storage technology development in China are sorted out.Finally,combined with the typical characteristics of the development of energy storage industry,the paper analyzes the application status and Prospect of energy storage in power system.(2)The evolution trend of energy storage development cost and the model of optimal equipment selection are put forward.In view of physical energy storage.electrochemical energy storage and other types of energy storage.the maturity of different energy storage technologies is compared,and the calculation model of energy storage cost based on the whole life cycle is proposed,and the learning curve is introduced into energy storage cost analysis to establish the evolution trend of different energy storage costs.Finally,the evaluation index system of energy storage equipment type selection is constructed from four dimensions of economy,society,environment and technology,and the evaluation model of energy storage equipment type selection based on consistency principle and fuzzy optimal worst method is proposed.The results of case analysis show that although the economy of lithium-ion battery is poor,its sociality,environment and technology are relatively good,and its comprehensive benefits are the most.which has a bright future.(3)The economic boundary analysis model of energy storage participating in electricity market transaction is proposed.Considering the scenario of clean energy subsidy,the concept of net load curve considering the fluctuation of clean energy output is proposed,and the clustering optimization model of peak and valley period is proposed to divide the peak,flat and valley periods of load curve flexibly.Furthermore,from the perspective of life cycle,the paper analyzes the cost and benefit of energy storage participating in the electricity market,puts forward the calculation model of the optimal peak valley time-of-use price difference of energy storage,and analyzes the examples of lithium-ion battery and liquid vanadium battery.The results show that in 2025 and 2030,the investment cost per unit capacity of lithium-ion batteries and liquid flow batteries will be reduced to 7500 yuan/kW,4900 yuan/kW,5500 yuan/kW and 2800 yuan/kW The corresponding critical profit price differences are 0.68 yuan/kW·h,0.79 yuan/kW·h,0.45 yuan/kW·h and 0.52 yuan/kW·h,respectively,which approach to the critical profit price of near pumped storage and compressed air energy storage.(4)A multi-level cooperative transaction optimization model of energy storage participating in electricity market is proposed.Considering the long-term contract,day ahead spot and real-time equilibrium time difference in electricity market,the paper analyzes the difference effect of energy storage participating in different power market strategic transactions,and proposes the coordination model of energy storage participating in power contract transactions,the optimization model of energy storage participating in micro grid day ahead transactions and the optimization model of energy storage participating in wind power real-time transactions.By building the above three-level market transaction model,the energy storage can participate in the”medium and long term-day ahead-real-time" three-level market optimization step by step,especially-the real-time balance market.Considering the uncertainty of wind power,the wind storage joint bidding transaction optimization model is constructed.Finally,through the case analysis of the above three-level market transaction optimization model,the applicability of the transaction strategy is established.(5)The boundary value analysis model of transaction economy of energy storage participating in auxiliary service market is proposed.This paper compares the rules of energy storage participating in peak load regulation in Northwest and Northeast China regional markets,and studies the optimal capacity of energy storage participating in peak load regulation from the perspective of economic load rate.Further,under the guidance of Qinghai energy storage peak regulation trading rules in Northwest China,the paper puts forward an economic boundary value analysis model of energy storage participating in auxiliary service market.The results show that:1)the best valley filling proportion of energy storage participating in peak load regulation is 20%.and the best energy storage system capacity of power grid accounts for 9%:2)when the hours of peak load regulation are 500h,the price of peak load regulation of energy storage should reach 1.385 yuan/kW·h.If there is a time-of-use price of peak and valley,the price of peak load regulation of energy storage is 1.008 yuan/kW·h.If obtainning the subsidy of clean energy generation(50%),the price of peak load regulation can be reduced to 0.585 yuan/kW·h;3)If the cost is recovered in a fully market-oriented way,the peak regulation price is 1.602 yuan/kW·h.With the increase of the hours of energy storage peak regulation,the price threshold of energy storage peak regulation gradually decreases.(6)A transaction optimization model of energy storage participating in peak regulation auxiliary service market is put forward.The costs of thermal power,energy storage and flexible load participating in peak load regulation auxiliary service transaction are calculated respectively,in which three peak load regulation states are considered:conventional peak load regulation,deep peak load regulation and oil input peak load regulation.Then,the optimal model of energy storage participating in PV peak regulation auxiliary service transaction is constructed,and the schemes of PV peak regulation auxiliary service transaction before and after energy storage in different weather conditions are compared.Finally,the optimization model of peak load regulation is put forward.The results show that when thermal power,energy storage and demand response jointly participate in the system,the system peak load regulation cost and wind abandonment rate are the lowest,which shows that multi-sources joint peak load regulation has collaborative optimization effect and will bring incremental benefits to the system.(7)The value analysis and business model of energy storage participating in electricity market transaction are designed.Considering the comprehensive value of energy storage in auxiliary services,power grid,power users and renewable energy access,this paper analyzes the function and comprehensive value of energy storage system,selects the comprehensive value evaluation index system of energy storage,and calculates the comprehensive value of energy storage to power side,power grid side and user side from the dimensions of economic benefits,external benefits and emission reduction benefits.Furthermore,the business models of energy storage operation for power supply side,grid side and user side are designed respectively.Finally,the profitability of different business models is analyzed. |
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