Research On Economic Dispatch Of The Pumped-Storage Power Station Assisting Coal-fired Units With Deep Peak Shaving

Large-scale wind power integration increases the peak shaving pressure of the system.Coal-fired units have undertaken the main peak shaving tasks and frequently participate in deep peak shaving.However,the peak shaving level of traditional coal-fired units has generally reached the lower limit,hindering the further development of wind power.In order to further improve the peak shaving capacity,China government encourages coal-fired units to carry out the flexibility retrofits.But coal-fired units frequently participating in deep peak shaving still generates high energy costs.At the same time,pumped-storage power stations with fast adjustment performance have low operating efficiency.Therefore,this article studies the economic dispatch of the pumped-storage power station assisting coal-fired units with deep peak shaving.The research content is as follows:Firstly,the methods to improve the flexibility of power system on the load side are analyzed.Market-based distributed energy trading is focused.The trading characteristics are analyzed,and three typical trading modes are summarized.Combined with the results of existing foreign pilot projects,suggestions are made for pilot projects in China at the current stage.Under current technical level and market conditions,it is believed that load-side flexibility plays a relatively limited role and the improvement of system flexibility still mainly depends on the flexibility retrofits of coal-fired units currently.Secondly,the technology to improve the flexibility of power system on the power supply side is studied.An energy consumption cost model that considering the hidden costs of coal-fired units is established,and an economic dispatch strategy for the power system that considers the deep peak shaving is proposed.Taking a 10-unit system as an example,the effectiveness of the proposed strategy is verified.The results show that the proposed strategy can effectively reduce the frequency of coal-fired units to operating at the deep peak shaving period,and the marginal price of the unit with and without compensation are both significantly lower than that of the conventional dispatch strategy.Therefore,the proposed strategy has better peak shaving economy.Finally,an economic dispatch of the pumped-storage power station assisting coal-fired units with deep peak shaving is proposed.According to the peak-shaving pressure of coal-fired units in the high-volatility wind power output scenario,combined with the problems of low pumped-storage operation flexibility,an economic dispatch of the pumped-storage power station assisting coal-fired units with deep peak shaving is proposed;the effectiveness of the proposed strategy is verified;the substitution benefit is introduced to analyze the applicability of the proposed strategy.The results show that the proposed dispatch strategy can effectively reduce the operating time of coal-fired units in the deep peak-shaving period,improving the utilization rate of pumped-storage stations and power grid company dispatch economy.