| In order to ensure the operation reliability of power system,it is necessary to balance the power supply and demand in real time.Because the generation and load need to achieve near real-time balance,so for the second level to minute level load fluctuations to achieve real-time balance,power grid operators need to rely on frequency modulation resources to adjust the small power supply and demand mismatch.Frequency modulation resources automatically adjust the output according to the operator’s signal to suppress short-term fluctuations.With the large-scale integration of new energy and the rapid growth of the installed capacity of electric vehicle charging piles,the inherent volatility and uncertainty increase the volatility of the power grid.It is necessary to further improve the power grid frequency regulation ability to ensure that the frequency fluctuates within the allowable range of the power grid.The traditional FM resources are affected by their own limitations,which are difficult to meet the growing demand of FM.Energy storage system can assist conventional units to participate in the auxiliary service of power grid frequency regulation,which can improve the safety,economy and service ability of auxiliary service of power plant frequency regulation.Battery energy storage system is an excellent frequency modulation resource with fast power response,adjustable capacity and high control precision.In addition,the power spot market is the latest trend of domestic power market development,so this paper studies and explores the control strategy and capacity allocation strategy of energy storage participating in FM auxiliary service in the power spot market.On the basis of combing and summarizing the domestic and foreign FM auxiliary service policies and the research status of energy storage participating in FM,this paper analyzes the significance of energy storage participating in FM in the spot market.By comparing the performance differences of common lithium batteries,the Li Fe PO4 battery which is more suitable for frequency modulation application scenario is selected,and the energy degradation model of Li Fe PO4 battery based on discharge depth is established to prepare for the control strategy and capacity configuration proposed in the later paper.Then,through the analysis of the evaluation performance index of each stage of FM auxiliary service,including regulation rate index,response time index and regulation accuracy index.According to the evaluation period of the three FM performance indexes,it is divided into three FM periods.Combined with the characteristics of battery SOC,a charging and discharging strategy based on different periods is proposed.In different frequency modulation periods,different charging and discharging strategies are selected according to the battery available capacity.Finally,the capacity allocation scheme is proposed based on the economy of energy storage participating in ancillary service market.In this paper,the cost-benefit model of battery energy storage participating in power system auxiliary frequency regulation under different market compensation policies is established by analyzing the evaluation and compensation rules of different auxiliary frequency regulation service markets.By analyzing the real data of auxiliary frequency regulation of 600 MW thermal power units,the paper analyzes the net income of the whole life cycle and the payback period of investment of the project respectively,and obtains the optimized battery system capacity allocation scheme by using particle swarm optimization algorithm.The results show that the proposed control strategy can effectively improve the FM effect of the joint system,and the capacity allocation scheme based on payback period can well participate in the project bidding of FM market. |
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