Economic Analysis And Comprehensive Evaluation Method For Electric Energy Storage

The efficient and clean utilization of energy is one of the key issues concerned worldwide.Energy saving and emission reduction in the electric power industry is an important way for efficient and clean use of energy.Electric energy storage(EES)technology is a key technology to improve the operating efficiency,security,and economy of the power system,and to promote the utilization efficiency of renewable energy.Establishing a scientific,reasonable and comprehensive EES evaluation method will clarify the value flow of the EES,give play to the multi-functional characteristics of the EES,and make the EES better use its due effect.Discovering the importance and the existing problems of the evaluation methods of EES economics,this dissertation devotes to theoretical analysis of EES from the aspects of capacity value and power value,and conducts evaluation method research.Based on the summarization of the production cost simulation method and the characteristics of Chinese power system,an economic dispatch model considering the performance of EES ancillary ability was proposed.A comprehensive analysis method for assessing the true value of grid-level energy storage was also proposed based on this model.The cost-benefit method was used to conduct a research on the economic evaluation of EES in the monopoly power system.A new energy storage compensation mechanism-the value-driven price compensation mechanism-was proposed.Taking China's current power system as an example,the economics of EES under the two-part tariff mechanism,time-of-use mechanism,and value-driven mechanism were studied.The key factors affecting the economic benefits of EES are analyzed in the form of theoretical derivation.The Monte Carlo method was used to analyze the uncertainty of technical and economic parameters.The research results show that the fuel cost,the start-up cost and grid-loss cost are the major part of the production cost.The grid node selection for the EES has little effect on the total production cost.The major role of EES is to reduce power grid losses,start-stop cost and fuel consumption.Under the two-part tariff mechanism,when the size of the energy storage power station is ralatively small,the efficiency of the energy storage system and the charge and discharge price have significant impact on the EES economy.If the scale of the EES is increased,the impact of the compensation coefficients will increase accordingly.Under the time-of-use mechanism,the benefits of EES are closely related to the peak-valley electricity price difference and the way in which EES operates.Under the value-driven mechanism,the impact of unit fuel prices,start-up cost,and wind power penetration on EES economy is particularly significant.The net present value fluctuation caused by parameter uncertainty even exceeds the difference caused by policy.A frequency regulation model was established for A-CAES,and the frequency regulation performance of CAES was analyzed.According to the requirements of power grid frequency regulation simulation,the relative-micro-increment method was used to build a state-space model for A-CAES sub-components.The mathematical model of A-CAES expansion and compression process was put forward for design conditions,off-design conditions and state-space model combination steps.The regional grid frequency regulation simulation model was put forward,and a novel A-CAES control strategy-the Transform Direction Ratio(TDR)control method-was given.The frequency regulation performance and economic benefits of A-CAES in the regional power grid were analyzed.Case study shows that the operation of A-CAES has a beneficial effect on frequency regulation.The frequency regulation effect of A-CAES adopting the TDR control strategy is better than that of the PID control strategy.Under the existing domestic frequency regulation compensation mechanism,A-CAES will get considerable benefits when offering frequency regulation service.The benefit of using the Shanxi frequency modulation compensation mechanism is higher than that of the Southern Power Grid frequency modulation compensation mechanism.A-CAES has limited value in reducing the cycling cost of thermal power units.A multi-entity comprehensive evaluation method for the EES power station was proposed.Starting from the evaluation indexes of the EES power stations by related agents in the power grid,two comprehensive evaluation criteria for the construction of the EES were proposed,and the characteristics of the two evaluation criteria were analyzed and compared.The expert weighting method and entropy weighting method were used to weight the evaluation indexes of the agents in order to obtain the final criteria.The result of the study indicates that the construction and operation of EES are beneficial to the individual power grid entities.The evaluation criteria based on the main body of the power grid is easier to implement than the evaluation criteria based on the profit-loss.However,the evaluation criteria based on the profit-loss can detail the flow direction of the profit and loss among the main bodies of the interest and weaken the subjective randomness of expert empowerment.When entropy technology is adopted,the evaluation criteria based on the main body of the power grid can distinguish the weight differences of different experts better than the evaluation criteria based on the profit-loss.When inclined to a certain subject,with the increase of the maximum weight coefficient or income weight coefficient,the difference between the final evaluation criteria of inclined to the whole society,wind power and users and the final evaluation criteria of inclined thermal power and power grid will increase,and the final evaluation criteria retain the characteristics of single subject evaluation indicators.