| With the energy crisis and the depletion of fossil energy,there is an urgent need for a renewable,clean and efficient way to use energy.As a result,the development and application of multi-energy microgrid has been emerged.The multi-energy microgrid is composed of multiple forms of energy,which utilizes mutual transformation among different energy to supply cold and thermal loads efficiently.Compared with traditional power system,multi-energy microgrid becomes more flexible in terms of operation scheduling through mutual coupling among different energy sources.In addition,energy storage is an important part of multi-energy microgrid.Due to the high cost of energy storage equipment,the energy storage capacity configuration will directly affect the reliability and economy of dispatch in microgrid.The paper is supported by National Key R&D Program of China(2017YFB0902200)and Science and Technology Project of State Grid Corporation of China(5228001700CW),focusing on the optimal dispatch of multi-energy microgrid and the allocation of hybrid energy storage capacity.The contents are as follows:A temperature control model of thermal load by heat pump is studied and an optimal economic dispatch model of multi-energy microgrid considering the temperature control equipment is established.Different from the real-time matching requirement between electric supply and demand,the thermal load is mainly characterized by the temperature index,which only need to reach a specified interval to meet the user's demand.The paper regards the heat pump as a temperature control device.Based on the first law of thermodynamics,the linear differential equation between thermal power and temperature rise is derived.Considering the temperature control characteristics of the thermal load,the optimal dispatch model of the multi-energy microgrid with temperature control equipment is established by taking the minimum total operating cost in scheduling period as the objective function.The results of the case study show that the temperature control equipment can increase consumption rate of the renewable energy and the economic of the system is improved.Considering the temperature control characteristics of thermal load,an optimal economic operation model of multi-energy microgrid with concentrating solar plant(CSP)and temperature control equipment is established.Considering the electro-thermal conversion of heat pump and the thermo-electric conversion of CSP,a closed-loop coupled temperature control model between CSP and heat pump is established,in which the heat exchange and heat loss between the heat pump and the thermal storage system is taken into account.The net load curve is calculated through forecast data of wind speed,solar radiation and load.Considering the difference of response time scales between electric and thermal energy storage,the net load curve is divided into high frequency and low frequency components based on discrete Fourier transform,which are respectively allocated to electric and thermal storage.Considering the heating cost and the heat curtailment cost of the CSP,the optimal dispatch model of the multi-energy microgrid is established with the minimum total operating cost in scheduling period as the objective function.The results of the case study show that the consideration of CSP and energy storage response can further improve the renewable consumption rate and optimize operational efficiency and economy.Based on the optimal dispatch model of multi-energy microgrid,the importance of the electric load is further considered.Based on the classification of electric load,an operation strategy of hybrid electric energy storage is established,and a two-layer optimal configuration model of multi-energy storage capacity is proposed.The system investment cost,operation and maintenance cost,loss of load penalty cost and wind(solar)energy curtailment penalty cost are set as the model objective function.The upper model is used to optimize the frequency segmentation point,and the lower model calculates the optimal operating cost through the optimal economic dispatch model.Since the variable of upper model contains only one dimension,the frequency segmentation point is enumerated by selecting the appropriate step size;the lower model is solved by particle swarm optimization and mixed integer linear programming.An unified capacity configuration of the hybrid energy storage system can be realized by the proposed model in the case study.In addition,considering the importance classification of electric load can reduce the power outage loss and the investment cost of electric energy storage. |
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