Energy storage rate optimization method based on cold and hot dual energy storage system

Abstract

The invention relates to the technical field of energy storage rate optimization, and discloses an energy storage rate optimization method based on a cold and hot dual energy storage system, which comprises the following steps: constructing an energy storage rate optimization model, the energy storage rate optimization model comprises an objective function and an energy storage constraint, wherein the objective function takes the life cycle annual converted cost of the cold and hot dual-energy storage system as an optimization objective and takes the investment payback period of the cold and hot dual-energy storage system as a main constraint condition; respectively determining the design daily cumulative loads of the building needing energy supply and where the cold and hot energy storage system is located in summer and winter; setting a plurality of energy storage rates, and successively substituting the plurality of energy storage rates into the energy storage rate optimization model to solve the energy storage rate optimization model, so as to obtain solving results of the energy storage rate optimization model corresponding to different energy storage rates, and finally finding the energy storage rate corresponding to the optimal solving result of the energy storage rate optimization model. The method provides an objective basis for performance evaluation of the energy storage system.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage rate optimization, and in particular to an energy storage rate optimization method based on a cold and hot dual energy storage system. Background Art

[0002] In traditional cold and heat source systems, the combination of chillers and boilers has long dominated. Among them, chillers are driven by electricity and can reduce operating costs by using cold storage technology to take advantage of the difference in peak and valley electricity prices; however, gas boilers have no significant advantages in terms of economic efficiency due to the lack of time-period differences in fuel prices. This essential difference has led to previous studies focusing on the single-dimensional optimization of cold storage technology.

[0003] However, with the advancement of full electrification, heat pumps have gradually replaced traditional boilers. Heat pumps and chillers are both electrically driven devices, and their energy costs are significantly affected by the peak-valley electricity price mechanism, which makes thermal storage technology economically feasible. Therefore, under the new energy utilization model, the synergy of cold storage and heat storage should be considered at the same time to further optimize the energy utilization efficiency of the system.

[0004] In the design of energy storage systems, the determination of energy storage rate is crucial. The larger the energy storage rate, the higher the initial investment of the energy storage device, but the cost-saving benefits it brings are also more obvious, and the long-term operating costs are lower. How to strike a balance between the economy and investment efficiency of the entire life cycle and find the optimal energy storage rate under multi-dimensional objective constraints is an important issue that needs to be solved urgently.

[0005] The optimization of energy storage rate of dual cold storage system is different from that of single cold storage system. On the one hand, compared with the electricity price arbitrage of single cold storage system which only covers the cooling period, the peak-valley electricity price arbitrage window of dual cold storage system is extended to the whole climate cycle, which can reduce the operation cost to a greater extent; on the other hand, the reuse characteristics of energy storage device make the system not need to add new heat storage investment on the basis of retaining the original cold storage capacity, but can simultaneously reduce the installed capacity of cooling / heating host, forming an intensive configuration of "one storage and double reduction", further reducing the initial investment of the host. In summary, the dual cold storage system is different from the single cold storage system, and it is more affected by the energy storage rate. Therefore, it is necessary to propose an effective optimization method for the energy storage rate of the dual cold storage system. Summary of the invention

[0006] The present invention provides an energy storage rate optimization method based on a cold and hot dual energy storage system to solve the above problems.

[0007] The present invention is achieved through the following technical solutions: A method for optimizing energy storage rate based on a cold and hot dual energy storage system, the method comprising: Build an energy storage rate optimization model, where the energy storage rate optimization model includes an objective function with the annual equivalent cost of the cold and heat dual energy storage system life cycle as the optimization goal and the investment payback period of the cold and heat dual energy storage system as the main constraint condition, and an energy storage capacity constraint; Respectively determine the cumulative daily loads of the energy supply-demand building where the cold and heat dual energy storage system is located in summer and winter; Set multiple energy storage rates, and substitute the multiple energy storage rates into the energy storage rate optimization model one by one to solve the energy storage rate optimization model, so as to obtain the solution results of the energy storage rate optimization model corresponding to different energy storage rates, and finally find the energy storage rate corresponding to the optimal solution result of the energy storage rate optimization model.

[0008] As an optimization, the objective function includes an optimization goal and main constraint conditions. Among them, the optimization goal is: ; ; The main constraint conditions are: ; ; Among them, represents the annual equivalent cost of the cold and heat dual energy storage system life cycle; represents the investment payback period of the cold and heat dual energy storage system; represents the annual operating electricity cost of the cold and heat dual energy storage system, in ten thousand yuan; represents the equipment maintenance cost of the cold and heat dual energy storage system, in ten thousand yuan; represents the equipment life of the cold and heat dual energy storage system; represents the total initial investment in building the cold and heat dual energy storage system, in ten thousand yuan; represents the total initial investment of the benchmark scheme system, in ten thousand yuan; represents the annual operating electricity cost of the benchmark scheme system, in ten thousand yuan; is the annual equipment maintenance cost of the benchmark scheme system, in ten thousand yuan, is a positive number.

[0009] As an optimization, the annual operating cost of the cold and heat dual energy storage system is composed of the sum of the refrigeration operating cost and the heating operating cost for 8,760 hours throughout the year. The specific expression is: ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; Among them, is the electricity unit price at time i , with the unit of yuan / kWh; represents the system energy consumption at time i in summer, with the unit of kW; represents the chilled water storage energy consumption of the chiller at time i , with the unit of kW; represents the energy consumption of the circulating chilled water pump at time i , with the unit of kW; represents the energy consumption of the chilled water release pump at time i , with the unit of kW; represents the energy consumption of the direct supply chilled water pump of the chiller at time i , with the unit of kW; represents the energy consumption of the chilled water storage pump of the chiller at time i , with the unit of kW; represents the energy consumption of the chiller during direct supply at time i , with the unit of kW; represents the energy consumption of the cooling water pump at time i , with the unit of kW; represents the energy consumption of the cooling tower at time i , with the unit of kW; represents the winter i system energy consumption at time , with the unit of kW; i represents the heat storage energy consumption of the heat pump at time , with the unit of kW; i represents the energy consumption of the circulating hot water pump at time , with the unit of kW; i represents the energy consumption of the hot water release pump at time is the i energy consumption of the direct supply hot water pump of the heat pump at time Indicates i The energy consumption of the heat pump thermal energy storage hot water pump at time, unit: kW; Indicates i The direct supply energy consumption of the heat pump at time, unit: kW Indicates i The chilled water storage capacity of the chiller at time, unit: kW; Indicates i The corrected coefficient of performance of the chiller during chilled water storage at time; Indicates the power consumption of the circulating chilled water pump per unit refrigerating capacity, unit: kW / kW; Indicates the power consumption of the chilled water release pump per unit refrigerating capacity, unit: kW / kW; Indicates i The cold quantity released by the energy storage device at time, unit: kW; Indicates the power consumption of the chilled water pump per unit refrigerating capacity, unit: kW / kW; Indicates i The cold quantity of the chiller during direct supply at time, unit: kW; Indicates i The corrected coefficient of performance of the chiller during direct supply at time; Indicates the power consumption of the cooling water pump per unit refrigerating capacity, unit: kW / kW; Indicates the power consumption of the cooling tower per unit refrigerating capacity, unit: kW / kW; Indicates i The heat storage quantity of the heat pump at time, unit: kW; Indicates i The corrected coefficient of performance of the heat pump during heat storage at time; Indicates the power consumption of the circulating hot water pump per unit heating capacity, unit: kW / kW; Indicates the power consumption of the hot water release pump per unit heating capacity, unit: kW / kW; Indicates i The total heat quantity released by the energy storage device at time, unit: kW; Indicates the power consumption of the hot water pump per unit heating capacity, unit: kW / kW; Indicates i The heat quantity released by the direct supply of the heat pump at time, unit: kW; Indicates i The corrected coefficient of performance of the heat pump during direct supply at time.

[0010] As an optimization, the total initial investment of the construction of the combined cooling and heat energy storage system The specific calculation formula is: ; Among them, , , , , , , respectively represent the initial investment of the chiller, heat pump, energy storage device, plate heat exchanger, water pump, floor area, and power capacity increase, with the unit of ten thousand yuan.

[0011] As an optimization, the annual maintenance cost of the equipment The specific calculation formula is: ; where represents the annual maintenance cost ratio.

[0012] As an optimization, the energy storage capacity constraint is specifically: During the energy storage period, the reservoir is filled, and the energy corresponding to the reservoir capacity plus the actual cumulative direct supply energy of the host meets the daily cumulative load of the building to be supplied with energy; where the host includes a chiller for refrigeration in summer and a heat pump for heating in winter.

[0013] As an optimization, the specific process of substituting multiple energy storage rates into the energy storage rate optimization model to solve the energy storage rate optimization model, thereby obtaining the solution results of the energy storage rate optimization model corresponding to different energy storage rates, and finally finding the optimal energy storage rate corresponding to the energy storage rate optimization model is as follows: Define the energy storage rate as x times the cumulative cooling load on the summer design day; Calculate the reservoir capacity through the energy storage rate; Based on the reservoir capacity, the design day cumulative loads of the building to be supplied with energy in summer and winter, and based on the energy storage capacity constraint, calculate the required capacity of the host; Select the host according to the required capacity; Calculate the energy consumption of the selected host based on the set energy storage and discharge scheduling strategy, and calculate the operating cost and total initial investment based on the calculated energy consumption; Calculate the annual discounted cost of the life cycle of the cold and heat dual energy storage system and the investment payback period of the cold and heat dual energy storage system based on the operating cost and total initial investment respectively; Judge whether all energy storage rates have been substituted into the energy storage rate optimization model and the corresponding solution results have been calculated. If so, jump to the next step; otherwise, change the energy storage rate and return to the first step; Obtain the solution results of the energy storage rate optimization model corresponding to different energy storage rates.

[0014] As an optimization, the energy storage and discharge scheduling strategy is specifically as follows: First-round energy discharge: When the load demand of the building requiring energy supply exceeds the design capacity of the main machine, the priority energy storage device starts to discharge energy to meet the excess load of the building requiring energy supply that exceeds the design capacity of the main machine. If there is no remaining energy after the energy storage device discharges energy, the remaining load of the building requiring energy supply is directly supplied by the main machine discharging energy. If there is remaining energy after the energy storage device discharges energy, the remaining energy of the energy storage device enters the second-round energy discharge; Second-round energy discharge: Determine whether the remaining energy of the energy storage device meets the cumulative load during the peak period of the building requiring energy supply. If it does not meet, the remaining energy of the energy storage device is evenly distributed to each moment during the peak period, and the remaining load is directly supplied by the main machine discharging energy; if it meets, all the loads during the peak period are supplied by the energy storage device discharging energy, and the remaining energy enters the third-round energy discharge; Third-round energy discharge: Determine whether the remaining energy of the energy storage device meets the cumulative load during the high-peak period of the building requiring energy supply. If it does not meet, the remaining energy of the energy storage device is evenly distributed to each moment during the high-peak period, and the remaining load is directly supplied by the main machine discharging energy; if it meets, all the loads during the high-peak period are supplied by the energy storage device discharging energy, and the remaining energy enters the fourth-round energy discharge; Fourth-round energy discharge: Determine whether the remaining energy of the energy storage device meets the cumulative load during the flat-peak period of the building requiring energy supply. If it does not meet, the remaining energy of the energy storage device is evenly distributed to each moment during the flat-peak period, and the remaining load is directly supplied by the main machine discharging energy; if it meets, all the loads during the flat-peak period are supplied by the energy storage device discharging energy; after the four rounds of energy discharge end, the energy storage device enters the energy storage period.

[0015] As an optimization, the energy storage rate optimization method further includes: Quantify the flexible adjustment ability of the cold and heat dual energy storage system corresponding to the optimal solution result to evaluate the flexible effect under the optimal energy storage rate.

[0016] As an optimization, the quantification content for quantifying the flexible adjustment ability includes the maximum adjustment power under sub-periods, the average adjustment power under sub-periods, the maximum adjustment ratio under sub-periods, the average adjustment ratio under sub-periods, the cumulative adjustment power ratio under sub-periods, the summer load transfer rate under sub-periods, and the winter load transfer rate under sub-periods. Among them, the specific calculation formula for the maximum adjustment power under sub-periods is: ; ; ; Among them, represents the maximum adjustment power of the cold and heat dual energy storage system during the peak period, with the unit of kW; Indicates peak hours i The energy consumption of the cold and heat double energy storage system at the moment, unit: kW; Indicates peak hours i The energy consumption of the reference scheme system at the moment, unit: kW; Indicates the maximum regulation power of the cold and heat double energy storage system during peak hours, unit: kW; Indicates peak hours i The energy consumption of the cold and heat double energy storage system at the moment, unit: kW; Indicates peak hours i The energy consumption of the reference scheme system at the moment, unit: kW; Indicates the maximum regulation power during off-peak hours, unit: kW; Is the off-peak hour i The energy consumption of the energy storage system at the moment, unit: kW; Indicates off-peak hours i The energy consumption of the reference scheme system at the moment, unit: kW; The specific calculation formula for the average regulation power under the time periods is: ; ; ; Among them, Indicates the average regulation power during peak hours, unit: kW; Indicates the total duration of the annual peak hours, unit: h; Indicates the average regulation power during peak hours, unit: kW; Indicates the total duration of the annual peak hours, unit: h; Indicates the average regulation power during off-peak hours, unit: kW; Indicates the total duration of the annual off-peak hours, unit: h; The specific calculation formula for the maximum regulation ratio under the time periods is: ; ; ; Among them, Indicates the maximum regulation ratio during peak hours; Indicates the maximum regulation ratio during peak hours; Indicates the maximum regulation ratio during off-peak hours; The specific calculation formula for the average regulation ratio under the time periods is: ; ; ; Among them, represents the average regulation ratio during peak hours; represents the average regulation ratio during high-peak hours; represents the average regulation ratio during flat-rate hours; The specific calculation formula for the cumulative regulation power ratio under different time periods is: ; ; ; Among them, represents the cumulative regulation power ratio during peak hours; represents the start time of the peak hours in 24 hours a day, in unit of h; represents the end time of the peak hours in 24 hours a day, in unit of h; represents the cumulative regulation power ratio during high-peak hours; represents the start time of the high-peak hours in 24 hours a day, in unit of h; represents the end time of the high-peak hours in 24 hours a day, in unit of h; represents the cumulative regulation power ratio during flat-rate hours; represents the start time of the flat-rate hours in 24 hours a day, in unit of h; represents the end time of the flat-rate hours in 24 hours a day, in unit of h; The specific calculation formula for the summer load transfer rate under different time periods is: ; ; ; Among them, represents the summer peak-hour load transfer rate; represents the start time of summer cooling, in unit of h; represents the end time of summer cooling, in unit of h; represents the start time of the peak hours in 24 hours a day in summer, in unit of h; represents the end time of the peak hours in 24 hours a day in summer, in unit of h; represents the summer peak hours i energy consumption of the combined cooling and heat energy storage system at time, in unit of kW; represents the summer peak hours i energy consumption of the reference scenario system at time, in unit of kW; represents the summer high-peak-hour load transfer rate; represents the start time of the high-peak hours in 24 hours a day in summer, in unit of h; Indicates the end time of the peak period within 24 hours in summer, with the unit of h; Indicates the peak period in summer i The energy consumption of the cold and heat energy storage system at the moment, with the unit of kW; Indicates the peak period in summer i The energy consumption of the reference scheme system at the moment, with the unit of kW; Indicates the load transfer rate during the flat price period in summer; Indicates the start time of the flat price period within 24 hours in summer, with the unit of h; Indicates the end time of the flat price period within 24 hours in summer, with the unit of h; Indicates the flat price period in summer i The energy consumption of the cold and heat energy storage system at the moment, with the unit of kW; Indicates the flat price period in summer i The energy consumption of the reference scheme system at the moment, with the unit of kW; The specific calculation formula for the load transfer rate in winter under sub-time periods is: ; ; ; Among them, Indicates the load transfer rate during the peak period in winter; Indicates the start time of cooling supply in winter, with the unit of h; Indicates the end time of cooling supply in winter, with the unit of h; Indicates the start time of the peak period within 24 hours in winter, with the unit of h; Indicates the end time of the peak period within 24 hours in winter, with the unit of h; Indicates the peak period in winter i The energy consumption of the cold and heat energy storage system at the moment, with the unit of kW; Indicates the peak period in winter i The energy consumption of the reference scheme system at the moment, with the unit of kW; Indicates the load transfer rate during the peak period in winter; Indicates the start time of the peak period within 24 hours in winter, with the unit of h; Indicates the end time of the peak period within 24 hours in winter, with the unit of h; Indicates the peak period in winter i The energy consumption of the cold and heat energy storage system at the moment, with the unit of kW; Indicates the peak period in winter i The energy consumption of the reference scheme system at the moment, with the unit of kW; Indicates the load transfer rate during the flat price period in winter; Indicates the starting moment of the flat-rate period in a 24-hour winter day, with the unit of h; Indicates the ending moment of the flat-rate period in a 24-hour winter day, with the unit of h; Indicates the winter flat-rate period i The energy consumption of the cold and heat dual energy storage system at a certain moment, with the unit of kW; Indicates the winter flat-rate period i The system energy consumption of the reference scheme at a certain moment, with the unit of kW.

[0017] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1. The present invention comprehensively considers factors such as initial investment, operation cost, peak-valley electricity price, and load characteristics, and obtains the key factor curves of the annual cost value and investment payback period under different energy storage ratios, demonstrating the internal relationships between the energy storage ratio and key indicators such as initial investment, space demand, load transfer rate, operation cost in the cooling season, and operation cost in the heating season, providing a strong basis for project investment decisions, helping decision-makers comprehensively grasp the economic characteristics of the project, and making scientific and reasonable investment choices.

[0018] 2. Based on hourly load, design parameters such as the capacity of the main unit, energy storage device, and water supply temperature, the present invention obtains the hourly energy release strategy of the system under different optimized energy storage ratios, guides the efficient operation of the system, reduces the operation cost, and improves the economy of the system.

[0019] 3. The present invention can evaluate the power load regulation amount and power load transfer rate under different energy storage ratios, quantify the flexible regulation ability of the energy storage system, provide an objective basis for the performance evaluation of the energy storage system, and promote the energy storage system to play a greater role in the field of demand-side response. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, form a part of this application, and do not constitute a limitation to the embodiments of the present invention. In the drawings: Figure 1 is a flowchart of a method for optimizing the energy storage ratio based on a cold and heat dual energy storage system according to the present invention; Figure 2 is a flowchart of solving the energy storage ratio optimization model in the embodiment; Figure 3 is a flowchart of the main unit selection iteration in the embodiment; Figure 4 is a schematic diagram of the energy release strategy of the energy storage in the embodiment; Figure 5 is a specific flowchart of the first-round energy release in the embodiment; Figure 6 is a specific flowchart of the second-round energy release in the embodiment; Figure 7Specific flowchart of the third round of energy release in the embodiment; Figure 8 Specific flowchart of the fourth round of energy release in the embodiment; Figure 9 Flowchart for determining the capacity of the chiller; Figure 10 Flowchart for determining the capacity of the air source heat pump. Detailed implementation manners

[0021] To make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the embodiments and the accompanying drawings. The illustrative embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention.

[0022] In actual engineering, it is difficult to conveniently and accurately find the energy storage rate of the cold and heat dual energy storage system, and the appropriate energy storage rate happens to be the key to the success or failure of the cold and heat dual energy storage system. Therefore, it is necessary to find the balance point of influencing factors such as building type, floor area, electricity price policy, etc., and study the optimization design method of the energy storage rate under single-objective multi-dimensional constraints.

[0023] In actual engineering, the full life cycle economy evaluation and investment efficiency of the cold and heat dual energy storage system are often concerned. The energy storage system usually has a relatively high initial investment (such as equipment purchase and installation costs), but a relatively low long-term operation cost (such as using off-peak electricity prices for energy storage and reducing peak electricity consumption costs). Only focusing on the initial investment or short-term benefits will lead to decision-making biases. The life cycle annual equivalent cost (LCC) can more comprehensively reflect the long-term economy of the system by converting the costs within the full life cycle (initial investment, operation and maintenance, energy costs, salvage value, etc.) into annual average costs. The payback period directly reflects the time required for the project to recover the initial investment and is one of the most concerned indicators for investors. The shorter the payback period, the lower the risk of capital liquidity. By analyzing the payback period (such as the impact of different energy storage rates on the payback period), the sensitivity of the adjustment of the energy storage rate to the investment efficiency can be evaluated. Therefore, aiming at the life cycle annual equivalent cost as the optimization objective and the payback period as the main constraint condition, in essence, it incorporates the economy of the technical solution (optimal long-term cost) and the investment efficiency (short-term capital efficiency) into a unified framework to ensure that the selection of the energy storage rate can not only meet the long-term energy-saving and cost-reducing requirements but also meet the requirements of investors for risk control and return period.

[0024] The influencing factors of the energy storage rate include climate characteristics, building types, electricity price policies, and architecture characteristics. These influencing factors will affect the investment, floor space, operation cost, and operation and maintenance difficulty of the system, thus having an indirect impact on the economy and investment efficiency. Therefore, the present invention will comprehensively consider the coupling relationship and evaluation index of the above influencing factors, take the annual equivalent cost of the system life cycle as the optimization goal and the investment payback period as the main constraint condition, and obtain the appropriate energy storage rate of the cold and heat dual energy storage system, providing intuitive and convenient data support for the design of the energy storage system.

[0025] Embodiment 1 of the present invention provides an energy storage rate optimization method based on a cold and heat dual energy storage system, as Figure 1 shown, the energy storage rate optimization method includes: S1. Construct an energy storage rate optimization model, where the energy storage rate optimization model includes an objective function with the annual equivalent cost of the cold and heat dual energy storage system life cycle as the optimization goal and the investment payback period of the cold and heat dual energy storage system as the main constraint condition, and an energy storage capacity constraint; In some embodiments, the objective function includes an optimization goal and a main constraint condition. Among them, the optimization goal is: ; ; The main constraint condition is: ; ; is the annual equivalent cost of the cold and heat dual energy storage system life cycle, is the investment payback period of the cold and heat dual energy storage system; represents the annual operation electricity cost of the cold and heat dual energy storage system, in ten thousand yuan; represents the equipment maintenance cost of the cold and heat dual energy storage system, in ten thousand yuan; represents the equipment life of the cold and heat dual energy storage system; represents the total initial investment for building the cold and heat dual energy storage system, in ten thousand yuan; represents the total initial investment of the reference scheme system, in ten thousand yuan; represents the annual operation electricity cost of the reference scheme system, in ten thousand yuan; is the annual equipment maintenance cost of the reference scheme system, in ten thousand yuan, is a positive number.

[0026] The common cold and heat dual energy storage system is 5 years. Therefore, generally speaking, NN it is sufficient to take the value of 5.

[0027] In some embodiments, the energy storage capacity constraint is specifically: During the energy storage period, the reservoir is filled up, and the energy corresponding to the reservoir capacity plus the actual energy accumulated by the direct supply of the main unit meets the daily cumulative load of the energy-required building; wherein, the main unit includes a chiller for refrigeration in summer and a heat pump for heating in winter, and in this embodiment, the heat pump usually adopts an air source heat pump.

[0028] In this way, with the annual equivalent cost of the whole life cycle as the optimization goal and the investment payback period as the main constraint condition, the optimal energy storage rate of a single target under multiple constraints is accurately solved, comprehensively reflecting the economy of the whole life cycle and the investment efficiency of the system, and ensuring the best balance between cost and benefit in long-term operation.

[0029] S2. Determine the daily cumulative loads of the energy-required building where the cold and heat dual energy storage system is located in summer and winter respectively; S3. Set multiple energy storage rates, and substitute the multiple energy storage rates into the energy storage rate optimization model one by one to solve the energy storage rate optimization model, so as to obtain the solution results of the energy storage rate optimization model corresponding to different energy storage rates, and finally find the energy storage rate corresponding to the optimal solution result of the energy storage rate optimization model.

[0030] The specific process of S3 is as follows: S3.1. Define the energy storage rate as x times the daily cumulative cooling load in summer; S3.2. Calculate the reservoir capacity through the energy storage rate; S3.3. Calculate the required capacity of the main unit based on the reservoir capacity, the daily cumulative loads of the energy-required building in summer and winter, and based on the energy storage constraint; S3.4. Select the main unit according to the required capacity; S3.5. Calculate the energy consumption of the selected main unit based on the set energy storage and release strategy, and calculate the operation cost and total initial investment according to the calculated energy consumption; S3.6. Calculate the annual equivalent cost of the cold and heat dual energy storage system life cycle and the investment payback period of the cold and heat dual energy storage system according to the operation cost and total initial investment respectively; S3.7. Determine whether all energy storage rates have been substituted into the energy storage rate optimization model and the corresponding solution results have been calculated. If so, jump to S3.8; otherwise, change the energy storage rate and return to S3.1; S3.8. Obtain the solution results of the energy storage rate optimization model corresponding to different energy storage rates.

[0031] Here, the energy storage rate gradually changes from 0% to 100%, and the change rate each time is 1%. The whole flow chart is as Figure 2 shown.

[0032] The iteration flow chart of the main unit selection is asFigure 3 as shown

[0033] Next, the implementation method of each step in step S3 will be introduced through specific cases.

[0034] I. Determination of energy storage capacity In summer, the energy storage capacity is reflected in the chilled water storage capacity of the cold and heat dual energy storage system. In winter, the energy storage capacity is reflected in the heat storage capacity of the cold and heat dual energy storage system. In the design of the entire building energy system, the determination of the energy storage capacity is a key link. Its input conditions are mainly based on the annual cooling and heating loads of the building and the cooling and heating loads on the design day. The annual cooling and heating loads reflect the overall demand for cooling and heating in the building over a one-year period, while the cooling and heating loads on the design day focus on the cooling and heating demand conditions on a specific design day. For the calculation of the chilled water storage capacity in summer, the energy storage rate needs to be defined first. The energy storage rate refers to the percentage of the cumulative cooling load on the summer design day. Through this proportional relationship, the chilled water storage capacity in summer can be obtained, as shown in the following formula: ; (1-1) In the formula: is the chilled water storage capacity in summer, kW; is the energy storage rate; is the cumulative cooling load on the summer design day, kW; The specific heat capacity of water at different temperatures is shown in Table 1-1: Table 1-1 Specific heat capacity of water at different temperatures 4℃ 11℃ 41℃ 46℃ 4.217 kj / (kg·k) 4.203 kj / (kg·k) 4.177 kj / (kg·k) 4.176 kj / (kg·k) It can be seen that the specific heat capacity of water at different temperatures varies little within a certain temperature range. To simplify the calculation, it is assumed that the mass of the energy storage medium in the system remains unchanged in summer and winter, and the specific heat capacity is taken as the average temperature of the supply and return water in winter and summer. According to the balance relationship of heat exchange, the heat storage capacity in winter can be calculated, and the calculation formula is as follows: ; (1-2) In the formula: is the heat storage capacity in winter, kW; is the supply water temperature of the winter host, °C; is the return water temperature of the winter host, °C; is the supply water temperature of the summer host, °C; is the return water temperature of the summer host, °C; is the specific heat capacity of water at the average temperature of the summer supply and return water, j / (kg·k); It is the specific heat capacity of water at the average temperature of the supply and return water in winter, J / (kg·K).

[0035] II. Determination of the host capacity: The commonly used electric refrigeration host is a chiller, and the electric heating host is an air source heat pump. Since the energy efficiency of the chiller is much higher than that of the air source heat pump in summer, the chiller is used for both summer chilled water storage and direct supply; the actual capacity of the chiller needs to be determined by comparing two values. The chiller capacity needs to meet the following two conditions: (1) Fill the water storage tank during the energy storage period; (2) The sum of the water storage tank capacity and the cumulative direct supply of the host (chiller) meets the daily cumulative load. First, calculate the actual cooling capacity of the chiller by trial, and the calculation formula is as follows: ; (1 - 3) In the formula: It is the trial-calculated actual cooling capacity of the chiller, kW; It is the energy storage hours, h; It is the building's daytime usage duration, h.

[0036] Bring the obtained trial-calculated actual cooling capacity of the chiller into the design day, and distribute the hourly energy for 24 hours according to the above energy storage and release strategy to obtain the actual cumulative direct supply of the chiller on the summer design day , if the chilled water storage volume plus the actual cumulative direct supply of the chiller during the day on the summer design day is less than the cumulative load on the summer design day , then magnify , until the actual cumulative supply load on the summer design day exactly equals the cumulative load on the summer design day .

[0037] As Figure 9 shown, the process for determining the chiller capacity is as follows: 1. Input the trial-calculated actual cooling capacity of the chiller ; 2. ; 3. Calculate ; 4. Calculate ; 5. ; No, return to 2, increase ; Yes, go to the next step; 6. Output .

[0038] The specific formula is as follows: ; ; ; Wherein: is the actual cumulative direct supply volume of the chiller on the summer design day, kWh; is i the actual refrigerating capacity of the chiller at time, kW; is the actual refrigerating capacity of the chiller under the design conditions, kW.

[0039] The air source heat pump has low environmental requirements, flexible installation, and is widely applicable to various places such as residences, commercial buildings, schools, etc. It is simple to select models. Therefore, in winter, the heat storage and direct supply heat source scheme of the air source heat pump is adopted (the air source heat pump only supplies heat and does not supply cold); the calculation method of the actual capacity of the air source heat pump is similar to that in summer. It is also necessary to consider the heat release of the heat storage device during the heat storage hours and the direct heat supply of the air source heat pump during the daytime use period of the building to ensure sufficient heat supply in winter. At the same time, the air source heat pump needs to consider defrost correction and temperature correction in winter. First, the actual heating capacity of the air source heat pump is calculated by trial, and the calculation formula is as follows: ; (1-4) Wherein: is the trial-calculated actual heating capacity of the air source heat pump, kW; is the cumulative heat load on the winter design day, kWh; is the comprehensive correction coefficient considering defrost correction and temperature correction.

[0040] The obtained trial-calculated actual heating capacity of the air source heat pump is brought into the design day, and the hourly energy distribution for 24 hours is carried out according to the above heat storage and release strategy to obtain the actual cumulative direct supply volume of the air source heat pump on the winter design day. If the heat storage plus the actual cumulative direct supply volume during the daytime on the winter design day of the air source heat pump is less than the cumulative load on the winter design day, then is amplified until the actual cumulative supply load on the winter design day is exactly equal to the cumulative load on the winter design day.

[0041] As Figure 10 shown, the process for determining the capacity of the air source heat pump is as follows: 1. Input the trial-calculated actual heating capacity ; 2. ; 3. Calculate ; 4. Calculate ; 5. ; No, return 2 and increase ; Yes, proceed to the next step; 6. Output .

[0042] The specific formula is as follows: ; ; ; In the formula: is the actual cumulative direct supply amount of the air source heat pump on the winter design day, kWh; is i the actual heating capacity of the air source heat pump at time is the actual heating capacity of the air source heat pump under the design conditions, kW.

[0043] In this way, fully considering the capacity correction and energy efficiency correction of the main unit under different water supply temperatures and outdoor meteorological parameters, it truly and accurately reflects the energy consumption of the main unit under various working conditions, ensures that the energy consumption analysis of the system is closer to the actual operating conditions, and provides reliable data support for optimizing the system operation strategy.

[0044] III. Determination of the energy storage and release scheduling strategy: The determination of the energy storage and release scheduling strategy is an important link in the operation of the entire cold and heat dual energy storage system, which is directly related to the energy utilization efficiency and the operation cost of the system.

[0045] Overall principle: The energy storage device stores energy during the valley price period, making full use of the advantage of the lower valley electricity price to reduce the operation cost. It releases energy during the daytime use period of the energy-requiring building to meet the heating and cooling demands of the energy-requiring building.

[0046] The energy storage device here specifically refers to the device that stores cold and heat in the cold and heat dual energy storage system.

[0047] The determination of the entire energy release strategy is divided into four rounds, as Figure 4 shown: The first-round energy release judgment: When the load demand of the energy-requiring building exceeds the design capacity of the main unit, the priority energy storage device starts to release energy to meet the excess load of the energy-requiring building that exceeds the design capacity of the main unit. If there is no remaining energy after the energy storage device releases energy, the remaining load of the energy-requiring building is directly supplied by the main unit's energy release. If there is remaining energy after the energy storage device releases energy, the remaining energy of the energy storage device enters the second-round energy release judgment.

[0048] The load demand of the energy - required building here exceeds the design capacity of the main unit, which means that at a certain moment, the load of the energy - required building is greater than the output energy of the main unit at that moment. When such a moment occurs, the stored energy needs to first meet the moment exceeding the maximum output energy of the main unit, that is, the first - round energy - release judgment is carried out. The specific flow chart of the first - round energy - release judgment is as Figure 5 shown.

[0049] If it is judged that there is no moment when the building load demand exceeds the capacity of the main unit on a certain day, then no energy is released in the first round, and the second - round energy - release judgment is entered.

[0050] As Figure 5 shown, the hourly energy supply is the energy required by the energy - required building per hour, and the rated capacity of the main unit is the energy that the main unit can release per hour.

[0051] Second - round energy - release: Judge whether the remaining energy of the energy - storage device can meet the cumulative load of the peak period of the energy - required building. If not, the remaining energy of the energy - storage device is evenly distributed to each moment of the peak period, and the remaining load is directly supplied by the main unit for energy release; if it is satisfied, all the loads during the peak period are supplied by the energy - storage device for energy release, and the remaining energy enters the third - round energy - release.

[0052] The specific flow chart of the second - round energy - release is as Figure 6 shown.

[0053] This energy - release is to preferentially meet the load demand during the peak period. The peak period is usually the period when the building load demand is the highest. At this time, the energy - storage device continues to release energy to reduce the burden on the main unit. After the energy - release, the remaining energy situation of the energy - storage device is judged again. If there is no remaining, the remaining load is directly supplied by the unit; if there is remaining, it enters the third - round energy - release.

[0054] Third - round energy - release: Judge whether the remaining energy of the energy - storage device can meet the cumulative load of the peak period of the energy - required building. If not, the remaining energy of the energy - storage device is evenly distributed to each moment of the peak period, and the remaining load is directly supplied by the main unit for energy release; if it is satisfied, all the loads during the peak period are supplied by the energy - storage device for energy release, and the remaining energy enters the fourth - round energy - release; This energy - release is to preferentially meet the load during the peak period. The load during the peak period is also relatively high, and the energy - storage device continuously releases energy to ensure the stable operation of the system. Similarly, after the energy - release, check whether there is remaining energy in the energy - storage device. If there is no remaining, the remaining load is directly supplied by the unit; if there is remaining, it enters the fourth - round energy - release.

[0055] The specific flow chart of the third - round energy - release is as Figure 7 shown.

[0056] Fourth round of energy release: Determine whether the remaining energy of the energy storage device meets the cumulative load during the flat peak period of the building to be energy-supplied. If it does not meet, evenly distribute the remaining energy of the energy storage device to each moment during the flat peak period, and the remaining load is directly supplied by the host for energy release; if it meets, all loads during the flat peak period are supplied by the energy storage device for energy release; after the four rounds of energy release are completed, the energy storage device enters the energy storage period.

[0057] This energy release is used to meet the load demand during the flat price period. During the flat price period, the load demand is relatively low, but the energy support of the energy storage device may still be required. If there is still remaining load after energy release, it is directly supplied by the unit (or called the host) to meet.

[0058] The specific flow chart of the fourth round of energy release is as Figure 8 shown.

[0059] It should be noted that in the present invention, in the energy storage and release strategy, the energy release must be strictly executed in the order of the first round of energy release, the second round of energy release, the third round of energy release, and the fourth round of energy release, that is, it is necessary to first meet the load exceeding the host capacity to meet the cooling demand of the building, and secondly meet the sharp peak period, because the electricity price per unit is high at this time, and finally meet the flat price period with medium electricity price. Through such an energy release order, the electricity price generated by the host power supply can be reduced on the premise of meeting the energy supply demand of the building to be energy-supplied.

[0060] It should be noted that here, the first round, the second round, the third round, and the fourth round are the priority levels of energy release, not the time sequence of energy release.

[0061] If there is no first round of energy release on a certain day, then the energy release amount in the first round is 0 at this time. Since the air-conditioning energy storage system is for projects with time-of-use electricity price policies (peak, high peak, flat price, valley price), and there are time-of-use electricity price policies in each region. According to the time-of-use electricity price policy (related to the region), assuming that there is no peak electricity price (corresponding to the second round of energy release) in a certain region, then, after the first round is completed, the third round of energy release can be entered (at this time, the energy release amount in the second round is 0). If there is no first round of energy release on a certain day, the third round of energy release can be directly carried out (at this time, the energy release amounts in the first and second rounds are 0).

[0062] It should also be noted that for the size of the energy release of the energy storage device, it is defined as the energy release amount + the direct supply amount of the host = the building load.

[0063] This is because if the building load b is greater than the rated capacity a of the main unit, it is b - a; if the building load is less than the rated capacity of the main unit, there is no first-round energy release. Since it is to satisfy the demand with the highest priority and the hourly building load and the rated capacity of the main unit are known, the energy release in the first round can be directly determined by subtraction. That is to say, the energy release in each round during a day is determined. The energy released by the energy storage device in each round is not necessarily the same because the building load per hour is different. The energy released by the energy storage system per hour + the energy supplied by the main unit per hour = the building load per hour. And during a day, the energy release = the energy storage, that is, the sum of the energy releases in the four rounds is equal to the energy stored during the low-price period.

[0064] It should also be noted that the peak electricity price period, high electricity price period, normal electricity price period, and low electricity price period are time periods set according to the time-of-use electricity price policy of each region. That is, the electricity price period is an input quantity that varies according to the time-of-use electricity price policy. The time-of-use electricity price policies in different regions are different, and the time periods for each day are the same. Therefore, the specific time periods can be obtained according to this policy and will not be elaborated here.

[0065] IV. Cost Calculation: When comprehensively evaluating the entire cold and heat energy storage system (energy system), cost calculation is a crucial part. First, the hourly load data for 8,760 hours throughout the year needs to be introduced. This data covers the specific load situation of the building for each hour in a year and accurately reflects the dynamic change of the load over time. Based on the determined energy storage capacity, the selection of the main unit, and the energy storage and release strategy, the hourly energy consumption for 8,760 hours throughout the year can be calculated in detail.

[0066] (1) Calculation of Energy Consumption and Operating Cost The composition of energy consumption includes multiple parts. Among them, the direct supply of the main unit and the energy consumption during energy storage operation are important components of energy consumption. When the main unit directly supplies energy and operates in cooperation with the energy storage device, its energy consumption will vary with different operating conditions. The COP varies with the change of outdoor environmental parameters and needs to be corrected hourly, as shown in the following formula: ; (1 - 5) ; (1 - 6) ; (1 - 7) ; (1 - 8) ; (1 - 9) ; (1 - 10) In the formula: is i the corrected refrigeration performance coefficient during the direct supply of the chiller at time is the refrigeration coefficient under standard conditions when the chiller directly supplies cold water; is the refrigeration coefficient under standard conditions when the chiller stores cold; is i the correction coefficient of the chiller performance coefficient at time, for simplicity of calculation, only considering the influence of the cooling water temperature; is i the supply water temperature of the cooling water at time, °C, for simplicity of calculation, taking values according to the outdoor hourly wet bulb temperature and the rated approach temperature of the cooling tower (4°C); , , , are the correction curve coefficients respectively, and the correction curve is obtained by fitting the product sample parameters of the mainstream equipment manufacturers; is i the corrected heating performance coefficient of the air source heat pump during direct supply at time; is the heating performance coefficient under standard conditions when the air source heat pump directly supplies heat; is i the corrected heating performance coefficient of the air source heat pump during heat storage at time; is the heating performance coefficient under standard conditions when the air source heat pump stores heat; is i the correction coefficient of the air source heat pump heating performance coefficient at time, for simplicity of calculation, only considering the influence of the outdoor temperature; is i the outdoor dry bulb temperature at time, °C; , , , are the correction curve coefficients respectively, and the correction curve is obtained by fitting the product sample parameters of the mainstream equipment manufacturers.

[0067] The operating energy consumption of the cooling tower cannot be ignored. The cooling tower needs to consume a certain amount of energy to maintain the normal operation of the system during the heat dissipation process. In addition, the operating energy consumption of the pump is also part of the energy consumption. The pump is responsible for transporting the medium in the system to ensure the effective distribution of energy. The hourly energy consumption to be calculated in summer is shown in Table 1-2.

[0068] Table 1-2 Energy consumption calculated in summer Summer Summer Summer Summer Summer Summer Summer Summer Energy consumption of chilled water storage chiller Energy consumption of circulating chilled water pump Energy consumption of chilled water release pump Energy consumption of direct supply chilled water pump Energy consumption of chilled water storage pump Direct supply energy consumption of chiller Energy consumption of cooling water pump Energy consumption of cooling tower The hourly energy consumption calculation of the cold storage chiller is as follows: ; (1 - 11) Wherein: is i the cold storage energy consumption of the chiller at time, kW; is i the cold storage capacity of the chiller at time, kW.

[0069] The hourly energy consumption of the circulating chilled water pump is calculated as follows: ; (1 - 12) Wherein: is i the energy consumption of the circulating chilled water pump at time, kW; is the power consumption of the circulating chilled water pump per unit refrigerating capacity, kW / kW; is i the total cold released by the energy storage device at time, kW.

[0070] The hourly energy consumption of the cold release water pump is calculated as follows: ; (1 - 13) Wherein: is i the energy consumption of the cold release water pump at time, kW; is the power consumption of the cold release water pump per unit refrigerating capacity, kW / kW.

[0071] The hourly energy consumption of the directly supplied chilled water pump is calculated as follows: ; (1 - 14) Wherein: is i the energy consumption of the directly supplied chilled water pump of the chiller at time, kW; is the power consumption of the chilled water pump per unit refrigerating capacity, kW / kW; is i the cold released by the direct supply of the chiller at time, kW.

[0072] The hourly energy consumption of the cold storage chilled water pump is calculated as follows: ; (1 - 15) Wherein: is i the energy consumption of the cold storage chilled water pump of the chiller at time, kW.

[0073] The hourly energy consumption of the direct supply of the chiller is calculated as follows: ; (1 - 16) In the formula: is i the hourly energy consumption of the chiller in direct supply at time, kW.

[0074] The hourly energy consumption of the cooling water pump is calculated as follows: ; (1-17) In the formula: is i the hourly energy consumption of the cooling water pump at time, kW; is the power consumption of the cooling water pump per unit refrigerating capacity, kW / kW.

[0075] The hourly energy consumption of the cooling tower is calculated as follows: ; (1-18) In the formula: is i the hourly energy consumption of the cooling tower at time, kW; is the power consumption of the cooling tower per unit refrigerating capacity, kW / kW.

[0076] After determining the hourly energy consumption, based on the hourly electricity price and the hourly energy consumption, the total hourly electricity cost in summer can be obtained as shown in the following formula: ; (1-19) In the formula: is i the total energy consumption in summer at time, kW.

[0077] The hourly energy consumption to be calculated in winter is shown in Table 1-3.

[0078] Table 1-3 Calculated energy consumption in winter Winter Winter Winter Winter Winter Winter Energy consumption of heat storage heat pump Energy consumption of circulating hot water pump Energy consumption of hot water release pump Energy consumption of direct supply hot water pump Energy consumption of heat storage hot water pump Direct supply energy consumption of heat pump The hourly energy consumption of the heat storage heat pump is calculated as follows: ; (1-20) In the formula: is i the hourly heat storage energy consumption of the air source heat pump at time, kW; is i the hourly heat storage capacity of the air source heat pump at time, kW.

[0079] The hourly energy consumption of the circulating hot water pump is calculated as follows: ; (1-21) In the formula: is i the energy consumption of the circulating hot water pump at time, kW; is the power consumption of the circulating hot water pump per unit heat, kW / kW; is i the total heat released by the energy storage device at time , kW.

[0080] ; (1-22) In the formula: is i the energy consumption of the hot water release pump at time , kW; is the power consumption of the hot water release pump per unit heat, kW / kW.

[0081] The hourly energy consumption of the direct supply hot water pump is calculated as follows: ; (1-23) In the formula: is i the energy consumption of the air source heat pump direct supply hot water pump at time , kW; is the power consumption of the hot water pump per unit heat, kW / kW; is i the heat released by the air source heat pump direct supply at time , kW.

[0082] The hourly energy consumption of the heat storage hot water pump is calculated as follows: ; (1-24) In the formula: is i the energy consumption of the air source heat pump heat storage hot water pump at time , kW.

[0083] The hourly energy consumption of the heat pump direct supply is calculated as follows: ; (1-25) In the formula: is i the energy consumption of the air source heat pump direct supply at time , kW.

[0084] Then the hourly total electricity cost in winter is calculated as follows: ; (1-26) In the formula: is i the total energy consumption in winter at time , kW.

[0085] The hourly electricity unit price here varies with time, reflecting the price differences in the electricity market at different times. By calculating the hourly electricity costs for 8760 hours throughout the year and then summing up these hourly electricity costs, the annual operating electricity cost can finally be obtained, as shown in the following formula: ; (1 - 27) In the formula: is the annual operation electricity cost, in ten thousand yuan; is i the electricity unit price at time, in yuan / kWh

[0086] Introduce the hourly meteorological parameters and load data for 8760 hours throughout the year, accurately calculate the energy consumption of the host direct supply and energy storage operation, the energy consumption of the cooling tower operation, and the energy consumption of the pump operation, etc. Calculate the total hourly electricity cost throughout the year based on the hourly electricity unit price and hourly energy consumption, accurately calculate the annual operation electricity cost, and accurately quantify the operation cost of the cold and heat dual energy storage system in a year.

[0087] (2) Initial investment calculation In terms of the initial investment, its composition covers the costs related to multiple equipment and sites. The cost of the host depends on factors such as the type, capacity, and performance of the host. The cost of the energy storage device is closely related to the energy storage capacity and technical type of the energy storage device. The cost of the cooling tower varies according to the specifications and quality of the cooling tower. The cost of the plate heat exchanger and the cost of the pump are also affected by the equipment specifications and performance. The cost of the machine room involves the construction cost of the machine room, including site decoration, equipment installation, etc. The commercial land cost is the cost required to obtain the site for installing equipment. The cost of power capacity expansion is the cost generated for power capacity expansion to meet the system's power demand. Summing up these costs can obtain the total initial investment, as shown in the following formula: ; (1 - 28) In the formula: is the total initial investment, in ten thousand yuan; 、 、 、 、 、 、 respectively represent the initial investments of the chiller, heat pump, energy storage device, plate heat exchanger, pump, floor area, and power capacity expansion, in ten thousand yuan.

[0088] The maintenance cost per year is also part of the cost, calculated at 2.5% of the equipment cost. This ratio is determined by comprehensively considering the equipment wear, maintenance requirements, and the common maintenance cost ratio in the market, and is used to estimate the annual expenditure on equipment maintenance, as calculated in the following formula: ; (1 - 29) In the formula: is the equipment maintenance cost, in ten thousand yuan; is the maintenance cost ratio, taking 2.5%.

[0089] In summary, for the cold and heat dual energy storage system, comprehensively consider the initial investment, floor space of the cold and heat energy storage devices and the air conditioning system, as well as the key influencing factors such as the operating costs during the annual cooling season and heating season. Through multi-dimensional comprehensive analysis, objectively and comprehensively reflect the overall economy of the system, and provide a scientific basis for system design and operation.

[0090] 5. Flexible capacity assessment: In some embodiments, evaluate the flexible adjustment capacity of the cold and heat dual energy storage system corresponding to the optimal solution result. If it can pass the evaluation, take this optimal solution result as the final optimal solution result; otherwise, take the sub-optimal solution result compared with this optimal solution result as the new optimal solution result, and then return to this step.

[0091] The flexible adjustment capacity of the energy storage system refers to its ability to flexibly adjust the load during peak and valley periods of electricity demand to optimize energy use, reduce grid pressure, and improve system efficiency. Therefore, to comprehensively evaluate the flexible adjustment capacity of the system corresponding to the energy storage rate and help judge the actual effect and economy in grid regulation, the following indicators are introduced to evaluate its flexible adjustment capacity.

[0092] The maximum adjustment power under different time periods reflects the maximum adjustment potential of the system under different electricity demands, and evaluates its ability to alleviate the peak-valley difference of the grid. The calculation formula is as follows: ; (1-30) ; (1-31) ; (1-32) In the formula: is the maximum adjustment power during the peak period, in kW; is the i energy consumption of the energy storage system at time during the peak period, in kW; i is the system energy consumption of the reference scheme at time during the peak period, in kW; is the i energy consumption of the energy storage system at time during the peak period, in kW; i is the system energy consumption of the reference scheme at time is the maximum regulation power during the flat-rate period, in kW; is the flat-rate period i energy consumption of the energy storage system at time, in kW; is the flat-rate period i energy consumption of the reference scenario system at time, in kW.

[0093] In the present invention, the reference scenario refers to a conventional air-conditioning system without an energy storage system, and the set form of the cold and heat sources is a water-cooled chiller in summer + an air-source heat pump in winter (for heating only).

[0094] The average regulation power under time periods reflects the amount of regulation evenly distributed to each hour by the system and evaluates the reliability of its continuous participation in grid regulation. The calculation formula is as follows: ; (1-33) ; (1-34) ; (1-35) In the formula: is the average regulation power during the peak period, in kW; is the total duration of the annual peak period, in h; is the average regulation power during the high-peak period, in kW; is the total duration of the annual high-peak period, in h; is the average regulation power during the flat-rate period, in kW; is the total duration of the annual flat-rate period, in h.

[0095] The maximum regulation ratio under time periods reflects the regulation potential of the system relative to its own capacity and evaluates the size of its flexibility. The calculation formula is as follows: ; (1-36) ; (1-37) ; (1-38) In the formula: is the maximum regulation ratio during the peak period; is the maximum regulation ratio during the high-peak period; is the maximum regulation ratio during the flat-rate period.

[0096] The average regulation ratio under different time periods reflects the average hourly regulation capacity of the system and evaluates its performance in terms of flexibility during actual operation. The calculation formula is as follows: ; (1-39) ; (1-40) ; (1-41) In the formula: is the average regulation ratio during the peak period; is the average regulation ratio during the high-demand period; is the average regulation ratio during the flat-price period.

[0097] The cumulative regulation electricity quantity ratio (annual load transfer rate) under different time periods reflects the regulation contribution of the system during the annual operation and evaluates its overall effect on grid regulation. The calculation formula is as follows: ; (1-42) ; (1-43) ; (1-44) In the formula: is the cumulative regulation electricity quantity ratio during the peak period; is the cumulative regulation electricity quantity ratio during the high-demand period; is the cumulative regulation electricity quantity ratio during the flat-price period; is the starting time of the peak period within 24 hours of a day, in h; is the ending time of the peak period within 24 hours of a day, in h; is the starting time of the high-demand period within 24 hours of a day, in h; is the ending time of the high-demand period within 24 hours of a day, in h; is the starting time of the flat-price period within 24 hours of a day, in h; is the ending time of the flat-price period within 24 hours of a day, in h.

[0098] The summer load transfer rate under different time periods reflects the regulation capacity of the system under different electricity demands in summer and evaluates its effect on summer grid regulation. The calculation formula is as follows: ; (1-45) ; (1-46) ; (1 - 47) Wherein: is the load transfer rate during the summer peak period; is the start time of summer cooling supply, h; is the end time of summer cooling supply, h; is the start time of the peak period in 24 hours of a summer day, h; is the end time of the peak period in 24 hours of a summer day, h; is the energy consumption of the cold and heat dual energy storage system at the i time during the summer peak period, kW; is the energy consumption of the reference scheme system at the i time during the summer peak period, kW; is the load transfer rate during the summer peak period; is the start time of the peak period in 24 hours of a summer day, h; is the end time of the peak period in 24 hours of a summer day, h; is the energy consumption of the cold and heat dual energy storage system at the i time during the summer peak period, kW; is the energy consumption of the reference scheme system at the i time during the summer peak period, kW; is the load transfer rate during the summer flat rate period; is the start time of the flat rate period in 24 hours of a summer day, h; is the end time of the flat rate period in 24 hours of a summer day, h; is the energy consumption of the cold and heat dual energy storage system at the i time during the summer flat rate period, kW; is the energy consumption of the reference scheme system at the i time during the summer flat rate period, kW.

[0099] The load transfer rate under sub - time periods in winter reflects the regulation ability of the system under different electricity demands in winter and evaluates its effect on winter power grid regulation. The calculation formula is as follows: ; (1 - 48) ; (1 - 49) ; (1 - 50) Wherein: is the load transfer rate during the winter peak period; is the start time of winter cooling supply, h; is the end time of winter cooling supply, h; is the start time of the peak period in 24 hours of a winter day, h; is the end time of the peak period in 24 hours of a winter day, h; is the winter peak period i energy consumption of the cold and heat dual energy storage system at the moment, kW; is the winter peak period i energy consumption of the reference scheme system at the moment, kW; is the load transfer rate during the winter peak period; is the start time of the peak period in 24 hours of a winter day, h; is the end time of the peak period in 24 hours of a winter day, h; is the winter peak period i energy consumption of the cold and heat dual energy storage system at the moment, kW; is the winter peak period i energy consumption of the reference scheme system at the moment, kW; is the load transfer rate during the winter flat rate period; is the start time of the flat rate period in 24 hours of a winter day, h; is the end time of the flat rate period in 24 hours of a winter day, h; is the winter flat rate period i energy consumption of the cold and heat dual energy storage system at the moment, kW; is the winter flat rate period i energy consumption of the reference scheme system at the moment, kW.

[0100] 6. Optimization objective: Taking the annual equivalent cost (economics) and the payback period (investment efficiency) of the system life cycle as the optimization objectives respectively, analyze the appropriate energy storage rate of the cold and heat dual energy storage system under different application conditions.

[0101] The annual discounted cost of the system's full life cycle is calculated based on the equipment life, and the calculation formula is as follows: ; (1-51) In the formula: is the annual discounted cost of the system's full life cycle, in ten thousand yuan; is the equipment life, generally taken as 20, with the unit of year.

[0102] means to evenly allocate the total initial investment I to n years, reflecting the annual equipment investment cost. The annual discounted cost of the system's full life cycle calculated by this formula can intuitively reflect the average annual cost of the system throughout its life cycle, so as to evaluate the economy of the system.

[0103] The calculation of the investment payback period is also very important, which is used to measure the investment efficiency. The benchmark scheme is direct supply by the chiller in summer + direct supply by the air source heat pump in winter. Calculate the investment payback period, and the formula is as follows: ; (1-52) In the formula: is the investment payback period of the system, in years; is the total initial investment of the benchmark scheme system, in ten thousand yuan; is the annual operating electricity cost of the benchmark scheme system, in ten thousand yuan; is the annual equipment maintenance cost of the benchmark scheme system, in ten thousand yuan.

[0104] The numerator represents the increased investment cost of the energy storage system (energy storage air conditioning system) relative to the benchmark scheme. The denominator represents the annual cost savings of the cold and heat dual energy storage system relative to the benchmark scheme. By dividing the two, the obtained investment payback period can clearly show how many years it takes to recover the increased investment cost through the saved cost, so as to evaluate the investment efficiency.

[0105] In summary, in order to deeply analyze the impact of the cold storage rate on the system, a series of calculations are required. The specific method is to iteratively calculate the cold storage rate from 1% to 100%, and respectively obtain the relationship curves between the cold storage rate and the annual equivalent cost of the system's entire life cycle and the payback period, visually showing the economic changes of the system under different cold storage rates, providing a strong basis for the optimal design and operation of the system. At the same time, obtain the power load regulation amount and power load transfer rate under different energy storage amounts, quantify the flexible regulation ability of the energy storage system, and provide an objective basis for the performance evaluation of the energy storage system. In addition, based on the optimized energy storage amount, output the daily energy storage and discharge strategies to guide the optimal operation of the system and improve the system economy.

[0106] The specific implementation manners described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above description is only the specific implementation manners of the present invention and is not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for optimizing energy storage rate based on a cold and hot dual energy storage system, characterized in that: The energy storage rate optimization method comprises: Constructing an energy storage rate optimization model, the energy storage rate optimization model including an objective function with the annual discounted cost of the cold and hot dual energy storage system life cycle as the optimization target and the investment payback period of the cold and hot dual energy storage system as the main constraint condition and the storage capacity constraint; Determine the design daily cumulative load of the energy demand and supply building where the cold and hot dual energy storage system is located in summer and winter respectively; A plurality of energy storage rates are set, and the plurality of energy storage rates are successively substituted into the energy storage rate optimization model to solve the energy storage rate optimization model, thereby obtaining solution results of the energy storage rate optimization model corresponding to different energy storage rates, and finally finding the energy storage rate corresponding to the optimal solution result of the energy storage rate optimization model.

2. The energy storage rate optimization method based on the cold and hot dual energy storage system according to claim 1 is characterized in that: The objective function includes an optimization objective and main constraints, wherein the optimization objective is: ； ； The main constraints are: ； ； in, It represents the annual discounted cost of the life cycle of the cold and hot dual energy storage system; Indicates the investment payback period of the hot and cold dual energy storage system; It represents the annual operating cost of the hot and cold dual energy storage system, in ten thousand yuan; It represents the equipment maintenance cost of the hot and cold dual energy storage system, in ten thousand yuan; Indicates the equipment life of the hot and cold dual energy storage system; It represents the total initial investment in building a cold and hot dual energy storage system, in ten thousand yuan; It represents the total initial investment of the benchmark scheme system, in ten thousand yuan; It represents the annual operating electricity cost of the benchmark scheme system, in ten thousand yuan; The annual equipment maintenance cost of the benchmark solution system is in ten thousand yuan. Is a positive number.

3. The energy storage rate optimization method based on the cold and hot dual energy storage system according to claim 2 is characterized in that: The annual operating cost of the hot and cold dual energy storage system It is composed of the sum of the cooling and heating operating costs for 8760 hours throughout the year. The specific expression is: ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； in, for i The unit price of electricity at that moment, in yuan / kWh; Indicates summer i System energy consumption at the moment, in kW; express i The energy consumption of the chiller at each moment, in kW; express i Energy consumption of the circulating chilled water pump at all times, in kW; express i Energy consumption of the chilled water pump at each moment, in kW; express i Energy consumption of the direct supply chiller pump at any given moment, in kW; express i Energy consumption of the chiller unit's cold storage water pump at any given moment, in kW; express i Energy consumption of chiller when directly supplying water at any time, in kW; express i Energy consumption of cooling water pump at any moment, in kW; express i Cooling tower energy consumption at any given moment, in kW; Indicates winter i System energy consumption at the moment, in kW; express i The heat storage energy consumption of the heat pump at each moment, in kW; express i Energy consumption of hot water pump for constant circulation, in kW; express i Energy consumption of hot water pump at each moment, in kW; for i Energy consumption of the direct heat pump hot water pump at any moment, in kW; express i Energy consumption of heat pump thermal storage hot water pump at each moment, in kW; express i Energy consumption of direct heat pump supply at any moment, in kW; express i The cooling capacity of the chiller at that moment, in kW; express i Corrected refrigeration performance coefficient when the chiller is storing cold; Indicates the power consumption of the circulating chiller pump per unit refrigeration capacity, in kW / kW; Indicates the power consumption of the cooling water pump per unit cooling capacity, in kW / kW; express i The cooling capacity released by the energy storage device at any given moment, in kW; Indicates the power consumption of the chiller pump per unit cooling capacity, in kW / kW; express i The cooling capacity of the chiller when it is directly supplied at any given moment, in kW; express i Corrected refrigeration coefficient of performance when the chiller is directly supplied at all times; Indicates the cooling water pump power consumption per unit cooling capacity, in kW / kW; Indicates the cooling tower power consumption per unit cooling capacity, in kW / kW; express i The heat storage of the heat pump at the moment, in kW; express i Corrected heating performance coefficient when the heat pump is storing heat at all times; Indicates the power consumption of the circulating hot water pump per unit heating capacity, in kW / kW; Indicates the power consumption of the heat pump per unit of heat released, in kW / kW; express i The total heat released by the energy storage device at any moment, in kW; Indicates the power consumption of the hot water pump per unit heating capacity, in kW / kW; express i The amount of heat released by the direct heat pump at any given moment, in kW; express i Corrected heating performance coefficient when the heat pump is directly supplied at the moment.

4. The energy storage rate optimization method based on the cold and hot dual energy storage system according to claim 2 is characterized in that: The total initial investment for building a cold and hot dual energy storage system The specific calculation formula is: ； in, , , , , , , They represent the initial investment in chillers, heat pumps, energy storage devices, plate heat exchangers, water pumps, floor space, and power capacity expansion, respectively, in ten thousand yuan.

5. The energy storage rate optimization method based on the cold and hot dual energy storage system according to claim 4 is characterized in that: Annual maintenance cost of the equipment The specific calculation formula is: ； in, Indicates the annual maintenance cost ratio.

6. The energy storage rate optimization method based on the cold and hot dual energy storage system according to claim 1 is characterized in that: The energy storage constraint is specifically: Fill the water tank within the energy storage period, and the energy corresponding to the water tank capacity plus the actual cumulative direct energy supplied by the host meet the cumulative load of the energy-demanding building on that day; The host includes a chiller for cooling in summer and a heat pump for heating in winter.

7. The energy storage rate optimization method based on the cold and hot dual energy storage system according to claim 1 is characterized in that: Substituting the multiple energy storage rates into the energy storage rate optimization model one by one to solve the energy storage rate optimization model, thereby obtaining the solution results of the energy storage rate optimization model corresponding to different energy storage rates, and finally finding the energy storage rate corresponding to the optimal solution of the energy storage rate optimization model. The specific process is: The energy storage rate is defined as the cumulative cooling load of the summer design day x times; Calculate the reservoir capacity through the storage rate; The required capacity of the host is calculated based on the capacity of the water storage tank, the cumulative load of the energy-demanding building in summer and winter, and the energy storage constraint; Selecting the host according to the required capacity; Calculate the energy consumption of the selected host based on the set energy storage and release scheduling strategy, and calculate the operating cost and total initial investment based on the calculated energy consumption; Calculate the annual discounted cost of the cold and hot dual energy storage system life cycle and the investment payback period of the cold and hot dual energy storage system based on the operating cost and the total initial investment; Determine whether all energy storage rates are substituted into the energy storage rate optimization model and calculate the corresponding solution results. If so, jump to the next step; otherwise, change the energy storage rate and return to the first step; The solution results of the energy storage rate optimization model corresponding to different energy storage rates are obtained.

8. The method for optimizing the energy storage rate based on the cold and hot dual energy storage system according to claim 7 is characterized in that: The energy storage and release scheduling strategy is specifically as follows: The first round of energy discharge: when the load demand of the energy-demanding building exceeds the design capacity of the host, the priority energy storage device starts to discharge energy to meet the excess load of the energy-demanding building that exceeds the design capacity of the host. If the energy storage device has no residual energy after discharging energy, the residual load of the energy-demanding building is directly supplied by the host. If the energy storage device has residual energy after discharging energy, the residual energy of the energy storage device enters the second round of energy discharge. The second round of energy release: determine whether the remaining energy of the energy storage device meets the accumulated load of the building in need of energy during the peak period. If not, the remaining energy of the energy storage device is evenly distributed to each moment during the peak period, and the remaining load is directly released by the host; if it is satisfied, all loads during the peak period are released by the energy storage device, and the remaining energy enters the third round of energy release; The third round of energy release: determine whether the remaining energy of the energy storage device meets the accumulated load of the building in peak hours. If not, the remaining energy of the energy storage device is evenly distributed to each moment during the peak hours, and the remaining load is directly released by the host. If it is satisfied, all loads during the peak hours are released by the energy storage device, and the remaining energy enters the fourth round of energy release. The fourth round of energy discharge: determine whether the remaining energy of the energy storage device can meet the cumulative load of the energy-demanding building during the off-peak period. If not, the remaining energy of the energy storage device will be evenly distributed to each moment during the off-peak period, and the remaining load will be directly discharged by the main engine; if it is satisfied, all loads during the off-peak period will be discharged and supplied by the energy storage device; after four rounds of energy discharge, the energy storage device enters the energy storage period.

9. The energy storage rate optimization method based on the cold and hot dual energy storage system according to claim 1 is characterized in that: The energy storage rate optimization method also includes: The flexible regulation capability of the cold and hot dual energy storage system corresponding to the optimal solution result is quantified to judge the flexible effect under the optimal energy storage rate.

10. The method for optimizing energy storage rate based on a cold and hot dual energy storage system according to claim 9, characterized in that: The quantification contents of the flexible regulation capability include the maximum regulation power in time periods, the average regulation power in time periods, the maximum regulation ratio in time periods, the average regulation ratio in time periods, the cumulative regulation power ratio in time periods, the summer load transfer rate in time periods, and the winter load transfer rate in time periods. The specific calculation formula of the maximum regulation power in time periods is: ； ； ； in, Indicates the maximum regulating power of the hot and cold dual energy storage system during peak hours, in kW; Indicates peak hours i Energy consumption of the hot and cold dual energy storage system at all times, in kW; Indicates peak hours i Energy consumption of the time-based solution system, in kW; It indicates the maximum regulating power of the hot and cold dual energy storage system during peak hours, in kW; Indicates peak hours i Energy consumption of the hot and cold dual energy storage system at all times, in kW; Indicates peak hours i Energy consumption of the time-based solution system, in kW; Indicates the maximum regulated power during the parity period, in kW; For parity period i Energy consumption of the energy storage system at any moment, in kW; Indicates the parity period i Energy consumption of the time-based solution system, in kW; The specific calculation formula for the average regulated power in the time period is: ； ； ； in, Indicates the average regulated power during peak hours, in kW; Indicates the total duration of the peak period throughout the year, in hours; Indicates the average regulated power during peak hours, in kW; It indicates the total duration of the peak period throughout the year, in h; It represents the average regulated power during the parity period, in kW; It represents the total duration of the parity period throughout the year, in h; The specific calculation formula for the maximum adjustment ratio under the time period is: ； ； ； in, Indicates the maximum regulation ratio during peak hours; Indicates the maximum regulation ratio during peak hours; Indicates the maximum adjustment ratio during the parity period; The specific calculation formula for the average adjustment ratio under the time period is: ； ； ； in, Indicates the average regulation ratio during peak hours; It indicates the average regulation ratio during peak hours; It indicates the average adjustment ratio during the parity period; The specific calculation formula for the cumulative adjustment power ratio under the time period is: ； ； ； in, Indicates the proportion of cumulative power regulation during peak hours; Indicates the starting time of the peak period in 24 hours a day, in hours; Indicates the end time of the peak period in 24 hours a day, in h; Indicates the proportion of cumulative regulated electricity during peak hours; Indicates the starting time of the peak period in 24 hours a day, in hours; Indicates the end time of the peak period in 24 hours a day, in h; Indicates the proportion of cumulative regulated electricity during the parity period; Indicates the starting time of the parity period in 24 hours a day, in hours; Indicates the end time of the parity period in 24 hours a day, in h; The specific calculation formula of the summer load transfer rate under the time period is: ； ； ； in, represents the load transfer rate during the summer peak period; Indicates the start time of summer cooling, in h; Indicates the end time of summer cooling, in h; It indicates the starting time of the peak period in a 24-hour day in summer, in h; Indicates the end time of the peak period in a 24-hour day in summer, in h; Indicates the peak period in summer i Energy consumption of hot and cold dual energy storage system at all times, in kW; Indicates the peak period in summer i Time base scheme system energy consumption, in kW; represents the load transfer rate during the summer peak period; It indicates the starting time of the peak period in a 24-hour day in summer, in h; Indicates the end time of the peak period in a 24-hour day in summer, in h; Indicates the peak summer season i Energy consumption of hot and cold dual energy storage system at all times, in kW; Indicates the peak summer season i Time base scheme system energy consumption, in kW; represents the load transfer rate during the summer parity period; It indicates the starting time of the parity period in a 24-hour day in summer, in h; Indicates the end time of the parity period in a 24-hour day in summer, in h; Indicates the summer parity period i Energy consumption of hot and cold dual energy storage system at all times, in kW; Indicates the summer parity period i Time base scheme system energy consumption, in kW; The specific calculation formula of the winter load transfer rate under the time period is: ； ； ； in, represents the load transfer rate during winter peak period; Indicates the start time of winter cooling, in h; Indicates the end time of winter cooling, in h; It indicates the starting time of the peak period in 24 hours in winter, in h; Indicates the end time of the peak period in a 24-hour day in winter, in h; Indicates winter peak period i Energy consumption of hot and cold dual energy storage system at all times, in kW; Indicates winter peak period i Time base scheme system energy consumption, in kW; represents the load transfer rate during winter peak period; It indicates the starting time of the peak period in a 24-hour day in winter, in h; Indicates the end time of the peak period in a 24-hour day in winter, in h; Indicates peak winter season i Energy consumption of hot and cold dual energy storage system at all times, in kW; Indicates peak winter season i Time base scheme system energy consumption, in kW; represents the load transfer rate during the winter parity period; Indicates the starting time of the parity period in a 24-hour winter day, in hours; Indicates the end time of the parity period in a 24-hour winter day, in h; Indicates winter parity period i Energy consumption of hot and cold dual energy storage system at all times, in kW; Indicates winter parity period i Time base scheme system energy consumption, in kW.

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