Method for enabling ice storage air conditioner to participate in joint demand response transaction in consideration of tri-state operation mechanism

Abstract

The invention relates to the technical field of energy management systems, and particularly discloses a method for an ice storage air conditioner to participate in joint demand response transaction by considering a three-state operation mechanism, which comprises the following steps: constructing an energy balance model, a temperature and ice water proportion evolution model and a power constraint model of the ice storage air conditioner, and constructing a cold supply field commercial energy optimization model; and constructing a power distribution network operator incentive clearing model, establishing a master-slave game framework and a double-layer optimization model according to the established model, and solving an optimal incentive price by adopting a bisection method. According to the method, the temperature evolution, the ice-water proportion and the heat transfer boundary are accurately described, the physical consistency and the optimization precision are improved, the price-excitation combined strategy is put forward, the electricity price signal and the physical constraint are coordinated through the master-slave game double-layer optimization framework, insufficient response or over-limit transfer is avoided, and the economical efficiency and the flexibility are improved.

Description

Technical Field

[0001] This invention relates to the field of energy management system technology, and in particular to a method for ice storage air conditioning to participate in joint demand response transactions, taking into account the three-state operation mechanism. Background Technology

[0002] While the scale of new energy power generation continues to grow, its volatility leads to a widening peak-valley gap in the power system. Demand response, as a flexible resource on the demand side, can guide users to adjust their electricity consumption patterns through pricing or incentives, achieving peak shaving and valley filling. Ice storage air conditioning systems convert electrical energy into cooling capacity and transfer it across time periods, exhibiting good controllability. However, existing models often simplify and neglect the three-state operating mechanism, resulting in inaccurate optimization. Current research lacks refined three-state models and joint demand response mechanisms, hindering the efficient utilization of the potential of ice storage air conditioning.

[0003] Therefore, it is necessary to invent a method for ice storage air conditioning to participate in joint demand response transactions, taking into account the three-state operation mechanism, in order to improve the system's responsiveness and economy. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing ice storage air conditioning modeling and demand response strategies, and to provide a method for ice storage air conditioning to participate in joint demand response transactions that considers the three-state operation mechanism.

[0005] To achieve the above objectives, this invention provides a method for ice storage air conditioning systems to participate in joint demand response transactions, considering a three-state operating mechanism, comprising the following steps: S1. Construct an energy balance model for ice storage air conditioning: including calculation of the total energy state of the ice storage tank, composition of energy changes, and charging, heat loss, and cooling constraints. S2. Construct a temperature and ice-water ratio evolution model for ice storage air conditioning: Divide the operation of the ice storage tank into three states: pure ice, phase change, and pure water. Define the temperature change formula, ice-water ratio change formula, and state transition conditions for each state. S3. Construct a power constraint model for ice storage air conditioning: including mutual exclusion constraints of the three states of ice storage tank charging, discharging, and idle, charging and discharging rate limits, total power composition of the chiller, and power-energy conversion relationship; S4. Construct a commercial energy optimization model for cooling plant: including the calculation of electricity purchase cost, response revenue, bid-winning capacity, effective response quantity, penalty cost, and over-limit penalty during non-response periods, with the objective function being to minimize the cost of the cooling plant. S5. Construct an incentive-clearing model for distribution network operators: including the calculation of incentive costs, additional electricity purchase costs, load shedding costs, and load balance constraints, with the objective function being the minimization of distribution network operator costs; S6. Establish a master-slave game framework and a two-level optimization model, and use the bisection method to solve for the optimal incentive price.

[0006] Furthermore, S1 specifically refers to: The ice storage tank is the component that stores energy, operates in three states, and participates in demand response in ice storage air conditioning. The total energy state formula for an ice storage tank is expressed as: ; in, and These are the masses of ice and water, respectively. and These are the specific heat capacities of ice and water, respectively. The latent heat of melting ice, The temperature of the refrigerant ethylene glycol. The temperature of ice, water, or a mixture of ice and water in the ice storage tank; The cooling capacity of an ice storage tank can be expressed using the ice-to-water ratio as follows: ; ; in, and These are the masses of ice and water, respectively. The ratio is ice to water; The change in energy within an ice storage tank over a period of time is the cooling charge minus the heat loss and cooling release, and its mathematical expression is: ; in, This represents the change in energy in the ice storage tank. The specific components of the energy change in the ice storage tank are as follows: ; in, This refers to the amount of cooling energy supplied by the refrigeration unit to the ice storage tank. This refers to the heat loss caused by heat exchange between the ice storage tank and the outside environment. The cooling capacity supplied by the ice storage tank to the building-side load; The cooling capacity of the refrigeration unit to charge the ice storage tank is constrained as follows: ; in, The power of the chiller supplying cooling to the ice storage tank. This indicates the cooling capacity produced by the refrigeration unit under a given electrical power. The heat loss constraints caused by heat exchange between the ice storage tank and the outside environment are as follows: ; in, Indicates ambient temperature. The temperature of ice, water, or a mixture of ice and water in the ice storage tank. This indicates the heat exchange area between the ice storage tank and the outside environment. and These are the thickness of the coil and the thickness of the ice layer, respectively. and The heat transfer coefficients of the coil and the ice layer are respectively. Indicates the convective heat transfer coefficient; The cooling capacity constraints of the ice storage tank for the building-side load are as follows: ; ; ; in, This indicates the contact area between the refrigerant and the coil. This indicates the temperature of the refrigerant ethylene glycol. The thermal resistance during cooling consists of two parts: the thermal resistance of the coil and the thermal resistance of the ice layer. The ratio of ice to water is [missing information]. This represents the maximum value of the ice layer thickness.

[0007] Furthermore, S2 specifically refers to: The ice storage tank operates in three stages: pure ice state, phase change state, and pure water state. The specific temperature and ice-water ratio changes in each stage are as follows: In the pure ice state, the medium in the ice storage tank is entirely ice, and its temperature is below the freezing point of 0℃. At this point, the energy input or output into the ice storage tank is directly used for the sensible heat change of the ice. The formula for calculating the temperature change in the pure ice state is: ; When the temperature of the ice in the ice storage tank reaches or exceeds the freezing point after this temperature change, that is: If the medium in the ice storage tank enters a phase change state, the remaining energy will be used to melt the ice. In the phase change state, the temperature of the medium in the ice storage tank is maintained at the freezing point of 0℃. The energy input or output in the ice storage tank is used for the phase change process between ice and water. The formula for the change in the ice-water ratio in the phase change state is as follows: ; When the ice-to-water ratio is calculated and the following situation occurs: If If the water is completely frozen, the medium in the ice storage tank will re-enter a pure ice state, and the remaining energy will be used to lower the ice temperature. like This indicates that the ice has completely melted, the medium in the ice storage tank has entered a pure water state, and the remaining energy is used to raise the water temperature. In a pure water state, the medium in the ice storage tank is entirely water, and the temperature is above the freezing point of 0°C. The energy input or output in the ice storage tank is used for the sensible heat change of the water, as shown in the specific formula: ; When the temperature of the water in the ice storage tank reaches or falls below the freezing point after this temperature change, that is... Then the medium in the ice storage tank enters a phase change state, and the remaining energy is used for the freezing of water into ice; The iterative formula for updating the temperature of the ice storage tank is expressed as follows: ; The iterative formula for updating the ice-water ratio temperature in the ice storage tank is expressed as follows: ; in, The phase transition ratio is at time step t.

[0008] Furthermore, S3 specifically refers to: An ice storage tank can only be in one of three states at a time: charging, discharging, or idle. These three states are mutually exclusive, as expressed by the formula: ; in, , , These represent the binary components of the ice storage tank in the states of charging, discharging, and idle, respectively. The charge / discharge cooling rates are each limited by the maximum charge / discharge cooling capacity, as expressed by the formula: ; ; in, and These represent the maximum values ​​for cooling supplied by the chiller to the ice storage system and the maximum values ​​for cooling supplied by the ice storage system to the building, respectively. The total power of the refrigeration unit includes two parts: charging the ice storage tank and direct cooling. ; in, This refers to the operating power of the refrigeration unit. The power of the chiller supplying cooling to the ice storage tank. The power of the chiller to cool the building; The operating power of the refrigeration unit is limited by its maximum capacity: ; in, This is the maximum power of the refrigeration unit; The expression for the power-energy conversion of a refrigeration unit is: ; ; in, and These represent the power of the chiller supplying cooling to the ice storage tank and the power of the ice storage tank supplying cooling to the building, respectively. This represents the coefficient of performance (COP).

[0009] Furthermore, S4 specifically refers to: Calculation of electricity purchase costs for cooling suppliers: ; in, for Electricity price during specific time periods The duration is the length of the time period. Electricity purchase costs for businesses; Calculation of revenue for cooling suppliers: ; in, In response to the subsidy, for t Demand response power clearing price for a given period for t Effective response capacity for users during a given time period; Calculation of winning bid capacity: ; ; in, The baseline power supply for time period t; The power limit of the chiller during time period t; for t The maximum power limit for regular power purchases by the distribution network during specific time periods; for t Other critical loads during the period; Calculation of effective response quantity: ; ; in, for t Actual response volume of time-of-use cooling providers; Calculation of penalty costs: ; in, For assessment fees, This is the penalty coefficient; The final response benefits are as follows: ; in, For response costs; Calculation of power over-limit penalty during non-response periods: ; in, Indicates the non-response period. The unit price for power exceeding the limit during non-response periods. Power limit for each time step; The objective function for cooling suppliers to participate in demand response is as follows: ; in, Electricity purchase costs for businesses, Penalty for exceeding power limits during non-response periods. For response costs.

[0010] Furthermore, S5 specifically refers to: Incentive cost calculation: ; ; in, and To set a lower and upper limit for incentive prices; Calculation of additional electricity purchase costs: ; in, This indicates the additional cost of purchasing electricity. This indicates the additional electricity purchase price for the distribution network. Purchase additional electricity for the power distribution network; Calculation of load reduction costs: ; in, This indicates the cost of load reduction. As a load shedding penalty, Indicates the load shedding amount; Load balance constraints: ; The objective function of the incentive-clearing model for distribution network operators is as follows: .

[0011] Furthermore, S6 specifically refers to: Master-slave game framework: The distribution network supplier aims to minimize its own costs, generates compensation incentive prices and publishes them to the cooling suppliers. The cooling suppliers respond with the goal of minimizing their own costs and feed the response results back to the distribution network operator. The distribution network operator is the decision-maker, and the cooling suppliers are the followers. Two-level optimization model: In the incentive-driven demand response process, the upper-level distribution network operator incentive-clearing model seeks the optimal incentive price and penalizes power overruns during non-incentive periods to limit overruns. The objective function is the objective function of the distribution network operator incentive-clearing model. The objective function of the energy optimization model for lower-level cooling manufacturers is the objective function for cooling manufacturers to participate in demand response. The optimal response amount is determined based on time-of-use electricity pricing, incentive information released by distribution network suppliers, and their own circumstances. Bisection Method Solution: The bisection method is used to solve the master-slave game framework and the two-level optimization model to determine the optimal incentive price for the distribution network operator.

[0012] The present invention employs the above-mentioned method for ice storage air conditioning to participate in joint demand response transactions, which considers the three-state operation mechanism. The beneficial effects are as follows: (1) The present invention constructs a refined model covering the three states of ice, phase change and water, accurately characterizing temperature evolution, ice-water ratio and heat transfer boundary, and improving physical consistency and optimization accuracy; (2) This invention proposes a price-incentive joint strategy, which coordinates electricity price signals and physical constraints through a master-slave game two-layer optimization framework to avoid insufficient response or excessive transfer, thereby improving economy and flexibility. Attached Figure Description

[0013] Figure 1 This is a flowchart of the steps of a method for ice storage air conditioning to participate in joint demand response transactions, which takes into account the three-state operation mechanism of the present invention. Figure 2 This is a flowchart of the bisection method for solving a method of ice storage air conditioning participating in joint demand response transactions that considers the three-state operation mechanism of the present invention. Figure 3 This is a typical daily cooling load curve of a method for ice storage air conditioning to participate in joint demand response transactions, which considers the three-state operation mechanism of the present invention. Figure 4 This is a refrigerant power limit diagram for a method of ice storage air conditioning participating in joint demand response transactions that considers the three-state operation mechanism of the present invention; Figure 5 This invention relates to the method for ice storage air conditioning to participate in joint demand response transactions, which considers the three-state operation mechanism, and the incentive price clearing result of distribution network operators during critical periods; Figure 6 This is a comparison chart of the incentive response amount and load deficit amount of a method for ice storage air conditioning to participate in joint demand response transactions that considers the three-state operation mechanism of the present invention. Figure 7 This is the result of chiller power scheduling under joint demand response in a method for ice storage air conditioning to participate in joint demand response transactions that considers the three-state operation mechanism of the present invention. Figure 8 This is a temperature change curve of a method for ice storage air conditioning to participate in joint demand response transactions, which considers the three-state operation mechanism of the present invention. Figure 9This is the ice-water ratio variation curve of a method for ice storage air conditioning to participate in joint demand response transactions that considers the three-state operation mechanism of the present invention; Figure 10 This is a schematic diagram of the cooling load vs. system cooling capacity of a method for ice storage air conditioning to participate in joint demand response transactions, which considers the three-state operation mechanism of the present invention. Figure 11 This is a comparison chart of the ice storage tank charging / discharging rate and upper limit of a method for ice storage air conditioning to participate in joint demand response transactions, which considers the three-state operation mechanism of the present invention. Figure 12 This is the cold loss curve of a method for ice storage air conditioning to participate in joint demand response transactions, which considers the three-state operation mechanism of the present invention. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0015] like Figure 1 As shown, the present invention provides a method for ice storage air conditioning systems to participate in joint demand response transactions, considering a three-state operating mechanism, comprising the following steps: S1. Construct an energy balance model for ice storage air conditioning, specifically as follows: The ice storage tank is the component that stores energy, operates in three states, and participates in demand response in ice storage air conditioning. The total energy state formula for an ice storage tank is expressed as: ; in, and These are the masses of ice and water, respectively. and These are the specific heat capacities of ice and water, respectively. The latent heat of melting ice, The temperature of the refrigerant ethylene glycol. The temperature of ice, water, or a mixture of ice and water in the ice storage tank; According to the law of conservation of mass, the combined mass of ice and water should remain constant. Therefore, according to the total energy state formula, the ice-to-water ratio can be used to represent the cooling capacity of an ice storage tank, as expressed by: ; ; in, and These are the masses of ice and water, respectively. The ratio is ice to water; The energy change in an ice storage tank follows the law of conservation of energy. The energy change within the tank over a given period is the cooling charge minus the heat loss and cooling release. Its mathematical expression is: ; in, This represents the change in energy in the ice storage tank. The specific components of the energy change in the ice storage tank are as follows: ; in, This refers to the amount of cooling energy supplied by the refrigeration unit to the ice storage tank. This refers to the heat loss caused by heat exchange between the ice storage tank and the outside environment. The cooling capacity supplied by the ice storage tank to the building-side load; The cooling capacity of the refrigeration unit to charge the ice storage tank is constrained as follows: ; in, The power of the chiller supplying cooling to the ice storage tank. This indicates the cooling capacity produced by the refrigeration unit under a given electrical power. The heat loss constraints caused by heat exchange between the ice storage tank and the outside environment are as follows: ; in, Indicates ambient temperature. The temperature of ice, water, or a mixture of ice and water in the ice storage tank. This indicates the heat exchange area between the ice storage tank and the outside environment. and These are the thickness of the coil and the thickness of the ice layer, respectively. and The heat transfer coefficients of the coil and the ice layer are respectively. Indicates the convective heat transfer coefficient; The cooling capacity constraints of the ice storage tank for the building-side load are as follows: ; ; ; in, This indicates the contact area between the refrigerant and the coil. This indicates the temperature of the refrigerant ethylene glycol. The thermal resistance during cooling consists of two parts: the thermal resistance of the coil and the thermal resistance of the ice layer. The ratio of ice to water is [missing information]. This represents the maximum value of the ice layer thickness.

[0016] S2. Construct a model for the evolution of temperature and ice-to-water ratio in ice storage air conditioning, specifically: During operation, the cooling medium inside the ice storage tank exhibits different temperature and ice-to-water ratio changes depending on its energy state. These changes can be categorized into three stages: pure ice state, phase change state, and pure water state. The specific temperature and ice-to-water ratio changes in each stage are as follows: In the pure ice state, the medium in the ice storage tank is entirely ice, and its temperature is below the freezing point of 0℃. At this point, the energy input or output into the ice storage tank is directly used for the sensible heat change of the ice. The formula for calculating the temperature change in the pure ice state is: ; When the temperature of the ice in the ice storage tank reaches or exceeds the freezing point after this temperature change, that is: If the medium in the ice storage tank enters a phase change state, the remaining energy will be used to melt the ice. In the phase change state, the temperature of the medium in the ice storage tank is maintained at the freezing point of 0℃. The energy input or output in the ice storage tank is used for the phase change process between ice and water, resulting in a change in the ice-water mass ratio. The formula for the change in the ice-water ratio in the phase change state is as follows: ; When the ice-to-water ratio is calculated and the following situation occurs: If If the water is completely frozen, the medium in the ice storage tank will re-enter a pure ice state, and the remaining energy will be used to lower the ice temperature. like This indicates that the ice has completely melted, the medium in the ice storage tank has entered a pure water state, and the remaining energy is used to raise the water temperature. In a pure water state, the medium in the ice storage tank is entirely water, and the temperature is above the freezing point of 0°C. The energy input or output in the ice storage tank is used for the sensible heat change of the water, as shown in the specific formula: ; When the temperature of the water in the ice storage tank reaches or falls below the freezing point after this temperature change, that is... Then the medium in the ice storage tank enters a phase change state, and the remaining energy is used for the freezing of water into ice; To uniformly describe the changes in ice storage tank temperature and ice-to-water ratio, the iterative formula for updating ice storage tank temperature is expressed as follows: ; The iterative formula for updating the ice-water ratio temperature in the ice storage tank is expressed as follows: ; in, The phase transition ratio is at time step t.

[0017] S3. Construct a power constraint model for ice storage air conditioning, specifically as follows: An ice storage tank can only be in one of three states at a time: charging, discharging, or idle. These three states are mutually exclusive, as expressed by the formula: ; in, , , These represent the binary components of the ice storage tank in the states of charging, discharging, and idle, respectively. The charge / discharge cooling rates are each limited by the maximum charge / discharge cooling capacity, as expressed by the formula: ; ; in, and These represent the maximum values ​​for cooling supplied by the chiller to the ice storage system and the maximum values ​​for cooling supplied by the ice storage system to the building, respectively. The total power of the refrigeration unit includes two parts: charging the ice storage tank and direct cooling. ; in, This refers to the operating power of the refrigeration unit. The power of the chiller supplying cooling to the ice storage tank. The power of the chiller to cool the building; The operating power of the refrigeration unit is limited by its maximum capacity: ; in, This is the maximum power of the refrigeration unit; The expression for the power-energy conversion of a refrigeration unit is: ; ; in, and These represent the power of the chiller supplying cooling to the ice storage tank and the power of the ice storage tank supplying cooling to the building, respectively. This represents the coefficient of performance (COP).

[0018] S4. Construct a commercial energy optimization model for the cooling yard, specifically: Calculation of electricity purchase costs for cooling suppliers: ; in, for Electricity price during specific time periods The duration is the length of the time period. Electricity purchase costs for businesses; Calculation of revenue for cooling suppliers: ; in, In response to the subsidy, for t Demand response power clearing price for a given period for t Effective response capacity for users during a given time period; Calculation of winning bid capacity: ; ; in, The baseline power supply for time period t; The power limit of the chiller during time period t; for t The maximum power limit for regular power purchases by the distribution network during specific time periods; for t Other critical loads during the period; Calculation of effective response quantity: ; ; in, for t Actual response volume of time-of-use cooling providers; Calculation of penalty costs: ; in, For assessment fees, This is the penalty coefficient; The final response benefits are as follows: ; in, For response costs; Calculation of power over-limit penalty during non-response periods: ; in, Indicates the non-response period. The unit price for power exceeding the limit during non-response periods. Power limit for each time step; The objective function for cooling suppliers to participate in demand response is as follows: ; in, Electricity purchase costs for businesses, Penalty for exceeding power limits during non-response periods. For response costs.

[0019] S5. Construct an incentive-based clearing model for distribution network operators, specifically: Incentive cost calculation: ; ; in, and To set a lower and upper limit for incentive prices; Calculation of additional electricity purchase costs: ; in, This indicates the additional cost of purchasing electricity. This indicates the additional electricity purchase price for the distribution network. Purchase additional electricity for the power distribution network; Calculation of load reduction costs: ; in, This indicates the cost of load reduction. As a load shedding penalty, Indicates the load shedding amount; Load balance constraints: ; The objective function of the incentive-clearing model for distribution network operators is as follows: .

[0020] S6. Establish a master-slave game framework and a two-layer optimization model, and use the bisection method to solve for the optimal incentive price to optimize the participation of ice storage air conditioning in joint demand response. Specifically: Master-Slave Game Framework: As independent decision-makers, distribution network operators and cooling suppliers have conflicting objective functions, making direct solutions difficult. Therefore, this paper constructs a master-slave game framework between the distribution network operator and the cooling supplier, achieving efficient solutions through a hierarchical decision-making mechanism. The distribution network supplier aims to minimize its own costs, generating compensation incentive prices and publishing them to the cooling supplier. The cooling supplier, in turn, responds with the goal of minimizing its own costs and feeds back the response to the distribution network operator. The strategies of both parties interact, with the distribution network operator as the decision-maker and the cooling supplier as the follower.

[0021] Two-level optimization model: In the incentive-driven demand response process, the upper-level distribution network operator incentive clearing model seeks the optimal incentive price to minimize its own cost. In order to prevent cooling suppliers from exceeding power limits during non-incentive periods, it is necessary to penalize power exceeding limits during non-incentive periods to limit the limits. The objective function is the objective function of the distribution network operator incentive clearing model in step S5. The objective function of the energy optimization model for lower-level cooling manufacturers is the same as the objective function for cooling manufacturers to participate in demand response in step S4. Based on time-of-use electricity prices, incentive information released by distribution network suppliers, and their own circumstances, they determine the optimal response amount in order to maximize their own interests.

[0022] Bisection Method Solution: Because the lower-level optimization problem involves complex nonlinear constraints and a large number of 0-1 variables, traditional solution methods (such as KKT conditions) are difficult to apply directly, while general heuristic algorithms suffer from the problems of easily getting trapped in local optima and low solution efficiency. Therefore, the classic bisection method is used to solve the master-slave game framework and the two-level optimization model to quickly and efficiently determine the optimal incentive price for the distribution network operator. The solution process is as follows: Figure 2 As shown.

[0023] The bisection method is an efficient interval search algorithm that gradually approaches the optimal solution of a function by repeatedly dividing the interval into two. This method is suitable for solving the extremum problem of a single-peak function. In the model of this invention, the cost function of the upper-level distribution network operator exhibits typical convex function characteristics in response to changes in incentive prices, making it particularly suitable for solving using the bisection method.

[0024] Example: A typical 24-hour intraday scenario was selected as the case study, with a time step of 1 hour. Cooling load curve reference. Figure 3 The time-of-use (TOU) pricing adopts a four-stage structure: Off-peak (1–7, 24 hours) 0.2357 yuan / kWh, flat (8–10, 13–15 hours) 0.5892 yuan / kWh, peak (11–12, 16–19, 22–23 hours) 0.9427 yuan / kWh, and peak (20–21 hours) 1.1313 yuan / kWh. Power limits are derived based on the TOU trend, as shown in the curve. Figure 4 As shown in Table 1, the rated performance parameters of the refrigeration unit are a maximum electrical power of 95.6 MW and a COP of 1.855. The parameters for the ice storage air conditioning unit are also shown in Table 1.

[0025] The incentive price for demand response is cleared within the identified response period, with a price range set at [0.3, 2.0] yuan / kWh; power exceeding the limit outside the response period is penalized at 5 yuan / kWh. The optimization algorithm uses a binary search method to search for hourly incentives, with a convergence accuracy set to 10. -6 The maximum number of iterations is 30, and the step size coefficient is 0.005.

[0026] Table 1. Parameter Information for Ice Storage Air Conditioning

[0027] Market clearing situation as follows Figure 5 , Figure 6 and Figure 7As shown: Baseline identification reveals two major load deficit plateaus forming in periods 8, 9, 10, and 13, 14, 15, with a secondary deficit in period 18, and the weakest deficit in period 11. Correspondingly, the upper-layer clearing occurs in periods 8 / 9 / 10 / 13 / 14 / 15 due to similar and higher load deficits compared to other periods; therefore, the hourly incentive price is set at the same and relatively high level (1.82 yuan·kWh). -1 The price was slightly lower during the 18-hour period (1.12 yuan / kWh). -1 The lowest price of the day (0.63 yuan / kWh) was taken during the 11-hour period. -1 The response curve satisfies the upper and lower limits of the incentive and is positively correlated with the deficit intensity. The response curve is well coupled with the deficit curve on the distribution side: within the two high deficit platforms, the deficit can be basically closed by the incentive response, and only a small amount of additional power purchase is needed for marginal compensation during the 18th period. Load shedding is almost zero due to its high cost. This result can be explained from both cost and physical perspectives: on the one hand, the weighted marginal cost of the incentive is significantly lower than the segmentation coefficient of additional power purchase and load shedding, making manufacturers tend to prioritize "response"; on the other hand, the three-state mechanism provides sufficient latent heat release capacity during the peak period, thus eliminating the need to rely on more costly means. Finally, under the superposition of TOU and incentive, the chiller power during the response period drops significantly from the baseline and stabilizes below the power limit; due to the power over-limit penalty set in the non-response period, there is no "secondary peak shift", and the overall power trajectory of the main unit fits the limit curve.

[0028] Figure 8 and Figure 9 The trajectory of temperature and ice-water ratio changes within a 24-hour time step is given. Figure 10 The comparison between the cooling capacity supplied by the chiller and the cooling capacity supplied by the ice storage tank is given. Combined with the market clearing results (the incentives are highest during the 8-10 and 13-15 periods, followed by the 18 period, and lowest during the 11 period), it can be seen that manufacturers form an operating trajectory of "deep charging before the peak - phase change cooling release during the peak - stabilization after the peak" around the key response window: before the peak (1-8h), driven by the low off-peak electricity price and the upcoming high incentives, they actively increase the charging of the ice storage tank to prepare for "low temperature - high ice". Figure 8 , Figure 9The data shows that before the arrival of the first high-deficit plateau, the tank temperature rapidly dropped to the cryogenic zone, with an ice-to-water ratio of 1. During the peak period (9–18h), under the combined effect of power limits and hourly excitation, the system prioritized the phase change plateau (tank temperature maintained near 0℃), and the ice-to-water ratio decreased monotonically over time, using heat release to undertake the main peak-shaving task for the two high-deficit plateaus (8–10h, 13–15h). In the low-excitation window of 11h, the heat release intensity relatively converged, and the proportion of direct power supply from the main unit slightly increased. After the peak (19–24h), as α approached 0 (latent heat release decayed), the system naturally returned to the combination of "mainly direct power supply with moderate recharge" to close the intraday state. The main unit power trajectory throughout the day still adhered to the power limit during non-response periods, without "secondary peak shift," indicating that the power over-limit penalty during non-response periods effectively suppressed strategy arbitrage (see...). Figure 10 and Figure 7 (Correspondence relationship).

[0029] The charging and discharging cooling rates, upper limits, and cooling loss distribution of the ice storage tank are as follows: Figure 11 and Figure 12 As shown, the upper limit of cooling charge is mainly constrained by the primary side and the unit's rated parameters, and is approximately constant; the upper limit of cooling discharge, however, varies with the equivalent thermal resistance as the ice thickness and state change. Figure 11 The time-sharing curves show the following: Before the peak, during the phase transition cooling period, the temperature remains constant, the ice-to-water ratio increases, the ice layer gradually thickens, the upper limit of cooling release decreases, and the cooling loss also gradually decreases. At time step 8, the ice storage tank temperature jumps to -8℃, the temperature difference with ethylene glycol and the outside environment increases sharply, and the upper limit of cooling release and the cooling loss also increase. After entering the peak segment, the ice storage tank temperature remains constant, the ice-to-water ratio decreases, the ice layer gradually thins, and the upper limit of cooling release and the cooling loss gradually increase. After the peak, the ice storage tank temperature jumps to 8℃, and the sharp drop in temperature difference with ethylene glycol and the outside environment causes the cooling rate and cooling loss of the ice storage tank to decrease compared to before the peak. As the ice storage cooling process returns to its original state in the last time step, the upper limit of cooling release and the cooling loss become the same as in the first time step.

[0030] Therefore, this invention adopts the above-mentioned method for ice storage air conditioning to participate in joint demand response transactions, which considers the three-state operation mechanism. It constructs a refined model covering the three states of full ice, phase change, and full water, accurately characterizing temperature evolution, ice-water ratio, and heat transfer boundary, thereby improving physical consistency and optimization accuracy. It proposes a price-incentive joint strategy, which coordinates electricity price signals and physical constraints through a master-slave game two-layer optimization framework, avoiding insufficient response or over-limit transfer, and improving economy and flexibility.

[0031] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for ice storage air conditioning systems to participate in joint demand response transactions, considering a three-state operating mechanism, characterized in that, Includes the following steps: S1. Construct an energy balance model for ice storage air conditioning: including calculation of the total energy state of the ice storage tank, composition of energy changes, and charging, heat loss, and cooling constraints. S2. Construct a temperature and ice-water ratio evolution model for ice storage air conditioning: Divide the operation of the ice storage tank into three states: pure ice, phase change, and pure water. Define the temperature change formula, ice-water ratio change formula, and state transition conditions for each state. S3. Construct a power constraint model for ice storage air conditioning: including mutual exclusion constraints of the three states of ice storage tank charging, discharging, and idle, charging and discharging rate limits, total power composition of the chiller, and power-energy conversion relationship; S4. Construct a commercial energy optimization model for cooling plant: including the calculation of electricity purchase cost, response revenue, bid-winning capacity, effective response quantity, penalty cost, and over-limit penalty during non-response periods, with the objective function being to minimize the cost of the cooling plant. S5. Construct an incentive-clearing model for distribution network operators: including the calculation of incentive costs, additional electricity purchase costs, load shedding costs, and load balance constraints, with the objective function being the minimization of distribution network operator costs; S6. Establish a master-slave game framework and a two-level optimization model, and use the bisection method to solve for the optimal incentive price.

2. The method for ice storage air conditioning systems considering a three-state operating mechanism to participate in joint demand response transactions according to claim 1, characterized in that, S1 specifically refers to: The ice storage tank is the component that stores energy, operates in three states, and participates in demand response in ice storage air conditioning. The total energy state formula for an ice storage tank is expressed as: ； in, and These are the masses of ice and water, respectively. and These are the specific heat capacities of ice and water, respectively. The latent heat of melting ice, The temperature of the refrigerant ethylene glycol. The temperature of ice, water, or a mixture of ice and water in the ice storage tank; The cooling capacity of an ice storage tank can be expressed using the ice-to-water ratio as follows: ； ； in, and These are the masses of ice and water, respectively. The ratio is ice to water; The change in energy within an ice storage tank over a period of time is the cooling charge minus the heat loss and cooling release, and its mathematical expression is: ； in, This represents the change in energy in the ice storage tank. The specific components of the energy change in the ice storage tank are as follows: ； in, This refers to the amount of cooling energy supplied by the refrigeration unit to the ice storage tank. This refers to the heat loss caused by heat exchange between the ice storage tank and the outside environment. The cooling capacity supplied by the ice storage tank to the building-side load; The cooling capacity of the refrigeration unit to charge the ice storage tank is constrained as follows: ； in, The power of the chiller supplying cooling to the ice storage tank. This indicates the cooling capacity produced by the refrigeration unit under a given electrical power. The heat loss constraints caused by heat exchange between the ice storage tank and the outside environment are as follows: ； in, Indicates ambient temperature. The temperature of ice, water, or a mixture of ice and water in the ice storage tank. This indicates the heat exchange area between the ice storage tank and the outside environment. and These are the thickness of the coil and the thickness of the ice layer, respectively. and The heat transfer coefficients of the coil and the ice layer are respectively. Indicates the convective heat transfer coefficient; The cooling capacity constraints of the ice storage tank for the building-side load are as follows: ； ； ； in, This indicates the contact area between the refrigerant and the coil. This indicates the temperature of the refrigerant ethylene glycol. The thermal resistance during cooling consists of two parts: the thermal resistance of the coil and the thermal resistance of the ice layer. The ratio of ice to water is [missing information]. This represents the maximum value of the ice layer thickness.

3. The method for ice storage air conditioning systems considering a three-state operating mechanism to participate in joint demand response transactions according to claim 2, characterized in that, S2 specifically refers to: The ice storage tank operates in three stages: pure ice state, phase change state, and pure water state. The specific temperature and ice-water ratio changes in each stage are as follows: In the pure ice state, the medium in the ice storage tank is entirely ice, and its temperature is below the freezing point of 0℃. At this point, the energy input or output into the ice storage tank is directly used for the sensible heat change of the ice. The formula for calculating the temperature change in the pure ice state is: ； When the temperature of the ice in the ice storage tank reaches or exceeds the freezing point after this temperature change, that is: If the medium in the ice storage tank enters a phase change state, the remaining energy will be used to melt the ice. In the phase change state, the temperature of the medium in the ice storage tank is maintained at the freezing point of 0℃. The energy input or output in the ice storage tank is used for the phase change process between ice and water. The formula for the change in the ice-water ratio in the phase change state is as follows: ； When the ice-to-water ratio is calculated and the following situation occurs: If If the water is completely frozen, the medium in the ice storage tank will re-enter a pure ice state, and the remaining energy will be used to lower the ice temperature. like This indicates that the ice has completely melted, the medium in the ice storage tank has entered a pure water state, and the remaining energy is used to raise the water temperature. In a pure water state, the medium in the ice storage tank is entirely water, and the temperature is above the freezing point of 0°C. The energy input or output in the ice storage tank is used for the sensible heat change of the water, as shown in the specific formula: ； When the temperature of the water in the ice storage tank reaches or falls below the freezing point after this temperature change, that is... Then the medium in the ice storage tank enters a phase change state, and the remaining energy is used for the freezing of water into ice; The iterative formula for updating the temperature of the ice storage tank is expressed as follows: ； The iterative formula for updating the ice-water ratio temperature in the ice storage tank is expressed as follows: ； in, The phase transition ratio is at time step t.

4. The method for ice storage air conditioning systems considering a three-state operating mechanism to participate in joint demand response transactions according to claim 3, characterized in that, S3 specifically refers to: An ice storage tank can only be in one of three states at a time: charging, discharging, or idle. These three states are mutually exclusive, as expressed by the formula: ； in, , , These represent the binary components of the ice storage tank in the states of charging, discharging, and idle, respectively. The charge / discharge cooling rates are each limited by the maximum charge / discharge cooling capacity, as expressed by the formula: ； ； in, and These represent the maximum values ​​for cooling supplied by the chiller to the ice storage system and the maximum values ​​for cooling supplied by the ice storage system to the building, respectively. The total power of the refrigeration unit includes two parts: charging the ice storage tank and direct cooling. ； in, This refers to the operating power of the refrigeration unit. The power of the chiller supplying cooling to the ice storage tank. The power of the chiller to cool the building; The operating power of the refrigeration unit is limited by its maximum capacity: ； in, This is the maximum power of the refrigeration unit; The expression for the power-energy conversion of a refrigeration unit is: ； ； in, and These represent the power of the chiller supplying cooling to the ice storage tank and the power of the ice storage tank supplying cooling to the building, respectively. This represents the coefficient of performance (COP).

5. The method for ice storage air conditioning systems considering a three-state operating mechanism to participate in joint demand response transactions according to claim 4, characterized in that, S4 specifically refers to: Calculation of electricity purchase costs for cooling suppliers: ； in, for Electricity price during specific time periods The duration is the length of the time period. Electricity purchase costs for businesses; Calculation of revenue for cooling suppliers: ； in, In response to the subsidy, for t Demand response power clearing price for a given period for t Effective response capacity for users during a given time period; Calculation of winning bid capacity: ； ； in, The baseline power supply for time period t; The power limit of the chiller during time period t; for t The maximum power limit for regular power purchases by the distribution network during specific time periods; for t Other critical loads during the period; Calculation of effective response quantity: ； ； in, for t Actual response volume of time-of-use cooling providers; Calculation of penalty costs: ； in, For assessment fees, This is the penalty coefficient; The final response benefits are as follows: ； in, For response costs; Calculation of power over-limit penalty during non-response periods: ； in, Indicates the non-response period. The unit price for power exceeding the limit during non-response periods. Power limit for each time step; The objective function for cooling suppliers to participate in demand response is as follows: ； in, Electricity purchase costs for businesses, Penalty for exceeding power limits during non-response periods. For response costs.

6. The method for ice storage air conditioning systems considering a three-state operating mechanism to participate in joint demand response transactions according to claim 5, characterized in that, S5 specifically refers to: Incentive cost calculation: ； ； in, and To set a lower and upper limit for incentive prices; Calculation of additional electricity purchase costs: ； in, This indicates the additional cost of purchasing electricity. This indicates the additional electricity purchase price for the distribution network. Purchase additional electricity for the power distribution network; Calculation of load reduction costs: ； in, This indicates the cost of load reduction. As a load shedding penalty, Indicates the load shedding amount; Load balance constraints: ； The objective function of the incentive-clearing model for distribution network operators is as follows: 。 7. The method for ice storage air conditioning systems considering a three-state operating mechanism to participate in joint demand response transactions according to claim 6, characterized in that, S6 specifically refers to: Master-slave game framework: The distribution network supplier aims to minimize its own costs, generates compensation incentive prices and publishes them to the cooling suppliers. The cooling suppliers respond with the goal of minimizing their own costs and feed the response results back to the distribution network operator. The distribution network operator is the decision-maker, and the cooling suppliers are the followers. Two-level optimization model: In the incentive-driven demand response process, the upper-level distribution network operator incentive-clearing model seeks the optimal incentive price and penalizes power overruns during non-incentive periods to limit overruns. The objective function is the objective function of the distribution network operator incentive-clearing model. The objective function of the energy optimization model for lower-level cooling manufacturers is the objective function for cooling manufacturers to participate in demand response. The optimal response amount is determined based on time-of-use electricity pricing, incentive information released by distribution network suppliers, and their own circumstances. Bisection Method Solution: The bisection method is used to solve the master-slave game framework and the two-level optimization model to determine the optimal incentive price for the distribution network operator.

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