A day-ahead scheduling optimization strategy for microgrid systems considering thermal and humidity load response

Abstract

This invention discloses a day-ahead scheduling optimization strategy for a microgrid system considering thermal and humidity load responses. The strategy includes: supplying energy to an air conditioning system via the microgrid system; the air conditioning system processing return air using reheat; obtaining the return air temperature and relative humidity by setting a range based on known indoor temperature and relative humidity; calculating the supply air temperature and relative humidity by establishing a thermal-humidity balance equation; obtaining the cooling capacity of the air conditioning system using the enthalpy difference between the return and supply air; and, based on the mathematical models of the main equipment in the microgrid system and the cooling capacity of the air conditioning system, minimizing the overall operating cost min C of the microgrid system by using a particle swarm optimization algorithm to obtain the optimal hourly output of the main equipment in the microgrid system. Compared to existing optimization strategies that only consider thermal load responses, this invention also incorporates humidity load responses, simultaneously implementing temperature and humidity control to improve load transfer capacity and system economic efficiency.

Description

Technical Field

[0001] This invention belongs to the field of optimized scheduling methods for distributed integrated energy systems, and specifically relates to a day-ahead scheduling optimization strategy for microgrid systems that considers thermal and humid load response. Background Technology

[0002] Combined cooling, heating, and power (CCHP) microgrid systems have the advantages of high primary energy utilization and low environmental pollution impact, making them a hot topic of interest in recent years. A CCHP microgrid system can simultaneously generate cooling, heating, and electricity, achieving a primary energy utilization rate of 75%-80%, while consuming only 3 / 4 of the energy required for traditional separate heating and power systems. A typical CCHP microgrid system includes (1) generator sets, such as gas turbines, internal combustion engines, and fuel cells; (2) heating equipment, such as waste heat boilers and gas boilers; and (3) refrigeration equipment, such as lithium bromide absorption chillers and electric chillers.

[0003] Current research on demand response in air conditioning systems primarily focuses on adjusting indoor temperature setpoints to achieve load response. However, studies on thermal and humidity loads only consider indoor temperature control and thermal load response, lacking exploration of indoor relative humidity control and humidity load response. In reality, factors such as relative humidity and wind speed significantly impact human comfort. Air humidity affects energy balance, thermal sensation, skin moisture, and heat loss through perspiration. Especially in warmer environments, increased relative humidity significantly reduces thermal comfort, causing a feeling of stuffiness and deteriorated air quality. Therefore, to ensure human thermal comfort and achieve greater economic efficiency in microgrid system operation, thermal and humidity load responses must be considered simultaneously during building demand response. Summary of the Invention

[0004] The purpose of this invention is to overcome the deficiencies in the prior art and to provide a day-ahead scheduling optimization strategy for microgrid systems that takes into account thermal and humidity load response.

[0005] The specific technical solution adopted in this invention is as follows:

[0006] This invention provides a day-ahead scheduling optimization strategy for microgrid systems that considers thermal and humidity load response, as detailed below:

[0007] Step 1): Construct mathematical models of the main equipment in the microgrid system based on the actual energy conversion process;

[0008] Step 2): The microgrid system supplies energy to the air conditioning system, which uses reheating to cool the return air to the dew point temperature for cooling and dehumidification. During this process, the return air temperature at time (τ-1) is obtained based on the known indoor temperature and relative humidity setpoints. and return air relative humidity Based on the indoor temperature under the indoor air conditions at time τ and relative humidity The supply air temperature was obtained by establishing a heat and humidity balance equation. and relative humidity of the supply air According to the income and The cooling capacity of the air conditioning system is obtained by using the enthalpy difference between the return air and the supply air.

[0009] Step 3): Based on the mathematical model of the main equipment in the microgrid system and the cooling capacity of the air conditioning system, with the goal of minimizing the overall operating cost min C of the microgrid system, the optimal hourly output of the main equipment in the microgrid system is obtained through the particle swarm optimization algorithm.

[0010] Preferably, the microgrid system includes a prime mover, a waste heat boiler, an absorption chiller, a gas boiler, an electric chiller, and a water storage tank. The electrical energy generated by the prime mover is transmitted via wires to an external power supply network that supplies electricity to users. When the power supply from the prime mover is insufficient, it is supplemented by the power grid. A battery is also installed on the power supply network. The heat energy generated by the prime mover is transmitted to the waste heat boiler and the absorption chiller via a first pipeline. The heat generated by the waste heat boiler is transmitted to the heating pipeline that supplies heat to users, and the cold energy generated by the absorption chiller is transmitted to the cooling pipeline that supplies cold to users. Part of the heat energy generated by the gas boiler is transmitted to the absorption chiller via a second pipeline, and part is directly transmitted to the heating pipeline. An electric chiller is connected to the power supply network, and the cold energy generated by the electric chiller is transmitted to the cooling pipeline via a third pipeline. The water storage tank is connected to both the heating pipeline and the cooling pipeline.

[0011] Furthermore, the prime mover is a gas turbine or an internal combustion engine.

[0012] Furthermore, the air conditioning system includes an air handling unit, a reheater, and an indoor fan; the air outlet of the air handling unit is sent out through the indoor fan after passing through the reheater, and the indoor air, as return air, enters the air handling unit after passing through the reheater to exchange heat with the cooling water; the cooling water comes from the water storage tank of the microgrid system and is cooled by electric chillers and absorption chillers.

[0013] Preferably, the main equipment of the microgrid system includes a prime mover, a waste heat boiler, an absorption chiller, a gas boiler, and an electric chiller.

[0014] Preferably, step 2) is as follows:

[0015] Utilizing indoor temperature The heat balance equation is established as shown in formula (5):

[0016]

[0017] In the formula, Q sen (τ) represents the sensible heat and cooling load of the indoor environment, in kW; C p ρ is the specific heat of air, taken as 1.005 kJ / (kg·K); ρ is the density of moist air, kg / m³. 3 V represents the volume of the indoor environment, in meters. 3 ; The rate of change of indoor air temperature over time; This refers to the indoor ambient temperature response section; v S The supply air flow rate for return air, m 3 / s;

[0018] Using relative humidity The wet balance equation is established as shown in formula (6):

[0019]

[0020] In the formula, M(τ) is the wet load, g / s; The rate of change of indoor air humidity over time; This refers to the indoor humidity response section.

[0021] Subsequently and As an optimization variable, it participates in the day-ahead scheduling of the microgrid system, and The fluctuation range meets the known indoor temperature set range value. The fluctuation range meets the known relative humidity set range value; then, using the enthalpy difference between the return air and the supply air, the cooling capacity Q of the air conditioning system is obtained. cold (τ), as shown in formulas (7) to (9):

[0022]

[0023]

[0024]

[0025] In the formula, and The specific enthalpy (kJ / kg) of the return air passing through the inlet and outlet of the air conditioning system are respectively; Q ac (τ) and Q ec (τ) represents the cooling power of the absorption chiller and the electric chiller at time τ, respectively, in kW; Q wt_dis (τ) and Q wt_chr (τ) represents the cooling power and storage power of the reservoir at time τ, respectively, in kW.

[0026] Preferably, the minimum comprehensive operating cost min C of the microgrid system is calculated using formulas (1) to (4), which are as follows:

[0027]

[0028]

[0029]

[0030]

[0031] Where T represents the entire optimization cycle, 24 hours; C represents the overall operating cost of the microgrid system, C0 gas (τ), C grid (τ) and C om (τ) represents the natural gas cost, electricity purchase cost, and operation and maintenance cost of the microgrid system, respectively, all in yuan; P gt (τ) represents the electrical power released by the combustion of natural gas in the prime mover at time τ, in kW; η gt_ele (τ) represents the power generation efficiency of the prime mover, which has no unit; HV is the calorific value of natural gas, 38931 kJ / m³. 3 ;R gas The price of natural gas is expressed in yuan / m³. 3 ; △τ represents the microgrid system operating time interval, in hours; P grid (τ) represents the electrical power purchased from the grid at time τ, in kW; R grid (τ) represents the electricity purchase price at time τ, in yuan; F ac (τ), F ec (τ), H wb (τ), H gb (τ), P bt_dis (τ), P bt_chr (τ), Q wt_dis (τ) and Q wt_chr (τ) represents the cooling power of the absorption chiller, the cooling power of the electric chiller, the power of the waste heat boiler, the power of the gas boiler, the discharge power of the battery, the charging power of the battery, the energy release power of the water storage tank, and the energy storage power of the water storage tank, respectively, all in kW; R om_gt R om_ac R om_ec R om_wb and R om_wt The prices listed are the operating and maintenance costs for gas-fired internal combustion engines, absorption chillers, electric chillers, batteries, and water storage tanks, all in yuan / kWh.

[0032] Preferably, the optimization factors of the particle swarm optimization algorithm include grid power, prime mover power, absorption chiller power, electric chiller power, gas boiler power, waste heat boiler power, and the charging and discharging power of batteries and water tanks.

[0033] Compared with the prior art, the present invention has the following advantages:

[0034] This invention allows indoor temperature and relative humidity setpoints to fluctuate within a certain range, enabling both thermal and humidity loads to participate in demand response. This strategy is compared with no-demand-response strategies and thermal load response strategies. Particle swarm optimization is used to obtain the overall operating cost of the microgrid system and the hourly changes in indoor temperature and humidity setpoints under different strategies. The overall power output characteristics of the system are further analyzed, and the power output of different energy supply units under different strategies is compared. Compared to existing optimization strategies that only consider thermal load response, this invention also incorporates humidity load response, simultaneously regulating temperature and humidity to improve load transfer capacity and system economic efficiency. Attached Figure Description

[0035] Figure 1 A schematic diagram of a combined cooling, heating and power microgrid system;

[0036] Figure 2 This is a schematic diagram of an air conditioning system;

[0037] Figure 3 This is a schematic diagram of the reheat process.

[0038] Figure 4 Flowchart for calculating cooling capacity under heat and humidity load response strategy;

[0039] Figure 5 The comfort range for PPD and PMV;

[0040] Figure 6 To illustrate the cooling energy supply of each device in the embodiment, Figure (a) shows the hourly cooling load, and Figures (bd) show the output of the absorption chiller, electric chiller, and water storage tank under three different demand response strategies, respectively.

[0041] Figure 7 In the example (a), a heat load response strategy is adopted. Figure 6 (b) shows the cooling load curves before and after adopting the heat and humidity load response strategy. Detailed Implementation

[0042] The present invention will be further described and illustrated below with reference to the accompanying drawings and specific embodiments. The technical features of each embodiment of the present invention can be combined accordingly, provided that there is no mutual conflict.

[0043] like Figure 1 As shown, this invention provides a microgrid system that can adopt a CCHP system, ensuring the supply of cooling, heating, and power loads. The microgrid system mainly includes a prime mover (PM), a waste heat boiler (WB), an absorption chiller (AC), a gas boiler (GB), an electric chiller (EC), and a water storage tank (WT). The connection methods and structures of each device are described in detail below.

[0044] The prime mover can be a gas turbine (GT) or an internal combustion engine (ICE), which generates heat or electricity by consuming natural gas. The electricity generated by the prime mover is transmitted via wires to an external power grid that supplies electricity to users, providing the system with electrical load. The system can also meet its electricity demand by purchasing electricity from the grid. Furthermore, when the system has a surplus of power, the excess electricity can be stored in batteries (BT), achieving both energy storage and release. The heat generated by the prime mover is transmitted via a first pipeline to a waste heat boiler and an absorption chiller. The waste heat boiler generates heat using hot flue gas to provide the system with a heat load, and the generated heat is transmitted to the heating pipeline that supplies heat to users. The absorption chiller generates cooling energy using hot flue gas or jacketed water to provide a cooling load, and the generated cooling energy is transmitted to the cooling pipeline that supplies cooling to users. Therefore, in the microgrid mode of this invention, since "cooling" is achieved by the prime mover, gas boiler, or electric chiller providing heat energy to drive the absorption chiller, "cooling" also refers to "heat" in a broad sense.

[0045] The gas-fired boiler consumes natural gas to meet the system's heat demand and provide the heat energy needed for the absorption chiller's cooling load. Specifically, part of the heat energy generated by the gas-fired boiler is transferred to the absorption chiller via a second pipeline, and the other part is directly transferred to the heating pipeline. An electric chiller is connected to the power supply network; the cooling capacity generated by the electric chiller is transferred to the cooling pipeline via a third pipeline, providing the cooling load for the system and meeting part of its heat demand. A water storage tank is connected to both the heating and cooling pipelines, capable of storing and releasing the heat and cold energy from both pipelines.

[0046] This invention utilizes the aforementioned microgrid system to provide a day-ahead scheduling optimization strategy for microgrid systems that considers thermal and humidity load response. This method does not merely adjust indoor temperature to meet cooling load demands, but simultaneously adjusts indoor temperature and humidity to meet cooling load demands and achieves more economical optimized scheduling results for the microgrid system. The specific steps are as follows:

[0047] Step 1): Based on the above microgrid system, construct mathematical models of the main equipment in the microgrid system according to the actual energy conversion process. The main equipment in the microgrid system includes a prime mover, waste heat boiler, absorption chiller, gas boiler, and electric chiller. The specific mathematical models of each device are as follows:

[0048] 1. The prime mover will be explained using an internal combustion engine as an example, as follows:

[0049] The amount of natural gas consumed by an internal combustion engine is expressed as follows:

[0050]

[0051] In the formula, G represents the amount of natural gas consumed by the internal combustion engine, in cubic meters per second (m³). 3 P represents the power generation of the internal combustion engine, in kW; η e For internal combustion engines, CV represents the calorific value of natural gas, in kWh / m³. 3 .

[0052] 2. The waste heat boiler, as the main heat-generating equipment in a combined cooling, heating, and power (CCHP) system, has the following heat generation model:

[0053] H out,boiler =H in,boiler ×η boiler (11)

[0054] In the formula, H out,boiler Heat output of waste heat boiler, unit: kW; H in,boiler The amount of heat entering the waste heat boiler, expressed in kW; η boiler This refers to the thermal efficiency of the waste heat boiler.

[0055] 3. The absorption chiller is the main cooling equipment in a combined cooling, heating, and power (CCHP) system. Higher-temperature flue gas enters the chiller for a double-effect refrigeration cycle, while lower-temperature cylinder liner water enters for a single-effect refrigeration cycle. The mathematical model of the chiller can be expressed as follows:

[0056] C ac =H in,ac ×COP ac (12)

[0057] In the formula, C ac The cooling capacity of the absorption chiller is expressed in kW (H). in,ac The heat of the flue gas entering the chiller, expressed in kW; COP ac This refers to the refrigeration efficiency of an absorption chiller.

[0058] 4. Gas-fired boilers serve as supplementary heating equipment in a combined heat and power (CHP) system, providing additional heat when the waste heat boiler's heat production and storage are insufficient. The model is as follows:

[0059] H out,gas_boiler =H in,gas_boiler ×η gas_boiler (13)

[0060] In the formula, H out,gas_boiler Heat output of gas-fired boilers, in kW; H in,gas_boilerThe amount of heat entering the gas-fired boiler, expressed in kW; η gas_boiler This refers to the thermal efficiency of a gas-fired boiler.

[0061] 5. The electric chiller serves as a supplementary cooling device to the system, providing additional cooling when the chiller and cold storage are insufficient. The model is as follows:

[0062] C hp =E in,hp ×COP hp (14)

[0063] In the formula, C hp The cooling capacity of the electric chiller is expressed in kW; E in,hp The amount of electricity entering the electric chiller, measured in kW; COP hp This refers to the refrigeration efficiency of the electric chiller.

[0064] Step 2): The microgrid system supplies energy to the air conditioning system, which then uses reheating to cool the return air to its dew point temperature, achieving both cooling and dehumidification. During this process, the indoor temperature is set within a known range (i.e., the maximum indoor temperature setting). and indoor temperature setting minimum value and the relative humidity setting range value (i.e., the maximum relative humidity setting value) and relative humidity set to minimum value ), thus obtaining the return air temperature at time (τ-1). and return air relative humidity Based on the indoor temperature under the indoor air conditions at time τ and relative humidity The supply air temperature was obtained by establishing a heat and humidity balance equation. and relative humidity of the supply air According to the income and The cooling capacity of the air conditioning system is obtained by utilizing the enthalpy difference between the return air and the supply air. The details are explained below:

[0065] The response to heat and humidity loads is primarily achieved through the air conditioning system's regulation of indoor temperature and humidity. The air conditioning system is a crucial system for controlling the building's indoor environment and typically includes air handling units, reheaters, supply air duct fans, return air duct fans, and indoor fans. The air handling units facilitate heat exchange between the return air and cooling water; water pumps drive the cooling water circulation; and the supply air duct fans, return air duct fans, and indoor fans drive the circulation of return air between the air handling units and the terminal rooms of the air conditioning system. Figure 2As shown, indoor air enters the air handling unit as return air and exchanges heat with the cooling water. Once the return air temperature decreases, it is sent to the room by a fan to balance the indoor cooling load. The cooling water, driven by a water pump, exchanges heat with an absorption chiller, an electric chiller, and a water storage tank, gradually lowering its temperature. After accumulating cold, it exchanges heat with the return air again. In other words, the cooling water comes from the water storage tank of the microgrid system and is cooled by electric chillers and absorption chillers.

[0066] This invention utilizes a reheat method to treat return air. This is because, to meet indoor heat and humidity load requirements, the temperature and humidity of the return air need to be simultaneously controlled, cooling it to the dew point temperature for both cooling and dehumidification. However, if the dew point air supply method is used directly, the temperature and humidity of the return air are coupled during the cooling and dehumidification process. After meeting the humidity requirements, the return air is in an overcooled state, making it impossible to simultaneously and accurately reach the indoor temperature and humidity setpoints. Therefore, this invention utilizes a reheat method to treat return air. The specific steps of the return air reheat method are as follows (e.g.) Figure 3 As shown):

[0067] Return air condenses after being cooled to its dew point temperature by the return air duct fan coil unit, reducing its absolute moisture content. Once the return air humidity reaches the set value, a reheater heats the saturated return air at the outlet of the return air duct fan coil unit, raising its temperature to the set value, thus achieving precise temperature and humidity control. During the reheat process, fresh return air supplied from the room is used as the system's reheat heat source. This pre-cools the fresh return air while simultaneously reheating the dehumidified return air after cooling by the return air duct fan coil unit to reach the supply air state. The reheat process consumes no additional energy.

[0068] like Figure 4 As shown, the return air temperature at time (τ-1) is first obtained based on the known indoor temperature and relative humidity set range values. and return air relative humidity Subsequently, based on the indoor air conditions at time τ, the indoor temperature... The heat balance equation is established as shown in formula (5):

[0069]

[0070] In the formula, Q sen (τ) represents the sensible heat and cooling load of the indoor environment, in kW; C p ρ is the specific heat of air, taken as 1.005 kJ / (kg·K); ρ is the density of moist air, kg / m³. 3 V represents the volume of the indoor environment, in meters. 3 ; The rate of change of indoor air temperature over time; This refers to the indoor ambient temperature response section; v S The supply air flow rate for return air, m3 / s.

[0071] Reuse relative humidity The wet balance equation is established as shown in formula (6):

[0072]

[0073] In the formula, M(τ) is the wet load, g / s; The rate of change of indoor air humidity over time; This is the indoor humidity response section.

[0074] Subsequently and As an optimization variable, it participates in the day-ahead scheduling of the microgrid system, and The fluctuation range meets the known indoor temperature set range value. The fluctuation range satisfies the known relative humidity set range value, as shown in formula (15):

[0075]

[0076] Then, by utilizing the enthalpy difference between the return air and the supply air, the cooling capacity of the air conditioning system, i.e., the indoor cooling load Q, can be obtained. cold (τ), kW, as shown in formulas (7) to (9):

[0077]

[0078]

[0079]

[0080] In the formula, and The specific enthalpy (kJ / kg) of the return air passing through the inlet and outlet of the air conditioning system are respectively; Q ac (τ) and Q ec (τ) represents the cooling power of the absorption chiller and the electric chiller at time τ, respectively, in kW; Q wt_dis (τ) and Q wt_chr (τ) represents the cooling power and storage power of the reservoir at time τ, respectively, in kW.

[0081] Step 3): Based on the mathematical model of the main equipment in the microgrid system and the cooling capacity of the air conditioning system, with the goal of minimizing the overall operating cost min C of the microgrid system, the optimal hourly output of the main equipment in the microgrid system is obtained through the particle swarm optimization algorithm.

[0082] The minimum comprehensive operating cost of the microgrid system, min C, is calculated using formulas (1) to (4), which are as follows:

[0083]

[0084]

[0085] C grid (τ)=P grid (τ)·R grid (τ)·△τ (3)

[0086]

[0087] Where T represents the entire optimization cycle, 24 hours; C represents the overall operating cost of the microgrid system, C0 gas (τ), C grid (τ) and C om (τ) represents the natural gas cost, electricity purchase cost, and operation and maintenance cost of the microgrid system, respectively, all in yuan; P gt (τ) represents the electrical power released by the combustion of natural gas in the prime mover at time τ, in kW; η gt_ele (τ) represents the power generation efficiency of the prime mover, which has no unit; HV is the calorific value of natural gas, 38931 kJ / m³. 3 ;R gas The price of natural gas is expressed in yuan / m³. 3 ; △τ represents the microgrid system operating time interval, in hours; P grid (τ) represents the electrical power purchased from the grid at time τ, in kW; R grid (τ) represents the electricity purchase price at time τ, in yuan; F ac (τ), F ec (τ), H wb (τ), H gb (τ), P bt_dis (τ), P bt_chr (τ), Q wt_dis (τ) and Q wt_chr (τ) represents the cooling power of the absorption chiller, the cooling power of the electric chiller, the power of the waste heat boiler, the power of the gas boiler, the discharge power of the battery, the charging power of the battery, the energy release power of the water storage tank, and the energy storage power of the water storage tank, respectively, all in kW; R om_gt R om_ac R om_ec R om_wb and R om_wt The prices listed are the operating and maintenance costs for gas-fired internal combustion engines, absorption chillers, electric chillers, batteries, and water storage tanks, all in yuan / kWh.

[0088] The optimization factors of the particle swarm optimization algorithm include grid power, prime mover power, absorption chiller power, electric chiller power, gas boiler power, waste heat boiler power, and the charging and discharging power of batteries and water tanks.

[0089] Example

[0090] To illustrate the superiority of the thermal and humidity load response optimization strategy (denoted as S3) adopted in this invention, the following comparative study was also conducted.

[0091] For example S1, a no-demand response strategy is adopted, as follows:

[0092] When indoor heat and humidity loads do not participate in demand response, indoor air temperature relative humidity and air humidity It is a fixed value, that is At this point, the heat and moisture balance relationship is as follows:

[0093] Sensible thermal equilibrium:

[0094] Moisture balance:

[0095] Comparative example S2 adopts a heat load response strategy, as follows:

[0096] When indoor heat load participates in demand response, indoor temperature fluctuates within a certain range, while indoor relative humidity remains constant. At this time, the heat and humidity balance relationship is as follows:

[0097] Sensible thermal equilibrium:

[0098] Moisture balance:

[0099] In the formula, W sen (τ) represents the sensible heat and cooling load of the indoor environment, in kW; M(τ) represents the wet load, in g / s; and V represents the volume of the indoor environment, in m³. 3 C p The specific heat of air is taken as 1.005 kJ / (kg·K); The rate of change of indoor air temperature over time; This is the indoor ambient temperature response section; and The temperatures of indoor air and supply air are respectively, in °C; and The moisture content of indoor air and supply air are respectively expressed in g / kg.

[0100] When a heat load response strategy is adopted, the indoor temperature As an optimization variable participating in the scheduling response, the fluctuation range of indoor temperature is:

[0101]

[0102] Relative humidity (RH) R It does not participate in demand response and remains a fixed value.

[0103] During the process of air conditioning systems regulating indoor temperature and humidity, due to individual differences in preferences, the indoor environment cannot satisfy the comfort of everyone. This study uses the thermal comfort indices PMV and PPD to assess the thermal comfort of the indoor environment. PMV describes a person's overall thermal sensation and is related to factors such as air temperature, relative humidity, airflow velocity, and human metabolic rate. Specific thermal sensation scales are shown in Table 1 below. PPD reflects thermal dissatisfaction by predicting the percentage of people who feel too hot or too cold in a given environment; it is a function of PMV, and the specific formula is as follows:

[0104] PPD=100-95×exp(-0.03353×PMV 4 -0.2179×PMV 2 ) (twenty one)

[0105] Table 1 Thermal Sensation Scale

[0106]

[0107] This invention references the Chinese standard "Code for Design of Heating, Ventilation and Air Conditioning of Civil Buildings GB50736-2012" to constrain indoor environmental temperature, humidity, and thermal comfort. Specifically, the calculation parameters for comfort air conditioning are specified as follows: For Class I cooling conditions, the indoor design temperature is 24–26℃ and the relative humidity is 40–60%; for Class II cooling conditions, the indoor design temperature is 26–28℃ and the relative humidity is ≤70%. Furthermore, a PPD below 27% and a PMV within ±1 range are considered to indicate a comfortable indoor environment. The comfort ranges for PPD and PMV are as follows: Figure 5 .

[0108] The above three strategies were used to optimize the power output of the main equipment in the microgrid system. Through the comparative experiments, the cooling performance of the main equipment corresponding to the lowest overall operating cost of the system under different strategies can be obtained, such as... Figure 6 As shown in the diagram, by analyzing the cooling energy supply, it can be found that the overall trends of the three strategies are similar. Since the absorption chiller consumes the waste heat of the gas internal combustion engine for cooling, it does not incur additional electricity purchase costs or natural gas consumption costs. Therefore, the cooling load is mainly met by the absorption chiller, and the cooling supply changes of the absorption chiller are similar to the power supply changes of the gas internal combustion engine.

[0109] During off-peak electricity pricing periods (0-7 AM, 11-12 AM, and 10-11 PM), due to the large volume of electricity purchased by the grid, electric chillers primarily provide cooling, while absorption chillers operate at a lower capacity, and water storage tanks flexibly release or store cold energy. Cooling load is low during 0-7 AM, resulting in limited energy supply from refrigeration equipment. The microgrid system is mainly cooled by electric chillers; absorption chillers are largely inactive due to limitations imposed by the amount of waste heat from the gas-fired internal combustion engines, and water storage tanks store energy in advance. During 11-12 AM, electric chillers reach their rated power, but the cooling capacity is limited; absorption chillers provide cooling, and water storage tanks release cold energy to supplement the cooling capacity. During 10-11 PM, electric chillers primarily provide cooling, and water storage tanks store energy, returning to their initial energy levels near the start of the dispatch cycle to meet the end-of-cycle energy storage constraints.

[0110] During the periods of flat electricity price (8-10 AM and 1-6 PM) and peak electricity price (7-9 PM), the system is mainly cooled by absorption chillers. This is because the overall electricity price is higher, the gas-fired internal combustion engine has a larger output, and there is more waste heat available for the absorption chillers. The upper limit of the absorption chiller output is constrained by the amount of waste heat and the rated power of the gas-fired internal combustion engine. When the absorption chiller's cooling is insufficient, it is supplemented by electric chillers and water storage tanks.

[0111] like Figure 7 As shown, strategies S2 and S3 optimize system operating costs by shifting thermal and moisture loads from peak electricity price periods to off-peak electricity price periods. The overall operating costs of the microgrid system under different strategies are shown in Table 2.

[0112] Table 2. Overall operating costs of the current microgrid system

[0113]

[0114] The results show that the overall operating cost of the microgrid system decreases sequentially under the demand-no response, heat load response, and heat and humidity load response strategies. Compared with the demand-no response and heat load response strategies, the heat and humidity load response strategy can effectively respond to time-of-use pricing to achieve load transfer and improve the economics of the microgrid system. Therefore, the optimization effect of this strategy is more significant.

[0115] In summary, this invention allows indoor temperature and relative humidity setpoints to fluctuate within a certain range, enabling both thermal and humidity loads to participate in demand response. This strategy is compared with no-demand-response strategies and thermal load response strategies. Particle swarm optimization was used to obtain the overall operating cost of the microgrid system and the hourly variations of indoor temperature and humidity setpoints under different strategies. Furthermore, the overall power output characteristics of the system were analyzed, and the power output of different energy supply units under different strategies was compared. Compared to existing optimization strategies that only consider thermal load response, this invention also incorporates humidity load response, simultaneously regulating temperature and humidity to improve load transfer capacity and system economic efficiency.

[0116] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, all technical solutions obtained through equivalent substitution or transformation fall within the protection scope of the present invention.

Claims

1. A day-ahead scheduling optimization method for a microgrid system considering thermal and moisture load response, characterized in that, Specifically as follows: Step 1): Construct mathematical models of the main equipment in the microgrid system based on the actual energy conversion process; Step 2): The microgrid system supplies energy to the air conditioning system, which uses reheating to process the return air, cooling it to the dew point temperature for cooling and dehumidification. During this process, based on the known indoor temperature and relative humidity setpoints, the following is obtained: -1) Return air temperature at time and return air relative humidity ;according to Indoor temperature under constant indoor air conditions and relative humidity The supply air temperature was obtained by establishing a heat and humidity balance equation. and relative humidity of the supply air According to the results , , and The cooling capacity of the air conditioning system is obtained by utilizing the enthalpy difference between the return air and the supply air. Step 3): Based on the mathematical models of the main equipment in the microgrid system and the cooling capacity of the air conditioning system, minimize the overall operating cost of the microgrid system. With the objective of obtaining the optimal hourly output of the main equipment in the microgrid system through the particle swarm optimization algorithm; Step 2) is as follows: Utilizing indoor temperature The heat balance equation is established as shown in formula (5): （5）； In the formula, The sensible heat and cooling load of the indoor environment is expressed in kW. The specific heat of air; The density of moist air is kg / m³. 3 V represents the volume of the indoor environment. ; The rate of change of indoor air temperature over time; This is the indoor ambient temperature response section; The supply airflow rate for return air. / s; Using relative humidity The wet balance equation is established as shown in formula (6): （6）； In the formula, Wet load, g / s; The rate of change of indoor air humidity over time; This refers to the indoor humidity response section. Subsequently and As an optimization variable, it participates in the day-ahead scheduling of the microgrid system, and The fluctuation range meets the known indoor temperature set range value. The fluctuation range meets the known relative humidity set range value; then, the cooling capacity of the air conditioning system is obtained by utilizing the enthalpy difference between the return air and the supply air. .

2. The day-ahead scheduling optimization method for a microgrid system considering thermal and humidity load response according to claim 1, characterized in that, The microgrid system includes a prime mover, a waste heat boiler, an absorption chiller, a gas boiler, an electric chiller, and a water storage tank. The electrical energy generated by the prime mover is transmitted via power lines to an external power grid supplying electricity to users; when the prime mover's power supply is insufficient, it is supplemented by the power grid. A battery is also installed on the power grid. The heat energy generated by the prime mover is transmitted via a first pipeline to the waste heat boiler and the absorption chiller. The heat generated by the waste heat boiler is transmitted to the heating pipeline supplying heat to users, and the cold energy generated by the absorption chiller is transmitted to the cooling pipeline supplying cooling to users. Part of the heat energy generated by the gas boiler is transmitted to the absorption chiller via a second pipeline, and part is directly transmitted to the heating pipeline. An electric chiller is connected to the power grid, and the cold energy generated by the electric chiller is transmitted to the cooling pipeline via a third pipeline. The water storage tank is connected to both the heating and cooling pipelines.

3. The day-ahead scheduling optimization method for a microgrid system considering thermal and humidity load response according to claim 2, characterized in that, The prime mover is a gas turbine or an internal combustion engine.

4. The day-ahead scheduling optimization method for a microgrid system considering thermal and humidity load response according to claim 1, characterized in that, The main equipment of the microgrid system includes a prime mover, a waste heat boiler, an absorption chiller, a gas boiler, and an electric chiller.

5. The day-ahead scheduling optimization method for a microgrid system considering thermal and humidity load response according to claim 2, characterized in that, The air conditioning system includes an air handling unit, a reheater, and an indoor fan. The air outlet of the air handling unit is sent out through the indoor fan after passing through the reheater, and the indoor air, as return air, enters the air handling unit after passing through the reheater to exchange heat with the cooling water. The cooling water comes from the water storage tank of the microgrid system and is cooled by electric chillers and absorption chillers.

6. The day-ahead scheduling optimization method for a microgrid system considering thermal and humidity load response according to claim 1, characterized in that, The cooling capacity of the air conditioning system As shown in formulas (7) to (9): （7）； （8）； （9）； In the formula, and The specific enthalpy (kJ / kg) of the return air passing through the inlet and outlet of the air conditioning system are respectively. and They are respectively Cooling power of absorption chillers and electric chillers, in kW; and They are respectively The cooling capacity and cold storage capacity of the water storage tank at any given time, in kW.

7. The day-ahead scheduling optimization method for a microgrid system considering thermal and humidity load response according to claim 1, characterized in that, Minimize the overall operating cost of the microgrid system The results are obtained by formulas (1) to (4), and the specific formulas (1) to (4) are as follows: （1）； （2）； （3）； （4）； Where T represents the entire optimization cycle, 24 hours; and C represents the overall operating cost of the microgrid system. , and These figures represent the natural gas cost, electricity purchase cost, and operation and maintenance cost of the microgrid system, all in yuan. Let τ be the electrical power released by the combustion of natural gas in the prime mover at time τ, in kW; HV represents the power generation efficiency of the prime mover; HV represents the calorific value of natural gas (38931 kJ / m³). ; The price of natural gas is expressed in yuan / ; This refers to the operating time interval of the microgrid system, in hours. for The amount of electricity purchased from the power grid at any given time, measured in kW; for The electricity price at any given time, in yuan; , , , , , , and These are the cooling power of the absorption chiller, the cooling power of the electric chiller, the power of the waste heat boiler, the power of the gas boiler, the discharge power of the battery, the charging power of the battery, the energy release power of the water storage tank, and the energy storage power of the water storage tank, all in kW. , , , and The prices listed are the operating and maintenance costs for gas-fired internal combustion engines, absorption chillers, electric chillers, batteries, and water storage tanks, all in yuan / kWh.

8. The day-ahead scheduling optimization method for a microgrid system considering thermal and humidity load response according to claim 1, characterized in that, The optimization factors of the particle swarm optimization algorithm include grid power, prime mover power, absorption chiller power, electric chiller power, gas boiler power, waste heat boiler power, and the charging and discharging power of batteries and water tanks.

Images