Composite energy storage control method based on variable frequency air conditioner and energy storage battery

Abstract

The present invention discloses a composite energy storage control method based on a variable frequency air conditioner and an energy storage battery. The method comprises the following steps: calculating the equivalent heat capacity and equivalent thermal resistance of the room according to the characteristics of the room where the variable frequency air conditioner is installed; using a first-order equivalent thermal parameter model to process and obtain the real-time temperature in the room; establishing a functional relationship between the working frequency, operating power and real-time temperature of the variable frequency air conditioner, and processing and obtaining the operating power of the variable frequency air conditioner; calculating the available capacity and real-time power of the virtual energy storage; using the room equivalent thermal model, processing and obtaining the discrete response power provided by the virtual energy storage; combining the virtual energy storage and the energy storage battery to form a composite energy storage, and controlling the charge state of the composite energy storage. The present invention uses a variable frequency air conditioner and an energy storage battery to form a composite energy storage, which increases the capacity of the energy storage, reduces the cost of the energy storage, increases the power of the energy storage, and extends the service life of the energy storage battery, effectively responding to the continuous increase in the penetration rate of renewable energy.

Description

Technical Field

[0001] The invention relates to a composite energy storage control method, and in particular to a composite energy storage control method based on a variable frequency air conditioner and an energy storage battery. Background Art

[0002] At present, with the increasing prominence of energy, environment and climate change issues, the development of renewable energy has become a new trend in the world's energy development; renewable energy represented by photovoltaics and wind power has intermittent and random output, and cannot provide a certain power generation capacity like traditional units. After a large number of grid-connected, it will bring challenges to the safe and stable operation of the power system.

[0003] In order to realize the local consumption of renewable energy and friendly grid connection, energy storage equipment represented by energy storage batteries needs to be configured in large quantities. However, the current configuration cost of energy storage batteries is high, the life is short, and it is difficult to apply them on a large scale. In addition, the safety of energy storage batteries during use is also an issue that cannot be ignored. Long-term high-power charging and discharging may cause performance degradation, or even explosions and other safety accidents.

[0004] The power consumption of temperature control loads represented by variable frequency air conditioners accounts for a high proportion and is widely distributed. Therefore, based on the heat storage capacity of the room, the power of the air conditioner can be increased or reduced in a short period of time without causing a significant change in the room temperature, and the variable frequency air conditioner can be equivalent to a virtual energy storage. Compared with traditional fixed frequency air conditioners, variable frequency air conditioners can change the operating power of the variable frequency air conditioner by adjusting the frequency of the inverter, and have more flexible adjustment capabilities. However, the actual variable frequency air conditioner can only use the temperature adjustment method, resulting in it only having discrete power adjustment capabilities, and cannot provide continuous power adjustment capabilities like energy storage batteries. Summary of the invention

[0005] In order to solve the problems existing in the background technology, the present invention provides a composite energy storage control method of a variable frequency air conditioner and an energy storage battery, which compensates for the discontinuous response power of the variable frequency air conditioner through the flexibility of the energy storage battery, and uses the virtual power of the variable frequency air conditioner to reduce the charge and discharge power of the battery, thereby reducing the charge and discharge energy of the battery. The composite energy storage of the variable frequency air conditioner and the energy storage battery has a larger capacity, a longer service life, and a higher charge and discharge power, and can effectively promote the consumption of renewable energy.

[0006] The technical solution adopted by the present invention is:

[0007] The method of the present invention comprises the following steps:

[0008] Step 1) Calculate the equivalent heat capacity and equivalent thermal resistance of the room according to the characteristics of the room where the variable frequency air conditioner is installed; the equivalent heat capacity corresponds to the heat storage capacity of the room, and the equivalent heat capacity characterizes the difficulty of temperature change in the room. The larger the equivalent heat capacity, the smaller the degree of change of room temperature caused by the same heat change; the equivalent thermal resistance corresponds to the thermal insulation capacity of the room, and the equivalent thermal resistance characterizes the thermal insulation performance of the room. The larger the equivalent thermal resistance, the smaller the heat loss caused by heat conduction between the inside and outside of the room;

[0009] Step 2) Considering the heat generated by the variable frequency air conditioner cooling / heating in the room, the heat generated by other electrical appliances in the room, the solar radiation heat absorbed in the room, the heat lost by heat exchange inside and outside the room, and the heat lost by the exchange of hot and cold air caused by opening and closing the door when people enter and exit the room, a first-order equivalent thermal parameter model is used to obtain the real-time temperature in the room in combination with the equivalent heat capacity and equivalent thermal resistance of the room;

[0010] Step 3) Compared with a fixed-frequency air conditioner, a variable-frequency air conditioner changes the operating power of the variable-frequency air conditioner by changing the operating frequency of its own inverter, thereby adjusting the cooling power of the variable-frequency air conditioner compressor. When the variable-frequency air conditioner reaches a stable state, the cooling power of the variable-frequency air conditioner is equal to the heat increase power of the room, and the temperature in the room remains stable;

[0011] The difference between the real-time temperature in the room and the preset optimal setting temperature is related to the operating frequency of the inverter of the variable frequency air conditioner. By analyzing the relationship between the two, the amount of virtual energy storage that the variable frequency air conditioner can provide can be accurately evaluated. Therefore, a functional relationship between the difference between the real-time temperature in the room and the preset optimal setting temperature, the operating frequency of the inverter of the variable frequency air conditioner and the operating power of the variable frequency air conditioner is established;

[0012] By presetting the optimal set temperature of the room, a functional relationship between the working frequency, operating power and real-time temperature of the variable frequency air conditioner is established, and the operating power of the variable frequency air conditioner is obtained;

[0013] Step 4) Referring to the power expression method of the energy storage battery, the variable frequency air conditioner is equivalent to the virtual energy storage, the heat in the room is converted into the power of the virtual energy storage, and then the power of the virtual energy storage is equivalent to the response capacity of the variable frequency air conditioner, the maximum adjustable time of the variable frequency air conditioner is pre-set, and the available capacity of the virtual energy storage is calculated according to the response capacity of the variable frequency air conditioner and the pre-set comfortable temperature range and the maximum adjustable time, and the real-time power of the virtual energy storage is calculated according to the operating status of the variable frequency air conditioner, so as to realize the flexible regulation of the response capacity of the variable frequency air conditioner;

[0014] After the user turns on the variable frequency air conditioner, the variable frequency air conditioner begins to adjust its own temperature value so that the real-time temperature in the room obtained in step 2) is always kept within the preset comfortable temperature range. When the control time of the variable frequency air conditioner reaches the longest adjustable time, the temperature value of the variable frequency air conditioner is immediately adjusted to the optimal set temperature.

[0015] Step 5) The unmodified variable frequency air conditioner can only change its operating power by adjusting the temperature. Since the settable temperature of the air conditioner is discrete, the operating power adjustment is discontinuous.

[0016] Using the room equivalent thermal model, the discrete response power provided by the virtual energy storage through temperature adjustment is obtained according to the real-time temperature in the room and the air conditioning temperature value input by the user;

[0017] Step 6) Combine virtual energy storage and energy storage battery to form composite energy storage, solve the problem that the virtual energy storage response capability cannot be continuously adjusted, and reduce the configuration capacity and charge and discharge energy of the energy storage battery; control the charge state, charge and discharge power, output power of the energy storage battery, real-time temperature in the room and control time of the composite energy storage to achieve the superposition of power and continuous adjustment of power, solve the problem that the virtual energy storage response capability cannot be continuously adjusted, and reduce the configuration capacity and charge and discharge energy of the battery.

[0018] When the variable frequency air conditioner is running, the energy storage battery compensates for the deviation between the power of the virtual energy storage and the operating power that the variable frequency air conditioner needs to achieve by adjusting the air conditioning temperature value in step 5); when the state of charge of the virtual energy storage battery is lower than 50% of the energy storage battery's own capacity, the energy storage battery is charged so that the state of charge of the energy storage battery always remains at about 50% of its own capacity, thereby realizing the superposition of the power of the composite energy storage and the continuous adjustment of the discrete response power of the variable frequency air conditioner in step 5).

[0019] The step 1) is specifically as follows:

[0020] According to the length of the room L room , Width W room and high H room Calculate the volume and surface area of ​​a room with the following formula:

[0021] V room =L room ·W room ·H room

[0022] S room =2(L room W room +L room H room +W room H room )

[0023] Among them, V room and S room Respectively represent the volume and surface area of ​​the room;

[0024] Calculate the room parameters where the variable frequency air conditioner is installed, that is, the volume V of the room room and surface area S room , calculate the equivalent heat capacity C of the air in the room according to the following formula room And the equivalent thermal resistance R room :

[0025] C room =c air ρ air V room

[0026] R room =αS room

[0027] Among them, c air is the specific heat capacity of air, ρ air is the density of air, and α is the thermal conductivity of the outer wall of the room.

[0028] The step 2) is specifically as follows:

[0029] The real-time temperature T in the room at time t is calculated using the first-order equivalent thermal parameter model of the following formula: in :

[0030]

[0031] Among them, C room is the equivalent heat capacity of air, Q gain is the heat absorbed in the room per unit time, Q loss is the heat loss in the room per unit time;

[0032] The amount of heat absorbed in the room per unit time Q gain Use the following formula to obtain:

[0033] Q gain =Q AC +Q loads +Q solar

[0034] Among them, Q AC Q is the heat generated by the variable frequency air conditioner cooling / heating in the room per unit time, AC If it is greater than 0, it means the inverter air conditioner is in heating mode. AC Less than 0 means the inverter air conditioner is in cooling mode; Q loads Q is the heat generated by other electrical appliances in the room per unit time. solaris the amount of solar radiation absorbed in the room per unit time;

[0035] Heat loss in the room per unit time Q loss Use the following formula to obtain:

[0036] Q loss =R room (T in -T out )+k d c air ρ air V d (T in -T out )

[0037] Among them, R room (T in -T out ) is the heat lost by heat exchange between the inside and outside of the room per unit time, R room is the equivalent thermal resistance of the room, T in is the real-time temperature in the room, T out is the real-time temperature outside the room, k d c air ρ air V d (T in -T out ) is the heat lost in unit time due to the exchange of hot and cold air caused by opening and closing the door when people enter and leave the room, k d is the number of door openings per unit time, c air is the specific heat capacity of air, ρ air Represents the density of air, V d The volume of air exchange between the room and outside caused by each door opening;

[0038] The step 3) is specifically as follows:

[0039] First, the operating frequency f of the air conditioner inverter is obtained by the following method: AC :

[0040] When the real-time temperature in the room is T in And preset the optimal set temperature T of the room set The difference exceeds ΔT max When the inverter air conditioner is turned on, it will run at the preset maximum working power;

[0041] When the real-time temperature T in The difference from the set temperature is less than ΔT min When the inverter air conditioner enters the standby state, it runs at the preset minimum working power;

[0042] When the real-time temperature T inThe difference between the set temperature and the min and ΔT max When the temperature difference is greater, the frequency is higher;

[0043] It is expressed as:

[0044]

[0045] Among them, f max is the maximum operating frequency of the inverter of the variable frequency air conditioner, ΔT max The maximum temperature deviation value when the variable frequency air conditioner is running at the highest frequency, k is the proportional control coefficient of the variable frequency air conditioner inverter, b is the basic operating frequency of the variable frequency air conditioner inverter, ΔT min The minimum temperature deviation value when the variable frequency air conditioner is running at the lowest operating frequency, f min is the minimum operating frequency of the inverter of the variable frequency air conditioner; T in is the real-time temperature in the room, T set The best setting temperature for inverter air conditioner;

[0046] Next, the operating frequency f of the variable frequency air conditioner inverter is expressed by the following formula: AC And the operating power P of the inverter air conditioner AC The linear relationship between them is used to obtain the operating power P of the variable frequency air conditioner. AC :

[0047] P AC =S AC (c×f AC +d)

[0048] Among them, S AC is the operating state of the variable frequency air conditioner, S AC When the inverter air conditioner is operating normally, it is 1, S AC When the variable frequency air conditioner is turned off, it is 0; c and d represent the working frequency f of the air conditioner inverter. AC And the operating power P of the inverter air conditioner AC The two coefficients of the linear relationship between .

[0049] The step 4) is specifically as follows: convert the heat in the room into the amount of electricity of the virtual energy storage, and obtain the available capacity of the virtual energy storage according to the following formula:

[0050]

[0051] in, To increase the maximum amount of heat in the room, is the maximum heat reduction in the room, and EER is the energy efficiency ratio of the variable frequency air conditioner;

[0052] Maximum heat increase in the room and maximum heat reduction According to the preset optimal setting temperature T set And the comfortable temperature range is obtained:

[0053]

[0054]

[0055] Among them, T set is the optimal setting temperature, T max is the highest temperature in the comfortable temperature range, T min is the lowest temperature in the comfortable temperature range, c air represents the specific heat capacity of air, ρ air Represents the density of air, V room is the volume of the room, t max is the longest adjustable time;

[0056] At the same time, the following formula is used to use the state of charge SOC of the virtual energy storage at time t v (t) Calculate the real-time power of virtual energy storage:

[0057]

[0058] Among them, EER is the energy efficiency ratio of the variable frequency air conditioner, T in The real-time temperature in the room.

[0059] The step 5) is specifically as follows:

[0060] The room equivalent thermal model is calculated according to the following formula to obtain the discrete response power provided by the variable frequency air conditioner by adjusting the air conditioning temperature value T to T+n. The following takes the case where the variable frequency air conditioner is in cooling mode and the air conditioner temperature value T is increased as an example:

[0061]

[0062] Among them, M AC The working mode of the inverter air conditioner is AC When M is 1, the inverter air conditioner is in cooling mode. AC When it is -1, the variable frequency air conditioner is in heating mode; n is an integer, which represents the adjustment amount of the air conditioning temperature value T preset by the variable frequency air conditioner, specifically the difference between the air conditioning temperature value T and the real-time temperature T in the room. in The difference between α and S is the thermal conductivity of the room’s exterior wall. room is the surface area of ​​the room; EER is the energy efficiency ratio of the variable frequency air conditioner, is the operating power of the variable frequency air conditioner at temperature T+n, is the operating power of the variable frequency air conditioner at the air conditioning temperature value T;

[0063] when When it is greater than 0, it means reducing the operating power of the inverter air conditioner. When it is less than 0, it means increasing the operating power of the variable frequency air conditioner; Discontinuous, the operating power of the variable frequency air conditioner is difficult to just meet the power required when adjusting to the temperature T+n, so there is a cyclic power deviation; but when the total virtual energy storage power is determined, the variable frequency air conditioner can provide different operating powers according to user needs;

[0064] The variable frequency air conditioner provides different operating powers when the adjustment amount n of the preset air conditioning temperature value T is different, but the amount of virtual energy storage provided by the variable frequency air conditioner during the process of adjusting the air conditioning temperature value T to different temperatures is the same. The discrete response power provided by the variable frequency air conditioner satisfies the following formula relationship:

[0065]

[0066] Among them, t start is the start time of the variable frequency air conditioner response, t end1 is the end time of the variable frequency air conditioner temperature change from T to T+1, t end2 is the end time of the variable frequency air conditioner temperature change from T to T+2, t endn P is the end time when the variable frequency air conditioner responds to the temperature change from T to T+n, AC is the operating power of the variable frequency air conditioner, is the operating power of the variable frequency air conditioner at temperature T+1, It is the operating power of the variable frequency air conditioner at temperature T+2.

[0067] In the process of the variable frequency air conditioner changing its own operating power through temperature adjustment, the temperature in the room does not exceed the comfortable temperature range pre-set by the user, and the adjustment time of the variable frequency air conditioner does not exceed the maximum adjustable time pre-set by the user.

[0068] The step 6) specifically includes the following aspects:

[0069] A) Calculate the state of charge SOC(t) of the composite energy storage according to the following formula:

[0070]

[0071] Among them, E max is the capacity of the composite energy storage, SOC r (t) is the state of charge of the energy storage battery at time t, is the capacity of the energy storage battery, SOC v (t) is the charge state of the virtual energy storage at time t, is the capacity of virtual energy storage;

[0072] Composite energy storage capacity E max It is the sum of the capacity of the energy storage battery and the capacity of the virtual energy storage:

[0073]

[0074] In addition, in order to avoid the rapid decline of battery performance caused by overcharging and overdischarging of the energy storage battery, the control makes the composite energy storage meet the minimum state of charge SOC during operation. min and maximum state of charge SOC max Between, that is,

[0075] SOC min <SOC(t)<SOC max

[0076] B) First, in order to ensure that the composite energy storage can accurately output power according to user needs, while reducing the charge and discharge power of the energy storage battery and extending the battery life, during the operation of the variable frequency air conditioner, the adjustment amount n of the air conditioning temperature value T pre-set by the variable frequency air conditioner is first determined. Since the power provided by the variable frequency air conditioner is discrete, according to the optimal setting temperature T of the variable frequency air conditioner set and the variable frequency air conditioner adjusts from the air conditioning temperature value T to T set The corresponding required power P D , find the optimal setting temperature T set The working power at the two closest set temperatures T+n and T+(n+1) is shown in the following formula:

[0077]

[0078] in, Indicates that it is less than the required power P D The working power is specifically the discrete response power provided by the virtual energy storage by adjusting the air conditioning temperature value T to T+n. Indicates that it is greater than the required power P D The working power is specifically the discrete response power provided by the virtual energy storage by adjusting the air conditioning temperature value T to T+(n+1);

[0079] Then calculate ΔP according to the following formula D %:

[0080]

[0081] ΔP D % is the required power P D and less than the required power P D Working power Deviation of power and required power P D and greater than the required power P D Working power Deviation of ΔP D % is smaller, the required power P D and The smaller the deviation, the greater the ΔP D %The larger the required power P D and The smaller the deviation:

[0082] Next, for the required power P D , according to ΔP D % and real-time state of charge SOC of the energy storage battery r The final adjustment amount n of the preset air conditioning temperature value T of the variable frequency air conditioner is determined according to the following formula:

[0083] When the required power P D and less than the required power P D Working power When the deviation between them is less than p, regardless of the real-time charge state of the energy storage battery, the variable frequency air conditioner will increase by n degrees Celsius and provide The discrete response power of

[0084] When the required power P D and less than the required power P D Working power If the deviation between p and q is between p and q, if the real-time state of charge of the energy storage battery is higher than 50% of its own capacity, the inverter air conditioner will increase the temperature by n degrees Celsius and provide If the real-time state of charge of the energy storage battery is less than 50% of its capacity, the inverter air conditioner will increase the temperature by n+1 degrees Celsius and provide The discrete response power of

[0085] When the required power P D and less than the required power P D Working power When the deviation is greater than q, regardless of the real-time charge state of the energy storage battery, the inverter air conditioner will increase the temperature by n+1 degrees Celsius and provide The discrete response power of

[0086] As shown below:

[0087]

[0088] Among them, P v The discrete response power provided by the virtual energy storage by adjusting the air conditioning temperature value T;

[0089] p and q are two parameters set by the control method between the variable frequency air conditioner and the energy storage battery used in the formula, satisfying the following formula:

[0090] 0 <p<50%<q<100%

[0091] Determined P v Afterwards, the required power P D and energy storage batteries to compensate for the power provided by the inverter air conditioner

[0092] P r The deviation between them is used to calculate the output power P of the energy storage battery. r :

[0093] P r =P D -P v

[0094] By adopting the above control method, when the battery state of charge is low, the variable frequency air conditioner can provide more energy to charge the energy storage battery, so that the real-time state of charge SOC of the energy storage battery is r Always maintain about 50% of its capacity, so that the energy storage battery has greater charging and discharging energy;

[0095] C) In addition, the real-time charging and discharging power P of the composite energy storage at time t bat (t) satisfies the following formula:

[0096]

[0097]

[0098]

[0099] in, is the maximum charging power of the composite energy storage, is the maximum discharge power of the composite energy storage, is the maximum charging power of the energy storage battery, The maximum discharge power of the energy storage battery, is the rated power of the variable frequency air conditioner, P AC (t) is the real-time operating power of the variable frequency air conditioner at time t;

[0100] D) To ensure the user's comfort, control the variable frequency air conditioner to adjust the real-time temperature T in the room in Always keep in the comfortable temperature range, satisfying the following formula:

[0101] T min ≤T in ≤T max

[0102] Among them, Tmin is the lowest temperature in the comfortable temperature range, T in is the real-time temperature in the room, T max The highest temperature in the comfortable temperature range;

[0103] E) Simultaneously control the control time t of the variable frequency air conditioner DR Satisfies the following formula:

[0104] 0≤t DR ≤t max

[0105] Among them, t max is the longest adjustable time; when the adjustment time t DR Reach the maximum adjustable time t max When the inverter air conditioner is set to the optimal temperature T set , so that the room temperature is adjusted to the optimal set temperature T set .

[0106] The control method is based on a composite energy storage system, which includes an energy storage battery and a variable frequency air conditioner; the energy storage battery and the variable frequency air conditioner are both connected to the power grid and can be powered by the power grid; the variable frequency air conditioner is connected to the energy storage battery, and the energy storage battery can power the variable frequency air conditioner; the virtual energy storage of the variable frequency air conditioner can replace part of the capacity of the energy storage battery, so that the variable frequency air conditioner can adjust the operating power during operation to replace part of the charging and discharging energy of the energy storage battery, and the increase in power consumption of the variable frequency air conditioner is equivalent to the charging of the energy storage battery, and the increase in power consumption of the variable frequency air conditioner is equivalent to the discharging of the energy storage battery.

[0107] The beneficial effects of the present invention are:

[0108] 1) The variable frequency air conditioner and energy storage battery form a composite energy storage, which makes up for the continuous power adjustment capability that the variable frequency air conditioner does not have when responding alone, avoids the power deviation of the response, and makes the response capacity of the variable frequency air conditioner equivalent to virtual power, which has a more flexible scheduling method.

[0109] 2) The variable frequency air conditioner and energy storage battery form a composite energy storage, which can reduce the configuration capacity of the traditional energy storage battery. At the same time, relying on the virtual power of the variable frequency air conditioner, the charging and discharging energy of the energy storage battery during operation is reduced, which effectively extends the service life of the energy storage battery and reduces the configuration and operation costs of the energy storage battery.

[0110] 3) The variable frequency air conditioner and energy storage battery form a composite energy storage, which increases the capacity of energy storage, reduces the cost of energy storage, and can effectively extend the service life of the energy storage battery. The composite energy storage control method can effectively cope with the continuous increase in the penetration rate of renewable energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0111] Figure 1is a room heat diagram based on an equivalent thermal parameter model of the present invention;

[0112] Figure 2 It is a schematic diagram of the variable frequency air conditioner response power discontinuity of the present invention;

[0113] Figure 3 is a schematic diagram of a constant response capacity of a variable frequency air conditioner of the present invention;

[0114] Figure 4 It is a schematic diagram of the specific connection of photovoltaic power generation and supporting equipment;

[0115] Figure 5 is a statistical graph of output data under cloudy weather in a specific embodiment;

[0116] Figure 6 It is the operating power statistics diagram of the composite energy storage;

[0117] Figure 7 It is a schematic diagram of the control status of the variable frequency air conditioner. DETAILED DESCRIPTION

[0118] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0119] The specific embodiment of the present invention comprises the following steps:

[0120] Step 1) Calculate the equivalent heat capacity and equivalent thermal resistance of the room according to the characteristics of the room where the variable frequency air conditioner is installed; the equivalent heat capacity corresponds to the heat storage capacity of the room, and the equivalent heat capacity characterizes the difficulty of temperature change in the room. The larger the equivalent heat capacity, the smaller the degree of change of room temperature caused by the same heat change; the equivalent thermal resistance corresponds to the thermal insulation capacity of the room, and the equivalent thermal resistance characterizes the thermal insulation performance of the room. The larger the equivalent thermal resistance, the smaller the heat loss caused by heat conduction between the inside and outside of the room;

[0121] According to the length of the room L room , Width W room and high H room Calculate the volume and surface area of ​​a room with the following formula:

[0122] V room =L room ·W room ·H room

[0123] S room =2(L room W room +L room H room +W room H room )

[0124] Among them, Vroom and S room Respectively represent the volume and surface area of ​​the room;

[0125] Calculate the room parameters where the variable frequency air conditioner is installed, that is, the volume V of the room room and surface area S room , calculate the equivalent heat capacity C of the air in the room according to the following formula room And the equivalent thermal resistance R room :

[0126] C room =c air ρ air V room

[0127] R room =αS room

[0128] Among them, c air is the specific heat capacity of air, ρ air is the density of air, and α is the thermal conductivity of the outer wall of the room.

[0129] Step 2) Figure 1 As shown, considering the heat generated by the cooling / heating of the variable frequency air conditioner in the room, the heat generated by the operation of other electrical appliances in the room, the solar radiation heat absorbed in the room, the heat lost by heat exchange inside and outside the room, and the heat lost by the exchange of hot and cold air caused by opening and closing the door when people enter and leave the room, the first-order equivalent thermal parameter model is used, combined with the equivalent heat capacity and equivalent thermal resistance of the room to obtain the real-time temperature in the room;

[0130] The real-time temperature T in the room at time t is calculated using the first-order equivalent thermal parameter model of the following formula: in :

[0131]

[0132] Among them, C room is the equivalent heat capacity of air, Q gain is the heat absorbed in the room per unit time, Q loss is the heat loss in the room per unit time;

[0133] The amount of heat absorbed in the room per unit time Q gain Use the following formula to obtain:

[0134] Q gain =Q AC +Q loads +Q solar

[0135] Among them, Q AC Q is the heat generated by the variable frequency air conditioner cooling / heating in the room per unit time,AC If it is greater than 0, it means the inverter air conditioner is in heating mode. AC Less than 0 means the inverter air conditioner is in cooling mode; Q loads Q is the heat generated by other electrical appliances in the room per unit time. solar is the amount of solar radiation absorbed in the room per unit time;

[0136] Heat loss in the room per unit time Q loss Use the following formula to obtain:

[0137] Q loss =(T in -T out ) / R room +k d c air ρ air V d (T in -T out )

[0138] Among them, (T in -T out ) / R room R is the heat lost by heat exchange inside and outside the room per unit time, room is the equivalent thermal resistance of the room, T in is the real-time temperature in the room, T out is the real-time temperature outside the room, k d c air ρ air V d (T in -T out ) is the heat lost in unit time due to the exchange of hot and cold air caused by opening and closing the door when people enter and leave the room, k d is the number of door openings per unit time, c air is the specific heat capacity of air, ρ air Represents the density of air, V d The volume of air exchange between the inside and outside of the room caused by each door opening.

[0139] Step 3) Compared with a fixed-frequency air conditioner, a variable-frequency air conditioner changes the operating power of the variable-frequency air conditioner by changing the operating frequency of its own inverter, thereby adjusting the cooling power of the variable-frequency air conditioner compressor. When the variable-frequency air conditioner reaches a stable state, the cooling power of the variable-frequency air conditioner is equal to the heat increase power of the room, and the temperature in the room remains stable;

[0140] The difference between the real-time temperature in the room and the preset optimal setting temperature is related to the operating frequency of the inverter of the variable frequency air conditioner. By analyzing the relationship between the two, the amount of virtual energy storage that the variable frequency air conditioner can provide can be accurately evaluated. Therefore, a functional relationship between the difference between the real-time temperature in the room and the preset optimal setting temperature, the operating frequency of the inverter of the variable frequency air conditioner and the operating power of the variable frequency air conditioner is established;

[0141] By presetting the optimal set temperature of the room, a functional relationship between the working frequency, operating power and real-time temperature of the variable frequency air conditioner is established, and the operating power of the variable frequency air conditioner is obtained;

[0142] First, the operating frequency f of the air conditioner inverter is obtained by the following method: AC :

[0143] When the real-time temperature in the room is T in And preset the optimal set temperature T of the room set The difference exceeds ΔT max When the inverter air conditioner is turned on, it will run at the preset maximum working power;

[0144] When the real-time temperature T in The difference from the set temperature is less than ΔT min When the inverter air conditioner enters the standby state, it runs at the preset minimum working power;

[0145] When the real-time temperature T in The difference between the set temperature and the min and ΔT max When the temperature difference is greater, the frequency is higher;

[0146] It is expressed as:

[0147]

[0148] Among them, f max is the maximum operating frequency of the inverter of the variable frequency air conditioner, ΔT max is the maximum temperature deviation value when the variable frequency air conditioner is running at the highest frequency, k is the proportional control coefficient of the variable frequency air conditioner inverter, b is the basic operating frequency of the variable frequency air conditioner inverter, ΔT min is the minimum temperature deviation value when the variable frequency air conditioner runs at the lowest frequency, f min is the minimum operating frequency of the inverter of the variable frequency air conditioner; T in is the real-time temperature in the room, T set The best setting temperature for inverter air conditioner;

[0149] Next, the operating frequency f of the variable frequency air conditioner inverter is expressed by the following formula: AC And the operating power P of the inverter air conditionerAC The linear relationship between them is used to obtain the operating power P of the variable frequency air conditioner. AC :

[0150] P AC =S AC (c×f AC +d)

[0151] Among them, S AC is the operating state of the variable frequency air conditioner, S AC When the inverter air conditioner is operating normally, it is 1, S AC When the variable frequency air conditioner is turned off, it is 0; c and d represent the working frequency f of the air conditioner inverter. AC And the operating power P of the inverter air conditioner AC The two coefficients of the linear relationship between .

[0152] Step 4) Referring to the power expression method of the energy storage battery, the variable frequency air conditioner is equivalent to the virtual energy storage, the heat in the room is converted into the power of the virtual energy storage, and then the power of the virtual energy storage is equivalent to the response capacity of the variable frequency air conditioner, the maximum adjustable time of the variable frequency air conditioner is pre-set, and the available capacity of the virtual energy storage is calculated according to the response capacity of the variable frequency air conditioner and the pre-set comfortable temperature range and the maximum adjustable time, and the real-time power of the virtual energy storage is calculated according to the operating status of the variable frequency air conditioner, so as to realize the flexible regulation of the response capacity of the variable frequency air conditioner;

[0153] After the user turns on the variable frequency air conditioner, the variable frequency air conditioner starts to adjust its own temperature value so that the real-time temperature in the room obtained in step 2) is always kept within the preset comfortable temperature range. When the control time of the variable frequency air conditioner reaches the maximum controllable time, the temperature value of the variable frequency air conditioner is immediately adjusted to the optimal set temperature;

[0154] Convert the heat in the room into the amount of electricity for virtual energy storage, and obtain the available capacity of virtual energy storage according to the following formula:

[0155]

[0156] in, To increase the maximum amount of heat in the room, is the maximum heat reduction in the room, and EER is the energy efficiency ratio of the variable frequency air conditioner;

[0157] Maximum heat increase in the room and maximum heat reduction According to the preset optimal setting temperature T set And the comfortable temperature range is obtained:

[0158]

[0159]

[0160] Among them, T set is the optimal setting temperature, T max is the highest temperature in the comfortable temperature range, T min is the lowest temperature in the comfortable temperature range, c air represents the specific heat capacity of air, ρ air Represents the density of air, V room is the volume of the room, t max is the longest adjustable time;

[0161] At the same time, the following formula is used to use the state of charge SOC of the virtual energy storage at time t v (t) Calculate the real-time power of virtual energy storage:

[0162]

[0163] Among them, EER is the energy efficiency ratio of the variable frequency air conditioner, T in The real-time temperature in the room.

[0164] Step 5) Figure 2 As shown, the unmodified variable frequency air conditioner can only change its operating power by adjusting the temperature. Since the settable temperature of the air conditioner is discrete, its operating power adjustment is discontinuous.

[0165] Using the room equivalent thermal model, the discrete response power provided by the virtual energy storage through temperature adjustment is obtained according to the real-time temperature in the room and the air conditioning temperature value input by the user;

[0166] The room equivalent thermal model is calculated according to the following formula to obtain the discrete response power provided by the variable frequency air conditioner by adjusting the air conditioning temperature value T to T+n. The following takes the case where the variable frequency air conditioner is in cooling mode and the air conditioner temperature value T is increased as an example:

[0167]

[0168] Among them, M AC The working mode of the inverter air conditioner is AC When M is 1, the inverter air conditioner is in cooling mode. AC When it is -1, the variable frequency air conditioner is in heating mode; n is an integer, which represents the adjustment amount of the air conditioning temperature value T preset by the variable frequency air conditioner, specifically the difference between the air conditioning temperature value T and the real-time temperature T in the room. in The difference between α and S is the thermal conductivity of the room’s exterior wall. room is the surface area of ​​the room; EER is the energy efficiency ratio of the variable frequency air conditioner, is the operating power of the variable frequency air conditioner at temperature T+n, is the operating power of the variable frequency air conditioner at the air conditioning temperature value T;

[0169] when When it is greater than 0, it means reducing the operating power of the inverter air conditioner. When it is less than 0, it means increasing the operating power of the variable frequency air conditioner; Discontinuous, the operating power of the variable frequency air conditioner is difficult to just meet the power required when adjusting to the temperature T+n, so there is a cyclic power deviation; but when the total virtual energy storage power is determined, the variable frequency air conditioner can provide different operating powers according to user needs;

[0170] The variable frequency air conditioner provides different operating powers when the adjustment amount n of the preset air conditioning temperature value T is different, but the amount of virtual energy storage provided by the variable frequency air conditioner during the process of adjusting the air conditioning temperature value T to different temperatures is the same, such as Figure 3 As shown, the discrete response power provided by the above variable frequency air conditioner satisfies the following formula relationship:

[0171]

[0172] Among them, t start is the start time of the variable frequency air conditioner response, t end1 is the end time of the variable frequency air conditioner temperature change from T to T+1, t end2 is the end time of the variable frequency air conditioner temperature change from T to T+2, t endn P is the end time when the variable frequency air conditioner responds to the temperature change from T to T+n, AC is the operating power of the variable frequency air conditioner, is the operating power of the variable frequency air conditioner at temperature T+1, It is the operating power of the variable frequency air conditioner at temperature T+2.

[0173] In the process of the variable frequency air conditioner changing its own operating power through temperature adjustment, the temperature in the room does not exceed the comfortable temperature range pre-set by the user, and the adjustment time of the variable frequency air conditioner does not exceed the maximum adjustable time pre-set by the user.

[0174] Step 6) Combine virtual energy storage and energy storage battery to form composite energy storage, solve the problem that the virtual energy storage response capability cannot be continuously adjusted, and reduce the configuration capacity and charge and discharge energy of the energy storage battery; control the charge state, charge and discharge power, output power of the energy storage battery, real-time temperature in the room and control time of the composite energy storage to achieve the superposition of power and continuous adjustment of power, solve the problem that the virtual energy storage response capability cannot be continuously adjusted, and reduce the configuration capacity and charge and discharge energy of the battery.

[0175] When the variable frequency air conditioner is running, the energy storage battery compensates for the deviation between the power of the virtual energy storage and the operating power that the variable frequency air conditioner needs to achieve by adjusting the air conditioning temperature value in step 5); when the state of charge of the virtual energy storage battery is lower than 50% of the energy storage battery's own capacity, the energy storage battery is charged so that the state of charge of the energy storage battery always remains at about 50% of its own capacity, thereby realizing the superposition of the power of the composite energy storage and the continuous adjustment of the discrete response power of the variable frequency air conditioner in step 5).

[0176] Specifically include the following aspects:

[0177] A) Calculate the state of charge SOC(t) of the composite energy storage according to the following formula:

[0178]

[0179] Among them, E max is the capacity of the composite energy storage, SOC r (t) is the state of charge of the energy storage battery at time t, is the capacity of the energy storage battery, SOC v (t) is the charge state of the virtual energy storage at time t, is the capacity of virtual energy storage;

[0180] Composite energy storage capacity E max It is the sum of the capacity of the energy storage battery and the capacity of the virtual energy storage:

[0181]

[0182] In addition, in order to avoid the rapid decline of battery performance caused by overcharging and overdischarging of the energy storage battery, the control makes the composite energy storage meet the minimum state of charge SOC during operation. min and maximum state of charge SOC max Between, that is,

[0183] SOC min <SOC(t)<SOC max

[0184] B) First, in order to ensure that the composite energy storage can accurately output power according to user needs, while reducing the charge and discharge power of the energy storage battery and extending the battery life, during the operation of the variable frequency air conditioner, the adjustment amount n of the air conditioning temperature value T pre-set by the variable frequency air conditioner is first determined. Since the power provided by the variable frequency air conditioner is discrete, according to the optimal setting temperature T of the variable frequency air conditioner set and the variable frequency air conditioner adjusts from the air conditioning temperature value T to T set The corresponding required power P D , find the optimal setting temperature T setThe working power at the two closest set temperatures T+n and T+(n+1) is shown in the following formula:

[0185]

[0186] in, Indicates that it is less than the required power P D The working power is specifically the discrete response power provided by the virtual energy storage by adjusting the air conditioning temperature value T to T+n. Indicates that it is greater than the required power P D The working power is specifically the discrete response power provided by the virtual energy storage by adjusting the air conditioning temperature value T to T+(n+1);

[0187] Then calculate ΔP according to the following formula D %:

[0188]

[0189] ΔP D % is the required power P D and less than the required power P D Working power Deviation of power and required power P D and greater than the required power P D Working power Deviation of ΔP D % is smaller, the required power P D and The smaller the deviation, the greater the ΔP D %The larger the required power P D and The smaller the deviation:

[0190] Next, for the required power P D , according to ΔP D % and real-time state of charge SOC of the energy storage battery r The final adjustment amount n of the preset air conditioning temperature value T of the variable frequency air conditioner is determined according to the following formula:

[0191] When the required power P D and less than the required power P D Working power When the deviation between them is less than p, regardless of the real-time charge state of the energy storage battery, the variable frequency air conditioner will increase by n degrees Celsius and provide The discrete response power of

[0192] When the required power P D and less than the required power P D Working power If the deviation between p and q is between p and q, if the real-time state of charge of the energy storage battery is higher than 50% of its own capacity, the inverter air conditioner will increase the temperature by n degrees Celsius and provide If the real-time state of charge of the energy storage battery is less than 50% of its capacity, the inverter air conditioner will increase the temperature by n+1 degrees Celsius and provide The discrete response power of

[0193] When the required power P D and less than the required power P D Working power When the deviation is greater than q, regardless of the real-time charge state of the energy storage battery, the inverter air conditioner will increase the temperature by n+1 degrees Celsius and provide The discrete response power of

[0194] As shown below:

[0195]

[0196] Among them, P v The discrete response power provided by the virtual energy storage by adjusting the air conditioning temperature value T;

[0197] p and q are two parameters set by the control method between the variable frequency air conditioner and the energy storage battery used in the formula, satisfying the following formula:

[0198] 0 <p<50%<q<100%

[0199] Determined P v Afterwards, the required power P D and energy storage batteries to compensate for the power provided by the inverter air conditioner

[0200] P r The deviation between them is used to calculate the output power P of the energy storage battery. r :

[0201] P r =P D -P v

[0202] By adopting the above control method, when the battery state of charge is low, the variable frequency air conditioner can provide more energy to charge the energy storage battery, so that the real-time state of charge SOC of the energy storage battery is r Always maintain about 50% of its capacity, so that the energy storage battery has greater charging and discharging energy;

[0203] C) In addition, the real-time charging and discharging power P of the composite energy storage at time t bat (t) satisfies the following formula:

[0204]

[0205]

[0206]

[0207] in, is the maximum charging power of the composite energy storage, is the maximum discharge power of the composite energy storage, is the maximum charging power of the energy storage battery, The maximum discharge power of the energy storage battery, is the rated power of the variable frequency air conditioner, P AC (t) is the real-time operating power of the variable frequency air conditioner at time t;

[0208] D) To ensure the user's comfort, control the variable frequency air conditioner to adjust the real-time temperature T in the room in Always keep in the comfortable temperature range, satisfying the following formula:

[0209] T min ≤T in ≤T max

[0210] Among them, T min is the lowest temperature in the comfortable temperature range, T in is the real-time temperature in the room, T max The highest temperature in the comfortable temperature range;

[0211] E) Simultaneously control the control time t of the variable frequency air conditioner DR Satisfies the following formula:

[0212] 0≤t DR ≤t max

[0213] Among them, t max is the longest adjustable time; when the adjustment time t DR Reach the maximum adjustable time t max When the inverter air conditioner is set to the optimal temperature T set , so that the room temperature is adjusted to the optimal set temperature T set .

[0214] The control method of the present invention is based on a composite energy storage system, which includes an energy storage battery and a variable frequency air conditioner; the energy storage battery and the variable frequency air conditioner are both connected to the power grid and can be powered by the power grid; the variable frequency air conditioner is connected to the energy storage battery, and the energy storage battery can power the variable frequency air conditioner; the virtual energy storage of the variable frequency air conditioner can replace part of the capacity of the energy storage battery, so that the variable frequency air conditioner can adjust the operating power during operation to replace part of the charging and discharging energy of the energy storage battery, and the increase in power consumption of the variable frequency air conditioner is equivalent to the charging of the energy storage battery, and the increase in power consumption of the variable frequency air conditioner is equivalent to the discharging of the energy storage battery.

[0215] In the specific implementation, it can also include distributed photovoltaics, the energy storage battery is matched with the distributed photovoltaics, the distributed photovoltaics and energy storage batteries are connected to the power grid through an inverter, the inverter can bidirectionally convert and transmit electric energy between the AC power in the power grid and the DC power in the distributed photovoltaics and energy storage batteries, and the distributed photovoltaics, energy storage batteries and inverters are photovoltaic power generation and supporting equipment located on the same user side as the air conditioner. The specific connection situation is as follows Figure 4 shown.

[0216] The power generation of distributed photovoltaics first meets the electricity demand of variable-frequency air conditioners. When the power generation of distributed photovoltaics is higher than the power consumption of air conditioners, the excess electricity can be stored in energy storage batteries or transmitted to the power grid. When the power generation of distributed photovoltaics cannot meet the power demand of variable-frequency air conditioners, the power shortage can be supplemented by discharge of energy storage batteries or supplied by the power grid. Specific embodiment:

[0218] Set the volume and surface area of ​​the room to: V room =120m 3 , S room =100m 2 ; Set the specific heat capacity of air, the density of air and the thermal conductivity coefficient of the room's outer wall to: c air =1.005kJ / (kg·℃),ρ air =1.205kg / m 3 , α=6.65W / (m 2 ·℃).

[0219] The equivalent heat capacity and equivalent thermal resistance of the room are: C room =145.3kJ / ℃, R room =665W / ℃.

[0220] Set the air conditioner to the optimal temperature for the room: T set =25℃; set the lowest and highest temperatures of the room's comfortable temperature range to: T min =23℃, T max =27℃.

[0221] Therefore, the segmented adjustment capability of the variable frequency air conditioner is It means that by adjusting the air-conditioning temperature value to increase by 1°C, the discrete response power can be reduced by 220W; conversely, it means that by adjusting the air-conditioning temperature value to decrease by 1°C, the discrete response power can be increased by 220W.

[0222] The capacity of the energy storage battery is set to 1kWh, the initial power is set to 50%, and the inverter air conditioner is selected as a Gree inverter air conditioner (GREE KFR-72LW / (72555)FNhAd-A3). Its related parameters are shown in the following table:

[0223] Table 1 Main parameters of variable frequency air conditioner

[0224] Rated cooling capacity Rated cooling power Rated heat capacity Rated heating power Energy efficiency ratio of inverter 7210W 2410W 9110W 3100W 3.29

[0225] Distributed photovoltaics are pre-installed on the roof with an installed capacity of 5kW. The output data under cloudy weather is as follows Figure 5 As shown in the figure, the dotted line represents the predicted output of photovoltaic power, and the solid line represents the actual output of photovoltaic power. Due to the volatility and uncertainty of photovoltaic output, the actual photovoltaic output has obvious fluctuations. However, the power grid needs to ensure real-time power balance. A large amount of power fluctuation is not conducive to the safe and stable operation of the power grid. Therefore, it is necessary to smooth the fluctuation of photovoltaic power to achieve large-scale distributed photovoltaic grid connection.

[0226] Based on the energy storage battery-inverter air conditioner composite energy storage control method proposed in the present invention, the inverter air conditioner temperature and the operating power of the energy storage battery are controlled in real time. The operating power of the composite energy storage is as follows: Figure 6 As shown. Combined Figure 5 and Figure 6 It can be seen that when the actual photovoltaic output is lower than the predicted output, the composite energy storage discharges, and the composite energy storage power is greater than zero; conversely, when the actual photovoltaic output is higher than the predicted output, the composite energy storage charges. Through the charging and discharging of the composite energy storage, the deviation between the actual photovoltaic output and the predicted output can be eliminated, and the friendly photovoltaic grid connection can be achieved.

[0227] Compared with the traditional single battery control method, the energy storage-inverter air conditioner composite energy storage control strategy proposed in this invention has the following advantages:

[0228] 1. It can fully tap the regulation potential of existing variable frequency air conditioner resources, among which the regulation of variable frequency air conditioners is as follows: Figure 7 As shown, the dotted line represents the original operating power of the variable frequency air conditioner without regulation, and the solid line represents the operating power of the variable frequency air conditioner after participating in the composite energy storage regulation.

[0229] 2. It can reduce the capacity of battery energy storage in distributed photovoltaic supporting energy storage. As shown in Table 2, under the same scenario, the actual usage capacity of the battery for composite energy storage is only 0.33kWh, which is 51.5% lower than the single battery energy storage capacity, and can reduce the cost of distributed photovoltaic development.

[0230] 3. It can reduce the energy storage and smooth the charging and discharging energy of photovoltaics during operation. It is lossless to use the variable frequency air conditioner and the heat storage capacity of the room as virtual energy storage to absorb part of the photovoltaic fluctuations. As can be seen from Table 2, the total charge and discharge amount of the battery during the composite energy storage regulation process is 2.08kWh, which is 26.7% lower than that of a single battery energy storage. It can effectively extend the service life of the battery and reduce the operating cost of distributed photovoltaics.

[0231] Table 2 Comparison of battery energy storage and composite energy storage operation

[0232]

Claims

1. A composite energy storage control method based on variable frequency air conditioner and energy storage battery, characterized in that: The steps include: Step 1) calculating the equivalent heat capacity and equivalent thermal resistance of the room according to the characteristics of the room where the variable frequency air conditioner is installed; Step 2) using a first-order equivalent thermal parameter model, combined with the equivalent heat capacity and equivalent thermal resistance of the room to obtain the real-time temperature in the room; Step 3) by presetting the optimal set temperature of the room, establishing a functional relationship between the operating frequency, operating power and real-time temperature in the room of the variable frequency air conditioner, and processing to obtain the operating power of the variable frequency air conditioner; Step 4) The variable frequency air conditioner is equivalent to virtual energy storage, the maximum adjustable time of the variable frequency air conditioner is preset, the available capacity of the virtual energy storage is calculated according to the response capacity of the variable frequency air conditioner and the preset comfortable temperature range and the maximum adjustable time, and the real-time power of the virtual energy storage is calculated according to the operating status of the variable frequency air conditioner; Step 5) using the room equivalent thermal model, the discrete response power provided by the virtual energy storage through temperature adjustment is obtained according to the real-time temperature in the room and the air conditioning temperature value input by the user; Step 6) combining the virtual energy storage and the energy storage battery to form a composite energy storage, and controlling the charge state, charging and discharging power, output power of the energy storage battery, real-time temperature in the room, and control time of the composite energy storage; The step 3) is specifically as follows: First, the operating frequency f of the air conditioner inverter is obtained by the following method: AC : When the real-time temperature in the room is T in And preset the optimal set temperature T of the room set The difference exceeds ΔT max When the inverter air conditioner is turned on, it will run at the preset maximum working power; When the real-time temperature T in The difference from the set temperature is less than ΔT min When the inverter air conditioner enters the standby state, it runs at the preset minimum working power; When the real-time temperature T in The difference between the set temperature and the min and ΔT max When the temperature difference is greater, the frequency is higher; It is expressed as: Among them, f max is the maximum operating frequency of the inverter of the variable frequency air conditioner, ΔT max is the maximum temperature deviation value when the variable frequency air conditioner is running at the highest frequency, k is the proportional control coefficient of the variable frequency air conditioner inverter, b is the basic operating frequency of the variable frequency air conditioner inverter, ΔT min is the minimum temperature deviation value when the variable frequency air conditioner is running at the lowest operating frequency, f min is the minimum operating frequency of the inverter of the variable frequency air conditioner; T in is the real-time temperature in the room, T set The best setting temperature for inverter air conditioner; Next, the operating frequency f of the variable frequency air conditioner inverter is expressed by the following formula: AC And the operating power P of the inverter air conditioner AC The linear relationship between them is used to obtain the operating power P of the variable frequency air conditioner. AC : P AC =S AC (c×f AC +d) Among them, S AC is the operating state of the variable frequency air conditioner, S AC When the inverter air conditioner is operating normally, it is 1, S AC When the variable frequency air conditioner is turned off, it is 0; c and d represent the working frequency f of the air conditioner inverter. AC And the operating power P of the inverter air conditioner AC The two coefficients of the linear relationship between The step 4) is specifically as follows: convert the heat in the room into the amount of electricity of the virtual energy storage, and obtain the available capacity of the virtual energy storage according to the following formula: in, To increase the maximum amount of heat in the room, is the maximum heat reduction in the room, and EER is the energy efficiency ratio of the variable frequency air conditioner; Maximum heat increase in the room and maximum heat reduction According to the preset optimal setting temperature T set And the comfortable temperature range is obtained: Among them, T set is the optimal setting temperature, T max is the highest temperature in the comfortable temperature range, T min is the lowest temperature in the comfortable temperature range, c air represents the specific heat capacity of air, ρ air Represents the density of air, V room is the volume of the room, t max is the longest adjustable time; At the same time, the following formula is used to use the state of charge SOC of the virtual energy storage at time t v (t) Calculate the real-time power of virtual energy storage: Among them, EER is the energy efficiency ratio of the variable frequency air conditioner, T in The real-time temperature in the room; The step 5) is specifically as follows: The room equivalent thermal model is calculated according to the following formula to obtain the discrete response power provided by the variable frequency air conditioner by adjusting the air conditioning temperature value T to T+n. The following takes the case where the variable frequency air conditioner is in cooling mode and the air conditioner temperature value T is increased as an example: Among them, M AC The working mode of the inverter air conditioner is AC When M is 1, the inverter air conditioner is in cooling mode. AC When it is -1, the inverter air conditioner is in heating mode; n represents the adjustment amount of the air conditioning temperature value T preset by the inverter air conditioner, specifically the difference between the air conditioning temperature value T and the real-time temperature T in the room. in The difference between α and S is the thermal conductivity of the room’s exterior wall. room is the surface area of ​​the room; EER is the energy efficiency ratio of the variable frequency air conditioner, is the operating power of the variable frequency air conditioner at temperature T+n, is the operating power of the variable frequency air conditioner at the air conditioning temperature value T; when When it is greater than 0, it means reducing the operating power of the inverter air conditioner. When it is less than 0, it means increasing the operating power of the variable frequency air conditioner; The discrete response power provided by the above variable frequency air conditioner satisfies the following formula relationship: Among them, t start is the start time of the variable frequency air conditioner response, t end1 is the end time of the variable frequency air conditioner temperature change from T to T+1, t end2 is the end time of the variable frequency air conditioner temperature change from T to T+2, t endn P is the end time when the variable frequency air conditioner responds to the temperature change from T to T+n, AC is the operating power of the variable frequency air conditioner, is the operating power of the variable frequency air conditioner at temperature T+1, is the operating power of the variable frequency air conditioner at temperature T+2; The step 6) specifically includes the following aspects: A) Calculate the state of charge SOC(t) of the composite energy storage according to the following formula: Among them, E max is the capacity of the composite energy storage, SOC r (t) is the state of charge of the energy storage battery at time t, is the capacity of the energy storage battery, SOC v (t) is the charge state of the virtual energy storage at time t, is the capacity of virtual energy storage; Composite energy storage capacity E max It is the sum of the capacity of the energy storage battery and the capacity of the virtual energy storage: In addition, the control makes the composite energy storage meet the minimum state of charge SOC during operation. min and maximum state of charge SOC max Between, that is, SOC min <SOC(t)<SOC max B) First, according to the optimal setting temperature T of the inverter air conditioner set and the variable frequency air conditioner adjusts from the air conditioning temperature value T to T set The corresponding required power P D , find the optimal setting temperature T set The working power at the two closest set temperatures T+n and T+(n+1) is shown in the following formula: in, Indicates that it is less than the required power P D The working power is specifically the discrete response power provided by the virtual energy storage by adjusting the air conditioning temperature value T to T+n. Indicates that it is greater than the required power P D The working power is specifically the discrete response power provided by the virtual energy storage by adjusting the air conditioning temperature value T to T+(n+1); Then calculate ΔP according to the following formula D %: ΔP D % is the required power P D and less than the required power P D Working power Deviation of power and required power P D and greater than the required power P D Working power Deviation of ΔP D % is smaller, the required power P D and The smaller the deviation, the greater the ΔP D %The larger the required power P D and The smaller the deviation; Next, for the required power P D , according to ΔP D % and real-time state of charge SOC of the energy storage battery r The final adjustment amount n of the preset air conditioning temperature value T of the variable frequency air conditioner is determined according to the following formula: When the required power P D and less than the required power P D Working power When the deviation between them is less than p, regardless of the real-time charge state of the energy storage battery, the variable frequency air conditioner will increase by n degrees Celsius and provide The discrete response power of When the required power P D and less than the required power P D Working power If the deviation between p and q is between p and q, if the real-time state of charge of the energy storage battery is higher than 50% of its own capacity, the inverter air conditioner will increase the temperature by n degrees Celsius and provide If the real-time state of charge of the energy storage battery is less than 50% of its capacity, the inverter air conditioner will increase the temperature by n+1 degrees Celsius and provide The discrete response power of When the required power P D and less than the required power P D Working power When the deviation is greater than q, regardless of the real-time charge state of the energy storage battery, the inverter air conditioner will increase the temperature by n+1 degrees Celsius and provide The discrete response power of As shown below: Among them, P v The discrete response power provided by the virtual energy storage by adjusting the air conditioning temperature value T; p and q are two parameters set by the control method between the variable frequency air conditioner and the energy storage battery used in the formula, satisfying the following formula: 0<p<50%<q<100% By the required power P D and energy storage batteries to compensate for the power provided by the inverter air conditioner P r The deviation between them is used to calculate the output power P of the energy storage battery. r : P r =P D -P v By adopting the above control method, when the battery state of charge is low, the variable frequency air conditioner can provide more energy to charge the energy storage battery, so that the real-time state of charge SOC of the energy storage battery is r Always maintain 50% of its capacity; C) In addition, the real-time charging and discharging power P of the composite energy storage at time t bat (t) satisfies the following formula: in, is the maximum charging power of the composite energy storage, is the maximum discharge power of the composite energy storage, is the maximum charging power of the energy storage battery, The maximum discharge power of the energy storage battery, is the rated power of the variable frequency air conditioner, P AC (t) is the real-time operating power of the variable frequency air conditioner at time t; D) Control the variable frequency air conditioner to adjust the real-time temperature T in the room in Always keep in the comfortable temperature range, satisfying the following formula: T min ≤T in ≤T max Among them, T min is the lowest temperature in the comfortable temperature range, T in is the real-time temperature in the room, T max The highest temperature in the comfortable temperature range; E) Control the regulation time t of variable frequency air conditioner DR Satisfies the following formula: 0≤t DR ≤t max Among them, t max is the longest adjustable time; when the adjustment time t DR Reach the maximum adjustable time t max When the inverter air conditioner is set to the optimal temperature T set , so that the room temperature is adjusted to the optimal set temperature T set .

2. A composite energy storage control method based on variable frequency air conditioner and energy storage battery according to claim 1, characterized in that: The step 1) is specifically as follows: Calculate the room characteristics where the variable frequency air conditioner is installed, that is, the volume V of the room room and surface area S room , the equivalent heat capacity C of the air in the room is obtained according to the following formula room And the equivalent thermal resistance R room : C room =c air r air V room R room =αS room Among them, c air is the specific heat capacity of air, ρ air is the density of air, and α is the thermal conductivity of the outer wall of the room.

3. The composite energy storage control method based on variable frequency air conditioner and energy storage battery according to claim 1, characterized in that: The step 2) is specifically as follows: The real-time temperature T in the room at time t is calculated using the first-order equivalent thermal parameter model of the following formula: in : Among them, C room is the equivalent heat capacity of air, Q gain is the heat absorbed in the room per unit time, Q loss is the heat loss in the room per unit time; The amount of heat absorbed in the room per unit time Q gain Use the following formula to obtain: Among them, Q AC Q is the heat generated by the variable frequency air conditioner cooling / heating in the room per unit time, AC If it is greater than 0, it means the inverter air conditioner is in heating mode. AC Less than 0 means the inverter air conditioner is in cooling mode; Q loads Q is the heat generated by other electrical appliances in the room per unit time. solar is the amount of solar radiation absorbed in the room per unit time; Heat loss in the room per unit time Q loss Use the following formula to obtain: Q loss =(T in -T out ) / R room +k d c air ρ air V d (T in -T out ) Among them, (T in -T out ) / R room R is the heat lost by heat exchange inside and outside the room per unit time, room is the equivalent thermal resistance of the room, T in is the real-time temperature in the room, T out is the real-time temperature outside the room, k d c air ρ air V d (T in -T out ) is the heat lost in unit time due to the exchange of hot and cold air caused by opening and closing the door when people enter and leave the room, k d is the number of door openings per unit time, c air represents the specific heat capacity of air, ρ air Represents the density of air, V d The volume of air exchange between the inside and outside of the room caused by each door opening.

4. The composite energy storage control method based on variable frequency air conditioner and energy storage battery according to claim 1 is characterized in that: The control method is based on a composite energy storage system, which includes an energy storage battery and a variable frequency air conditioner; the energy storage battery and the variable frequency air conditioner are both connected to a power grid; and the variable frequency air conditioner is connected to the energy storage battery.

Images