Solar energy coupled electric auxiliary heating system and control method

Abstract

The application discloses a solar energy coupled electric auxiliary heat supply system and a control method, and relates to the field of heat exchange heat supply.The solar energy coupled electric auxiliary heat supply system comprises a heat storage water tank, a solar energy collector, a primary electric heater and a secondary electric heater; and the control method comprises the following steps: in a valley electricity time period, heat supply is preferentially performed by the solar energy collector, and when the heat supply heat is insufficient, the primary electric heater is started; in a time period before the valley electricity time period ends, meteorological data is predicted and used to calculate the heat supply capacity of the solar energy collector in a next peak electricity time period, and whether the secondary electric heater needs to be started to heat the heat storage water tank is judged according to the heat supply capacity; and in the peak electricity time period, only the solar energy collector is started to perform heat supply.Compared with the prior art, the application has the beneficial effect that the difference between peak electricity price and valley electricity price is fully utilized, and the electric auxiliary heat is not started in the peak electricity time period, so that the heat supply cost of the system is greatly reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of heat supply, and particularly relates to a solar energy coupled electric auxiliary heat supply system and a control method. BACKGROUND

[0002] In some heat supply areas in China, especially in summer-hot and winter-cold areas, the biomass resource is very small, and the humidity is large in the heating season, so the biomass boiler and the air source heat pump are difficult to be widely used, and the soil source heat pump also has high requirements for underground water resources and construction conditions. Therefore, in many cases, solar energy can only be selected as the main heat supply method. Due to the instability of solar energy, a heat storage water tank and electric auxiliary heating are needed as the overall heat supply system. The investment cost of electric auxiliary heating is very low, but the operation cost is much higher than that of the heat pump. Therefore, it is very important to reduce the operation cost as much as possible for the wide application of the solar energy coupled electric auxiliary heat supply system. However, the current operation mode of the system lacks reasonable design, and in many cases, the system often has a lagging reaction, and the processes are not matched, resulting in large temperature fluctuation, poor heat supply effect and energy waste. SUMMARY

[0003] The details of one or more embodiments of the application are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the application will be apparent from the description of the application and from the claims.

[0004] The application provides a solar energy coupled electric auxiliary heat supply system and a control method, which fully utilizes the difference between peak and valley electricity prices, avoids starting electric auxiliary heating during peak electricity period, and greatly reduces the heat supply cost of the system.

[0005] The application discloses a solar energy coupled electric auxiliary heat supply system and a control method.

[0006] A heat storage water tank;

[0007] A solar energy collector is arranged on one side of the heat storage water tank in a circulating manner;

[0008] A water supply pipeline and a return water pipeline are arranged on one side of the heat storage water tank;

[0009] A connecting pipeline is arranged between the water supply pipeline and the return water pipeline;

[0010] A primary electric heater and a secondary electric heater are arranged in the water tank;

[0011] The solar energy coupled electric auxiliary heat supply system and the control method comprise:

[0012] The valley electricity period heating operation method, in the valley electricity period heating process, the heating is preferentially performed by the solar heat collector, and when the heating quantity is insufficient, the first-stage electric heater is started; before the valley electricity period ends, the heating quantity of the solar heat collector in the next peak electricity period is predicted and calculated through meteorological data, and whether the second-stage electric heater needs to be started to heat the heat storage water tank is judged according to the heating quantity; when the water supply temperature exceeds the set water supply target temperature, the return water is mixed into the water supply pipeline through the return water pipeline and the connecting pipeline to reduce the water supply temperature.

[0013] The peak electricity period heating operation method, the solar heat collector is started to perform heating, and when the water supply temperature exceeds the set water supply target temperature, the return water is mixed into the water supply pipeline through the return water pipeline and the connecting pipeline to reduce the water supply temperature; when the heating quantity of the solar heat collector is insufficient, the heat storage water tank has been heated before the valley electricity period ends, so the first-stage electric heater and the second-stage electric heater are not started to perform electric auxiliary heating.

[0014] In some embodiments, the solar energy coupled electric auxiliary heating system further comprises:

[0015] A first temperature sensor T1 and a second temperature sensor T2 are arranged on the water supply pipeline, the first temperature sensor T1 is located at the water inlet end of the water supply pipeline, and the second temperature sensor T2 is located at the water outlet end of the connecting pipeline and the return water pipeline;

[0016] A third temperature sensor T3 is arranged on the return water pipeline; the third temperature sensor T3 is located at the water inlet end of the connecting pipeline and the return water pipeline;

[0017] A water supply pipeline electronic expansion valve V2 and a water supply pipeline water pump P2 are arranged on the water supply pipeline between the first temperature sensor T1 and the connecting pipeline and the return water pipeline;

[0018] A connecting pipeline electronic expansion valve V3 and a connecting pipeline check valve V4 are arranged on the connecting pipeline;

[0019] A return water pipeline gate valve V5 and a return water pipeline check valve V6 are arranged on the return water pipeline between the water outlet end of the return water pipeline and the connecting pipeline and the return water pipeline;

[0020] A return water pipeline water pump P3 is arranged on the return water pipeline at the water inlet end of the third temperature sensor T3;

[0021] A controller is connected with the first-stage electric heater, the second-stage electric heater, the water supply pipeline electronic expansion valve V2, and the connecting pipeline electronic expansion valve V3.

[0022] In some embodiments, the valley electricity period heating operation method comprises:

[0023] At the beginning of the valley electricity period, set the target water supply temperature T g1 * , calculate the heating amount Q x1 provided by the primary electric heater in the valley electricity period, and calculate the load rate f1 of the primary electric heater in the valley electricity period through the value, the calculation method is as follows:

[0024] Q x1 = (T g1 -T * )·m a1 ·c t ·t p g

[0025]

[0026] Wherein, T g1 * is the target water supply temperature in the valley electricity period, unit ℃, T a1 is the average ambient temperature around the water tank in the valley electricity period, unit ℃; m t is the mass flow of total water supply, unit kg / s; c p is the constant pressure specific heat capacity of water, taking 4200J / kg·℃; t g is the remaining time of the valley electricity period after the heat storage heating cannot meet the requirements, unit hour; P e1 is the maximum power of the primary electric heating, Kw;

[0027] Start the primary electric heater for heating according to the calculation result;

[0028] When the load rate f1 is greater than 1, it means that the primary electric heater cannot meet the heating demand, at this time, the secondary electric heater needs to be started, and the heat gap Q x2 required is calculated according to the meteorological data, and the load rate f2 of the secondary electric heater is calculated, the calculation method is as follows:

[0029] Q x2 = (T g2 -T * )·m a2 ·c t ·t p -I p ·A·η·t t t

[0030]

[0031] Wherein T g2 *The target water supply temperature during peak electricity hours, in °C, is determined based on the maximum heat load during peak electricity hours; T a2 The average ambient temperature around the water tank during this peak power period, in °C; t p For peak power duration, in hours; I t The average heat collection intensity of the solar collector, in J / m². 2 s; A is the area of ​​the solar collector, in meters. 2 η is the efficiency of the solar collector; t t P represents the operating time of the solar collector, expressed in hours. e2 t1 is the maximum power of the secondary electric heater, in kW; t1 is the working time of the secondary electric heater, in hours.

[0032] Based on the calculation results, the secondary electric heater is turned on to provide heat.

[0033] In some implementations, when the temperature exceeds the set target water supply temperature T g * At this time, the return water is mixed into the supply water pipeline through the return water pipeline and connecting pipeline to reduce the supply water temperature and thus achieve heat storage. The calculation method for the return water volume is as follows:

[0034] m1·(TT g * )·c p =M2·(T g * -T b )·c p

[0035] m1+m2=m t

[0036] Where m1 is the actual mass flow rate of water supplied by hot water storage tank 3, in kg / s; T b T represents the return water temperature measured by the third temperature sensor T3, in °C; T represents the outlet water temperature measured by the first temperature sensor T1.

[0037] Therefore, the method for calculating the return water volume can be derived:

[0038]

[0039] Based on the calculation results, the opening degree of the electronic expansion valve V2 in the water supply pipeline and the electronic expansion valve V3 in the connecting pipeline is adjusted to control the return water volume. T is re-monitored and m2 is calculated at regular intervals, and the opening degree of the electronic expansion valve V2 in the water supply pipeline and the electronic expansion valve V3 in the connecting pipeline is adjusted according to the calculation results.

[0040] In some embodiments, the solar-coupled electric auxiliary heating system further includes:

[0041] A heat exchange coil is arranged in the heat storage water tank and connected to both ends of the solar collector through a manifold.

[0042] In some embodiments, the steps of the valley electricity period heating operation method are as follows:

[0043] Step S1: First, start the control system and set the water supply target temperature T g1 * , temperature control precision δT, and temperature monitoring time interval Δt.

[0044] Step S2: At the beginning of the valley electricity period, use heat storage for heating first, and monitor the outlet water temperature T of the heat storage water tank every Δt, if T > T g1 * , continue to use the hot water of the heat storage for heating; if T < T g1 * , calculate the remaining time t g of the valley electricity period, calculate the required first-stage electric heater heating capacity Q x1 and the load rate f1 of the first-stage electric heater, and then start the first-stage electric heater for heating according to f1.

[0045] Step S3: Before the end of the valley electricity period, collect the climate data of the next peak electricity period, calculate the required supplementary heating capacity Q x2 , if the value is less than zero, the second-stage electric heater does not need to be started; if the value is greater than zero, calculate the load rate f2 of the second-stage electric heater 5 and start the second-stage electric heater for heating.

[0046] Step S4: Monitor the outlet water temperature T of the heat storage water tank every Δt, when T > T g1 * + δT, calculate the required return water quantity m2, and adjust the opening degree of the electronic expansion valve V2 of the water supply pipeline and the electronic expansion valve V3 of the connecting pipeline to control the return water quantity.

[0047] In some embodiments, the steps of the peak electricity period heating operation method are as follows:

[0048] Step S1: First, start the control system and set the water supply target temperature T g2 * , temperature control precision δT, and temperature monitoring time interval Δt.

[0049] Step S2: Start the solar collector for heating, and monitor the outlet water temperature T of the heat storage water tank, if T > T g2 *When +deltaT, calculate the required return water amount m2, and adjust the opening degree of the water supply pipeline electronic expansion valve V2 and the connecting pipeline electronic expansion valve V3 to control the return water amount.

[0050] In some embodiments, the time period before the end of the valley electricity period is 1 hour before the end of the valley electricity period.

[0051] Compared with the prior art, the present application has the following advantages: based on the characteristics of low cost of the solar energy mainly operating in the peak electricity period and the electric heater operating in the valley electricity period, the present application proposes a control method of a solar energy coupled electric auxiliary heating heating system, taking the solar energy collector as the main heating equipment in the peak electricity period and taking the electric heater as the main operating equipment in the valley electricity period, and simultaneously starting the heat storage one hour before the end of the valley electricity period when the heating amount of the solar energy collector is insufficient. Compared with the control method of the traditional solar energy coupled electric heating system, the main advantage of the present application is that the difference between the peak electricity price and the valley electricity price is fully utilized, and when the heating amount of the solar energy collector is insufficient, the required heat is supplemented in the form of valley electricity heat storage, thereby avoiding the starting of the electric heater in the peak electricity period, and thus the heating cost is greatly reduced. BRIEF DESCRIPTION OF DRAWINGS

[0052] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and serve to explain the principles of the application, and do not limit the application in any way.

[0053] Figure 1 It is a schematic diagram of the system structure of the present application.

[0054] Figure 2 It is a schematic diagram of the structure of the return water of the present application.

[0055] BRIEF DESCRIPTION OF DRAWINGS: solar energy collector 1, heat exchange coil 2, heat storage water tank 3, primary electric heater 4, secondary electric heater 5, controller 6, actuator 7. DETAILED DESCRIPTION

[0056] In order to make the purpose, technical scheme and advantages of the present application more clear and explicit, the present application is described and explained below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application. Based on the examples provided by the present application, all other examples obtained by those of ordinary skill in the art without making creative efforts fall within the scope of the present application.

[0057] Obviously, the accompanying drawings described below are merely some examples or embodiments of the present invention. Those skilled in the art can apply the present invention to other similar scenarios based on these drawings without any inventive effort. Furthermore, it is understood that although the efforts made in this development process may be complex and lengthy, for those skilled in the art related to the content disclosed in this invention, modifications to design, manufacturing, or production based on the technical content disclosed in this invention are merely conventional technical means and should not be construed as insufficient disclosure of the present invention.

[0058] In this invention, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this invention may be combined with other embodiments without conflict.

[0059] The control method for the solar-coupled electric auxiliary heating system includes:

[0060] The off-peak heating operation method is as follows: During the off-peak heating period, the solar collector 1 is given priority for heating. When the heating heat is insufficient, the primary electric heater 4 is turned on. In the period before the end of the off-peak period, the heating capacity of the solar collector 1 under the next peak period is predicted and calculated based on meteorological data, and it is used to determine whether the secondary electric heater 5 needs to be turned on to heat the hot water storage tank 3. When the water supply temperature exceeds the set target water supply temperature, the return water is mixed into the water supply pipeline through the return water pipeline and the connecting pipeline to reduce the water supply temperature.

[0061] During peak electricity hours, the solar collector 1 is turned on to provide heating. When the water supply temperature exceeds the set target temperature, the return water is mixed into the supply water pipeline through the return water pipeline and the connecting pipeline to reduce the water supply temperature. When the solar collector 1 is not producing enough heat, the primary electric heater 4 and the secondary electric heater 5 are not turned on for electric auxiliary heating because the hot water storage tank 3 has been heated before the end of off-peak electricity.

[0062] The system operation mode of valley electricity period and peak electricity period is set respectively because the operation cost of electric auxiliary heating is quite different between valley electricity period (22:00 to 8:00 of next day) and peak electricity period (8:00 to 22:00). When heating in valley electricity period, the heat storage is used preferentially, and the first-stage electric auxiliary heating is started when the heat is insufficient. Preferably, one hour before the end of valley electricity period, the heat production of solar collector in peak electricity period is predicted and calculated through the meteorological data of next day, if the difference between the required heat and the heat production is less than the required heat, the second-stage electric auxiliary heating is started to heat the heat storage tank, and when the temperature exceeds the set water supply target temperature, the return water is mixed into the water supply pipeline to reduce the water supply temperature, so as to realize heat storage. In peak electricity heating period, the solar collector is started to heat, and when the temperature exceeds the set water supply target temperature, the return water is mixed into the water supply pipeline. When the heat production of solar collector is insufficient, because heat storage has been carried out before the end of valley electricity period, the heat storage water is used to heat, and the electric auxiliary heating is not needed. The setting method fully utilizes the difference between peak electricity price and valley electricity price, avoids starting electric auxiliary heating in peak electricity period, and greatly reduces the heating cost of the system.

[0063] In order to achieve the above-mentioned purpose, the application provides a solar energy coupled electric auxiliary heating heating system, which comprises a solar collector 1, a heat storage tank 3, a water supply pipeline, a return water pipeline, a connecting pipeline, a first-stage electric heater 4 and a second-stage electric heater 5; the solar collector 1 is arranged on one side of the heat storage tank 3 and is in circulation; the water supply pipeline and the return water pipeline are arranged on one side of the heat storage tank 3; the connecting pipeline is arranged between the water supply pipeline and the return water pipeline; the first-stage electric heater 4 and the second-stage electric heater 5 are arranged in the heat storage tank 3.

[0064] The solar energy coupled electric auxiliary heating heating system further comprises a first temperature sensor T1, a second temperature sensor T2, a third temperature sensor T3, a water supply pipeline electronic expansion valve V2, a water supply pipeline water pump P2, a connecting pipeline electronic expansion valve V3, a connecting pipeline check valve V4, a return water pipeline gate valve V5, a return water pipeline check valve V6, a return water pipeline water pump P3, a controller 6 and a heat exchange coil 2.

[0065] The first temperature sensor T1 and the second temperature sensor T2 are arranged on the water supply pipeline, the first temperature sensor T1 is located at the water inlet end of the water supply pipeline, and the second temperature sensor T2 is located at the water outlet end at the joint between the connecting pipeline and the water return pipeline; the third temperature sensor T3 is arranged on the water return pipeline; the third temperature sensor T3 is located at the water inlet end at the joint between the connecting pipeline and the water return pipeline; the water supply pipeline electronic expansion valve V2 and the water supply pipeline water pump P2 are arranged on the water supply pipeline between the first temperature sensor T1 and the joint between the connecting pipeline and the water return pipeline; the connecting pipeline electronic expansion valve V3 and the connecting pipeline check valve V4 are arranged on the connecting pipeline; the water return pipeline gate valve V5 and the water return pipeline check valve V6 are arranged on the water return pipeline between the water outlet end of the water return pipeline and the joint between the connecting pipeline and the water return pipeline; the water return pipeline water pump P3 is arranged on the water return pipeline at the water inlet end of the third temperature sensor T3; the controller 6 is connected with the primary electric heater 4, the secondary electric heater 5, the water supply pipeline electronic expansion valve V2 and the connecting pipeline electronic expansion valve V3. The heat exchange coil 2 is arranged in the heat storage water tank 3 and is connected with both ends of the solar heat collector 1 through a pipe manifold; the pipe manifold is provided with the heat collection water pump P1 and the heat collection gate valve V1.

[0066] In some embodiments, the valley electricity period heating operation method comprises:

[0067] At the beginning of the valley electricity period, the target water supply temperature T g1 * is set according to the maximum heat load of the valley electricity period, the heating quantity Q x1 provided by the primary electric heater 4 in the valley electricity period is calculated, and the load rate f1 of the primary electric heater 4 in the valley electricity period is calculated through the value, and the calculation method is as follows:

[0068] Q x1 = (T g1 * -T a1 )·m t ·c p ·t g

[0069]

[0070] Wherein, T g1 * is the target water supply temperature of the valley electricity period, unit ℃, T a1 is the average ambient temperature around the water tank in the valley electricity period, unit ℃; m t is the mass flow of total water supply, unit kg / s; c p is the specific heat capacity of water at constant pressure, 4200 J / kg·℃; tg The remaining time of the valley electricity period, unit: hour; P e1 The maximum power of the first-stage electric heater, unit: Kw;

[0071] According to the calculation result, the first-stage electric heater 4 is started to supply heat;

[0072] When the load rate f1 is greater than 1, it means that the first-stage electric heater 4 cannot meet the heat supply demand, at this time, the second-stage electric heater 5 needs to be started, and the heat gap Q x2 required is calculated according to the meteorological data, and the load rate f2 of the second-stage electric heater 5 is calculated, the calculation method is as follows:

[0073] Q x2 = (T g2 * -T a2 )·m t ·c p ·t p -I t ·A·η·t t

[0074]

[0075] Wherein T g2 * is the target water supply temperature in the peak electricity period, unit: ℃, which is determined according to the maximum heat load in the peak electricity period; T a2 is the average ambient temperature around the water tank in the peak electricity period, unit: ℃; t p is the duration of the peak electricity, unit: hour; I t is the average heat collection intensity of the solar collector, unit: J / m 2 ·s; A is the area of the solar collector, unit: m 2 ; η is the efficiency of the solar collector; t t is the working duration of the solar collector, unit: hour; P e2 is the maximum power of the second-stage electric heater, unit: Kw; t1 is the working duration of the second-stage electric heater, unit: hour;

[0076] According to the calculation result, the second-stage electric heater 5 is started to supply heat.

[0077] In some embodiments, when the temperature exceeds the set water supply target temperature T g * , the return water is mixed into the water supply pipeline through the return water pipeline and the connecting pipeline to reduce the water supply temperature to realize heat storage, and the calculation method of the return water amount is as follows:

[0078] m1·(T-T g * )·cp = m2 · (T g * - T b ) · c p

[0079] m1 + m2 = m t

[0080] Wherein m1 is the actual water supply mass flow of the heat storage water tank 3, unit kg / s; T b is the return water temperature measured by the third temperature sensor T3, unit ℃; T is the outlet water temperature measured by the first temperature sensor T1;

[0081] Thus the calculation method of the return water quantity is obtained:

[0082]

[0083] According to the calculation result, the opening degree of the water supply pipeline electronic expansion valve V2 and the connecting pipeline electronic expansion valve V3 is opened to control the return water quantity, and T is monitored and m2 is calculated every interval time, and then the opening degree of the water supply pipeline electronic expansion valve V2 and the connecting pipeline electronic expansion valve V3 is adjusted according to the calculation result.

[0084] The above calculation method of the return water quantity is suitable for the above valley electricity period and peak electricity period mode.

[0085] In some embodiments, the steps of the valley electricity period heating operation method are:

[0086] Step S1: first start the control system, set the water supply target temperature T g1 * , temperature control precision δT, temperature monitoring time interval △t;

[0087] Step S2: when the valley electricity period starts, first use heat storage to heat, monitor the outlet water temperature T of the heat storage water tank 3 every interval △t, if T>T g1 * , continue to heat by the hot water of heat storage; if T<T g1 * , calculate the remaining time t g of the valley electricity period, and calculate the required first-stage electric heater 4 heating capacity Q x1 and the load rate f1 of the first-stage electric heater 4, then according to f1, open the first-stage electric heater 4 to heat;

[0088] Step S3: before the valley electricity period ends, collect the climate data of the next peak electricity period, calculate the required supplementary heating capacity Q x2 of the peak electricity period.If the value is less than zero, the secondary electric heater 5 does not need to be turned on; if the value is greater than zero, the load rate f2 of the secondary electric heater 5 is calculated and the secondary electric heater 5 is turned on to heat;

[0089] Step S4: The outlet water temperature T of the heat storage water tank 3 is monitored every time interval At, and when T > T g1 * + δT, the required return water quantity m2 is calculated, and the opening of the supply water pipeline electronic expansion valve V2 and the connecting pipeline electronic expansion valve V3 is adjusted to control the return water quantity.

[0090] In some embodiments, the steps of the peak electricity period heating operation method are:

[0091] Step S1: First, the control system is started, and the supply water target temperature T g2 * , the temperature control precision δT, and the temperature monitoring time interval At are set.

[0092] Step S2: The solar heat collector 1 is turned on for heating, and the outlet water temperature T of the heat storage water tank 3 is monitored, and when T > T g2 * + δT, the required return water quantity m2 is calculated, and the opening of the supply water pipeline electronic expansion valve V2 and the connecting pipeline electronic expansion valve V3 is adjusted to control the return water quantity.

[0093] In some embodiments, preferably, the time period before the end of the valley electricity period is 1 hour before the end of the valley electricity period.

[0094] Although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent replacements can be made to part of the technical features; and such modifications or replacements do not cause the essence of the corresponding technical solution to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A control method of a solar energy coupled electrically assisted heat supply system, characterized in that, The solar energy coupled electric auxiliary heating heat supply system comprises: a heat storage water tank (3); a solar energy collector (1) arranged on one side of the heat storage water tank (3) and in circulation; a water supply pipeline and a return water pipeline arranged on one side of the heat storage water tank (3); a connecting pipeline arranged between the water supply pipeline and the return water pipeline; a primary electric heater (4) and a secondary electric heater (5) arranged in the water tank (3); the control method of the solar energy coupled electric auxiliary heating heat supply system comprises: a valley electricity time period heat supply operation method, in which the solar energy collector (1) is used to supply heat preferentially in the valley electricity time period heat supply process, and the primary electric heater (4) is started when the heat supply heat is insufficient; a time period before the end of the valley electricity time period is used to predict and calculate the heat supply amount of the solar energy collector (1) in the next peak electricity time period through meteorological data, and the secondary electric heater (5) is determined to be started to heat the heat storage water tank (3) according to the calculation result; when the water supply temperature exceeds the set water supply target temperature, the return water is mixed into the water supply pipeline through the return water pipeline and the connecting pipeline to reduce the water supply temperature; a peak electricity time period heat supply operation method, in which the solar energy collector (1) is started to supply heat, the return water is mixed into the water supply pipeline through the return water pipeline and the connecting pipeline to reduce the water supply temperature when the water supply temperature exceeds the set water supply target temperature, and the primary electric heater (4) and the secondary electric heater (5) are not started to supply electric auxiliary heat because the heat storage water tank (3) has been heated before the end of the valley electricity time period; the valley electricity time period heat supply operation method comprises: At the beginning of the valley power period, the target water supply temperature T is set according to the maximum heat load of the valley power period g1 * The heating amount Q required to be provided by the primary electric heater (4) in the valley power period is calculated x1 The load rate f1 of the primary electric heater (4) in the valley power period is calculated by the value, and the calculation method is as follows: Q x1 = (T g1 * -T a1 ) · m t · c p · t g wherein, T g1 * T is the target water supply temperature during the valley period, unit ℃, T a1 T is the average ambient temperature around the water tank during the valley period, unit ℃; m t m is the total water supply mass flow rate, unit kg / s; c p c is the constant-pressure specific heat capacity of water, 4200 J / (kg·℃); t g t is the remaining time of the valley period after the heat storage and heat supply cannot meet the requirements, unit hour; P e1 P is the maximum power of the first-stage electric heating, Kw; starting the primary electric heater (4) to supply heat according to the calculation result; When the load rate f1 is greater than 1, it indicates that the primary electric heater (4) cannot meet the heating demand, at this time, the secondary electric heater (5) needs to be started, and the required heat gap Q is calculated according to the meteorological data x2 , and the load rate f2 of the secondary electric heater (5) is calculated, and the calculation method is as follows: Q x2 = (T g2 * -T a2 ) · m t · c p · t p -I t · A · η · t t wherein T g2 * is the target water supply temperature of the peak electricity period, unit ℃, which is determined according to the maximum heat load of the peak electricity period; T a2 is the average ambient temperature around the water tank of the peak electricity period, unit ℃; t p is the duration of the peak electricity, unit hour; I t is the average heat collection intensity of the solar collector, unit J / (m 2 ·s); A is the area of the solar collector, unit m 2 ; η is the efficiency of the solar collector; t t is the working duration of the solar collector, unit hour; P e2 is the maximum power of the secondary electric heating, unit Kw; t1 is the working duration of the secondary electric heater, unit hour; starting the secondary electric heater (5) to supply heat according to the calculation result.

2. The control method of a solar energy coupled electrically assisted heat supply heating system according to claim 1, characterized in that, The solar energy coupled electric auxiliary heating heat supply system further comprises: a first temperature sensor (T1) and a second temperature sensor (T2) arranged on the water supply pipeline, the first temperature sensor (T1) is located at the water inlet end of the water supply pipeline, and the second temperature sensor (T2) is located at the water outlet end of the connecting pipeline and the return water pipeline; a third temperature sensor (T3) arranged on the return water pipeline, the third temperature sensor (T3) is located at the water inlet end of the connecting pipeline and the return water pipeline; a water supply pipeline electronic expansion valve (V2) and a water supply pipeline water pump (P2) arranged on the water supply pipeline between the first temperature sensor (T1) and the connecting pipeline and the return water pipeline; a connecting pipeline electronic expansion valve (V3) and a connecting pipeline check valve (V4) arranged on the connecting pipeline; a return water pipeline gate valve (V5) and a return water pipeline check valve (V6) arranged on the return water pipeline between the water outlet end of the return water pipeline and the connecting pipeline and the return water pipeline; a return water pipeline water pump (P3) arranged on the return water pipeline at the water inlet end of the third temperature sensor (T3); a controller (6) connected with the primary electric heater (4), the secondary electric heater (5), the water supply pipeline electronic expansion valve (V2), and the connecting pipeline electronic expansion valve (V3).

3. The control method of a solar energy coupled electrically assisted heat supply heating system according to claim 2, characterized in that, When the temperature exceeds the set water supply target temperature T g * When the temperature exceeds the set water supply target temperature T The amount of return water is calculated as follows: m1 · (T - T g * ) · c p = m2 · (T g * - T b ) · c p m1 + m2 = m t wherein ml is the actual mass flow rate of the water supplied by the thermal storage water tank 3, in kg / s; T b T is the return water temperature measured by the third temperature sensor T3, in °C; T is the outlet water temperature measured by the first temperature sensor Tl; Thus, the calculation method of the return water amount is obtained: According to the calculation result, the opening degree of the electronic expansion valve (V2) of the water supply pipeline and the electronic expansion valve (V3) of the connecting pipeline is opened to control the return water amount, and T is monitored and m2 is calculated every certain time interval, and then the opening degree of the electronic expansion valve (V2) of the water supply pipeline and the electronic expansion valve (V3) of the connecting pipeline is adjusted according to the calculation result.

4. The control method of a solar energy coupled electrically assisted heat supply heating system according to claim 2, characterized in that, The solar energy coupled electric auxiliary heating heat supply system further comprises: The heat exchange coil (2) is arranged in the heat storage water tank (3) and is connected with both ends of the solar energy collector (1) through a manifold; the manifold is provided with a heat collection water pump (P1) and a heat collection gate valve (V1).

5. The control method of a solar energy coupled electrically assisted heat supply heating system according to claim 2, characterized in that, The steps of the heat supply operation method in the valley electricity period are: Step S1: First, start the control system, set the target temperature T of water supply in valley electricity period g1 * temperature control precision δT, temperature monitoring time interval Δt; Step S2: At the beginning of the valley period, heat supply is first carried out using heat storage. Every interval△t, the outlet water temperature T of the heat storage water tank (3) is monitored. If T>T g1 * , heat supply is continued by using hot water of heat storage; if T<T g1 * , the remaining time t g of the valley period is calculated, the required heating capacity Q x1 of the first electric heater (4) is calculated, and the load rate f1 of the first electric heater (4) is calculated, and then the first electric heater (4) is started according to f1 to carry out heat supply. Step S3: Collecting the climate data of the next peak electricity period at a time before the end of the valley electricity period, and calculating the supplemental heating quantity Q required by the peak electricity period x2 If the value is less than zero, the secondary electric heater (5) does not need to be started; if the value is greater than zero, the load rate f2 of the secondary electric heater (5) is calculated and the secondary electric heater (5) is started to heat. Step S4: Monitor the outlet water temperature T of the heat storage water tank (3) every interval At, and when T > T g1 * + δT, calculate the required backwater amount m2, and adjust the opening of the electronic expansion valve (V2) of the water supply line and the electronic expansion valve (V3) of the connecting line to control the backwater amount.

6. The control method of a solar energy coupled electrically assisted heat supply heating system according to claim 5, characterized in that, The steps of the heat supply operation method in the peak electricity period are: Step S1: First, start the control system, set the water supply target temperature T of the peak electricity period g2 * temperature control precision δT, temperature monitoring time interval Δt; Step S2: Start the solar collector (1) to supply heat, monitor the outlet water temperature T of the heat storage water tank (3), if T > T g2 * + δT, calculate the required return water quantity m2, and adjust the opening of the electronic expansion valve (V2) of the water supply pipeline and the electronic expansion valve (V3) of the connecting pipeline to control the return water quantity.

7. The control method of a solar energy coupled electrically assisted heat supply heating system according to claim 6, characterized in that, The time period before the valley electricity period ends is 1 hour before the valley electricity period ends.

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