Optical storage direct-flexible system and control method

Abstract

The invention discloses an optical storage direct-flexible system and a control method, the optical storage direct-flexible system comprises an optical storage direct-flexible module and an energy management module, the optical storage direct-flexible module is cooperatively connected with the energy management module, the energy management module receives data generated by the optical storage direct-flexible system, stores the data, calculates and generates an optimal control strategy, and the optimal control strategy is used for controlling the optical storage direct-flexible system. And a control instruction is issued to the direct current storage flexible module, so that the problem of control splitting of the power system and the heating and ventilation system is solved. According to the scheme, on the upper layer of a traditional building control and light storage direct flexible control system, an energy system overall optimization control platform is built, data generated by two control systems on the lower layer are received and stored, calculation is conducted, an optimization control strategy is generated, and control instructions are issued to the two control systems on the lower layer, so that the problem of control separation of an electric power system and a heating and ventilation system is solved.

Description

Technical Field

[0001] The present invention relates to the field of building new energy technology, and in particular to a photovoltaic storage direct-flexible system and a control method. Background Art

[0002] In the context of dual carbon, the power system is shifting from coal-fired power being the main source to reducing dependence on fossil fuels and increasing the proportion of renewable energy. The access of a high proportion of unstable power sources such as wind power and photovoltaics poses a challenge to the stable and safe operation of the power system. The "Photovoltaics, energy storage, direct current, flexibility" (PEDF) system consists of photovoltaic power generation, energy storage, direct current, flexibility, and is a new type of building distribution system that meets the needs of carbon neutrality goals. Flexible control is one of the key factors for the "Photovoltaics, energy storage, direct current, flexibility" system to achieve the advantages of grid friendliness and economic applicability.

[0003] The control of the photovoltaic storage direct-flexible system is simpler than that of the AC microgrid. It only needs to control the voltage and there is no frequency control. In the previous photovoltaic storage direct-flexible system control, the system adjusts the charging and discharging of the battery energy storage through the bus voltage, and uses the bus voltage to stabilize within a certain range to reduce the impact of load and power generation fluctuations on the power grid. However, due to the high risk of fire in lithium battery energy storage, there are requirements for the capacity and fire protection distance of lithium batteries in the current national standards and practices, so the capacity is often configured to be small in the field of civil buildings. On the one hand, when the photovoltaic power generation is large, the phenomenon of abandoned light will occur; when the photovoltaic power generation is small, a large amount of city electricity is required or some unimportant loads are shut down. On the other hand, small-capacity batteries can only meet the requirements of smoothing load and power generation fluctuations to a lesser extent, and it is difficult to meet the high requirements of grid demand response.

[0004] To solve the above problems, the following measures can be adopted:

[0005] (1) Increase the capacity of electrical energy storage, or increase heat and cold storage;

[0006] (2) Use bidirectional charging piles and utilize the electric vehicle’s power storage to increase system flexibility;

[0007] (3) Utilize the thermal inertia of the building and adjust the electrical load such as the air conditioning system to meet the system's flexible regulation goals.

[0008] However, the existing solar-storage direct-flexible control system has the following problems:

[0009] Economic efficiency is average: when the bus voltage is used as a signal to regulate the charge and discharge of the battery, it is difficult for the bus voltage to correspond to the peak and valley periods of the time-of-use electricity price, and the peak and valley of the building's distributed photovoltaic power generation do not completely correspond to the peak and valley of the grid demand. Therefore, it is impossible to fully enjoy the benefits generated by the peak-valley electricity price difference, nor can it generate benefits by utilizing the grid demand-side response;

[0010] The optimization scheduling mechanism for various electricity loads is unclear: there are many types of air conditioners in buildings, and common terminals include fan coil systems, radiant cooling and heating, variable air volume systems, chilled beam systems, etc. The optimization scheduling mechanism of the air-conditioning system during flexible adjustment, as well as the joint optimization scheduling mechanism of air conditioning and other loads with electrochemical energy storage are also unclear.

[0011] The control of the power system and the HVAC system are separated: The control system of the PV-storage DC-flexible system often only controls the circuit breaker and converter. For the safety of the HVAC system, the converter power and HVAC equipment of the HVAC system DC circuit cannot be directly adjusted. The control of HVAC equipment is often completed by the traditional building control system. The control of the power system and the HVAC system is independent of each other, and there is no overall optimization control platform and path.

[0012] Poor control model accuracy: In the predictive control process, the air-conditioning system is often simulated using a rough resistor-capacitor circuit model, and there is no basis for the system parameter values.

[0013] Therefore, the existing photovoltaic storage direct-flexible system has technical problems of low adjustability and economy due to the above-mentioned technical defects. It can be seen that how to improve the adjustability and economy of the photovoltaic storage direct-flexible system is a problem that needs to be solved in this field. Summary of the invention

[0014] In view of the technical problems of low adjustability and low economy of the existing photovoltaic-storage-direct-flexible system due to the above-mentioned technical defects, the present invention provides a photovoltaic-storage-direct-flexible system and a control method, which can solve the technical problems of the existing photovoltaic-storage-direct-flexible system and improve the adjustability and economy of the photovoltaic-storage-direct-flexible system.

[0015] In order to achieve the above-mentioned objectives, the present invention provides a photovoltaic, storage, direct-flexible system, including a photovoltaic, storage, direct-flexible module and an energy management module. The photovoltaic, storage, direct-flexible module is cooperatively connected with the energy management module. The energy management module receives data generated by the photovoltaic, storage, direct-flexible module, stores data, performs calculations, generates optimization control strategies, and sends control instructions to the photovoltaic, storage, direct-flexible module to solve the problem of disconnected control of the power system and the HVAC system.

[0016] Furthermore, the DC-flexible storage module includes a controller, a building automation control unit, a mains power supply component, a photovoltaic component, a DC bus, an energy storage component, a charging pile component, and a load component. The mains power supply component, the photovoltaic component, the energy storage component and the load component are arranged on the DC branch of the DC bus, and are connected to the controller with a communication component. The building automation control unit is controlled and connected to the load component.

[0017] Furthermore, the AC power supply component includes a AC power supply, an AC-DC bidirectional converter, a first current sensor and a first circuit breaker. The AC power supply is connected to the DC bus through the AC-DC bidirectional converter, and the output of the bidirectional power conversion is realized through the AC-DC bidirectional converter; the AC-DC bidirectional converter is connected to the controller through a communication component, and the controller can control the action of the AC-DC bidirectional converter. A first circuit breaker is provided between the AC-DC bidirectional converter and the DC bus and is connected to the controller. The first circuit breaker can be controlled by the controller to disconnect to protect the power circuit. The first current sensor is provided in conjunction with the AC-DC bidirectional converter and is connected to the controller through the communication component, and is used to automatically detect the current value output and input after conversion and transmit it to the controller.

[0018] Furthermore, the photovoltaic assembly includes a plurality of groups of photovoltaic units, and a second circuit breaker is provided between the plurality of groups of photovoltaic units and the DC bus, and the second circuit breaker is connected to the controller. The controller can control the second circuit breaker to disconnect to protect the power circuit. The plurality of groups of photovoltaic units respectively include photovoltaics, a first DC converter and a second current sensor. The photovoltaics are connected to the DC bus through the first DC converter to realize the DC output of the photovoltaic DC power supply to the AC bus. The first DC converter is connected to the controller through a communication component, and the controller can control the action of the first DC converter. The second current sensor is arranged in conjunction with the first DC converter and connected to the controller through the communication component, and is used to automatically detect the current value of the output input after conversion and transmit it to the controller.

[0019] Furthermore, the energy storage component includes an energy storage device, a DC-DC bidirectional converter and a third current sensor. The energy storage device is connected to the DC bus through the DC-DC bidirectional converter, and the input and output of the energy storage device conversion are realized through the DC-DC bidirectional converter. The DC-DC bidirectional converter is connected to the controller through a communication component, and the controller can control the action of the DC-DC bidirectional converter. A third circuit breaker is provided between the DC-DC bidirectional converter and the DC bus and is connected to the controller. The controller can control the third circuit breaker to disconnect to protect the power circuit. The third current sensor is provided in conjunction with the DC-DC bidirectional converter and is connected to the controller through the communication component, and is used to automatically detect the current value of the output and input after conversion and transmit it to the controller.

[0020] Furthermore, the charging pile component includes a charging pile, a fourth circuit breaker and a sixth current sensor. The charging pile is directly connected to the DC bus, and the current in the DC bus is input into the charging pile. A fourth circuit breaker is provided between the charging pile and the DC bus and is connected to the controller. The controller can control the fourth circuit breaker to disconnect to protect the power supply circuit. The sixth current sensor is provided in conjunction with the input path of the charging pile and is connected to the controller through a communication component, for automatically detecting the input current value and transmitting it to the controller.

[0021] Furthermore, the load component includes several loads with different voltage levels, each load is connected to the DC bus by setting a DC converter to realize the current output of the DC bus, the DC converter is connected to the controller through a communication component, the controller can control the action of the DC converter, a circuit breaker is provided between the DC converter and the DC bus and connected to the controller, the controller can control the circuit breaker to disconnect to protect the power circuit, the current sensor is set in conjunction with the DC converter and connected to the controller through the communication component, and is used to automatically detect the output and input current values ​​after conversion and transmit them to the controller.

[0022] Furthermore, the DC bus is equipped with a voltage sensor and is connected to the controller via a communication component, so as to automatically detect the DC bus voltage and transmit it to the controller.

[0023] Furthermore, the energy management module is connected to the photovoltaic storage direct-flexible system and senses outdoor meteorological parameters through the weather station. The energy management module includes an air-conditioning demand-side response control unit, a photovoltaic power generation power prediction unit, a power load prediction unit, an electrochemical energy storage control unit, and a mains node control unit;

[0024] The air conditioning demand side response control unit cooperates with the indoor set temperature and the outdoor data detected by the weather station to determine the indoor comfortable temperature range and the air conditioning demand side response. The photovoltaic power generation power prediction unit is connected with the photovoltaic components and the weather station to predict the solar radiation value received by the photovoltaic panel. The power load prediction unit cooperates with the weather station to predict the building power load based on the data collected by the weather station and the historical data of building operation. The electrochemical energy storage control unit cooperates with the energy storage component to control the charging and discharging power of the electrochemical energy storage cabinet. The mains node control unit cooperates with the mains power supply component to control the power taken from the power grid or sent to the power grid. The charging pile control unit cooperates with the charging pile component to control the total charging power of the electric vehicle during the demand side response time period.

[0025] In order to achieve the above object, the present invention provides a control method for a solar-storage direct-flexible system, the control method comprising the following steps:

[0026] Step 1: Collect basic data on buildings, PV-storage direct-flexible systems, electricity prices, etc.

[0027] Step 2: Use the building automation control system to tentatively set the indoor temperature;

[0028] Step 3: According to the relationship between the indoor temperature setting data of the temperature setting module and the outdoor data detected by the weather station, determine the indoor comfortable temperature range and the air conditioning demand side response model;

[0029] Step 4: Based on the solar radiation data collected by the meteorological station, a double exponential smoothing method is used to establish a photovoltaic power generation prediction model to predict the solar radiation value received by the photovoltaic panel and the photovoltaic power generation power;

[0030] Step 5: Based on the historical data of building operation and the outdoor meteorological parameters collected by the meteorological station, the power load prediction model is established by LSTM method for prediction of building power load;

[0031] Step 6: Establish an electrochemical energy storage model, a mains node model, and a charging pile model through calculation formulas, which are used to control the charging and discharging power of the electrochemical energy storage cabinet, control the power taken from or sent to the grid, and control the total charging power of the electric vehicle during the demand-side response period.

[0032] Step 7: Establish the energy balance model, economic optimal objective function and constraints of the PV-storage direct-flexible system;

[0033] Step 8: Using the optimization algorithm, with a natural day of 24 hours as a cycle, solve the simultaneous equations of the energy balance model and each module sub-model through the optimization algorithm to obtain the control parameter time series with the best system economy;

[0034] Step 9: Monitor the bus voltage and compare the bus voltage with the set range;

[0035] Step 10: If the bus voltage is within the setting range, the current value in the system control parameter time series is applied to the system control; if the bus voltage is not within the setting range, the energy storage power is changed to non-communication control with the bus voltage as the signal: when the bus voltage is lower than the bus voltage setting range, the energy storage is discharged; when the bus voltage is higher than the bus voltage setting range, the energy storage is charged;

[0036] Step 11: Feedback the state of charge of the energy storage in the current system, the input or output of the energy storage unit, the indoor air temperature, the mains input or output power, the load energy consumption and the photovoltaic power generation power to the model, and repeat steps 8 to 11 to recalculate the control parameters at a certain moment until the end of one day.

[0037] The present invention provides a storage-direct-flexible system and control method, which builds an overall optimization control platform for the energy system on the upper layer of the traditional building control and the photovoltaic storage-direct-flexible control system, receives data generated by the two control systems at the lower layer, stores data, performs calculations, generates optimization control strategies, and sends control instructions to the two control systems at the lower layer, thereby solving the problem of control separation between the power system and the HVAC system.

[0038] Secondly, based on historical data, fully evaluate the demand-side response potential and indicators of different air-conditioning systems, establish a model based on historical data, take economic efficiency as the goal, use optimization algorithms, formulate an optimization control strategy that considers polymer electrochemical energy storage and air-conditioning equipment, and consider the characteristics of different air-conditioning equipment in the control of air-conditioning equipment;

[0039] In addition, the time-of-use electricity price difference and demand-side response benefits are taken into consideration at the same time, and the flexible system control strategy is optimized with economy as the goal, which has good economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0041] Figure 1 This is the structural system diagram of the solar-storage direct-flexible system;

[0042] Figure 2 This is a flow chart of the control method of the solar-storage direct-flexible system;

[0043] Figure 3 It is the power generation prediction curve diagram;

[0044] Figure 4 It is a forecast curve diagram of building electricity load;

[0045] Figure 5 This is a curve chart of the city power, energy storage charging and discharging power, and photovoltaic power generation power predicted by the model. DETAILED DESCRIPTION

[0046] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below with reference to specific diagrams.

[0047] The photovoltaic, storage, direct-flexible system provided by the present invention includes a photovoltaic, storage, direct-flexible module and an energy management module. The photovoltaic, storage, direct-flexible module is cooperatively connected with the energy management module. The energy management module receives data generated by the photovoltaic, storage, direct-flexible module, stores data, performs calculations, generates optimized control strategies, and sends control instructions to the photovoltaic, storage, direct-flexible module, thereby solving the problem of disconnected control of the power system and the HVAC system.

[0048] Further, see Figure 1The DC-storage flexible module includes a controller 8, a building automation (BA) unit 9, a mains power supply component, a photovoltaic component, a DC bus 7, an energy storage component and a load component, wherein the mains power supply component, the photovoltaic component, the energy storage component and the load component are arranged on the DC branch of the DC bus 7, and are connected to the controller 8 with a communication component 102.

[0049] The AC power supply component includes a AC power supply 11, an AC-DC bidirectional converter 12, a first current sensor 14 and a first circuit breaker 13. The AC power supply 11 is connected to the DC bus 7 through the AC-DC bidirectional converter 12, and the AC-DC bidirectional converter 12 realizes the output of AC-DC and DC-AC bidirectional power conversion.

[0050] Meanwhile, the AC-DC bidirectional converter 12 is connected to the controller 8 via the communication component 102 , and the controller 8 can control the operation of the AC-DC bidirectional converter.

[0051] Secondly, a first circuit breaker 13 is provided between the AC-DC bidirectional converter 12 and the DC bus 7 and is connected to the controller 8. The controller 8 can control the first circuit breaker 13 to be disconnected to protect the power circuit.

[0052] The first current sensor 14 is arranged in cooperation with the AC-DC bidirectional converter 12 and connected to the controller 8 via the communication component 102 , and is used for automatically detecting the output and input current values ​​after conversion and transmitting them to the controller 8 .

[0053] The photovoltaic assembly includes several groups of photovoltaic units. A second circuit breaker 23 is provided between the several groups of photovoltaic units and the DC bus 7. The second circuit breaker 23 is connected to the controller 8. The controller 8 can control the second circuit breaker 23 to disconnect to protect the power circuit.

[0054] Several groups of photovoltaic units respectively include photovoltaic 21, a first DC converter 22 and a second current sensor 24. The photovoltaic 21 is connected to the DC bus 7 through the first DC converter 22 to realize the DC output of the photovoltaic DC power supply to the AC bus 7.

[0055] Meanwhile, the first DC converter 22 is connected to the controller 8 via the communication component 102 , and the controller 8 can control the operation of the first DC converter 22 .

[0056] The second current sensor 24 is arranged in cooperation with the first DC converter 22 and connected to the controller 8 via the communication component 102 , and is used for automatically detecting the current value of the output input after conversion and transmitting it to the controller 8 .

[0057] The energy storage component includes an energy storage device 31, a DC bidirectional converter 32, a third current sensor 34 and a third circuit breaker 33. The energy storage device 31 is connected to the DC bus 7 through the DC bidirectional converter 32 to realize the input and output of the energy storage device conversion.

[0058] At the same time, the DC-DC bidirectional converter 32 is connected to the controller 8 via the communication component 102 , and the controller 8 can control the operation of the DC-DC bidirectional converter 32 .

[0059] Secondly, a third circuit breaker 33 is provided between the DC bidirectional converter 32 and the DC bus 7 and is connected to the controller 8. The third circuit breaker 33 can be controlled by the controller 8 to be disconnected to protect the power circuit.

[0060] The third current sensor 33 is arranged in cooperation with the DC bidirectional converter 32 and connected to the controller 8 via the communication component 102 , so as to automatically detect the output and input current values ​​after conversion and transmit them to the controller 8 .

[0061] The load component includes a charging pile unit and a first load unit and a second load unit with different voltage levels.

[0062] Furthermore, the charging pile unit includes a charging pile 41 , a fourth circuit breaker 42 and a sixth current sensor 43 . The charging pile 41 is directly connected to the DC bus 7 , and the current in the DC bus 7 is input into the charging pile 41 .

[0063] A fourth circuit breaker 42 is provided between the charging pile 41 and the DC bus 7 and is connected to the controller. The fourth circuit breaker 42 can be controlled by the controller 8 to be disconnected to protect the power circuit.

[0064] The sixth current sensor 43 is arranged in cooperation with the input path of the charging pile 41 and is connected to the controller 8 via the communication component 102 , so as to automatically detect the input current value and transmit it to the controller 8 .

[0065] The first load unit is equipped with a first load 51, a fourth current sensor 54, a second DC-DC converter 52, and a fifth circuit breaker 53. The first load 51 is connected to the DC bus 7 through the second DC-DC converter 52 to realize the current output of the DC bus 7.

[0066] At the same time, the second DC-DC converter 52 is connected to the controller 8 via the communication component 102 , and the controller 8 can control the operation of the second DC-DC converter 52 .

[0067] Secondly, a fifth circuit breaker 53 is provided between the second DC converter 52 and the DC bus 7 and is connected to the controller 8. The fifth circuit breaker 53 can be controlled by the controller 8 to be disconnected to protect the power circuit.

[0068] The fourth current sensor 54 is arranged in cooperation with the second DC-DC converter 52 and connected to the controller 8 via the communication component 102 , and is used for automatically detecting the current value of the output input after conversion and transmitting it to the controller 8 .

[0069] The second load unit is equipped with a second load 61, a fifth current sensor 64, a third DC-DC converter 62, and a sixth circuit breaker 63. The second load 61 is connected to the DC bus 7 through the third DC-DC converter 62 to realize the current output of the DC bus 7.

[0070] Meanwhile, the third DC-DC converter 62 is connected to the controller 8 via the communication component 102 , and the controller 8 can control the operation of the third DC-DC converter 62 .

[0071] Secondly, a sixth circuit breaker 63 is provided between the third DC converter 62 and the DC bus 7 and is connected to the controller 8. The sixth circuit breaker 63 can be controlled by the controller 8 to be disconnected to protect the power circuit.

[0072] The fifth current sensor 64 is arranged in cooperation with the third DC-DC converter 62 and connected to the controller 8 via the communication component 102 , and is used for automatically detecting the current value of the output input after conversion and transmitting it to the controller 8 .

[0073] The DC bus 7 is equipped with a voltage sensor 71 and is connected to the controller 8 via a communication component 102 , so as to automatically detect the current value of the output input after conversion and transmit it to the controller 8 .

[0074] The energy management module 10 is the center and brain, which is connected to the solar-storage-direct-flexible controller 8 and the building automation control unit (BA) 11, and senses outdoor meteorological parameters through the weather station 101.

[0075] The energy management module 10 is connected to the photovoltaic storage direct flexible module and senses outdoor meteorological parameters through the meteorological station 101. The energy management module 10 includes an air conditioning demand side response control unit, a photovoltaic power generation power prediction unit, a power load prediction unit, an electrochemical energy storage control unit, and a mains node control unit.

[0076] The air conditioning demand side response control unit cooperates with the indoor set temperature and the outdoor data detected by the weather station to determine the indoor comfortable temperature range and the air conditioning demand side response.

[0077] The photovoltaic power generation prediction unit is connected with the photovoltaic components and the weather station to predict the solar radiation value and power generation power received by the photovoltaic panels.

[0078] The power load prediction unit cooperates with the meteorological station to predict the building power load based on the data collected by the meteorological station and the historical data of building operation.

[0079] The electrochemical energy storage control unit cooperates with the energy storage component to control the charging and discharging power of the electrochemical energy storage cabinet.

[0080] The mains node control unit cooperates with the mains power supply component to control the power taken from the grid or the power supplied to the grid.

[0081] The charging pile control unit cooperates with the charging pile assembly to control the total charging power of the electric vehicle during the demand side response time period.

[0082] The solar-storage direct-flexible system and control method based on the above scheme are provided with a control method, see Figure 2 , the control method comprises the following steps:

[0083] Step 1: Collect basic data on buildings, PV-storage direct-flexible systems, electricity prices, etc.

[0084] Step 2: Use the building automation (BA) system to try to set the indoor temperature.

[0085] As an example, the indoor set temperature (Tset,s) in cooling mode is tried to be set between 21 and 30°C, and the set temperature (Tset,w) in heating mode is tried to be set between 16 and 25°C;

[0086] Step 3: Determine the indoor comfortable temperature range and establish the air conditioning demand side response model

[0087] S3.1: Use the building automation (BA) system and building energy management system to collect information such as the set temperature Tset,i,n of each room, the actual indoor temperature Tindoor,i,n, the air conditioner operation state (State: -1 (heating), 0 (off), +1 (cooling)), the user's behavior of changing the room temperature setting (Change Behaviori,n: -1 (lower the set temperature), 0 (the set temperature remains unchanged), +1 (increase the set temperature)), the air conditioner operation power consumption (Eac,i,n) or cooling consumption (Qac,i,n), etc.;

[0088] The meteorological station is used to collect meteorological information such as outdoor air dry bulb temperature (Toutside,i), outdoor wet bulb temperature (Twetbulb,outside,i), solar radiation (Gsun,i), etc. The subscript i represents different time, and the subscript n represents different space.

[0089] S3.2 uses the actual indoor temperature Tindoor,i,n of each room, the set temperature Tset,i,n of the temperature control system, the manual temperature setting behavior Change Behavior of the room staff, and classifies them according to different space types (such as restaurants, offices, etc.) and usage time (summer, winter, transitional season). Use machine learning to perform random forest regression to find out the indoor comfortable temperature range [Tlow_end, Thigh_end] and the tolerable time τ of the boundary temperature of different spaces under different time and different outdoor meteorological conditions. low_end ,τ high_end .

[0090] S3.3 Using the room temperature setting value Tset,i+1,j, the duration after changing the temperature setting value τ change , the room temperature value before changing the temperature setting Tset,i,j, the cooling and heating value reduction or increase value ΔQ of different types of spaces i+1,j , establish the variable value ΔQ of heat and cold for different types of spaces through machine learning i+1,j and the outside air dry bulb temperature (Toutside,i), the outdoor wet bulb temperature (Twetbulb,outside,i), the total solar radiation (Isun,i), the room temperature setting value Tset,i,j, and the duration τ after changing the temperature setting value change , the relationship between the room temperature values ​​Tset,i,j before changing the temperature setting;

[0091] Step 4: Establish a photovoltaic power generation prediction model

[0092] Specifically, based on the solar radiation data collected by the meteorological station 12, a double exponential smoothing method is used to predict the solar radiation value G received by the photovoltaic panel.

[0093] The power generation model of the photovoltaic system is shown as follows:

[0094]

[0095] Among them, subscript i——values ​​at different moments;

[0096] Subscript k——different photovoltaic module values;

[0097] P ph,i ——PV power generation at time i, kW;

[0098] I sc,i ——The short-circuit current of the photovoltaic module at time i, A;

[0099] I sc,STC ——The short-circuit current of the photovoltaic module under standard working conditions, A, can be found in the product technical specification;

[0100] Voc,i ——Open-circuit voltage of the photovoltaic module at time i, V;

[0101] V oc,STC ——Open-circuit voltage of photovoltaic modules under standard operating conditions, V, can be found in the product technical specification;

[0102] G i ——Solar radiation received by the photovoltaic module at time i, W / m2;

[0103] G STC ——Solar radiation received by photovoltaic modules under standard conditions, 1000W / m2;

[0104] T i ——PV module temperature at time i, °C;

[0105] T STC ——PV panel temperature under standard operating conditions, 25°C;

[0106] k i ——The current temperature coefficient of the photovoltaic module, A / K, can be found in the product technical specification;

[0107] k v ——The voltage temperature coefficient of the photovoltaic module, V / K, can be found in the product technical specification;

[0108] Step 5: Establishment of power load forecasting model

[0109] The power load is predicted by the LSTM method based on the historical data of building operation and outdoor meteorological parameters.

[0110] P load,i =P ac,i +P light,i +P other,i ;

[0111] Among them, P ac,i To predict the air conditioning power, unit is kW;

[0112] P lighr,i To predict lighting power consumption, unit is kW;

[0113] P other,i To predict other power consumption, the unit is kW;

[0114] P ac,i The sum of the cooling and heating loads of each air-conditioned room is predicted Predict the overall efficiency COP of the air conditioning system i The calculation results are:

[0115]

[0116] Among them, Q i,j is the cooling and heating load of the j-th room at time i, kW;

[0117] COP i is the overall performance coefficient of the air-conditioning system at the i-th moment, dimensionless;

[0118] P acutal,i is the actual power load of the building, in kw, which can be calculated by the following formula;

[0119]

[0120] Step 6: Establish energy storage model, mains node model and charging pile model

[0121] S6.1 Electrochemical Energy Storage Model

[0122] The charging and discharging power model of the electrochemical energy storage cabinet can be expressed by the following formula:

[0123]

[0124] SOC i+1 ——The state of charge of the electrochemical energy storage at time i+1;

[0125] SOC i ——the state of charge of the electrochemical energy storage at time i;

[0126] SOC i ——the state of charge of the electrochemical energy storage at time i;

[0127] P b,i ——The charging and discharging power of the electrochemical energy storage at time i, kW; this value is positive when charging and negative when discharging; P b,i ≤P b,max ;

[0128] Δτ——the time interval between time i+1 and time i, h;

[0129] E b ——Rated capacity of electrochemical energy storage, kWh;

[0130] When SOC i =SOC max When P b,i ≤0;

[0131] When SOC i =SOC min When P b,i ≥0;

[0132] When SOC min >SOC i <SOC maxWhen P b,i Determined by the energy management system, and SOC min >SOC i+1 <SOC max ;

[0133] S6.2 Mains Node Model

[0134] P net,i The power taken from or sent to the grid in the i-th hour, in kW; it can be calculated by the following formula:

[0135]

[0136] in,

[0137] P down,i The power taken from the mains in the ith hour, in kW;

[0138] P up,i is the online power in the ith hour, in kW;

[0139] S6.3 Charging Pile Model

[0140] P charge,i is the total charging power of the electric vehicle, in kW; it can be calculated by the following formula:

[0141]

[0142] in,

[0143] N is the number of charging vehicles;

[0144] P average,i is the average charging power of the electric vehicle in the i-th hour, in kW;

[0145] During the demand-side response period, the electric vehicle charging power is 0.

[0146] Step 7: Establish the energy balance model, economic optimal objective function and constraints of the PV-storage direct-flexible system. This model can solve the control parameter time series in step 8.

[0147] S7.1 Constraints

[0148] Soc min ≤Soc i ≤Soc max ;

[0149] P b,i ≤P b,max ;

[0150] T low_end ≤T i,j ≤T high_end;

[0151] T low_end ≤T set,i,j ≤T high_end ;

[0152] U min ≤U main,i ≤U max ;

[0153] P net,min ≤P net ≤P net,max ;

[0154] Wherein, Umain is the DC bus voltage, in V;

[0155] U min The minimum voltage for safe and stable operation of the DC bus, in V;

[0156] U max The maximum voltage for safe and stable operation of the DC bus, in V;

[0157] P net,min The maximum value of power delivered by the DC bus to the grid, in kW;

[0158] P net,max It is the maximum value of power that the DC bus can draw from the grid, in kW.

[0159] The energy balance equation of the S7.2 system is as follows:

[0160] P ph,i +P net,i =P b,i +P actual,i ;

[0161] in,

[0162] P b,i It is the charging and discharging power of the energy storage battery, which is positive when charging and negative when discharging, and the unit is kW;

[0163] S7.3 Objective function

[0164] The time-of-use electricity price of the system using part of the city electricity is ce i , then the electricity cost of the system for one day is CE, which can be calculated by the following formula:

[0165]

[0166] Photovoltaic grid-connected electricity price is cpv i , then the CPV of one-day on-grid electricity revenue can be calculated by the following formula:

[0167]

[0168] The day-ahead or daytime demand-side response subsidy price is cds. The reward CD obtained by the system using demand-side response measures can be calculated by the following formula:

[0169]

[0170] Among them, m is the corresponding start time of the demand side, and n is the end time of the demand side response.

[0171] Among them, CE, CPV, CD, CC and CCD are in yuan, ce i ,cpv i , cd, cc and ccd are in yuan / kWh;

[0172] The objective function is to take the system operation economy as the objective function, that is:

[0173] J = max{CPV+CD-CE};

[0174] Step 8: Using the optimization algorithm, with a natural day of 24 hours as a cycle, solve the simultaneous equations of the energy balance model and each module sub-model through the optimization algorithm to obtain the control parameter time series with the best system economy, which includes the time series of different room temperature setting values ​​T set,i,j 、Energy storage charging and discharging power time series P b,i .

[0175] Step 9: Monitor the bus voltage and compare the bus voltage with the set range;

[0176] Step 10: If the bus voltage is within the setting range, the current value in the system control parameter time series is applied to the system control; if the bus voltage is not within the setting range, the energy storage power is changed to non-communication control with the bus voltage as the signal: when the bus voltage is lower than the bus voltage setting range, the energy storage is discharged; when the bus voltage is higher than the bus voltage setting range, the energy storage is charged.

[0177] Step 11: Feedback the state of charge of the energy storage in the current system, the input or output of the energy storage unit, the indoor air temperature, the mains input or output power, the load energy consumption and the photovoltaic power generation power to the model, and repeat steps 8 to 11 to recalculate the control parameters at a certain moment until the end of one day.

[0178] Based on the above-mentioned scheme, the solar-storage direct-flexible system and control method are described below with examples of their working process in specific applications. It should be noted that the working process here is only an example.

[0179] The following case further illustrates the specific technical implementation plan as follows:

[0180] S1. An office building is about 4000m2, with a 600m2 monocrystalline silicon photovoltaic module array on the roof, and a photovoltaic installed capacity of about 180kWp. The office building's air conditioning cold and hot sources are two small ground-source heat pumps. Most of the air conditioning systems are fan coils combined with fresh air systems, and a small number are radiant air conditioning terminals combined with fresh air systems. Under the design conditions, the air conditioning system power load (Pac) is about 180kW, the lighting power load (Plight) is about 25kW, and the other power loads (Pother) are about 95kW. The total power load (excluding charging piles) is about 300kW. The office building is equipped with a rated capacity (Eb) of 180kWh electrochemical energy storage, the discharge depth is set to 95%, and the minimum state of charge (SOCmin) is set to 5%. 25 one-way charging piles are set, and the charging power of each charging pile is about 30-60kW according to the power consumption. The charging pile utilization rate is 75%, and the average daily charging of each charging pile is about 40kWh, and the daily charging volume is about 750kWh. The demand side response time is from 12:00 to 15:00.

[0181] The electricity price information for the office building is shown in Figure 1. The photovoltaic grid-connected electricity price is 0.4 yuan / kWh. The demand-side response electricity price on the day before is 2.4 yuan / kWh.

[0182] Table 1 Electricity price information table

[0183] Time period 0:00～7:00 8:00～10:00 11:00～12:00 13:00～14:00 15:00～18:00 17:00～23:00 Electricity price (yuan / kWh) 0.285 1.00 1.36 1.00 1.36 1.00

[0184] S2. Resetting the indoor temperature of the building through the building automation system;

[0185] S3. The indoor comfortable temperature range of fan coil air conditioning in summer is [23℃, 29℃], and the upper and lower boundary temperature tolerance time is 40min and 35min respectively. The indoor comfortable temperature range of radiant air-conditioned room is [24℃, 30℃], and the upper and lower boundary temperature tolerance time is 45min and 30min respectively. Using a large amount of data, the cooling and heating reduction or increase value ΔQ of fan coil room and radiant air-conditioned room is obtained through machine learning. i+1,j The relationship between outdoor air dry-bulb temperature, outdoor air wet-bulb temperature, solar radiation intensity, indoor air dry-bulb temperature, and indoor air temperature setting value.

[0186] S4. Using the historical meteorological data of the weather station, the photovoltaic power generation curve within one natural day is predicted by double exponential smoothing. Figure 3 The photovoltaic power generation time is from 6 to 19 o'clock, and the maximum power is reached at 12 noon, with a maximum power of about 140kW. The total photovoltaic power generation on that day is about 1480kWh.

[0187] S5. Use the energy management system and weather station historical data to predict building power load data such as Figure 4 shown.

[0188] S6. Establish energy storage model and mains node model;

[0189] The charging and discharging power model of the electrochemical energy storage cabinet can be expressed by the following formula:

[0190]

[0191] SOC i+1 ——The state of charge of the electrochemical energy storage at time i+1;

[0192] SOC i ——the state of charge of the electrochemical energy storage at time i;

[0193] SOC i ——the state of charge of the electrochemical energy storage at time i;

[0194] P b,i ——The charging and discharging power of the electrochemical energy storage at time i, kW; this value is positive when charging and negative when discharging; P b,i ≤P b,max ;

[0195] Δτ——the time interval between time i+1 and time i, h;

[0196] E b ——Rated capacity of electrochemical energy storage, kWh;

[0197] When SOC i =SOC max When P b,i ≤0;

[0198] When SOC i =SOC min When P b,i ≥0;

[0199] When SOC min >SOC i <SOC max When P b,i Determined by the energy management system, and SOC min >SOC i+1 <SOC max ;

[0200] S6.2 Mains Node Model

[0201] P net,i The power taken from or sent to the grid in the i-th hour, in kW; it can be calculated by the following formula:

[0202]

[0203] in,

[0204] P down,i The power taken from the mains in the ith hour, in kW;

[0205] P up,i is the online power in the ith hour, in kW;

[0206] S6.3 Charging Pile Model

[0207] P charge,i is the total charging power of the electric vehicle, in kW; it can be calculated by the following formula:

[0208]

[0209] in,

[0210] N is the number of charging vehicles;

[0211] P average,i is the average charging power of the electric vehicle in the i-th hour, in kW;

[0212] During the demand-side response period, the electric vehicle charging power is 0.

[0213] 7. Establish the energy balance model, economic optimal objective function and constraint conditions of the solar-storage direct-flexible system

[0214] S7.1 Constraints

[0215] 5%≤Soc i ≤95%;

[0216] P b,i ≤90kW;

[0217] 23℃≤T i,j ≤29℃(fan coil air-conditioning room)

[0218] 24℃≤T i,j ≤30℃(Radiant air-conditioned room)

[0219] 23℃≤T set,i,j ≤29℃(fan coil air-conditioning room)

[0220] 24℃≤T set,i,j ≤30℃(Radiant air-conditioned room)

[0221] 700V≤U main,i ≤770V;

[0222] -160kW≤P net ≤1500kW;

[0223] The energy balance equation of the system is as follows:

[0224] P ph,i +P net,i =P b,i +P actual,i ;

[0225] in,

[0226] P b,i It is the charging and discharging power of the energy storage battery, which is positive when charging and negative when discharging, and the unit is kW;

[0227] S7.2 Objective function

[0228] The time-of-use electricity price of the system using part of the city electricity is ce i , then the electricity cost of the system for one day is CE, which can be calculated by the following formula:

[0229]

[0230] Photovoltaic grid-connected electricity price is cpv i , then the CPV of one-day on-grid electricity revenue can be calculated by the following formula:

[0231]

[0232] The day-ahead or daytime demand-side response subsidy price is cds. The reward CD obtained by the system using demand-side response measures can be calculated by the following formula:

[0233]

[0234] Among them, m is the corresponding start time of the demand side, and n is the end time of the demand side response.

[0235] Among them, CE, CPV, CD, CC and CCD are in yuan, ce i ,cpv i , cd, cc and ccd are in yuan / kWh;

[0236] The objective function is to take the system operation economy as the objective function, that is:

[0237] J = max{CPV+CD-CE};

[0238] The predictive control result obtained at a certain moment in S8-S11 is as follows Figure 5 In demand response, the fan coil air-conditioning room set temperature is 27.5℃, and the radiant air-conditioning room set temperature is 28.5℃.

[0239] After the implementation of this control method, the power peak can be reduced by about 40%, which saves 25% of the operating cost compared with the conventional peak shaving and valley filling system, and saves 608 yuan of operating cost.

[0240] The photovoltaic storage direct and flexible system and control system composed of the above-mentioned solution connects the photovoltaic storage direct and flexible control and the building automation control through the energy management system, takes the demand-side response benefits into account in the objective function of the model predictive control, and realizes control with better economic benefits.

[0241] Secondly, through historical data and user behavior statistics, the demand-side response and power load model are obtained, and the control accuracy is higher than that of the traditional resistor-capacitor circuit model.

[0242] In addition, through model predictive control, the energy storage charging and discharging power, charging pile charging and discharging power, air conditioning set temperature, etc. are continuously optimized to improve the economic efficiency of system operation. At the same time, the bus voltage is monitored to make the system operation safer.

[0243] Finally, this solution sets up an energy management system on the platform of the traditional PV-storage direct-flexible system control and building automation system, formulates control strategies in the energy management system, stores control programs and related data, links the two control systems through the energy management system, and issues control instructions to the PV-storage direct-flexible control system and the building automation control system. Most of the traditional control systems can be used, and only modules need to be added to the energy management system, which is simple to implement.

[0244] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A solar storage direct-flexible system, characterized in that: It includes a photovoltaic, storage, direct and flexible module and an energy management module. The photovoltaic, storage, direct and flexible module is connected with the energy management module. The energy management module receives the data generated by the photovoltaic, storage, direct and flexible module, stores the data, performs calculations, generates optimized control strategies, and sends control instructions to the photovoltaic, storage, direct and flexible module to solve the problem of disconnected control of the power system and the HVAC system.

2. The solar-storage direct-flexible system according to claim 1, characterized in that: The DC-flexible storage module includes a controller, a building automatic control unit, a mains power supply component, a photovoltaic component, a DC bus, an energy storage component, a charging pile component, and a load component. The mains power supply component, the photovoltaic component, the energy storage component and the load component are arranged on the DC branch of the DC bus, and are connected to the controller with a communication component. The building automatic control unit is controlled and connected to the load component.

3. The solar-storage direct-flexible system according to claim 1, characterized in that: The AC power supply component includes a AC power supply, an AC-DC bidirectional converter, a first current sensor and a first circuit breaker. The AC power supply is connected to the DC bus through the AC-DC bidirectional converter, and the output of the bidirectional power conversion is realized through the AC-DC bidirectional converter; the AC-DC bidirectional converter is connected to the controller through the communication component, and the controller can control the action of the AC-DC bidirectional converter. A first circuit breaker is provided between the AC-DC bidirectional converter and the DC bus and is connected to the controller. The first circuit breaker can be controlled by the controller to disconnect to protect the power circuit. The first current sensor is provided in conjunction with the AC-DC bidirectional converter and is connected to the controller through the communication component, and is used to automatically detect the current value of the output and input after conversion and transmit it to the controller.

4. The solar-storage direct-flexible system according to claim 1, characterized in that: The photovoltaic assembly includes a plurality of groups of photovoltaic units, and a second circuit breaker is provided between the plurality of groups of photovoltaic units and the DC bus. The second circuit breaker is connected to the controller, and the controller can control the second circuit breaker to disconnect to protect the power circuit. The plurality of groups of photovoltaic units respectively include photovoltaics, a first DC converter and a second current sensor. The photovoltaics are connected to the DC bus through the first DC converter to realize the DC output of the photovoltaic DC power supply to the AC bus. The first DC converter is connected to the controller through a communication component, and the controller can control the action of the first DC converter. The second current sensor is arranged in conjunction with the first DC converter and is connected to the controller through the communication component, and is used to automatically detect the current value of the output input after conversion and transmit it to the controller.

5. The solar-storage direct-flexible system according to claim 1, characterized in that: The energy storage component includes an energy storage device, a DC bidirectional converter and a third current sensor. The energy storage device is connected to the DC bus through the DC bidirectional converter, and the input and output of the energy storage device conversion are realized through the DC bidirectional converter. The DC bidirectional converter is connected to the controller through a communication component, and the controller can control the action of the DC bidirectional converter. A third circuit breaker is provided between the DC bidirectional converter and the DC bus and is connected to the controller. The third circuit breaker can be controlled by the controller to disconnect to protect the power circuit. The third current sensor is provided in conjunction with the DC bidirectional converter and is connected to the controller through the communication component, and is used to automatically detect the current value of the input and output after conversion and transmit it to the controller.

6. The solar-storage direct-flexible system according to claim 1, characterized in that: The charging pile component includes a charging pile, a fourth circuit breaker and a sixth current sensor. The charging pile is directly connected to the DC bus, and the current in the DC bus is input into the charging pile. A fourth circuit breaker is provided between the charging pile and the DC bus and is connected to a controller. The fourth circuit breaker can be controlled by the controller to disconnect to protect the power circuit. The sixth current sensor is provided in conjunction with the input path of the charging pile and is connected to the controller through a communication component, so as to automatically detect the input current value and transmit it to the controller.

7. The solar-storage direct-flexible system according to claim 1, characterized in that: The load component includes several loads with different voltage levels. Each load is connected to the DC bus by setting a DC converter to realize the current output of the DC bus. The DC converter is connected to the controller through a communication component. The controller can control the action of the DC converter. A circuit breaker is provided between the DC converter and the DC bus and is connected to the controller. The controller can control the circuit breaker to disconnect to protect the power circuit. The current sensor is set in conjunction with the DC converter and connected to the controller through the communication component. It is used to automatically detect the current value of the output input after conversion and transmit it to the controller.

8. The solar-storage direct-flexible system according to claim 1, characterized in that: The DC bus is equipped with a voltage sensor and connected to the controller through a communication component, so as to automatically detect the DC bus voltage and transmit it to the controller.

9. The solar-storage direct-flexible system according to claim 1, characterized in that: The energy management module is connected to the photovoltaic storage direct-flexible system and senses outdoor meteorological parameters through the weather station. The energy management module includes an air-conditioning demand-side response control unit, a photovoltaic power generation power prediction unit, a power load prediction unit, an electrochemical energy storage control unit, and a mains node control unit; The air conditioning demand side response control unit cooperates with the indoor set temperature and the outdoor data detected by the weather station to determine the indoor comfortable temperature range and the air conditioning demand side response. The photovoltaic power generation power prediction unit is connected with the photovoltaic components and the weather station to predict the solar radiation value received by the photovoltaic panel. The power load prediction unit cooperates with the weather station to predict the building power load based on the data collected by the weather station and the historical data of building operation. The electrochemical energy storage control unit cooperates with the energy storage component to control the charging and discharging power of the electrochemical energy storage cabinet. The mains node control unit cooperates with the mains power supply component to control the power taken from the power grid or sent to the power grid. The charging pile control unit cooperates with the charging pile component to control the total charging power of the electric vehicle during the demand side response time period.

10. A control method for a solar-storage direct-flexible system, characterized in that: The control method comprises the following steps: Step 1: Collect basic data on buildings, PV-storage direct-flexible systems, electricity prices, etc. Step 2: Use the building automation control system to tentatively set the indoor temperature; Step 3: According to the relationship between the indoor temperature setting data of the temperature setting module and the outdoor data detected by the weather station, determine the indoor comfortable temperature range and the air conditioning demand side response model; Step 4: Based on the solar radiation data collected by the meteorological station, a double exponential smoothing method is used to establish a photovoltaic power generation prediction model to predict the solar radiation value received by the photovoltaic panel and the photovoltaic power generation power; Step 5: Based on the historical data of building operation and the outdoor meteorological parameters collected by the meteorological station, the power load prediction model is established by LSTM method for prediction of building power load; Step 6: Establish an electrochemical energy storage model, a mains node model, and a charging pile model through calculation formulas, which are used to control the charging and discharging power of the electrochemical energy storage cabinet, control the power taken from or sent to the grid, and control the total charging power of the electric vehicle during the demand-side response period. Step 7: Establish the energy balance model, economic optimal objective function and constraints of the PV-storage direct-flexible system; Step 8: Using the optimization algorithm, with a natural day of 24 hours as a cycle, solve the simultaneous equations of the energy balance model and each module sub-model through the optimization algorithm to obtain the control parameter time series with the best system economy; Step 9: Monitor the bus voltage and compare the bus voltage with the set range; Step 10: If the bus voltage is within the setting range, the current value in the system control parameter time series is applied to the system control; if the bus voltage is not within the setting range, the energy storage power is changed to non-communication control with the bus voltage as the signal: when the bus voltage is lower than the bus voltage setting range, the energy storage is discharged; when the bus voltage is higher than the bus voltage setting range, the energy storage is charged; Step 11: Feedback the state of charge of the energy storage in the current system, the input or output of the energy storage unit, the indoor air temperature, the mains input or output power, the load energy consumption and the photovoltaic power generation power to the model, and repeat steps 8 to 11 to recalculate the control parameters at a certain moment until the end of one day.

Images