Photovoltaic power generation cooling system and method

Abstract

The invention discloses a photovoltaic power generation cooling system and method, and relates to the technical field of photovoltaic panel cooling of a photovoltaic power generation system.The system comprises a temperature collecting device, the temperature collecting device collects and processes the temperature of the surface of a photovoltaic panel and then transmits the temperature to an upper computer, and a semiconductor heat dissipation device is tightly attached to the back face of the photovoltaic panel and absorbs heat to cool the photovoltaic panel; the upper computer generates a control signal according to the set temperature and the collected temperature deviation value; the PWM generator regulates and controls the duty ratio of the PWM signal according to the control signal of the upper computer, regulates and controls the cooling power of the semiconductor heat dissipation device, and cools the photovoltaic panel. According to the cooling system based on the semiconductor heat dissipation cooling photovoltaic panel, the incremental PID algorithm is designed, feedback adjustment of the cooling system is achieved in a parameter adjusting mode, the temperature of the surface of the photovoltaic panel tends to the set temperature, and the power generation efficiency of the photovoltaic power generation system is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic panel cooling in a photovoltaic power generation system, and in particular to a photovoltaic power generation cooling system and method. Background Art

[0002] Photovoltaic power generation systems generate a lot of heat during operation, and this heat accumulates on the surface of photovoltaic panels, which will reduce photovoltaic efficiency and shorten the operating life. Under standard test conditions, the theoretical maximum conversion efficiency of single-junction photovoltaic cells is about 30%, and the theoretical maximum conversion efficiency of multi-junction photovoltaic cells is about 60%. More than half of the solar energy cannot be converted into electrical energy, and the unconverted solar energy will be converted into heat and accumulated in the photovoltaic panel cells, which will have an adverse effect on the performance and life of the photovoltaic panel cells. Excessive temperature will reduce the operating life of photovoltaic panels by about 30%, so the operating temperature is one of the key factors to be considered when designing photovoltaic power generation systems.

[0003] Existing natural air cooling cannot achieve temperature control, while the operating life of forced air cooling and liquid cooling devices is relatively low.

[0004] The patent document with application number 202120755392.8 discloses a photovoltaic panel cooling system and photovoltaic panel, which belongs to the field of solar energy technology. It utilizes the heat dissipation characteristics of super-hydrophilic materials and the capillary water transport effect to realize the spraying of super-hydrophilic materials on the back of photovoltaic panels, and uses photovoltaic panels as the main heat source to accelerate the evaporation of water to achieve the cooling of photovoltaic panels. It includes a mesh pipe and a hydrophilic coating. The hydrophilic coating is arranged on the back of the solar photovoltaic panel, and the mesh pipe is arranged on the surface of the hydrophilic coating. The end of the mesh pipe is connected to the outside world, and the mesh pipe is in contact with the hydrophilic coating; the mesh pipe is connected to the water tank through a U-shaped pipe; the water tank is also connected to the rainwater collector. However, its solution also has the problem that the cooling temperature control cannot be achieved. Summary of the invention

[0005] In view of the above-mentioned problems, the purpose of the present invention is to provide a photovoltaic power generation cooling system and method, which can realize autonomous feedback adjustment and cooling according to the temperature monitored by the photovoltaic panels, thereby improving the power generation efficiency of the photovoltaic power generation system.

[0006] The purpose of the present invention can be achieved through the following technical solution: A photovoltaic power generation cooling system, comprising:

[0007] The temperature acquisition device collects and processes the temperature of the photovoltaic panel surface and transmits it to the host computer.

[0008] The semiconductor heat dissipation device is closely attached to the back of the photovoltaic panel to absorb heat and cool the photovoltaic panel;

[0009] The upper computer generates a control signal according to the set temperature and the collected temperature deviation value;

[0010] The PWM generator adjusts the duty cycle of the PWM signal according to the control signal of the host computer, adjusts the cooling power of the semiconductor heat sink, and cools the photovoltaic panel.

[0011] As a further solution of the present invention, the PWM signal generator cooperates with MOSFET to regulate the semiconductor heat dissipation device to achieve a cooling power control function of the semiconductor heat dissipation device.

[0012] As a further solution of the present invention, the semiconductor heat dissipation device is a Peltier element, wherein:

[0013] The cold end of the Peltier element is closely attached to the back of the photovoltaic panel, and the hot end of the Peltier element is equipped with a heat dissipation fin for heat dissipation.

[0014] As a further solution of the present invention, the Peltier element is adhered to the back of the photovoltaic panel through a copper sheet.

[0015] As a further solution of the present invention, thermal conductive silicone grease is coated between the copper sheet and the back of the photovoltaic panel, and thermal conductive silicone grease is coated between the cold end of the Peltier element and the copper sheet.

[0016] A photovoltaic power generation cooling method applied to the above cooling system, the method comprising:

[0017] S1. Install a semiconductor heat dissipation device close to the back of the photovoltaic panel and install a temperature collection device on the surface of the photovoltaic panel;

[0018] S2, collect the surface temperature of the photovoltaic panel and transmit it to the host computer;

[0019] S3, the host computer generates a control signal according to the set temperature and the collected temperature deviation value;

[0020] S4, using the control signal to adjust the duty cycle of the PWM signal of the PWM generator;

[0021] S5. Use the duty cycle of the PWM signal to control the power of the semiconductor heat dissipation device to cool the photovoltaic panel.

[0022] As a further solution of the present invention, the step of adjusting the duty cycle of the PWM signal of the PWM generator includes:

[0023] S41, setting the control signal to 0;

[0024] S42, collecting temperature signals after a sampling period;

[0025] S43, using the PID algorithm to calculate the control signal increment according to the deviation between the collected temperature and the set temperature, and adding it to the total control signal;

[0026] S44, sending the total amount of the control signal to the PWM signal generator to convert it into a duty cycle of the corresponding PWM signal;

[0027] S45. Repeat S42-S44 until the cooling control is completed.

[0028] As a further solution of the present invention, the PID algorithm is as follows:

[0029] Δu(k)=K p [e(k)-e(k-1)]+K i e(k)+K d [e(k)-2e(k-1)+e(k-2)]

[0030] Among them, Δu(k) is the output signal increment, e(k) is the deviation between the collected temperature and the set temperature, k is the discrete kth sampling point, K i is the integral gain, K p is the proportional gain, K d is the proportional gain.

[0031] As a further solution of the present invention, the host computer controls the cooling system through a human-computer interaction interface, including: PWM signal duty cycle working parameter adjustment, display of photovoltaic panel surface temperature and working voltage display.

[0032] Beneficial effects of the present invention:

[0033] 1. The present invention proposes a semiconductor heat dissipation cooling system based on Peltier elements, designs an incremental PID algorithm to achieve feedback regulation of the cooling system by adjusting parameters, so that the temperature of the photovoltaic panel surface tends to the set temperature, thereby improving the power generation efficiency of the photovoltaic power generation system.

[0034] 2. The present invention designs a human-computer interaction interface to realize dynamic and intuitive control of system status and data storage, and can control the temperature fluctuation range within 1°C, which is of great significance to improving the power generation efficiency of photovoltaic power generation systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a structural schematic diagram of the photovoltaic power generation cooling system of the present invention;

[0036] Figure 2 It is a schematic diagram of the installation of the Peltier element of the present invention;

[0037] Figure 3 It is a schematic diagram of the PID algorithm flow of the present invention;

[0038] Figure 4 This is a functional schematic diagram of the human-computer interaction interface of the present invention;

[0039] Figure 5This is a comparison chart of the actual measurement of the method of the present invention. DETAILED DESCRIPTION

[0040] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar symbols throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0041] like Figure 1 As shown, the present invention discloses a photovoltaic power generation cooling system and method, including: a temperature acquisition device, a semiconductor heat dissipation device, a host computer, a PWM generator and other components.

[0042] The temperature acquisition device is installed on the surface of the photovoltaic panel to collect the temperature of the photovoltaic panel surface and transmit it to the host computer after real-time processing.

[0043] The temperature acquisition device may include a K-type thermocouple, a temperature transmitter, an analog measurement module (A / D) and a data converter. The temperature data collected by the cooling system may have voltage and current that are too large to be used directly. A temperature transmitter can be used to uniformly convert the signal into a 0-5V voltage signal, which is then output to the analog measurement module (A / D) for analog-to-digital conversion and then sent to the host computer using a data converter.

[0044] The semiconductor heat dissipation device adopts a Peltier element, which can be a TEC1 type with a rated voltage of 12V. In order to enhance the cooling and heat dissipation effect of the semiconductor element, a heat dissipation fin is installed at the hot end of the Peltier element for heat dissipation. The heat dissipation fin mainly includes an upper aluminum plate, a lower heat dissipation copper tube bifurcated structure, two layers of heat dissipation fins connected by copper tubes, and a heat dissipation fan located in the fins.

[0045] Under the action of an external electric field, the Peltier element can continuously transfer the temperature from the cold end to the hot end, thereby reducing the temperature of the cold end. The cold end of the Peltier element is placed close to the back of the photovoltaic panel to achieve cold end heat absorption, and heat dissipation fins are added to the hot end to enhance heat dissipation.

[0046] The cooling system adjusts the voltage by collecting temperature feedback to control the cooling power of the Peltier element; the PWM controller is used to regulate the voltage of the Peltier element, and the PWM controller cooperates with MOSFET to perform signal conversion to realize the cooling system control function.

[0047] The temperature changes on the front and back sides of the photovoltaic panel are almost the same during operation. If the Peltier element is arranged on the front side of the photovoltaic panel, it will not only affect the output power of the photovoltaic panel, but also block the light to a certain extent, thereby reducing the power generation efficiency. Therefore, the Peltier element is chosen to be arranged on the back side of the photovoltaic panel.

[0048] Since the photovoltaic panel area is too large and the Peltier element heat dissipation module is small, direct use cannot achieve a good cooling effect, such as Figure 2 As shown, a copper sheet can be stacked on top of the Peltier element to enhance the cooling effect, wherein the copper sheet can be 0.5 mm thick and have a length and width that can cover the core heating area on the back of the photovoltaic panel.

[0049] In order to further enhance the heat dissipation between the copper sheet and the Peltier element, thermal conductive silicone grease may be applied between the copper sheet and the back of the photovoltaic panel, and between the copper sheet and the Peltier element to enhance the heat exchange.

[0050] The host computer generates a control signal according to the set temperature and the collected temperature deviation value. The PWM generator adjusts the PWM signal duty cycle based on the control signal, adjusts the cooling power of the semiconductor heat sink, and cools the photovoltaic panel.

[0051] Specifically, the cooling system can use the PWM signal to control the on and off of the MOSFET, thereby controlling the cooling power of the Peltier element. The PWM signal selection frequency can be set to 25Hz, and the PID algorithm is designed to achieve power regulation by adjusting the PWM signal duty cycle.

[0052] Utilizing the above cooling system, the present invention also discloses a photovoltaic power generation cooling method, comprising:

[0053] S1. Install a semiconductor heat dissipation device close to the back of the photovoltaic panel and install a temperature collection device on the surface of the photovoltaic panel;

[0054] S2, collect the surface temperature of the photovoltaic panel and transmit it to the host computer;

[0055] S3, the host computer generates a control signal according to the set temperature and the collected temperature deviation value;

[0056] S4, using the control signal to adjust the duty cycle of the PWM signal of the PWM generator;

[0057] S5. Use the duty cycle of the PWM signal to control the power of the semiconductor heat dissipation device to cool the photovoltaic panel.

[0058] The cooling system uses a digital PWM controller, such as Figure 3 As shown, the duty cycle of the PWM signal is adjusted, and the process includes:

[0059] To calculate the increment of the PWM output signal, it is necessary to obtain the temperature data at the current time point and the previous two time points. When the cooling system starts, the control signal is set to 0; the temperature signal is collected at the sampling period frequency; based on the deviation value between the collected temperature and the set temperature, the control signal increment is calculated using the PID algorithm and added to the total PWM control signal. The total PWM control signal is sent to the PWM signal generator and converted into the corresponding PWM signal duty cycle. The PWM signal duty cycle is used to control the on and off of the MOSFET, thereby controlling the cooling power of the Peltier element, and then the above process is repeated until the cooling control is completed.

[0060] The PID algorithm is used to calculate the increment of the PWM output signal. The PWM output signal increment is adjusted by adjusting the integral gain, proportional gain and proportional gain. The formula is:

[0061] Δu(k)=K p [e(k)-e(k-1)]+K i e(k)+K d [e(k)-2e(k-1)+e(k-2)]

[0062] Among them, Δu(k) is the output signal increment, e(k) is the deviation between the collected temperature and the set temperature, k is the discrete kth sampling point, K i is the integral gain, K p is the proportional gain, K d is the proportional gain.

[0063] The host computer can control the cooling system through the human-computer interaction interface, including the adjustment of the PWM signal duty cycle working parameters (K i is the integral gain, K p is the proportional gain, K d is the proportional gain), and the photovoltaic panel surface temperature and operating voltage graphs can also be displayed.

[0064] like Figure 4 As shown in the figure, the recorded image of the photovoltaic panel surface temperature and the working voltage of the photovoltaic panel can be seen at the top of the human-computer interaction interface. The target temperature and signal adjustment parameters of the current cooling system can be set at the bottom of the human-computer interaction interface. The buttons for starting and pausing recording are at the bottom right, which can control the operation of the entire cooling system. The current operating status of the cooling system can be displayed at the bottom of the interface, namely the time, total operating time, PWM signal duty cycle, surface temperature and power supply voltage, etc.

[0065] During the operation of the cooling system, the PWM signal parameters can be adjusted dynamically, and the cooling system will automatically operate after responding.

[0066] The actual test results are as follows: The test was conducted outdoors at an ambient temperature of 18°C. Two identical photovoltaic panels were selected, one with a cooling system and the other without a cooling system. The temperature changes of the two photovoltaic panels after working for a period of time are as follows: Figure 5 As shown, Figure 5 The upper middle curve is the temperature change curve of the photovoltaic panel without the cooling system installed, and the lower curve is the temperature change curve of the photovoltaic panel after the cooling system is installed. It can be seen that after the cooling system is installed, the incremental PID algorithm can be used to well control the temperature of the photovoltaic panel surface.

[0067] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

[0068] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

Claims

1. A photovoltaic power generation cooling system, characterized in that: include: The temperature acquisition device collects and processes the temperature of the photovoltaic panel surface and transmits it to the host computer. The semiconductor heat dissipation device is closely attached to the back of the photovoltaic panel to absorb heat and cool the photovoltaic panel; The upper computer generates a control signal according to the set temperature and the collected temperature deviation value; The PWM generator adjusts the duty cycle of the PWM signal according to the control signal of the host computer, adjusts the cooling power of the semiconductor heat sink, and cools the photovoltaic panel.

2. The photovoltaic power generation cooling system according to claim 1, characterized in that: The PWM signal generator cooperates with MOSFET to regulate the semiconductor heat sink to achieve the cooling power control function of the semiconductor heat sink.

3. The photovoltaic power generation cooling system according to claim 1, characterized in that: The semiconductor heat dissipation device is a Peltier element, wherein: The cold end of the Peltier element is closely attached to the back of the photovoltaic panel, and the hot end of the Peltier element is equipped with a heat dissipation fin for heat dissipation.

4. The photovoltaic power generation cooling system according to claim 3, characterized in that: The Peltier element is adhered to the back of the photovoltaic panel through a copper sheet.

5. The photovoltaic power generation cooling system according to claim 4, characterized in that: Thermal conductive silicone grease is coated between the copper sheet and the back of the photovoltaic panel, and thermal conductive silicone grease is coated between the cold end of the Peltier element and the copper sheet.

6. A photovoltaic power generation cooling method applied to the cooling system according to any one of claims 1 to 5, characterized in that: The method comprises: S1. Install a semiconductor heat dissipation device close to the back of the photovoltaic panel and install a temperature collection device on the surface of the photovoltaic panel; S2, collect the surface temperature of the photovoltaic panel and transmit it to the host computer; S3, the host computer generates a control signal according to the set temperature and the collected temperature deviation value; S4, using the control signal to adjust the duty cycle of the PWM signal of the PWM generator; S5. Use the duty cycle of the PWM signal to control the power of the semiconductor heat dissipation device to cool the photovoltaic panel.

7. The photovoltaic power generation cooling method according to claim 6, characterized in that: The step of adjusting the duty cycle of the PWM generator PWM signal comprises: S41, setting the control signal to 0; S42, collecting temperature signals after a sampling period; S43, using the PID algorithm to calculate the control signal increment according to the deviation between the collected temperature and the set temperature, and adding it to the total control signal; S44, sending the total amount of the control signal to the PWM signal generator to convert it into a duty cycle of the corresponding PWM signal; S45. Repeat S42-S44 until the cooling control is completed.

8. The photovoltaic power generation cooling method according to claim 7, characterized in that: The PID algorithm is formulated as follows: Δu(k)=K p [e(k)-e(k-1)]+K i e(k)+K d [e(k)-2e(k-1)+e(k-2)] Among them, Δu(k) is the output signal increment, e(k) is the deviation between the collected temperature and the set temperature, k is the discrete kth sampling point, K i is the integral gain, K p is the proportional gain, K d is the proportional gain.

9. The photovoltaic power generation cooling method according to claim 6, characterized in that: The host computer controls the cooling system through a human-computer interaction interface, including: PWM signal duty cycle working parameter adjustment, display of photovoltaic panel surface temperature and working voltage display.

Images