Photovoltaic power generation method, photovoltaic power generation system, heat supply system and heat supply control method

Abstract

The invention relates to a photovoltaic power generation method, a photovoltaic power generation system, a heat supply system and a heat supply control method.The photovoltaic power generation method comprises the steps that an energy storage device containing a water medium serves as the energy storage device, and after the output voltage of a photovoltaic module and the water medium temperature of the energy storage device are detected, the energy storage device is started; once the detected output voltage reaches the lowest input voltage of the stabilized power supply, the load impedance adjustment work is executed, and when the detected water medium temperature is within the preset temperature value range, the load impedance adjustment work is executed so that the photovoltaic module can operate near the maximum power point. Once the detected water medium temperature reaches the preset upper limit temperature value, the load impedance is controlled not to execute impedance work; and if the water medium temperature is lower than the preset lower limit temperature value, controlling the load impedance to continuously execute load impedance adjustment work. Thus, the water medium is used for replacing the energy storage battery for energy storage, the safety risk of thermal runaway of the battery can be eradicated, the energy storage device based on the water medium has a longer cycle use period, and the energy storage cost and the maintenance cost are reduced.

Description

Technical Field

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

[0002] Photovoltaic power generation, as a clean power generation technology, has been widely promoted and applied, and photovoltaic power generation systems have also been applied to different scenarios.

[0003] During the operation of a photovoltaic power generation system, photovoltaic power generation is a nonlinear process, and the volt-ampere characteristic of a photovoltaic module is not a linear curve. Therefore, in order to maximize the power generation efficiency of a photovoltaic power generation system, a maximum power point tracker (MPPT) is usually used to track the maximum power point of the photovoltaic power generation system under the current lighting conditions, adjust the load impedance in real time, and operate the photovoltaic module near the maximum power point to maximize power generation efficiency. Among them, the maximum power point tracker needs to be configured with an energy storage battery (such as a lithium battery or a lead-acid battery) to perform the maximum power point tracking work.

[0004] However, existing photovoltaic power generation methods have shortcomings: the maximum power point tracker has the defect of a short life cycle, and also requires the configuration of energy storage batteries to work properly. The energy storage battery has a limited cycle life and there is a risk of thermal runaway, which greatly increases the safety risk of the photovoltaic power generation process.

[0005] Therefore, it is necessary to provide another photovoltaic power generation method to overcome the shortcomings of the existing photovoltaic power generation method based on maximum power point tracker. Summary of the Invention

[0006] In view of this, the first technical problem to be solved by the present invention is to provide a photovoltaic power generation method that can replace the maximum power point tracker and adjust the load impedance in real time to maximize the power generation efficiency in response to the above-mentioned existing technology.

[0007] The second technical problem to be solved by the present invention is to provide a photovoltaic power generation system for realizing the above-mentioned photovoltaic power generation method.

[0008] The third technical problem to be solved by the present invention is to provide a heating system using the above photovoltaic power generation system.

[0009] The fourth technical problem to be solved by the present invention is to provide a heating control method for the above-mentioned heating system.

[0010] The technical solution adopted by the present invention to solve the first technical problem is: a photovoltaic power generation method, characterized by comprising the following steps:

[0011] Step 1: Detecting the output voltage of the photovoltaic module and the temperature of the water medium in the water medium energy storage device connected to the power output end of the photovoltaic power generation;

[0012] Step 2: Make a judgment based on the detected PV module output voltage:

[0013] When the output voltage of the photovoltaic module reaches the minimum input voltage of the voltage-stabilized power supply, the load impedance adjustment is performed to enable the photovoltaic module to operate near the maximum power point; otherwise, the process goes to step 1;

[0014] Step 3: Make a judgment based on whether the detected water medium temperature in the water medium energy storage device is within a preset temperature range:

[0015] When the temperature of the water medium is within the preset temperature range, the load impedance adjustment is performed to enable the photovoltaic module to operate near the maximum power point; otherwise, the process proceeds to step 4; wherein the preset temperature range is a temperature interval defined by a preset upper temperature limit and a preset lower temperature limit; the preset upper temperature limit is greater than the preset lower temperature limit;

[0016] Step 4: Make another judgment based on the detected water medium temperature in the water medium energy storage device:

[0017] When the water medium temperature reaches a preset upper limit temperature value, the load impedance is controlled not to perform impedance work; otherwise, the load impedance is controlled to continue to perform load impedance adjustment work to enable the photovoltaic module to operate near the maximum power point.

[0018] The technical solution adopted by the present invention to solve the second technical problem is: a photovoltaic power generation system, which implements the photovoltaic power generation method, is characterized by comprising:

[0019] Photovoltaic panels configured to convert solar energy into electrical energy;

[0020] a voltage detection module connected to the voltage output terminal of the photovoltaic module and configured to detect the output voltage of the photovoltaic module;

[0021] A voltage-stabilized power supply module, the input end of which is connected to the voltage output end of the photovoltaic module;

[0022] A load impedance module is connected to the voltage output terminal of the photovoltaic module and is configured to perform impedance work or not after being controlled and to adjust its own impedance when performing impedance work;

[0023] The control module is respectively connected to the voltage detection module, the voltage-stabilized power supply module and the load impedance module, and is configured to control the load impedance module according to the voltage detection status of the voltage detection module, so that the load impedance module adjusts its own impedance and realizes the operation of the photovoltaic module near the maximum power point.

[0024] As a first implementation of the load impedance module, in the photovoltaic power generation system of this invention, the load impedance module includes a first resistor, a second resistor, a first control switch and a second control switch; wherein:

[0025] a first resistor, configured such that a first end of the first resistor is connected to the positive electrode of the photovoltaic module via a first control switch, and a second end of the first resistor is connected to the negative electrode of the photovoltaic module; wherein the positive electrode of the photovoltaic module is the voltage output terminal of the photovoltaic module;

[0026] a second resistor, configured such that a first end of the second resistor is connected to the positive electrode of the photovoltaic module via a second control switch, and a second end of the second resistor is connected to the negative electrode of the photovoltaic module; wherein the second resistor and the first resistor are connected in parallel, and the resistance of the first resistor is greater than the resistance of the second resistor;

[0027] The control module is connected to the first control switch and the second control switch respectively to control the switching action of the first control switch and the switching action of the second control switch.

[0028] As a second implementation of the load impedance module, in the photovoltaic power generation system of this invention, the load impedance module includes a first resistor, a second resistor, a first control switch, a second control switch, and a third control switch; wherein:

[0029] A first resistor is configured such that a first end thereof is connected to the positive electrode of the photovoltaic module via a third control switch; wherein the positive electrode of the photovoltaic module is the voltage output end of the photovoltaic module;

[0030] A first control switch is connected in parallel to both ends of the first resistor;

[0031] a second resistor, configured such that a first end thereof is connected to a second end of the first resistor, and the second end of the second resistor is connected to a negative electrode of the photovoltaic module; wherein a resistance value of the first resistor is greater than a resistance value of the second resistor;

[0032] a second control switch connected in parallel to both ends of the second resistor, and the second control switch and the first control switch are connected in series;

[0033] The control module is connected to the first control switch, the second control switch and the third control switch respectively to control the switching action of the first control switch, the switching action of the second control switch and the switching action of the third control switch.

[0034] As a third implementation of the load impedance module, in the photovoltaic power generation system of this invention, the load impedance module includes a first resistor, a second resistor, a first control switch, a second control switch, a third control switch, and a fourth control switch; wherein:

[0035] a first resistor, configured such that a first end of the first resistor is connected to the positive electrode of the photovoltaic module via a first control switch, and a second end of the first resistor is connected to the negative electrode of the photovoltaic module via a third control switch; wherein the positive electrode of the photovoltaic module is the voltage output terminal of the photovoltaic module;

[0036] a second resistor, configured such that a first end of the second resistor is connected to a second end of the first resistor, the second end of the second resistor is connected to the negative electrode of the photovoltaic module via a second control switch, and the second end of the second resistor is further connected to the positive electrode of the photovoltaic module via a fourth control switch; the resistance of the first resistor is greater than the resistance of the second resistor;

[0037] The control module is connected to the first control switch, the second control switch, the third control switch and the fourth control switch respectively to control the switching action of the first control switch, the switching action of the second control switch, the switching action of the third control switch and the switching action of the fourth control switch.

[0038] As a further improvement, in this invention, the photovoltaic power generation system further includes a delay module, the input end of the delay module is connected to the instruction output end of the control module, and the output end of the delay module is respectively connected to the first control switch and the second control switch.

[0039] Furthermore, in the photovoltaic power generation system, the voltage detection module includes a diode, a current-limiting resistor, and a voltage-stabilizing capacitor connected in series in sequence, the positive electrode of the diode is connected to the positive electrode of the photovoltaic module, the negative electrode of the diode is connected to the first electrode of the voltage-stabilizing capacitor through the current-limiting resistor, and the second electrode of the voltage-stabilizing capacitor is connected to the negative electrode of the photovoltaic module;

[0040] Alternatively, in the photovoltaic power generation system, the voltage detection module includes a diode, a current limiting resistor and a voltage-stabilizing capacitor connected in series in sequence, the positive pole of the diode is connected to the positive pole of the photovoltaic module, the negative pole of the diode is connected to the first pole of the voltage-stabilizing capacitor through the current limiting resistor, and the second pole of the voltage-stabilizing capacitor is connected to the negative pole of the photovoltaic module; the voltage detection module is connected to the positive pole of the photovoltaic module through a DC circuit breaker, and the first pole of the current limiting resistor and the second pole of the voltage-stabilizing capacitor are respectively connected to the control module.

[0041] The technical solution adopted by the present invention to solve the third technical problem is: a heating system includes an energy storage device containing a water medium, characterized in that any one of the photovoltaic power generation systems described is applied.

[0042] Improved, in this invention, the heating system further comprises:

[0043] a heating device, disposed in the energy storage device, to heat the aqueous medium in the energy storage device;

[0044] The temperature detection device is configured to detect the temperature of the water medium in the energy storage device.

[0045] Further improvement, in this invention, the heating system also includes:

[0046] a cold water inlet pipe, one end of which is connected to the water inlet end of the energy storage device, and a second end of the cold water inlet pipe is configured to be connected to a tap water pipe;

[0047] A hot water outlet pipe has one end connected to the water outlet end of the energy storage device, and a second end of the hot water outlet pipe is configured to be connected to the hot water use end of the user.

[0048] Further improved, in this invention, the heating system further includes at least one of a cooling fan, an anti-corrosion component, an over-temperature and over-pressure safety valve, and a temperature display; wherein:

[0049] A cooling fan is configured to operate to ventilate and dissipate heat in the space where the control module is located;

[0050] an anti-corrosion component configured to have a portion disposed in the aqueous medium of the energy storage device to prevent devices in the energy storage device from being subjected to electrical corrosion;

[0051] The over-temperature and over-pressure safety valve is configured to be connected to the control module to automatically open the valve to release pressure when the temperature of the water medium in the energy storage device exceeds a specified temperature value or the water pressure exceeds a specified water pressure value.

[0052] The technical solution adopted by the present invention to solve the fourth technical problem is: a heating control method, characterized in that it is applied to the heating system.

[0053] Compared with the prior art, the advantages of the present invention are:

[0054] First, the photovoltaic power generation method of the invention uses water as an energy storage medium. An energy storage device containing a water medium is used as a photovoltaic power generation energy storage device, and after detecting the output voltage of the photovoltaic module and the temperature of the water medium in the energy storage device, once it is determined that the detected output voltage reaches the minimum input voltage of the voltage-stabilized power supply, the load impedance adjustment work is performed to enable the photovoltaic module to operate near the maximum power point, and when it is detected that the water medium temperature is within the preset temperature value range, the load impedance adjustment work is performed to enable the photovoltaic module to operate near the maximum power point, and once the detected water medium temperature reaches the preset upper limit temperature value, the load impedance is controlled not to perform the impedance work; and when the water medium temperature is lower than the preset lower limit temperature value, the load impedance is controlled to continue to perform the load impedance adjustment work to enable the photovoltaic module to operate near the maximum power point. In this way, the water medium is used to replace the energy storage battery for energy storage, and the energy storage device based on the water medium has a longer cycle, improves the power generation efficiency, reduces the energy storage cost and maintenance cost, and can also eliminate the safety risks caused by battery thermal runaway;

[0055] Secondly, the photovoltaic power generation system of the invention is based on the existing photovoltaic components and is additionally provided with a load impedance module formed by a first resistor, a second resistor, a controlled first control switch and a second control switch based on a heating resistor. The system utilizes the series relationship, the parallel relationship and the series-parallel relationship respectively formed between the first resistor and the second resistor, and cooperates with the switching action of the corresponding control switch to respectively complete the load adjustment of the load impedance module formed under the respective relationships, thereby ensuring that the photovoltaic components operate near the maximum power point and improving the efficiency of photovoltaic power generation.

[0056] In addition, the invention ensures that the output of the photovoltaic module will not be in an open-circuit state by ensuring that at least one heating resistor among the first resistor and the second resistor of the photovoltaic power generation system is always connected to the photovoltaic module. This can avoid the continuous and rapid jump of the photovoltaic module output voltage between an extremely low value and an open-circuit value when the last heating resistor is put into or withdrawn under extremely weak light conditions, thereby enhancing the safety of the entire photovoltaic system. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In order to more clearly illustrate the specific embodiments of the present disclosure or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0058] Figure 1 This is a schematic flow chart of the photovoltaic power generation method according to the first embodiment of the present invention;

[0059] Figure 2 Schematic diagram of a photovoltaic power generation system in Embodiment 1 of the present invention;

[0060] Figure 3 Schematic diagram of a heating system in Embodiment 1 of the present invention;

[0061] Figure 4 Schematic diagram of a photovoltaic power generation system in a second embodiment of the present invention;

[0062] Figure 5 Schematic diagram of a photovoltaic power generation system in embodiment 3 of the present invention. DETAILED DESCRIPTION

[0063] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0064] To facilitate understanding of the embodiments of the present invention, specific embodiments will be further explained below with reference to the accompanying drawings. The embodiments do not limit the embodiments of the present invention.

[0065] The present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

[0066] Example 1

[0067] This embodiment provides a photovoltaic power generation method. Figure 1 As shown, the photovoltaic power generation method in this embodiment includes the following steps:

[0068] Step 1: Detect the output voltage of the photovoltaic module and the temperature of the water medium in the water medium energy storage device connected to the power output end of the photovoltaic power generation; wherein, in this embodiment, the detected output voltage of the photovoltaic module is marked as U S , the detected water medium temperature in the energy storage device is marked as T;

[0069] Step 2: Make a judgment based on the detected PV module output voltage:

[0070] When the PV module output voltage reaches the minimum input voltage of the regulated power supply, the load impedance is adjusted to ensure that the PV module operates near the maximum power point. Otherwise, the process proceeds to step 1. The maximum input voltage allowed by the regulated power supply should be greater than the maximum open-circuit voltage of the PV module and should be able to adapt to changes in the PV module output voltage. For example, the output voltage of the regulated power supply should be 5V or 12V, and the output current of the regulated power supply should meet the power supply capacity requirements of the logic judgment and control circuit.

[0071] For example, in this embodiment, it is assumed that the lowest input voltage of the regulated power supply is marked as U th , then, when the PV module output voltage U S Reach the minimum input voltage U of the regulated power supply th When U S ≥U th When the load impedance is adjusted, the PV module can operate near the maximum power point.

[0072] Step 3: Make a judgment based on whether the detected water medium temperature in the water medium energy storage device is within a preset temperature range:

[0073] When the temperature of the water medium is within the preset temperature range, the load impedance adjustment is performed to enable the photovoltaic module to operate near the maximum power point; otherwise, the process proceeds to step 4; wherein the preset temperature range is a temperature interval defined by a preset upper temperature limit and a preset lower temperature limit; the preset upper temperature limit is greater than the preset lower temperature limit;

[0074] For example, in this embodiment, the maximum power point of the photovoltaic assembly during operation is marked as P m The corresponding voltage when the photovoltaic module is running at the maximum power point is marked as U m The corresponding current of the photovoltaic module when it is running at the maximum power point is marked as I m The preset temperature range is marked as (T1, T2), T1 is the preset upper limit temperature value, T2 is the preset lower limit temperature value, T1>T2; once the detected water medium temperature T does not reach the preset upper limit temperature value T1, the load impedance adjustment work is performed to achieve the photovoltaic module at the maximum power point P m Run nearby;

[0075] Step 4: Make another judgment based on the detected water medium temperature in the water medium energy storage device:

[0076] When the water medium temperature reaches a preset upper limit temperature value, the load impedance is controlled not to perform impedance work; otherwise, the load impedance is controlled to continue to perform load impedance adjustment work to enable the photovoltaic module to operate near the maximum power point.

[0077] That is, in this embodiment, when the detected water medium temperature T≥T1, it means that the water temperature has risen to the preset upper limit temperature, and the load impedance is controlled not to perform the impedance work, so that the photovoltaic power generation work no longer outputs electrical energy to the outside; otherwise, that is, when T≤T2, it means that the water temperature has dropped to the preset lower limit temperature, and the load impedance is controlled to continue to perform the load impedance adjustment work to enable the photovoltaic module to operate near the maximum power point.

[0078] In addition, this embodiment also provides a photovoltaic power generation system for implementing the above photovoltaic power generation method. Figure 2 As shown, the photovoltaic power generation system of this embodiment includes a photovoltaic module 11, a voltage detection module 12, a voltage stabilizing power supply module 13, a load impedance module 14 and a control module 15. Among them:

[0079] The photovoltaic module 11 is configured to convert solar energy into electrical energy. In this embodiment, various photovoltaic modules can be used, such as photovoltaic panels, photovoltaic tiles, photovoltaic glass, flexible photovoltaic panels, etc.

[0080] For example, in this embodiment, the photovoltaic module uses two 550W photovoltaic modules connected in parallel. The electrical performance parameters of the photovoltaic module are as follows:

[0081] Maximum power (Pmax): 550W

[0082] Open circuit voltage (Voc): 51.8V

[0083] Maximum power point voltage (Vmp): 41.4V

[0084] Short-circuit current (Isc): 16.47A

[0085] Maximum power point current (Imp): 13.29A

[0086] The voltage detection module 12 is connected to the voltage output terminal of the photovoltaic module 11 and is configured to detect the output voltage of the photovoltaic module;

[0087] A voltage-stabilized power supply module 13 , whose input end is connected to the voltage output end of the photovoltaic module 11 ;

[0088] The load impedance module 14 is connected to the voltage output terminal of the photovoltaic assembly 11 and is configured to perform impedance work or not after being controlled and to adjust its own impedance when performing impedance work;

[0089] The control module 15 is respectively connected to the voltage detection module 12, the voltage-stabilized power supply module 13 and the load impedance module 14, and is configured to control the load impedance module according to the voltage detection condition of the voltage detection module, so that the load impedance module adjusts its own impedance and the photovoltaic module operates near the maximum power point.

[0090] That is, in this embodiment, the control module controls the load impedance module in the following manner:

[0091] When the control module determines that the output voltage of the photovoltaic module detected by the voltage detection module reaches the minimum input voltage of the voltage-regulated power supply, the control module performs load impedance adjustment to enable the photovoltaic module to operate near the maximum power point;

[0092] When the control module determines that the detected water medium temperature in the water medium energy storage device is within a preset temperature value range, the control module performs a load impedance adjustment operation to enable the photovoltaic module to operate near the maximum power point;

[0093] When the control module determines that the detected water medium temperature in the water medium energy storage device reaches a preset upper limit temperature value, the load impedance is controlled not to perform impedance work; otherwise, the load impedance is controlled to continue to perform load impedance adjustment work to enable the photovoltaic component to operate near the maximum power point.

[0094] In the photovoltaic power generation system of this embodiment, see Figure 2 As shown, the load impedance module 14 includes a first resistor R1, a second resistor R2, a first control switch K1 and a second control switch K2; wherein:

[0095] The first resistor R1 is configured such that a first end thereof is connected to the positive electrode of the photovoltaic module 11 through the first control switch K1, and a second end thereof is connected to the negative electrode of the photovoltaic module 11; wherein the positive electrode of the photovoltaic module is the voltage output terminal of the photovoltaic module;

[0096] The second resistor R2 is configured such that its first end is connected to the positive electrode of the photovoltaic module 11 through the second control switch K2, and its second end is connected to the negative electrode of the photovoltaic module 11. The second resistor R2 is connected in parallel with the first resistor R1, and the resistance of the first resistor R1 is greater than the resistance of the second resistor R2. For example, in this embodiment, the first resistor R1 is 5Ω and has a rated power of 500W; the second resistor R2 is 2.5Ω and has a rated power of 1000W.

[0097] The control module 15 is connected to the first control switch K1 and the second control switch K2 to control the switching action of the first control switch and the second control switch. In this embodiment, the first control switch K1 is a normally closed switch, and the second control switch K2 is a normally open switch.

[0098] To meet the control module's need for delay control of the first and second control switches, the photovoltaic power generation system of this embodiment further includes a delay module (not shown). The input of the delay module is connected to the command output of the control module 15, and the output of the delay module is connected to the first and second control switches K1, K2, respectively. The delay length of the delay module can be set as needed.

[0099] As a way to implement voltage detection, in the photovoltaic power generation system of this embodiment, see Figure 2 As shown, the voltage detection module 12 in this embodiment includes a diode D, a current-limiting resistor R, and a voltage-stabilizing capacitor C connected in series. The positive electrode of the diode D is connected to the positive electrode of the photovoltaic module 11, the negative electrode of the diode D is connected to the first electrode of the voltage-stabilizing capacitor C via the current-limiting resistor R, and the second electrode of the voltage-stabilizing capacitor C is connected to the negative electrode of the photovoltaic module 11. To protect electrical appliances, the photovoltaic power generation system of this embodiment also includes a DC circuit breaker QF. The voltage detection module 12 is connected to the positive electrode of the photovoltaic module 11 via the DC circuit breaker QF. The first electrode of the current-limiting resistor R and the second electrode of the voltage-stabilizing capacitor C are respectively connected to the control module 15.

[0100] The voltage-stabilized power supply module 13 serves as the power supply of the power generation control system. One end of the voltage-stabilized power supply module 13 is connected to the positive electrode of the photovoltaic module 11 through the DC circuit breaker QF, and the other end of the voltage-stabilized power supply module 13 is connected to the negative electrode of the photovoltaic module.

[0101] This embodiment also provides a heating system using the above photovoltaic power generation system. Figure 3 As shown, the heating system of this embodiment includes an energy storage device 20 containing a water medium, a heating device 21 and a temperature detection device 22. The heating device 21 is arranged in the energy storage device 20 to heat the water medium in the energy storage device 20; the temperature detection device 22 is configured to detect the temperature of the water medium in the energy storage device 20. For example, in this embodiment, the heating device 21 adopts a heating rod to convert the electrical energy generated by the photovoltaic power generation system into thermal energy. Of course, by combining two or more heating rods, the photovoltaic module can be operated as close to the maximum power point as possible to improve the power generation efficiency of the photovoltaic module. As needed, a temperature control module 15' can be provided, and the temperature control module 15' can be connected to the temperature detection device 22 and the control module 15 respectively.

[0102] In this embodiment, the energy storage device for holding water medium is a pressurized heat-insulating water tank for holding hot water.

[0103] Of course, the photovoltaic power generation system of this embodiment can also include a cold water inlet pipe 23 and a hot water outlet pipe 24, where one end of the cold water inlet pipe 23 is connected to the water inlet of the energy storage device, and the second end of the cold water inlet pipe 23 is configured to be connected to a tap water pipe; one end of the hot water outlet pipe 24 is connected to the water outlet of the energy storage device, and the second end of the hot water outlet pipe 24 is configured to be connected to a user's hot water consumption end. For example, the user's hot water consumption end here can be a shower faucet.

[0104] In this embodiment, the heating system may also include a controlled cooling fan 16 so as to utilize the running cooling fan 16 to ventilate and dissipate heat for the space where the control module is located.

[0105] If necessary, an anti-corrosion component 25 may be provided in the water medium of the energy storage device 20 to prevent electrical corrosion of components therein. For example, the anti-corrosion component 25 is a magnesium rod, part of which is provided in the water medium of the energy storage device to prevent electrical corrosion of components such as the water tank liner and the heating rod.

[0106] Of course, the energy storage device can also be provided with an over-temperature and over-pressure safety valve 26, which is configured to connect to the control module to automatically open the valve to release pressure when the water medium temperature in the energy storage device exceeds a specified temperature value or the water pressure exceeds a specified water pressure value.

[0107] In order to facilitate understanding of the real-time temperature of the water medium in the energy storage device, in the heating system of this embodiment, a temperature display 27 can also be set on the energy storage device to use the temperature display 27 to display the water medium temperature in the energy storage device detected by the temperature detection device.

[0108] The following combination Figure 2 and Figure 3 , the heating control method process of the heating system in this embodiment is described:

[0109] Step S1: In the initial state, when the photovoltaic module does not output power, the first control switch K1 (normally closed switch) and the second control switch K2 (normally open switch) are both inactive, the first resistor R1 (heating resistor) is connected to the circuit, and the second resistor R2 (heating resistor) is disconnected;

[0110] Step S2: As the light intensity in the environment where the photovoltaic module is located increases, the output voltage of the photovoltaic module begins to increase. When the output voltage of the photovoltaic module reaches the minimum input voltage requirement of the voltage-stabilized power supply module, the voltage output by the voltage-stabilized power supply module causes the logic judgment and control circuit to start working normally.

[0111] Step S3: The voltage detection module determines whether to output an action signal by detecting the output voltage Us of the photovoltaic module:

[0112] When the output voltage of the photovoltaic module continues to rise and the output voltage Us of the photovoltaic module approaches the voltage Um value of the saturation segment, the first action voltage value of the voltage detection module is reached. The voltage detection module outputs an action signal to the delay module. After receiving the action signal, the delay module sends a control signal to the control circuit of the first control switch K1 and the second control switch K2 after a delay of time t1, so that the first control switch K1 and the second control switch K2 are both activated, thereby connecting the second resistor R2 to the circuit and disconnecting the first resistor R1;

[0113] When the output voltage of the photovoltaic module continues to rise and the output voltage Us of the photovoltaic module approaches the voltage Um value of the saturation section again, it reaches the second action voltage value of the voltage detection module. The voltage detection module also outputs an action signal to the delay module. After receiving the action signal, the delay module sends a control signal to the control loop of the first control switch K1 and the second control switch K2 after a delay of time t3, so that the first control switch K1 returns and the second control switch K2 is actuated, thereby connecting the first resistor R1 and the second resistor R2 in parallel to the circuit;

[0114] When the output voltage of the photovoltaic module is decreasing, the output voltage Us of the photovoltaic module reaches the second return voltage value of the voltage detection module; at this time, the voltage detection module outputs an action signal and returns, delays for a time t4, and gives a control signal to the control circuits of the first control switch K1 and the second control switch K2. Both the first control switch K1 and the second control switch K2 act, so that the second resistor R2 is connected to the circuit and the first resistor R1 is disconnected;

[0115] When the output voltage of the photovoltaic module continues to decrease, the output voltage Us of the photovoltaic module reaches the first return voltage value of the voltage detection module; at this time, the voltage detection module outputs an action signal and returns, delays for a time t2, and gives a control signal to the control circuits of the first control switch K1 and the second control switch K2. Both the first control switch K1 and the second control switch K2 do not act, the first resistor R1 is connected to the circuit, and the second resistor R2 is disconnected;

[0116] Step S4, at any time, when the temperature detection device detects that the water temperature in the energy storage device reaches the preset upper limit temperature value, the control module outputs an action signal and gives the control signal to the control circuits of the first control switch K1 and the second control switch K2 without delay, so that the first control switch K1 disconnects the first resistor R1 after acting and the second control switch K2 disconnects the second resistor R2 after returning; at this time, both heating resistors R1 and R2 do not work.

[0117] When the temperature detection device detects that the water temperature in the energy storage device drops to the preset lower limit temperature value, the action signal output by the temperature detection device returns, and gives the control signal to the control circuits of the first control switch K1 and the second control switch K2 without delay, so that the first control switch K1 and the second control switch K2 act according to the output results of the control logic in steps S1 to S3, and the two heating resistors R1 and R2 work according to the logic control results.

[0118] It should be noted that in this embodiment, the set values of the action delay time are t1 and t3, and t1 < t3; the set values of the return delay time are t2 and t4, and t2 > t4. Specifically, the set values of the action delay time t1 and t3 are set to 30 seconds and 45 seconds respectively; the set values of the return delay time t2 and t4 are set to 3 seconds and 0 seconds respectively.

[0119] Among them, the action voltage and the return voltage need to be set according to the electrical performance parameters of the photovoltaic module and the resistance value of the heating resistor, so that the photovoltaic module can output a larger power generation power under the current illumination conditions.

[0120] Embodiment 2

[0121] This embodiment provides a photovoltaic power generation method. Among them, the specific implementation manner of this photovoltaic power generation method is as described in Embodiment 1, and will not be elaborated here.

[0122] This embodiment also provides a photovoltaic power generation system for implementing the above photovoltaic power generation method. The difference from the photovoltaic power generation system in the first embodiment is that in the second embodiment, see Figure 4 As shown, the load impedance module 14 includes a first resistor R1, a second resistor R2, a first control switch K1, a second control switch K2 and a third control switch K3; wherein:

[0123] The first resistor R1 is configured such that a first end thereof is connected to the positive electrode of the photovoltaic module 11 through the third control switch K3; wherein the positive electrode of the photovoltaic module is the voltage output end of the photovoltaic module;

[0124] A first control switch K1 is connected in parallel to both ends of the first resistor R1;

[0125] The second resistor R2 is configured such that its first end is connected to the second end of the first resistor R1, and the second end of the second resistor R2 is connected to the negative electrode of the photovoltaic module 11; wherein the resistance of the first resistor R1 is greater than the resistance of the second resistor R2;

[0126] A second control switch K2 is connected in parallel to both ends of the second resistor R2, and the second control switch K2 and the first control switch K1 are connected in series;

[0127] The control module 15 is connected to the first control switch K1 , the second control switch K2 and the third control switch K3 respectively to control the switching action of the first control switch, the switching action of the second control switch and the switching action of the third control switch.

[0128] This embodiment also provides a heating system using the photovoltaic power generation system. Detailed descriptions can refer to the heating system described in the first embodiment.

[0129] The following combination Figure 4 , the heating control method process of the heating system in this embodiment is described:

[0130] Step a1: In the initial state, when the photovoltaic module has no output, the third control switch K3 (normally closed switch), the first control switch K1 (normally open switch), and the second control switch K2 (normally open switch) are all inactive, and the first resistor R1 (heating resistor) and the second resistor R2 (heating resistor) are connected in series and then connected to the circuit;

[0131] Step a2: As the light intensity in the environment of the photovoltaic module increases, the output voltage of the photovoltaic module begins to increase. When the output voltage of the photovoltaic module reaches the minimum input voltage requirement of the voltage-stabilized power supply module, the voltage output by the voltage-stabilized power supply module causes the logic judgment and control circuit to start working normally.

[0132] Step a3: The voltage detection module determines whether to output an action signal by detecting the output voltage Us of the photovoltaic module:

[0133] When the PV module output voltage continues to rise and approaches the saturation value Um, the PV module output voltage Us reaches the first action voltage value of the voltage detection module. At this time, the voltage detection module outputs an action signal to the delay module. After receiving the signal, the delay module sends a control signal to the control circuit of the second control switch K2 after a delay of time t1, causing the second control switch K2 to close, thereby short-circuiting the second resistor R2. At this time, only the first resistor R1 is connected to the main circuit.

[0134] When the PV module output voltage continues to rise and the PV module output voltage Us once again approaches the saturation segment Um value, it reaches the second action voltage value of the voltage detection module; at this time, the voltage detection module also outputs an action signal to the delay module. After receiving the signal, the delay module sends a control signal to the control circuit of the first control switch K1 and the second control switch K2 after a delay of time t3, causing the first control switch K1 to close and the second control switch K2 to return to open, thereby short-circuiting the first resistor R1. At this time, only the second resistor R2 is connected to the circuit;

[0135] When the PV module output voltage Us reaches the second return voltage value of the voltage detection module during the process of decreasing, the voltage detection module outputs an action signal and returns, delaying for time t4, and sends a control signal to the control circuit of the first control switch K1 and the second control switch K2. The first control switch K1 returns to open and the second control switch K2 closes, thereby connecting the first resistor R1 to the circuit and short-circuiting the second resistor R2.

[0136] When the PV module output voltage continues to drop, the PV module output voltage Us reaches the first return voltage value of the voltage detection module; at this time, the voltage detection module outputs an action signal and returns, delaying t2 time, and sends a control signal to the control circuit of the first control switch K1 and the second control switch K2. The first control switch K1 and the second control switch K2 are both turned off, and the first resistor R1 and the second resistor R2 are connected in series to the circuit;

[0137] Step a4: At any time, when the temperature detection device detects that the water temperature in the energy storage device reaches a preset upper temperature limit, the control module outputs an action signal and sends the control signal to the control circuit of the third control switch K3 without delay, so that the third control switch K3 is actuated and the main circuit is disconnected. At this time, the first resistor R1 and the second resistor R2 are both inoperative.

[0138] When the temperature detection device detects that the water temperature in the energy storage device drops to a preset lower temperature limit, the action signal output by the control module returns, and the control signal is sent to the control circuit of the third control switch K3 without delay. After the third control switch K3 returns, the main circuit is connected. The first control switch K1 and the second control switch K2 operate according to the logical output results of steps a1 to a3; the first resistor R1 and the second resistor R2 operate according to the results of the logical control.

[0139] The first control switch K1 and the second control switch K2 must be interlocked to ensure that only one of the two switches (K1 and K2) can be closed at the same time, otherwise the PV module output will be short-circuited.

[0140] Example 3

[0141] This embodiment provides a photovoltaic power generation method, wherein the specific implementation of the photovoltaic power generation method is described in Example 1 and will not be repeated here.

[0142] This embodiment also provides a photovoltaic power generation system for implementing the above photovoltaic power generation method. The difference from the photovoltaic power generation system in the first embodiment is that in the third embodiment, see Figure 5 As shown, the load impedance module 14 includes a first resistor R1, a second resistor R2, a first control switch K1, a second control switch K2, a third control switch K3 and a fourth control switch K4.

[0143] The first resistor R1 is configured such that a first end thereof is connected to the positive electrode of the photovoltaic module 11 via a first control switch K1, and a second end thereof is connected to the negative electrode of the photovoltaic module 11 via a third control switch K3; wherein the positive electrode of the photovoltaic module is the voltage output terminal of the photovoltaic module;

[0144] The second resistor R2 is configured such that its first end is connected to the second end of the first resistor R1, the second end of the second resistor R2 is connected to the negative electrode of the photovoltaic module 11 via the second control switch K2, and the second end of the second resistor R2 is also connected to the positive electrode of the photovoltaic module 11 via the fourth control switch K4; the resistance of the first resistor R1 is greater than the resistance of the second resistor R2;

[0145] The control module 15 is connected to the first control switch K1, the second control switch K2, the third control switch K3 and the fourth control switch K4 respectively to control the switching action of the first control switch, the second control switch, the third control switch and the fourth control switch.

[0146] This embodiment also provides a heating system using the photovoltaic power generation system. Detailed descriptions can refer to the heating system described in the first embodiment.

[0147] The following combination Figure 5 , the heating control method process of the heating system in this embodiment is described:

[0148] Step b1: In the initial state, when the photovoltaic module has no output, the first control switch K1 (normally closed switch), the second control switch K2 (normally closed switch), the third control switch K3 (normally open switch), and the fourth control switch K4 (normally open switch) are all inactive, and the first resistor R1 (heating resistor) and the second resistor R2 (heating resistor) are connected in series to the circuit;

[0149] Step b2: As the light intensity in the environment where the photovoltaic module is located increases, the output voltage of the photovoltaic module begins to increase. When the output voltage of the photovoltaic module reaches the minimum input voltage requirement of the voltage-stabilized power supply module, the voltage output by the voltage-stabilized power supply module causes the logic judgment and control circuit to start working normally.

[0150] Step b3: The voltage detection module determines whether to output an action signal by detecting the output voltage Us of the photovoltaic module:

[0151] When the PV module output voltage continues to rise and approaches the saturation value Um, the PV module output voltage Us reaches the first action voltage value of the voltage detection module. At this time, the voltage detection module outputs an action signal to the delay module. After receiving the action signal, the delay module sends a control signal to the control circuit of the third control switch K3 after a delay of time t1, causing the third control switch K3 to close, thereby short-circuiting the second resistor R2. At this time, only the first resistor R1 is connected to the main circuit.

[0152] When the output voltage of the photovoltaic module continues to rise and the output voltage Us of the photovoltaic module approaches the Um value of the saturation section again, it reaches the second action voltage value of the voltage detection module; at this time, the voltage detection module outputs an action signal to the delay module. After receiving the action signal, the delay module sends a control signal to the control circuit of the first control switch K1, the second control switch K2, the third control switch K3, and the fourth control switch K4 after a delay of time t3, so that all four control switches are activated, thereby disconnecting the first resistor R1. At this time, only the second resistor R2 is connected to the circuit;

[0153] When the output voltage of the photovoltaic module continues to rise and the output voltage Us of the photovoltaic module once again approaches the Um value of the saturation section, it reaches the third action voltage value of the voltage detection module; at this time, the voltage detection module outputs an action signal to the delay module. After receiving the action signal, the delay module sends a control signal to the control circuit of the first control switch K1, the second control switch K2, the third control switch K3 and the fourth control switch K4 after a delay of time t5, so that the second control switch K2, the third control switch K3 and the fourth control switch K4 remain in the action state, and the first control switch K1 returns to the closed state, thereby connecting the first resistor R1 and the second resistor R2 in parallel to the main circuit;

[0154] When the PV module output voltage drops, the PV module output voltage Us reaches the third return voltage value of the voltage detection module; at this time, the voltage detection module outputs an action signal and returns, delaying for time t6, and sends a control signal to the control circuits of the first control switch K1, the second control switch K2, the third control switch K3, and the fourth control switch K4, causing all four control switches to operate, thereby disconnecting the first resistor R1. At this time, only the second resistor R2 is connected to the circuit;

[0155] When the output voltage of the photovoltaic module decreases, the output voltage Us of the photovoltaic module reaches the second return voltage value of the voltage detection module; at this time, the voltage detection module outputs an action signal and returns, delaying for a time t4, and sends a control signal to the control circuits of the first control switch K1, the second control switch K2, the third control switch K3, and the fourth control switch K4, so that the first control switch K1, the second control switch K2, and the fourth control switch K4 are all returned, and the third control switch K3 is activated, thereby connecting the first resistor R1 to the circuit and short-circuiting the second resistor R2;

[0156] When the PV module output voltage continues to drop, the PV module output voltage Us reaches the first return voltage value of the voltage detection module; at this time, the voltage detection module outputs an action signal and returns, delaying for a time t2, and sending a control signal to the control circuits of the first control switch K1, the second control switch K2, the third control switch K3, and the fourth control switch K4, so that all four control switches are inactive, and the first resistor R1 and the second resistor R2 are connected in series to the circuit;

[0157] Step b4: At any time, when the temperature detection device detects that the water temperature in the energy storage device reaches a preset upper temperature limit, the control module outputs an action signal and sends the control signal to the control circuit of the first control switch K1, the second control switch K2, the third control switch K3, and the fourth control switch K4 without delay, so that the first control switch K1 and the second control switch K2 are activated and the third control switch K3 and the fourth control switch K4 are deactivated, thereby disconnecting the main circuit; at this time, both the first resistor R1 and the second resistor R2 are deactivated;

[0158] When the temperature detection device detects that the water temperature in the energy storage device drops to a preset lower temperature limit, the action signal output by the temperature detection device is returned, and the control signal is sent to the control circuits of the first control switch K1, the second control switch K2, the third control switch K3, and the fourth control switch K4 without delay, so that the four control switches are actuated according to the logical output results of steps b1 to b3, and the first resistor R1 and the second resistor R2 operate according to the results of the logical control;

[0159] The second control switch K2 and the fourth control switch K4 must be interlocked to ensure that only one of the two switches (K2 and K4) can be closed at the same time, otherwise the photovoltaic module output will be short-circuited.

[0160] Although the preferred embodiments of the present invention have been described in detail above, it should be clearly understood that various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A photovoltaic power generation method, characterized in that: The steps include: Step 1: Detecting the output voltage of the photovoltaic module and the temperature of the water medium in the water medium energy storage device connected to the power output end of the photovoltaic power generation; Step 2: Make a judgment based on the detected PV module output voltage: When the output voltage of the photovoltaic module reaches the minimum input voltage of the voltage-stabilized power supply, the load impedance adjustment is performed to enable the photovoltaic module to operate near the maximum power point; otherwise, the process goes to step 1; Step 3: Make a judgment based on whether the detected water medium temperature in the water medium energy storage device is within a preset temperature range: When the water medium temperature is within the preset temperature range, the load impedance adjustment is performed to enable the photovoltaic module to operate near the maximum power point; Otherwise, go to step 4; wherein the preset temperature value range is a temperature interval defined by a preset upper temperature limit and a preset lower temperature limit; the preset upper temperature limit is greater than the preset lower temperature limit; Step 4: Make another judgment based on the detected water medium temperature in the water medium energy storage device: When the water medium temperature reaches a preset upper limit temperature value, the load impedance is controlled not to perform impedance work; otherwise, the load impedance is controlled to continue to perform load impedance adjustment work to enable the photovoltaic module to operate near the maximum power point.

2. A photovoltaic power generation system, implementing the photovoltaic power generation method according to claim 1, characterized in that: include: a photovoltaic module (11) configured to convert solar energy into electrical energy; A voltage detection module (12) is connected to the voltage output terminal of the photovoltaic module (11) and is configured to detect the output voltage of the photovoltaic module; A voltage-stabilized power supply module (13), the input end of which is connected to the voltage output end of the photovoltaic module (11); A load impedance module (14), connected to the voltage output terminal of the photovoltaic component (11), is configured to perform impedance work or not after being controlled and to adjust its own impedance when performing impedance work; The control module (15) is respectively connected to the voltage detection module (12), the voltage-stabilized power supply module (13) and the load impedance module (14), and is configured to control the load impedance module according to the voltage detection condition of the voltage detection module, so as to enable the load impedance module to adjust its own impedance and enable the photovoltaic module to operate near the maximum power point.

3. The photovoltaic power generation system according to claim 2, characterized in that: The load impedance module (14) comprises a first resistor (R1), a second resistor (R2), a first control switch (K1) and a second control switch (K2); wherein: A first resistor (R1) is configured such that a first end thereof is connected to the positive electrode of the photovoltaic component (11) via a first control switch (K1), and a second end of the first resistor (R1) is connected to the negative electrode of the photovoltaic component (11); wherein the positive electrode of the photovoltaic component is the voltage output end of the photovoltaic component; A second resistor (R2) is configured such that a first end thereof is connected to the positive electrode of the photovoltaic component (11) via a second control switch (K2), and a second end of the second resistor (R2) is connected to the negative electrode of the photovoltaic component (11); wherein the second resistor (R2) and the first resistor (R1) are connected in parallel, and the resistance value of the first resistor (R1) is greater than the resistance value of the second resistor (R2); The control module (15) is respectively connected to the first control switch (K1) and the second control switch (K2) to control the switching action of the first control switch and the switching action of the second control switch.

4. The photovoltaic power generation system according to claim 2, characterized in that: The load impedance module (14) comprises a first resistor (R1), a second resistor (R2), a first control switch (K1), a second control switch (K2) and a third control switch (K3); wherein: A first resistor (R1) is configured such that a first end thereof is connected to the positive electrode of the photovoltaic module (11) via a third control switch (K3); wherein the positive electrode of the photovoltaic module is the voltage output end of the photovoltaic module; A first control switch (K1) is connected in parallel to both ends of the first resistor (R1); a second resistor (R2) configured such that a first end thereof is connected to a second end of the first resistor (R1), and a second end of the second resistor (R2) is connected to a negative electrode of the photovoltaic module (11); wherein the resistance value of the first resistor (R1) is greater than the resistance value of the second resistor (R2); A second control switch (K2) is connected in parallel to both ends of the second resistor (R2), and the second control switch (K2) and the first control switch (K1) are connected in series; The control module (15) is respectively connected to the first control switch (K1), the second control switch (K2) and the third control switch (K3) to control the switching action of the first control switch, the switching action of the second control switch and the switching action of the third control switch.

5. The photovoltaic power generation system according to claim 2, characterized in that: The load impedance module (14) comprises a first resistor (R1), a second resistor (R2), a first control switch (K1), a second control switch (K2), a third control switch (K3) and a fourth control switch (K4); wherein: A first resistor (R1) is configured such that a first end thereof is connected to the positive electrode of the photovoltaic component (11) via a first control switch (K1), and a second end thereof is connected to the negative electrode of the photovoltaic component (11) via a third control switch (K3); wherein the positive electrode of the photovoltaic component is the voltage output end of the photovoltaic component; A second resistor (R2) is configured such that its first end is connected to the second end of the first resistor (R1), the second end of the second resistor (R2) is connected to the negative electrode of the photovoltaic component (11) via a second control switch (K2), and the second end of the second resistor (R2) is also connected to the positive electrode of the photovoltaic component (11) via a fourth control switch (K4); the resistance value of the first resistor (R1) is greater than the resistance value of the second resistor (R2); The control module (15) is respectively connected to a first control switch (K1), a second control switch (K2), a third control switch (K3) and a fourth control switch (K4) to control the switching action of the first control switch, the switching action of the second control switch, the switching action of the third control switch and the switching action of the fourth control switch.

6. The photovoltaic power generation system according to any one of claims 3 to 5, characterized in that: It also includes a delay module (16), the input end of the delay module (16) is connected to the instruction output end of the control module (15), and the output end of the delay module (16) is respectively connected to the first control switch (K1) and the second control switch (K2).

7. The photovoltaic power generation system according to claim 6, characterized in that: The voltage detection module (12) comprises a diode (D), a current-limiting resistor (R), and a voltage-stabilizing capacitor (C) connected in series in sequence, the positive electrode of the diode (D) being connected to the positive electrode of the photovoltaic module (11), the negative electrode of the diode (D) being connected to the first electrode of the voltage-stabilizing capacitor (C) via the current-limiting resistor (R), and the second electrode of the voltage-stabilizing capacitor (C) being connected to the negative electrode of the photovoltaic module (11); Alternatively, in the photovoltaic power generation system, the voltage detection module (12) comprises a diode (D), a current-limiting resistor (R), and a voltage-stabilizing capacitor (C) connected in series in sequence, the positive electrode of the diode (D) being connected to the positive electrode of the photovoltaic module (1), the negative electrode of the diode (D) being connected to the first electrode of the voltage-stabilizing capacitor (C) via the current-limiting resistor (R), and the second electrode of the voltage-stabilizing capacitor (C) being connected to the negative electrode of the photovoltaic module (11); the voltage detection module (12) being connected to the positive electrode of the photovoltaic module (11) via a DC circuit breaker (QF), and the first electrode of the current-limiting resistor (R) and the second electrode of the voltage-stabilizing capacitor (C) being respectively connected to the control module (15).

8. A heating system comprising an energy storage device containing a water medium, characterized in that: The photovoltaic power generation system according to any one of claims 2 to 7 is used.

9. The heating system according to claim 8, characterized in that Also includes: a heating device (21), disposed in the energy storage device (20) to heat the aqueous medium in the energy storage device (20); The temperature detection device (22) is configured to detect the temperature of the water medium in the energy storage device (20).

10. A heating control method, characterized in that: Applicable to the heating system described in claim 8 or 9.

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