Off-line photovoltaic water pump system and working method thereof, electronic equipment and medium

Abstract

The invention discloses an off-line photovoltaic water pump system, a working method thereof, electronic equipment and a medium, and relates to the technical field of photovoltaic water pumps. The method comprises the following steps: when a water pump motor runs, collecting current bus voltage through a general frequency converter to obtain photovoltaic panel voltage; when the voltage of the photovoltaic panel is within the preset range, whether the water pump motor is in an initial starting stage or not is judged; when the water pump motor is not in the initial starting stage, the change direction of the output power of the universal frequency converter and the change direction of the target voltage are detected; according to the change direction of the output power of the general frequency converter and the change direction of the target voltage, adjusting the target voltage through a preset first adjustment step length; the target voltage serves as a given value of a PID module, the photovoltaic panel voltage serves as a feedback value of the PID module, the PID module conducts calculation according to the given value and the feedback value, a frequency value is obtained, and a water pump motor is driven to operate. According to the method, the maximum power point of the photovoltaic panel can be quickly found, and the cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic water pump technology, and in particular to an offline photovoltaic water pump system, its operating method, electronic equipment, and medium. Background Technology

[0002] Offline photovoltaic (PV) water pump systems are suitable for suburban areas without grid power supply, where the PV panels are fixed in location and require no human intervention. PV water pumps utilize solar panels to directly convert solar energy into electrical energy, which is then used by a frequency converter to drive the pump motor.

[0003] The optimal operating point of a solar panel is called its maximum power point (MPP), which primarily depends on the panel's operating temperature and the prevailing sunlight level. The MPP varies under different temperatures and light intensities. To ensure the solar panel operates as close to its MPP as possible, current methods require dedicated photovoltaic (PV) pump inverters to detect the panel's voltage and current, thus calculating the MPP. However, using dedicated PV pump inverters is costly and necessitates hardware development. Furthermore, current methods are not efficient at quickly determining the MPP. Summary of the Invention

[0004] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes an offline photovoltaic water pump system and its operating method, electronic equipment, and medium, which can apply a preset MPPT algorithm on a general-purpose frequency converter to quickly find the maximum power point of the photovoltaic panel and reduce costs.

[0005] In a first aspect, according to an embodiment of the present invention, a method for operating an offline photovoltaic water pump system includes a photovoltaic panel, a general-purpose frequency converter, and a water pump motor connected in sequence, wherein the general-purpose frequency converter is equipped with a PID module; the method includes:

[0006] When the water pump motor is running, the current bus voltage is collected through the general-purpose frequency converter to obtain the photovoltaic panel voltage;

[0007] When the voltage of the photovoltaic panel is within a preset range, the target voltage is obtained by performing a preset MPPT algorithm through the general-purpose frequency converter;

[0008] The target voltage is used as the given value of the PID module, and the photovoltaic panel voltage is used as the feedback value of the PID module, so that the PID module can calculate the frequency value based on the given value and the feedback value.

[0009] The water pump motor is driven to operate according to the frequency value;

[0010] The step of obtaining the target voltage by performing a preset MPPT algorithm through the general-purpose frequency converter includes:

[0011] Based on the initial value of the preset target voltage and the voltage of the photovoltaic panel, determine whether the water pump motor is in the initial start-up phase;

[0012] When the water pump motor is not in the initial startup phase, detect the direction of change of the output power of the general-purpose frequency converter and the direction of change of the target voltage.

[0013] The target voltage is adjusted by a preset first adjustment step size based on the direction of change of the output power of the general-purpose frequency converter and the direction of change of the target voltage.

[0014] According to some embodiments of the present invention, before the step of acquiring the bus voltage and obtaining the photovoltaic panel voltage through the general-purpose frequency converter when the water pump motor is running, the method further includes:

[0015] When the water pump motor stops, the current bus voltage is collected through the general-purpose frequency converter to obtain the open-circuit voltage of the photovoltaic panel;

[0016] The initial value of the target voltage is set based on the open-circuit voltage of the photovoltaic panel;

[0017] Initialize the first adjustment step size and the calculation cycle; the calculation cycle represents the processing cycle of the preset MPPT algorithm.

[0018] According to some embodiments of the present invention, after the step of acquiring the bus voltage and obtaining the photovoltaic panel voltage through the general-purpose frequency converter when the water pump motor is running, the method further includes:

[0019] When the voltage of the photovoltaic panel is not within the preset range, the target voltage is assigned the initial value;

[0020] The target voltage after assignment is used as the setpoint of the PID module, and the photovoltaic panel voltage is used as the feedback value of the PID module. The PID module performs PID adjustment based on the setpoint and the feedback value to adjust the photovoltaic panel voltage until the photovoltaic panel voltage is within the preset range.

[0021] According to some embodiments of the present invention, when the photovoltaic panel voltage is within a preset range, obtaining the target voltage by performing a preset MPPT algorithm through the general-purpose frequency converter includes:

[0022] When the voltage of the photovoltaic panel is within the preset range, it is determined whether the current moment conforms to the calculation cycle;

[0023] If the calculation cycle is met, the target voltage is obtained by performing a preset MPPT algorithm through the general-purpose frequency converter.

[0024] If the calculation cycle is not met, the target voltage is obtained by waiting until the calculation cycle is reached and then using the preset MPPT algorithm through the general-purpose frequency converter.

[0025] According to some embodiments of the present invention, before the step of determining whether the general-purpose frequency converter is in the initial startup phase, the method further includes:

[0026] Obtain the initial value of the preset target voltage and the difference between the photovoltaic panel voltage;

[0027] When the difference between the initial value of the preset target voltage and the voltage of the photovoltaic panel is greater than the first preset threshold, the target voltage is adjusted by the second adjustment step size so that the difference between the target voltage and the voltage of the photovoltaic panel is less than the first preset threshold; the second adjustment step size is greater than the first adjustment step size.

[0028] According to some embodiments of the present invention, after the step of determining whether the general-purpose frequency converter is in the initial startup phase based on the preset initial value of the target voltage and the photovoltaic panel voltage, the method further includes:

[0029] When the general-purpose inverter is in the initial startup phase, the target voltage remains unchanged; wherein, when the difference between the photovoltaic panel voltage and the initial value of the preset target voltage is greater than a second preset threshold, it indicates that the general-purpose inverter is in the initial startup phase, and when the difference between the photovoltaic panel voltage and the initial value of the preset target voltage is less than the second preset threshold, it indicates that the general-purpose inverter is not in the initial startup phase.

[0030] The target voltage is used as the setpoint of the PID module, and the photovoltaic panel voltage is used as the feedback value of the PID module. The PID module performs PID adjustment based on the setpoint and the feedback value until the general-purpose frequency converter passes through the initial start-up phase.

[0031] According to some embodiments of the present invention, adjusting the target voltage by a preset first adjustment step size based on the direction of change of the output power of the general-purpose frequency converter and the direction of change of the target voltage includes:

[0032] When the output power of the general-purpose frequency converter changes in an increasing direction, and the target voltage changes in an increasing direction, the target voltage is increased according to the first adjustment step size;

[0033] When the output power of the general-purpose frequency converter changes in an increasing direction and the target voltage changes in a decreasing direction, the target voltage is reduced according to the first adjustment step size;

[0034] When the output power of the general-purpose frequency converter changes in a decreasing direction and the target voltage changes in a increasing direction, the target voltage is reduced according to the first adjustment step size;

[0035] When the output power of the general-purpose frequency converter changes in a decreasing direction, and the target voltage changes in a decreasing direction, the target voltage is increased according to the first adjustment step size.

[0036] Secondly, according to an embodiment of the present invention, an offline photovoltaic water pump system includes a photovoltaic panel, a general-purpose frequency converter, and a water pump motor connected in sequence. The general-purpose frequency converter is equipped with a PID module, and the offline photovoltaic water pump system is used to execute the working method of the offline photovoltaic water pump system described in the first aspect embodiment.

[0037] Thirdly, an electronic device according to an embodiment of the present invention includes at least one control processor and a memory for communicatively connecting to the at least one control processor; the memory stores instructions executable by the at least one control processor, the instructions being executed by the at least one control processor to enable the at least one control processor to perform the operation method of the offline photovoltaic water pump system as described in the first aspect embodiment.

[0038] Fourthly, according to an embodiment of the present invention, the storage medium stores computer-executable instructions for causing a computer to perform the working method of the offline photovoltaic water pump system described in the first aspect embodiment.

[0039] The offline photovoltaic water pump system, its operating method, electronic equipment, and medium according to embodiments of the present invention have at least the following beneficial effects: by employing the MPPT algorithm preset in this application, the maximum power point can be found quickly, thereby enabling the photovoltaic panel to operate at the maximum power point and drive the water pump motor. Simultaneously, this MPPT algorithm can be applied to general-purpose frequency converters without requiring a dedicated photovoltaic water pump frequency converter, thus reducing hardware costs.

[0040] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0041] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0042] Figure 1 This is a flowchart illustrating the steps of an offline photovoltaic water pump system according to an embodiment of the present invention.

[0043] Figure 2 This is a schematic diagram of the PV characteristic curve of a photovoltaic panel according to an embodiment of the present invention;

[0044] Figure 3 This is a schematic diagram of the IV characteristic curve of the photovoltaic panel according to an embodiment of the present invention;

[0045] Figure 4 This is a flowchart illustrating the steps of an offline photovoltaic water pump system according to an embodiment of the present invention.

[0046] Figure 5 for Figure 4 The flowchart of the specific steps in step S200. Detailed Implementation

[0047] The embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. The step numbers in the following embodiments are set only for ease of explanation, and there is no limitation on the order between the steps. The execution order of each step in the embodiments can be adaptively adjusted according to the understanding of those skilled in the art.

[0048] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0049] The terms "first," "second," "third," and "fourth," etc., used in the specification, claims, and accompanying drawings of this invention are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0050] In this invention, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0051] Offline photovoltaic (PV) water pump systems are suitable for suburban areas without grid power supply, where the PV panels are fixed in location and require no human intervention. These systems utilize solar panels to directly convert solar energy into electrical energy, which is then used by a frequency converter to drive the water pump motor.

[0052] The optimal operating point of a solar panel is called its maximum power point (MPP), which primarily depends on the panel's operating temperature and the prevailing sunlight level. The MPP varies under different temperatures and light intensities. Currently, to ensure the solar panel operates as close to its MPP as possible, a dedicated photovoltaic (PV) pump inverter is needed to detect the panel's voltage and current, thereby calculating the MPP. However, using a dedicated PV pump inverter is costly and requires new hardware development. Furthermore, current methods are not efficient at quickly determining the MPP.

[0053] To address this, embodiments of the present invention provide an offline photovoltaic water pump system and its operating method, electronic equipment, and medium. By employing the MPPT algorithm pre-defined in this application, the maximum power point can be found quickly, thereby enabling the photovoltaic panel to operate at its maximum power point and drive the water pump motor. Furthermore, this MPPT algorithm can be applied to general-purpose frequency converters, eliminating the need for a dedicated photovoltaic water pump frequency converter, thus reducing hardware costs.

[0054] The offline photovoltaic water pump system, its working method, electronic equipment, and medium according to embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0055] On the one hand, embodiments of the present invention propose an offline photovoltaic water pump system, such as... Figure 1 As shown, the offline photovoltaic water pump system includes a photovoltaic panel 100, a general-purpose frequency converter 200 and a water pump motor 300 connected in sequence. The general-purpose frequency converter 200 is equipped with a main control unit 210, a PID module 220, a bus voltage detection module 230, a current detection module 240, a PWM module 250 and an IGBT module 260.

[0056] The bus voltage detection module 230 detects the current bus voltage and sends it to the main control unit 210. When the water pump motor 300 is running, the bus voltage is equal to the operating voltage of the photovoltaic panel 100. When the water pump motor 300 is stopped, the bus voltage is equal to the open-circuit voltage of the photovoltaic panel 100, at which point no current flows and the voltage reaches its peak value. It should be noted that the bus voltage detection module 230 can use a voltage sensor, voltage sampling circuit, integrated detection module, etc., to collect the bus voltage. The current detection module 240 collects the output current of the general-purpose inverter 200 and feeds it back to the main control unit 210. The current detection module 240 can use a current sensor, current sampling circuit, integrated detection module, etc., to collect the output current. The main control unit 210 obtains the voltage and current information collected by the bus voltage detection module 230 and the current detection module 240, obtains the output power of the general-purpose inverter 200, and calculates the maximum power point using a preset MPPT algorithm. The PID module 220 performs PID (Proportional-Integral-Derivative) adjustment based on the target voltage and the actual voltage to obtain the desired frequency value. This frequency value controls the duty cycle of the PWM (Pulse Width Modulation) signal output by the PWM module 250, thereby controlling the on / off state of the IGBT module 260 and ultimately controlling the operation of the water pump motor 300. The input terminal of the IGBT module 260 is connected to the bus voltage, and its output terminal is connected to the water pump motor 300. The controlled terminal of the IGBT module 260 is connected to the output terminal of the PWM module 250. The PWM signal controls the switching of the IGBT module 260, which in turn controls the power of the photovoltaic panel 100 driving the water pump motor 300, ensuring that the photovoltaic panel 100 operates at its maximum power point.

[0057] With the water pump motor 300 stopped, the current bus voltage is acquired by the bus voltage detection module 230 and stored as the photovoltaic panel open-circuit voltage VOC_Voltage. Then, the target voltage for the MPPT algorithm is initialized and stored as MPPT_InitVol. An inappropriate setting of this variable will affect the processing time of the MPPT algorithm. In this example, through testing, MPPT_InitVol is set to 80% of VOC_Voltage to expedite the MPPT algorithm's processing time. It should be noted that MPPT_InitVol can also be set to other values, such as 70% or 75% of VOC_Voltage, without specific limitations. Simultaneously, the first adjustment step size Vmpp_Add is initialized. Vmpp_Add refers to the adjustment step size of the target voltage in the MPPT algorithm. In this example, the first adjustment step size Vmpp_Add is set to 1V. It should be noted that the first adjustment step size Vmpp_Add can also be set to other reasonable values, and is not limited to this. It should be noted that setting the first adjustment step size Vmpp_Add too large will cause the operating voltage of the photovoltaic panel 100 to fluctuate during the adjustment process, while setting it too small will result in untimely adjustment, leading to a power outage of the general-purpose inverter 200. When the general-purpose inverter 200 drives the water pump motor 300, as the speed of the water pump motor 300 increases, the load increases, and the output current increases accordingly. Figure 2 and Figure 3 As shown in the characteristic curve of the photovoltaic panel 100, when the current increases to a certain level, the voltage drops rapidly. In sudden situations such as clouds blocking the sun, the output voltage of the photovoltaic panel 100 may become too low. Therefore, the MPPT algorithm is needed to quickly find the maximum power point and rapidly adjust the operating point of the general-purpose inverter 200 to prevent the inverter 200 from restarting after a power outage. Furthermore, the calculation cycle needs to be initialized and stored as MPPT_Search_DeteaTime, which is the processing cycle of the MPPT algorithm. In this example, MPPT_Search_DeteaTime is set to 2ms to ensure that the previous MPPT algorithm has completed before the next execution. It should be noted that MPPT_Search_DeteaTime can also be set to other reasonable values, and is not limited to this.

[0058] In summary, when the water pump motor 300 stops, it is necessary to obtain the open-circuit voltage VOC_Voltage of the photovoltaic panel and initialize MPPT_InitVol, the first adjustment step size Vmpp_Add, and the calculation period MPPT_Search_DeteaTime.

[0059] When the water pump motor 300 is running, the MPPT algorithm phase is executed:

[0060] 1.1: When the general-purpose frequency converter 200 starts, it obtains the current bus voltage through the bus voltage detection module 230 and stores it as the photovoltaic panel voltage MPPT_PV_Voltage.

[0061] 1.2: Voltage Over-Limit Detection. This step checks if MPPT_PV_Voltage is within the preset range. Excessively high or low photovoltaic panel voltage can cause abnormal MPPT algorithm calculations. When the photovoltaic panel voltage is too low, it may cause the general-purpose inverter 200 to run out of power, preventing the system from operating normally. Therefore, a reasonable preset range needs to be set based on the normal operating range of the photovoltaic panel 100, and the MPPT_PV_Voltage should be checked to ensure it is within the preset range. If the voltage exceeds the limit, proceed to step 1.3; otherwise, proceed to step 1.4.

[0062] 1.3: MPPT_PV_Voltage exceeds the limit. The target voltage MPPT_Vmpp is assigned the value MPPT_InitVol, and the process jumps to the subsequent step 2.1 to perform PID adjustment so that MPPT_PV_Voltage falls within the preset range.

[0063] 1.4: If MPPT_PV_Voltage is not exceeded, the MPPT algorithm begins. It checks whether the calculation period MPPT_Search_DeteaTime has been reached. If it has, it jumps to step 1.5; if it has not, it waits until the time period arrives before jumping to step 1.5. During the waiting period, the general-purpose inverter 200 can perform other tasks to make efficient use of time.

[0064] 1.5: Determine if fast adjustment mode is needed: Determine if the target voltage MPPT_Vmpp (at this time, the target voltage is equal to MPPT_InitVol) is greater than MPPT_PV_Voltage + 10V. If so, it means that the deviation between the target voltage MPPT_Vmpp and the photovoltaic panel voltage MPPT_PV_Voltage is too large, which is not conducive to quickly searching for the MPPT point. In this case, enter fast adjustment mode. In fast adjustment mode, MPPT_Vmpp is adjusted rapidly by subtracting 10 times the first adjustment step size Vmpp_Add, so that MPPT_Vmpp quickly approaches MPPT_PV_Voltage to facilitate rapid MPPT point search. If fast adjustment mode is not needed, i.e., MPPT_Vmpp is not greater than MPPT_PV_Voltage + 10V, then proceed to step 1.6.

[0065] 1.6: Startup Phase Judgment: Determine if the general-purpose inverter 200 is in the initial startup phase. In the initial startup phase, MPPT_PV_Voltage > MPPT_Vmpp, the PID output is positive, the frequency increases, and the water pump motor 300 accelerates. In this example, to determine if the general-purpose inverter 200 is in the initial startup phase, check if the target voltage MPPT_Vmpp is less than the photovoltaic panel voltage MPPT_PV_Voltage - 15V. If so, it is considered to be in the startup phase, and the process jumps to step 1.7; otherwise, the process jumps to step 1.8.

[0066] 1.7: During the initial startup phase, MPPT_Vmpp remains unchanged and jumps to step 2.1 to perform PID adjustment until the initial startup phase is completed.

[0067] 1.8: Power direction detection. If the output power of the current general-purpose inverter 200 is increasing, jump to step 1.9. If the output power of the general-purpose inverter 200 is decreasing or remains unchanged, jump to step 1.9.1.

[0068] 1.9: Determining the direction of change of the target voltage MPPT_Vmpp. If the target voltage MPPT_Vmpp is increasing, it means that the current voltage is to the left of the MPPT point, so let MPPT_Vmpp = MPPT_Vmpp + Vmpp_Add; if the target voltage MPPT_Vmpp is decreasing or unchanged, it means that the current voltage is to the right of the MPPT point, so let MPPT_Vmpp = MPPT_Vmpp - Vmpp_Add.

[0069] 1.9.1: If the target voltage MPPT_Vmpp changes in an increasing direction, it means that the current voltage is to the right of the MPPT point, so let MPPT_Vmpp = MPPT_Vmpp - Vmpp_Add; if the target voltage MPPT_Vmpp changes in a decreasing or unchanged direction, it means that the current voltage is to the left of the MPPT point, so let MPPT_Vmpp = MPPT_Vmpp + Vmpp_Add.

[0070] It should be noted that during the initial startup phase, as the water pump motor accelerates at 300 rpm, the current and power increase. Therefore, MPPT_Vmpp is not adjusted during the initial startup phase; instead, PID control is applied directly. When the motor reaches a certain frequency, MPPT_PV_Voltage decreases due to PV characteristics. When it decreases to a certain level, the MPPT algorithm is triggered, and MPPT_Vmpp is adjusted in real time based on the output power of the previous cycle and MPPT_Vmpp. When MPPT_PV_Voltage = MPPT_Vmpp, the inverter output frequency remains unchanged, operating at its maximum power point. When the illumination suddenly changes, MPPT_PV_Voltage will change abruptly, causing a change in output power, which in turn leads to a change in MPPT_Vmpp.

[0071] 1.9.2: Target voltage MPPT_Vmpp exceeds the limit, is limited to the preset range, and relevant parameters are backed up for future use.

[0072] After the MPPT stage, the PID stage begins:

[0073] 2.0: The target voltage MPPT_Vmpp is used as the given voltage of the PID module 220, and the photovoltaic voltage MPPT_PV_Voltage is used as the feedback voltage of the PID module 220. PID calculation is performed to obtain the required frequency value; based on this frequency value, the water pump motor 300 is driven to run.

[0074] The offline photovoltaic water pump system according to an embodiment of the present invention, by employing the fast MPPT algorithm of this application, can find the maximum power point relatively quickly, thereby enabling the photovoltaic panel 100 to operate at the maximum power point and drive the water pump motor 300 to run. Simultaneously, this method can be applied to a general-purpose frequency converter 200 without requiring a dedicated photovoltaic water pump frequency converter, thus reducing hardware costs.

[0075] On the other hand, based on the aforementioned offline photovoltaic water pump system, this embodiment of the invention also proposes a method for operating the offline photovoltaic water pump system, such as... Figure 4 and Figure 5 As shown, the method includes the following steps:

[0076] Step S100: When the water pump motor 300 is running, the current bus voltage is collected through the general-purpose frequency converter 200 to obtain the photovoltaic panel voltage (MPPT_PV_Voltage);

[0077] Step S200: When the photovoltaic panel voltage is within the preset range, the target voltage is obtained by performing the preset MPPT algorithm through the general-purpose frequency converter 200;

[0078] Step S300: Use the target voltage as the given value of the PID module 220 and the photovoltaic panel voltage as the feedback value of the PID module 220, so that the PID module 220 can calculate the frequency value based on the given value and the feedback value.

[0079] Step S300: Drive the water pump motor 300 to run according to the frequency value;

[0080] Step S200 includes the following four sub-steps:

[0081] Step S210: Determine whether the water pump motor 300 is in the initial startup stage based on the preset target voltage MPPT_Vmpp and photovoltaic panel voltage MPPT_PV_Voltage.

[0082] Step S220: When the water pump motor 300 is not in the initial start-up stage, detect the direction of change of the output power of the general-purpose frequency converter 200 and the direction of change of the target voltage;

[0083] Step S230: Based on the direction of change of the output power of the general-purpose frequency converter 200 and the direction of change of the target voltage, adjust the target voltage Vmpp_Add by a preset first adjustment step size.

[0084] Specifically, when the water pump motor 300 is running, the MPPT algorithm is executed: the general-purpose inverter 200 starts, obtains the current bus voltage through the bus voltage detection module 230, and stores it as the photovoltaic panel voltage MPPT_PV_Voltage; then, a start-up phase judgment is performed: it is determined whether the general-purpose inverter 200 is in the initial start-up phase. In the initial start-up phase, MPPT_PV_Voltage > MPPT_Vmpp, the PID output is positive, the frequency increases, and the water pump motor 300 accelerates. In this example, when the difference between the photovoltaic panel voltage MPPT_PV_Voltage and the preset target voltage MPPT_Vmpp is greater than the second preset threshold, it indicates that the general-purpose inverter 200 is in the initial start-up phase; when the difference between the photovoltaic panel voltage MPPT_PV_Voltage and the preset target voltage MPPT_Vmpp is less than the second preset threshold, it indicates that the general-purpose inverter is not in the initial start-up phase. In this example, the second preset threshold is set to 15V. That is, if the target voltage MPPT_Vmpp is less than the photovoltaic panel voltage MPPT_PV_Voltage - 15V, it is considered to be in the initial startup phase; otherwise, it indicates that the initial startup phase has been completed. It should be noted that setting the second preset threshold to 15V is based on actual testing. The initial startup phase may differ under different circumstances, and different second preset thresholds can be set according to different situations, not just this one.

[0085] If the general-purpose inverter 200 has completed the initial startup phase, i.e., MPPT_Vmpp is not less than the photovoltaic panel voltage MPPT_PV_Voltage - 15V, then the direction of change in the output power of the general-purpose inverter 200 is detected. The main control unit 210 calculates the output power based on the voltage and current information collected by the bus voltage detection module 230 and the current detection module 240. By judging whether the previous output power was gradually increasing or gradually decreasing, the direction of change in the output power is determined. After determining the direction of change in the output power of the general-purpose inverter 200, the direction of change in the target voltage MPPT_Vmpp is then determined. If both the output power and the target voltage are increasing, it means that the current voltage is to the left of the MPPT point, so MPPT_Vmpp = MPPT_Vmpp + Vmpp_Add is set. If the output power is increasing, but the target voltage is decreasing, it means that the current voltage is to the right of the MPPT point, so MPPT_Vmpp = MPPT_Vmpp - Vmpp_Add is set. If the output power changes in a decreasing direction, and the target voltage MPPT_Vmpp changes in an increasing direction, then the current voltage is to the right of the MPPT point, and we let MPPT_Vmpp = MPPT_Vmpp - Vmpp_Add. If the output power changes in a decreasing direction, and the target voltage MPPT_Vmpp changes in a decreasing or unchanged direction, then the current voltage is to the left of the MPPT point, and we let MPPT_Vmpp = MPPT_Vmpp + Vmpp_Add.

[0086] Then, the target voltage MPPT_Vmpp is used as the given voltage of the PID module 220, and the photovoltaic panel voltage MPPT_PV_Voltage is used as the feedback voltage of the PID module 220. PID calculation is performed to obtain the required frequency value. Based on this frequency value, the duty cycle of the PWM signal (Pulse Width Modulation) output by the PWM module 250 is controlled, thereby controlling the on and off of the IGBT module 260, which in turn controls the operation of the water pump motor 300, so that the photovoltaic panel 100 drives the water pump motor 300 to operate at the maximum power point.

[0087] If the general-purpose inverter 200 is found to be in the initial startup phase, the target voltage MPPT_Vmpp is kept unchanged; the target voltage MPPT_Vmpp is used as the setpoint of the PID module 220, and the photovoltaic voltage MPPT_PV_Voltage is used as the feedback value of the PID module 220, so that the PID module 220 performs PID adjustment according to the setpoint and feedback value until the general-purpose inverter 200 passes the initial startup phase.

[0088] It should be noted that during the initial startup phase, as the water pump motor accelerates at 300 rpm, the current and power increase. Therefore, MPPT_Vmpp is not adjusted during the initial startup phase; instead, PID control is applied directly. When the motor reaches a certain frequency, MPPT_PV_Voltage decreases due to PV characteristics. When it decreases to a certain level, the MPPT algorithm is triggered, and MPPT_Vmpp is adjusted in real time based on the output power of the previous cycle and MPPT_Vmpp. When MPPT_PV_Voltage = MPPT_Vmpp, the inverter output frequency remains unchanged, operating at its maximum power point. When the illumination suddenly changes, MPPT_PV_Voltage will change abruptly, causing a change in output power, which in turn leads to a change in MPPT_Vmpp.

[0089] In some embodiments, before the offline photovoltaic water pump system is put into operation, when the offline photovoltaic water pump system is shut down, the following three steps are also included:

[0090] The current bus voltage is collected by the general-purpose frequency converter 200 to obtain the open-circuit voltage VOC_Voltage of the photovoltaic panel;

[0091] Based on the open-circuit voltage VOC_Voltage of the photovoltaic panel, set the initial value of the target voltage MPPT_Vmpp to obtain the preset target voltage;

[0092] Initialize the first adjustment step size Vmpp_Add and the calculation period MPPT_Search_DeteaTime; the calculation period represents the preset processing period of the MPPT algorithm.

[0093] Specifically, with the water pump motor 300 stopped, the current bus voltage is acquired through the bus voltage detection module 230 and stored as the photovoltaic panel open-circuit voltage VOC_Voltage. Then, the target voltage for the MPPT algorithm is initialized and stored as MPPT_InitVol (this value is assigned to the target voltage MPPT_Vmpp). An unreasonable setting of this variable will affect the processing time of the MPPT algorithm. In this example, through testing, MPPT_InitVol is set to 80% of VOC_Voltage to speed up the MPPT algorithm's processing time as much as possible. It should be noted that MPPT_InitVol can also be set to other values, such as 70% or 75% of VOC_Voltage, without specific limitations. Simultaneously, the first adjustment step size Vmpp_Add is initialized. The first adjustment step size Vmpp_Add refers to the adjustment step size of the target voltage in the MPPT algorithm. In this example, the first adjustment step size Vmpp_Add is set to 1V. It should be noted that the first adjustment step size Vmpp_Add can also be set to other reasonable values, and is not limited to this. It should be noted that setting the first adjustment step size Vmpp_Add too large will cause the operating voltage of the photovoltaic panel 100 to fluctuate during the adjustment process, while setting it too small will result in untimely adjustment, leading to a power outage of the general-purpose inverter 200. When the general-purpose inverter 200 drives the water pump motor 300, as the speed of the water pump motor 300 increases, the load increases, and the output current increases. As can be seen from the characteristic curve of the photovoltaic panel 100, when the current increases to a certain level, the voltage will drop rapidly, or in sudden situations such as clouds blocking the sun, the output voltage of the photovoltaic panel 100 will be too low. Therefore, the MPPT algorithm needs to quickly find the maximum power point and quickly adjust the operating point of the general-purpose inverter 200 to prevent the general-purpose inverter 200 from powering down and restarting. In addition, it is also necessary to initialize the calculation cycle and store it as MPPT_Search_DeteaTime, which is the processing cycle of the MPPT algorithm. In this example, MPPT_Search_DeteaTime is set to 2ms to ensure that the previous MPPT algorithm has been completed before the next execution of the MPPT algorithm. It should be noted that MPPT_Search_DeteaTime can also be set to other reasonable values, and is not limited to this.

[0094] In summary, when the water pump motor 300 stops, it is necessary to obtain the open-circuit voltage VOC_Voltage of the photovoltaic panel and initialize MPPT_InitVol, the first adjustment step size Vmpp_Add, and the calculation period MPPT_Search_DeteaTime.

[0095] In some embodiments of this application, after obtaining the preset target voltage MPPT_Vmpp and photovoltaic panel voltage MPPT_PV_Voltage in step S110 above, it is necessary to first determine whether the photovoltaic panel voltage MPPT_PV_Voltage is within a preset range. If the photovoltaic panel voltage MPPT_PV_Voltage is within the preset range, it is further determined whether the water pump motor 300 is in the initial startup stage. If the photovoltaic panel voltage MPPT_PV_Voltage is not within the preset range, the following steps are performed:

[0096] When the photovoltaic panel voltage MPPT_PV_Voltage is not within the preset range, the target voltage MPPT_Vmpp is assigned the initial value MPPT_InitVol.

[0097] The assigned target voltage is used as the setpoint of the PID module 220, and the photovoltaic panel voltage MPPT_PV_Voltage is used as the feedback value of the PID module 220. The PID module 220 performs PID adjustment according to the setpoint and feedback value until the photovoltaic panel voltage MPPT_PV_Voltage is within the preset range.

[0098] It should be noted that determining whether MPPT_PV_Voltage is within the preset range is necessary because excessively high or low photovoltaic panel voltage can cause abnormal MPPT algorithm calculations. When the photovoltaic panel voltage is too low, it may cause the general-purpose inverter 200 to run out of power, preventing the system from operating normally. Therefore, it is necessary to set a reasonable preset range based on the normal operating range of the photovoltaic panel 100 and determine whether MPPT_PV_Voltage is within the preset range.

[0099] In some embodiments of this application, after determining that MPPT_PV_Voltage falls within a preset range, the following two steps are further included:

[0100] Obtain the difference between the preset target voltage MPPT_Vmpp and the photovoltaic panel voltage MPPT_PV_Voltage;

[0101] When the difference between the preset target voltage MPPT_Vmpp and the photovoltaic panel voltage MPPT_PV_Voltage is greater than the first preset threshold, the target voltage is adjusted by the second adjustment step size so that the difference between the target voltage and the photovoltaic panel voltage is less than the first preset threshold; the second adjustment step size is greater than the first adjustment step size.

[0102] Specifically, obtaining the difference between the preset target voltage MPPT_Vmpp and the photovoltaic panel voltage MPPT_PV_Voltage is to determine whether to enter the fast adjustment mode. In this example, the first preset threshold is set to 10V. When the target voltage MPPT_Vmpp is greater than MPPT_PV_Voltage + 10V, it indicates that the deviation between the target voltage MPPT_Vmpp and the photovoltaic panel voltage MPPT_PV_Voltage is too large, which is not conducive to quickly searching for the MPPT point, so the fast adjustment mode is entered. In the fast adjustment mode, MPPT_Vmpp is adjusted quickly with a second adjustment step size. In this example, the second adjustment step size is set to 10 times the first adjustment step size Vmpp_Add, so that MPPT_Vmpp quickly approaches MPPT_PV_Voltage, and then PID adjustment is performed to quickly search for the MPPT point. If the fast adjustment mode is not needed, that is, MPPT_Vmpp is not greater than MPPT_PV_Voltage + 10V, then the subsequent step of determining whether the water pump motor 300 is in the initial start-up stage is performed normally. It should be noted that the first preset threshold and the second adjustment step size can be set to other values ​​according to the actual situation, and are not limited to these.

[0103] In some embodiments, when performing the MPPT algorithm in step S200, the following three steps also need to be performed:

[0104] When the photovoltaic panel voltage MPPT_PV_Voltage is within the preset range, determine whether the current time meets the calculation period MPPT_Search_DeteaTime.

[0105] If the calculation period MPPT_Search_DeteaTime is met, the frequency value is obtained by performing the preset MPPT algorithm through the general-purpose frequency converter 200.

[0106] If the calculation cycle is not met, wait until the calculation cycle is reached, and then use the preset MPPT algorithm through the general-purpose inverter 200 to obtain the frequency value.

[0107] In this example, MPPT_Search_DeteaTime is set to 2ms to ensure that the previous MPPT algorithm has completed before the next execution. It should be noted that MPPT_Search_DeteaTime can also be set to other reasonable values, and is not limited to this one.

[0108] It should be noted that during the initial startup phase, as the water pump motor accelerates at 300 rpm, the current and power increase. During startup, MPPT_Vmpp is not adjusted. When the motor reaches a certain frequency, due to the PV characteristics, MPPT_PV_Voltage decreases. When it decreases to a certain level, the MPPT algorithm is triggered, and MPPT_Vmpp is adjusted in real time based on the output power of the previous cycle and MPPT_Vmpp. When MPPT_PV_Voltage = MPPT_Vmpp, the inverter output frequency remains constant, operating at its maximum power point. When the illumination suddenly changes, MPPT_PV_Voltage will change abruptly, causing a change in output power, which in turn leads to a change in MPPT_Vmpp.

[0109] According to the offline photovoltaic water pump system operation method of the embodiments of this application, by employing the fast MPPT algorithm of this application, the maximum power point can be found quickly, thereby enabling the photovoltaic panel 100 to operate at the maximum power point and drive the water pump motor 300 to run. Simultaneously, this method can be applied to a general-purpose frequency converter 200 without requiring a dedicated photovoltaic water pump frequency converter, thus reducing hardware costs.

[0110] On the other hand, embodiments of the present invention also provide an electronic device, including at least one control processor and a memory for communicatively connecting to the at least one control processor; the memory stores instructions executable by the at least one control processor, the instructions being executed by the at least one control processor to enable the at least one control processor to perform the above-described operating method of the offline photovoltaic water pump system.

[0111] On the other hand, embodiments of the present invention also provide a storage medium, which is a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described working method of the offline photovoltaic water pump system.

[0112] Memory, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs and non-transitory computer-executable programs. Furthermore, memory may include high-speed random access memory, and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some embodiments, memory may optionally include memory remotely located relative to the processor, and these remote memories can be connected to the processor via a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof. The device embodiments described above are merely illustrative, and the units described as separate components may or may not be physically separate, and may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0113] Although specific embodiments are described herein, those skilled in the art will recognize that many other modifications or alternative embodiments are also within the scope of this disclosure. For example, any of the functions and / or processing capabilities described in connection with a particular device or component can be performed by any other device or component. Furthermore, while various exemplary embodiments and architectures have been described according to embodiments of this disclosure, those skilled in the art will recognize that many other modifications to the exemplary embodiments and architectures described herein are also within the scope of this disclosure.

[0114] The foregoing description, with reference to block diagrams and flowcharts of systems, methods, systems, and / or computer program products according to exemplary embodiments, has described certain aspects of this disclosure. It should be understood that one or more blocks in the block diagrams and flowcharts, as well as combinations of blocks in the block diagrams and flowcharts, can be implemented by executing computer-executable program instructions, respectively. Similarly, according to some embodiments, some blocks in the block diagrams and flowcharts may not need to be executed in the order shown, or may not all need to be executed. Furthermore, additional components and / or operations beyond those shown in the blocks in the block diagrams and flowcharts may exist in some embodiments.

[0115] Therefore, blocks in block diagrams and flowcharts support combinations of means for performing a specified function, combinations of elements or steps for performing a specified function, and program instruction means for performing a specified function. It should also be understood that each block in a block diagram and flowchart, and combinations of blocks in block diagrams and flowcharts, can be implemented by a dedicated hardware computer system or a combination of dedicated hardware and computer instructions that performs a specific function, element, or step.

[0116] The program modules, applications, etc., described herein may include one or more software components, including, for example, software objects, methods, data structures, etc. Each such software component may include computer-executable instructions that, in response to execution, cause at least a portion of the functionality described herein (e.g., one or more operations of the exemplary methods described herein) to be performed.

[0117] Software components can be coded using any of a variety of programming languages. An exemplary programming language could be a low-level programming language, such as assembly language associated with a specific hardware architecture and / or operating system platform. Software components including assembly language instructions may need to be converted into executable machine code by an assembler before being executed by the hardware architecture and / or platform. Another exemplary programming language could be a higher-level programming language that is portable across multiple architectures. Software components including higher-level programming languages ​​may need to be converted into an intermediate representation by an interpreter or compiler before execution. Other examples of programming languages ​​include, but are not limited to, macro languages, shell or command languages, job control languages, scripting languages, database query or search languages, or report writing languages. In one or more exemplary embodiments, a software component containing instructions from one of the above-described programming language examples can be executed directly by the operating system or other software components without first being converted into another form.

[0118] Software components can be stored as files or other data storage structures. Software components of similar type or related function can be stored together in a specific directory, folder, or library. Software components can be static (e.g., pre-defined or fixed) or dynamic (e.g., created or modified at runtime).

[0119] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method of operating an off-grid photovoltaic water pumping system, characterized in that, The off-line photovoltaic water pump system comprises a photovoltaic panel, a general frequency converter and a water pump motor connected in sequence, and the general frequency converter is provided with a PID module; the method comprises: When the water pump motor is running, the current bus voltage is collected by the general frequency converter to obtain the photovoltaic panel voltage; When the photovoltaic panel voltage is within a preset range, a preset MPPT algorithm is performed by the general frequency converter to obtain a target voltage; The target voltage is taken as the given value of the PID module, and the photovoltaic panel voltage is taken as the feedback value of the PID module, so that the PID module calculates according to the given value and the feedback value to obtain a frequency value; According to the frequency value, the water pump motor is driven to run; The method further comprises the following steps before the step of collecting the current bus voltage by the general frequency converter to obtain the photovoltaic panel voltage when the water pump motor is running: When the water pump motor is stopped, the current bus voltage is collected by the general frequency converter to obtain the open-circuit voltage of the photovoltaic panel; According to the open-circuit voltage of the photovoltaic panel, the initial value of the target voltage is set; The first adjustment step and a calculation period are initialized; the calculation period represents the processing period of the preset MPPT algorithm.

2. The method of operating an off-grid photovoltaic water pumping system as claimed in claim 1, wherein, The method further comprises the following steps after the step of collecting the bus voltage by the general frequency converter to obtain the photovoltaic panel voltage when the water pump motor is running: When the photovoltaic panel voltage is not within the preset range, the target voltage is assigned the initial value; The assigned target voltage is taken as the given value of the PID module, and the photovoltaic panel voltage is taken as the feedback value of the PID module, so that the PID module performs PID adjustment according to the given value and the feedback value to adjust the photovoltaic panel voltage until the photovoltaic panel voltage is within the preset range. The method further comprises the following steps when the photovoltaic panel voltage is within the preset range:

3. The method of operating an off-grid photovoltaic water pumping system as claimed in claim 2, wherein, When the photovoltaic panel voltage is within the preset range, it is judged whether the current time meets the calculation period; If the calculation period is met, the preset MPPT algorithm is performed by the general frequency converter to obtain the target voltage; If the calculation period is not met, the preset MPPT algorithm is performed by the general frequency converter to obtain the target voltage after the calculation period is reached.

4. The method of operating an off-grid photovoltaic water pumping system as claimed in claim 2, wherein, The method further comprises the following steps before the step of judging whether the general frequency converter is in the initial starting stage: The difference between the initial value of the preset target voltage and the photovoltaic panel voltage is obtained. ​ ​ 5. The method of operating an off-grid photovoltaic water pumping system according to claim 1, wherein, ​ ​ When the difference between the initial value of the preset target voltage and the photovoltaic panel voltage is greater than a first preset threshold, the target voltage is adjusted by a second adjustment step, so that the difference between the target voltage and the photovoltaic panel voltage is less than the first preset threshold; the second adjustment step is greater than the first adjustment step.

6. The method of operating an off-grid photovoltaic water pumping system according to claim 1, wherein, After the step of determining whether the general frequency converter is in the initial starting stage according to the initial value of the preset target voltage and the photovoltaic panel voltage, the method further comprises: When the general frequency converter is in the initial starting stage, the target voltage is kept unchanged; wherein, when the difference between the photovoltaic panel voltage and the initial value of the preset target voltage is greater than a second preset threshold, it indicates that the general frequency converter is in the initial starting stage; when the difference between the photovoltaic panel voltage and the initial value of the preset target voltage is less than the second preset threshold, it indicates that the general frequency converter is not in the initial starting stage; The target voltage is taken as the given value of the PID module, and the photovoltaic panel voltage is taken as the feedback value of the PID module, so that the PID module performs PID adjustment according to the given value and the feedback value until the general frequency converter passes through the initial starting stage.

7. The method of operating an off-grid photovoltaic water pumping system as claimed in claim 2, wherein, The step of adjusting the target voltage by a preset first adjustment step according to the change direction of the output power of the general frequency converter and the change direction of the target voltage comprises: When the change direction of the output power of the general frequency converter is increasing, and the change direction of the target voltage is increasing, the target voltage is increased according to the first adjustment step; When the change direction of the output power of the general frequency converter is increasing, and the change direction of the target voltage is decreasing, the target voltage is decreased according to the first adjustment step; When the change direction of the output power of the general frequency converter is decreasing, and the change direction of the target voltage is increasing, the target voltage is decreased according to the first adjustment step; When the change direction of the output power of the general frequency converter is decreasing, and the change direction of the target voltage is decreasing, the target voltage is increased according to the first adjustment step.

8. An off-grid photovoltaic water pumping system characterized in that, The offline photovoltaic water pump system comprises a photovoltaic panel, a general frequency converter and a water pump motor connected in sequence, the general frequency converter is provided with a PID module, and the offline photovoltaic water pump system is used to execute the working method of the offline photovoltaic water pump system according to any one of claims 1 to 7.

9. An electronic device, comprising: The storage medium stores computer executable instructions, and the computer executable instructions are used to make a computer execute the working method of the offline photovoltaic water pump system according to any one of claims 1 to 7.

10. A storage medium, characterized by ​

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