Secondary pressurized cleaning system for rooftop photovoltaic modules

Abstract

This invention relates to the field of photovoltaic module cleaning and fluid control technology, specifically a secondary pressurization cleaning system for rooftop photovoltaic modules. The system includes a water tank, a mechanical float valve, an inlet solenoid valve, a booster pump, a frequency converter, nozzles, and an opening / closing status detection device. The system collects data on inlet water pressure, liquid level, instantaneous flow rate, and dynamic pressure. Based on the inlet water pressure, liquid level, and the status of the mechanical float valve, it controls the inlet solenoid valve to maintain constant pressure in the water tank. It calculates the rate of change of instantaneous flow rate and dynamic pressure, extracts resistance mutation signals, and generates target outlet pressure and frequency converter control signals according to a preset pipeline resistance model. The system is suitable for rooftop applications with alternating dual-nozzle operation, single-nozzle closure, and fluctuating inlet water pressure, enabling separation of water replenishment control and pressurization regulation.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic module cleaning and fluid control technology, specifically a secondary pressurization cleaning system for rooftop photovoltaic modules. Background Technology

[0002] In existing rooftop photovoltaic module cleaning systems, water is typically supplied directly to the cleaning nozzles via a water supply pipeline, or a simple water storage unit is installed between the water supply end and the booster device before the cleaning water is delivered to the nozzles. Multiple nozzles can be supplied with water by the same booster pump to meet the needs of two-person or alternating operations during roof cleaning. During the cleaning process, the number of nozzles that are turned on, the pipeline resistance, and the water pressure at the water supply end may all change, resulting in dynamic fluctuations in the flow rate and pressure at the nozzles. However, existing systems are prone to interference between the water inlet process and the water head pressurization process when switching between nozzle opening and closing, temporarily shutting down a single branch, or when the water supply pressure fluctuates. This can lead to problems such as unstable water tank replenishment, large fluctuations in nozzle outlet pressure, and lag in booster pump adjustment, making it difficult to balance the stability of normal pressure water replenishment with the timeliness of nozzle side pressure adjustment. Summary of the Invention

[0003] The purpose of this invention is to provide a secondary pressurization cleaning system for roof photovoltaic modules, which avoids the direct transmission of changes in inlet water pressure to the nozzle side, makes it easier to control the frequency conversion adjustment of the booster pump under different nozzle opening and closing conditions, and achieves long-term adaptive correction of the pipeline resistance model.

[0004] The objective of this invention can be achieved through the following technical solutions: The rooftop photovoltaic module secondary pressurization cleaning system includes: a water tank, a mechanical float valve, an inlet solenoid valve, a booster pump, a frequency converter, two nozzles, and opening / closing status detection devices connected to the two nozzles respectively, as well as: The hydraulic data acquisition module is used to acquire data collected by multiple hydraulic sensors to form parameter data characterizing the hydraulic state. The parameter data includes at least inlet pressure, liquid level, instantaneous flow rate data, and dynamic pressure data. The buffer tank control module is used to determine the tank status based on the inlet water pressure and liquid level, and the opening and closing status of the mechanical float valve, and generate a control signal for the inlet solenoid valve to control the opening and closing of the inlet solenoid valve. The resistance mutation identification module is used to calculate the rate of change of instantaneous flow rate and dynamic pressure data, obtain the flow rate change rate and pressure rate change rate, and extract the resistance mutation signal based on the flow rate change rate and pressure rate change rate. The variable frequency control module is used to calculate the target outlet pressure value according to the preset pipeline resistance model after receiving the resistance change signal, and convert it into the variable frequency control signal corresponding to the booster pump and send it to the frequency converter.

[0005] Furthermore, the resistance mutation identification module includes: The rate of change calculation unit is used to calculate the rate of change of instantaneous flow rate data and dynamic pressure data to obtain the flow rate of change and pressure rate of change; The feature extraction unit is used to output resistance change signals when the rate of change of flow and the rate of change of pressure are greater than the corresponding warning thresholds.

[0006] Furthermore, the parameter data also includes ambient temperature parameters and booster pump outlet dynamic pressure parameters; Instantaneous flow data includes the instantaneous flow parameters of the first nozzle and the instantaneous flow parameters of the second nozzle; The warning thresholds include the traffic warning threshold and the pressure warning threshold.

[0007] Furthermore, the buffer tank control module includes: The state threshold judgment unit is used to judge the relationship between the inlet pressure and the preset inlet safety pressure threshold, the liquid level height and the preset lower limit safety water level threshold and upper limit water level threshold, respectively. The valve control unit is used to generate a control signal for the inlet solenoid valve based on the judgment result of the state threshold judgment unit and in combination with the opening and closing status of the mechanical float valve.

[0008] Furthermore, the valve control unit is configured as follows: When the liquid level is less than the lower limit safe water level threshold and the inlet pressure is greater than the inlet safe pressure threshold, a control signal is generated to open the inlet solenoid valve. When the liquid level is greater than or equal to the upper limit water level threshold, or when the mechanical float valve is closed, a control signal to close the inlet solenoid valve is generated. In other states, a control signal is generated to maintain the current state of the inlet solenoid valve.

[0009] Furthermore, the frequency converter module includes: The target pressure calculation unit is used to obtain the total instantaneous flow of the nozzles currently in the open state based on the detection results of the open / closed state detection device, and to determine the target outlet pressure value by combining the preset comprehensive coefficient and the preset basic dynamic pressure. The frequency conversion unit is used to generate a frequency conversion control signal based on the target outlet pressure value; The ramp adjustment unit is used to limit the ramp of the frequency converter control signal to obtain the operating frequency control signal sent to the frequency converter.

[0010] Furthermore, the base dynamic pressure is a pressure value predetermined based on the nozzle installation height and spray distance; The target outlet pressure value is determined based on the positive correlation between the basic dynamic pressure, the preset comprehensive coefficient, and the sum of the instantaneous flow rate of the nozzle.

[0011] Furthermore, the slope adjustment unit is configured as follows: Obtain the difference parameter between the current frequency control signal and the previous operating frequency control signal. If the absolute value of the difference is greater than the preset frequency change rate limit threshold, then limit the increase or decrease of the operating frequency control signal to the frequency change rate limit threshold. If the absolute value of the difference is less than or equal to the frequency change rate limit threshold, the operating frequency control signal is updated directly according to the difference.

[0012] Furthermore, the system also includes a resistance coefficient correction module, which is used to obtain the actual outlet pressure and update the preset comprehensive coefficient in the pipeline resistance model based on the average deviation parameter between the actual outlet pressure and the target outlet pressure value within a preset time window, combined with a preset step size.

[0013] Furthermore, the system includes an atmospheric pressure buffer water supply device and a variable frequency booster device in the actuator section; The atmospheric pressure buffer water supply device corresponds to the buffer water tank control module. The water tank is an atmospheric pressure storage tank. The mechanical float valve is set at the water inlet of the atmospheric pressure storage tank, and the water inlet solenoid valve is set in series at the front end of the mechanical float valve. The variable frequency booster device corresponds to the variable frequency adjustment module. The booster pump draws water from the atmospheric pressure water storage tank. The frequency converter drives the booster pump. Two nozzles are connected to the roof and are adjustable nozzles.

[0014] The beneficial effects of this invention are: 1. This invention, by setting up a ramp adjustment unit during frequency conversion regulation, limits the difference between the current frequency conversion control signal and the previous operating frequency control signal, thereby preventing excessively rapid pump speed changes from causing significant hydraulic impact, reducing the risk of water hammer and mechanical impact, and improving the stability of system operation. 2. By setting a resistance coefficient correction module, this invention gradually updates the preset comprehensive coefficient in the pipeline resistance model based on the residual between the actual outlet pressure and the target outlet pressure value and the average residual within a preset time window. This can adapt to long-term operating conditions such as hose bending and local resistance changes, reduce the need for repeated calibration, and improve the system's adaptability to changes in on-site pipeline conditions. 3. This invention executes water replenishment control, resistance change identification, and pump speed adjustment along their respective data paths, ensuring that changes in the first part of the state do not directly interrupt the subsequent calculation process. This allows for the simultaneous consideration of the stability of normal pressure water replenishment and the timeliness of nozzle side pressure adjustment, effectively solving the problems of unstable water tank replenishment, large fluctuations in nozzle outlet pressure, and lag in booster pump adjustment in existing roof photovoltaic module cleaning systems. Attached Figure Description

[0015] Other features, objects, and advantages of the invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a structural block diagram of the secondary pressurization and cleaning system for roof photovoltaic modules in an embodiment of this application. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] Please see Figure 1 The roof photovoltaic module secondary pressurization cleaning system includes: a water tank, a mechanical float valve, an inlet solenoid valve, a booster pump, a frequency converter, two nozzles, an opening and closing status detection device connected to the two nozzles respectively, and a hydraulic data acquisition module, which is used to acquire data collected by multiple hydraulic sensors to form parameter data characterizing the hydraulic state. The parameter data includes at least inlet pressure, liquid level height, instantaneous flow rate data and dynamic pressure data. The buffer tank control module is used to determine the tank status based on the inlet water pressure and liquid level, and the opening and closing status of the mechanical float valve, and generate a control signal for the inlet solenoid valve to control the opening and closing of the inlet solenoid valve. The resistance mutation identification module is used to calculate the rate of change of instantaneous flow rate and dynamic pressure data, obtain the flow rate change rate and pressure rate change rate, and extract the resistance mutation signal based on the flow rate change rate and pressure rate change rate. The variable frequency control module is used to calculate the target outlet pressure value according to the preset pipeline resistance model after receiving the resistance change signal, and convert it into the variable frequency control signal corresponding to the booster pump and send it to the frequency converter. The resistance change identification module includes: a rate of change calculation unit, used to calculate the rate of change of instantaneous flow data and dynamic pressure data to obtain the flow rate of change and the pressure rate of change; and a feature extraction unit, used to output a resistance change signal when the flow rate of change and the pressure rate of change are greater than the corresponding warning thresholds. The parameter data also includes ambient temperature parameters and booster pump outlet dynamic pressure parameters; instantaneous flow data includes instantaneous flow parameters of the first nozzle and the second nozzle; warning thresholds include flow warning thresholds and pressure warning thresholds.

[0018] The system is installed at the photovoltaic module cleaning site on the roof of an industrial plant. The water supply end is connected to the plant's water intake pipeline, and the water outlet end is connected to two nozzles for the workers to use. When the system is running, the plant's pipeline network is not directly connected to the nozzle booster circuit. Instead, the incoming water is first introduced into the water tank, and then the booster pump draws water from the water tank and sends it to the nozzle. This decouples and isolates the water intake fluctuations from the nozzle water output process, and avoids the direct transmission of changes in inlet water pressure to the nozzle side. After the system is powered on, the hydraulic data acquisition module continuously reads the inlet pressure, liquid level, instantaneous flow rate of each nozzle, and dynamic pressure data in the pipeline, and organizes the data collected in the same period into parameter data for the current period for subsequent control modules to call. For two nozzles, the opening and closing status detection device indicates whether each nozzle is in the open state, so as to determine the number of branches currently participating in water output. The opening and closing status detection device is a micro switch installed at the nozzle valve or a water flow switch installed on the nozzle branch. If a sensor fails to generate a valid sample value in the current cycle, the module retains the valid data from the previous cycle for temporary use in the current cycle, and marks the data as missing to avoid interruption of subsequent judgments due to a single abnormal acquisition. After normal sampling resumes in subsequent cycles, the recovered real-time data will replace the missing data. After receiving the inlet water pressure, liquid level and the opening and closing status of the mechanical float valve for the current cycle, the buffer tank control module makes a judgment on whether the tank should continue to be replenished with water. Its basic control logic is to maintain the water tank in a normal pressure water inlet state, that is, the electronically controlled water inlet solenoid valve is only turned on when the water replenishment conditions are met, and water replenishment stops once the liquid level reaches the upper limit condition or the mechanical float valve is in the closed state. The control result does not need to participate in the pressure regulation calculation on the nozzle side, but is sent directly to the inlet solenoid valve as an independent valve control signal, thereby separating the water replenishment process from the pressurization process. If the inlet water pressure is insufficient to support continued water replenishment, the buffer tank control module will no longer issue an opening command and will maintain the current valve status to avoid continuing to draw water when the pressure at the water intake end is low. On the nozzle side, after receiving instantaneous flow rate data and dynamic pressure data, the resistance change identification module first calculates the rate of change of the sampling results for two consecutive cycles. For the flow rate, the instantaneous flow rate parameters of the first and second nozzles can be used to generate their respective changes, and then the flow rate changes related to the current pipeline conditions can be extracted from them; for the pressure, the pressure changes can be generated using the dynamic pressure parameters at the outlet of the booster pump. The rate of change calculation unit completes the above processing; the feature extraction unit compares the flow rate of change and the pressure rate of change with their respective warning thresholds; when both exceed the corresponding thresholds, a resistance change signal is output, indicating that the nozzle opening / closing or the branch resistance has changed beyond the warning threshold. If only one of the parameters exceeds the threshold, or if neither of the parameters exceeds the threshold, the signal will not be output and the system will maintain the voltage regulation result from the previous round. For example: Let the system sampling period be... s, the traffic warning threshold is set to The pressure warning threshold is set to ; In two consecutive sampling periods, if the flow rate of the first nozzle in the previous period is The second nozzle is That is, the total flow is The booster pump outlet dynamic pressure is ; The total flow rate suddenly changed during the current cycle due to a nozzle suddenly closing or a blockage in the pipeline. Dynamic pressure becomes ; The rate of change calculation unit calculates the absolute values ​​of the flow rate change rate and the pressure rate of change respectively: the flow rate change rate is... The rate of change of pressure ; The feature extraction unit compares the above results with the warning threshold, and determines the threshold accordingly. Greater than ,and Greater than Both exceed the threshold, thus reliably outputting the resistance mutation signal; The parameter data further includes ambient temperature parameters and booster pump outlet dynamic pressure parameters; the ambient temperature parameters are used to reflect the thermal environment around the roof and water tank. The dynamic pressure parameters at the booster pump outlet are directly involved in the calculation of the pressure change rate. Since the instantaneous flow data is subdivided into the instantaneous flow parameters of the first nozzle and the instantaneous flow parameters of the second nozzle, the system can distinguish whether a single nozzle suddenly closes or two nozzles change synchronously, and identify different forms of flow mutation accordingly. Correspondingly, the flow warning threshold and the pressure warning threshold together constitute the judgment condition, which is used to constrain the timing of the output of the resistance change signal and avoid unnecessary pressure regulation actions caused by fluctuations that have not reached the warning threshold. The flow warning threshold and pressure warning threshold are calibrated based on historical parameter fluctuation statistics under typical operating conditions such as normal nozzle spraying and sudden shut-off of a single nozzle during the system commissioning phase. The maximum value of the corresponding parameter fluctuation under normal operating conditions to The warning threshold is set at times, thereby ensuring that the inherent background noise of the water flow in the pipe network can be effectively filtered out and that it can be triggered sensitively when there is a substantial change in the pipe resistance condition. After receiving a resistance change signal, the frequency conversion control module no longer uses the control results before the change, but recalculates the target outlet pressure value required on the nozzle side based on the preset pipeline resistance model. Once the target outlet pressure value is formed, it is converted into a corresponding frequency converter control signal and sent to the frequency converter to change the operating frequency of the booster pump. In terms of the specific signal conversion mechanism, the frequency conversion control module is pre-installed with a two-dimensional lookup table of flow-pressure-frequency mapping formed based on the hydraulic characteristics calibration of the booster pump. The frequency conversion control module extracts the sum of the instantaneous flow of the nozzles currently in the open state as the first dimension horizontal index of the table, and uses the calculated target outlet pressure value as the second dimension vertical index of the table. Bilinear matching and grid interpolation calculation are performed in the two-dimensional lookup table, and the matching frequency set value is directly output as the frequency conversion control signal. If no resistance change signal is received in the current cycle, the frequency converter can continue to maintain the frequency converter control signal that was issued in the previous cycle and is still valid, thereby avoiding frequent adjustments under normal small fluctuations; Water tank replenishment control, resistance identification, and pump speed adjustment are executed along their respective data paths. Changes in the state of the former will not directly interrupt the calculation process of the latter. This is suitable for roof cleaning conditions where two nozzles are turned on alternately, a single nozzle is temporarily turned off, and the water inlet pressure of the plant area fluctuates.

[0019] In a preferred embodiment of the present invention, the buffer tank control module includes: a state threshold judgment unit, used to judge the relationship between the inlet pressure and a preset inlet safety pressure threshold, and the liquid level height and preset lower limit safety water level threshold and upper limit water level threshold, respectively. The valve control unit is used to generate a control signal for the inlet solenoid valve based on the judgment result of the state threshold judgment unit and in combination with the opening and closing state of the mechanical float valve. The valve control unit is configured to generate a control signal to open the inlet solenoid valve when the liquid level is less than the lower limit safe water level threshold and the inlet pressure is greater than the inlet safe pressure threshold. When the liquid level is greater than or equal to the upper limit water level threshold, or when the mechanical float valve is closed, a control signal is generated to close the inlet solenoid valve; in other states, a control signal is generated to maintain the current state of the inlet solenoid valve.

[0020] When continuous cleaning operations are carried out on the roof of an industrial plant, the water supply capacity of the water intake point in the plant area will fluctuate with the changes in production water load. The roof water tank needs to maintain a stable state between water replenishment and overflow prevention. The buffer tank control module is further equipped with a state threshold judgment unit and a valve control unit, so that the liquid level condition, the inlet pressure condition and the mechanical float valve status jointly participate in the valve decision. The state threshold judgment unit reads the inlet pressure and liquid level height in each system cycle, compares the inlet pressure with the preset inlet safety pressure threshold, and compares the liquid level height with the lower limit safety water level threshold and the upper limit water level threshold respectively. The preset safe inlet pressure threshold is obtained by algebraic calculation based on the height difference along the route from the water intake point in the factory area to the roof water tank and the full-load resistance of the inlet pipeline. The calculation logic is: safe inlet pressure threshold; In the formula, For the elevation difference along the route, This is the pressure drop test value of the pipeline under full load resistance. To allow for a safety pressure drop margin, this threshold is used to characterize the minimum network pressure that needs to be overcome to maintain stable water injection into the tank; the preset lower safety water level threshold is determined based on the anti-cavitation pumping margin of the booster pump at its maximum design flow rate, and the setting relationship is as follows: Lower safety water level threshold: In the formula, The required net positive suction head (NPSH) for booster pumps. For the head loss due to resistance in the suction pipe, To ensure a safe water level buffer margin and prevent damage to the water pump due to cavitation; the preset upper limit water level threshold is set based on the total physical volume of the water tank, minus the maximum inertial water inflow during the closing delay of the solenoid valve and mechanical float valve, to strictly prevent overflow; the comparison result does not directly control the hardware, but first forms the judgment result of the current cycle, which is then called by the valve control unit. Threshold judgment and valve output are processed separately. If it is necessary to record the water replenishment basis for each cycle in the future, only the judgment result needs to be retained, and there is no need to trace back the original sampling value. If the level sensor does not provide a valid level height in the current cycle, the state threshold judgment unit continues to use the level judgment result confirmed in the previous cycle and suspends updating the valve action. If the status signal of the mechanical float valve is missing, the valve control unit will prioritize processing it as a closed condition to prevent the continuous application of opening commands to the upstream pipe section when the float valve is actually closed. After receiving the above judgment result, the valve control unit generates the water inlet solenoid valve control signal in the limited manner. When the liquid level is lower than the lower limit safe water level threshold and the water inlet pressure is higher than the water inlet safe pressure threshold, it indicates that the water tank needs to be replenished and the water supply end has the conditions for replenishment. At this time, the conditions for generating the water inlet solenoid valve control signal are initially met. When the liquid level reaches or exceeds the upper limit water level threshold, it indicates that the water tank is close to full and water intake should be stopped; or even if the liquid level has not reached the upper limit, the mechanical float valve is closed, which will also generate a control signal to close the water intake solenoid valve. In the specific logical arbitration sequence, the safety protection of preventing overflow and preventing physical blockage always takes higher priority than the water replenishment request; Therefore, even if the aforementioned liquid level and inlet pressure conditions for opening the inlet solenoid valve are met simultaneously, once the mechanical float valve is detected to be in a closed state, such as due to abnormal closure caused by mechanical jamming, the valve control unit will trigger a hardware state interlock mechanism on the control link and force the priority output of the control signal to close the inlet solenoid valve. This ensures the consistency between software control actions and physical water circuit opening and closing, effectively preventing the solenoid valve from being continuously energized and magnetized under conflicting conditions of physical blockage of the pipeline, which could lead to coil overload and burnout. For other states that do not fall into the above two categories, such as when the liquid level is between the upper and lower limits, the inlet water pressure does not meet the opening requirements and the mechanical float valve is not closed, the valve control unit does not change the existing state of the solenoid valve, but generates a control signal to maintain the current state. In the water tank replenishment control, when the liquid level is too low but the inlet water pressure is insufficient, the system will not force the inlet solenoid valve to open, so as to avoid improper water intake to the upstream pipeline network. When the liquid level is high or the float valve is closed, the system will promptly shut off the solenoid valve to prevent further water from entering the tank. For liquid levels in the intermediate range, the system will maintain its original state and will not frequently switch on and off due to slight fluctuations in the liquid level. This process is suitable for continuous cleaning conditions where dual sprinklers on the roof alternately draw water. Even when the flow rate on the sprinkler side changes intermittently, the water tank can still maintain normal pressure water supply conditions according to an independent water replenishment logic.

[0021] In a preferred embodiment of the present invention, the frequency conversion adjustment module includes: a target pressure calculation unit, used to obtain the total instantaneous flow of the nozzle currently in the open state based on the detection results of the open / closed state detection device, and determine the target outlet pressure value by combining a preset comprehensive coefficient and a preset basic dynamic pressure; and a frequency conversion unit, used to generate a frequency conversion control signal according to the target outlet pressure value. The ramp adjustment unit is used to limit the ramp of the frequency converter control signal to obtain the operating frequency control signal sent to the frequency converter. The base dynamic pressure is a pressure value predetermined based on the nozzle installation height and spray distance; the target outlet pressure value is determined based on the positive correlation between the base dynamic pressure, the preset comprehensive coefficient, and the sum of the nozzle's instantaneous flow rate. The ramp adjustment unit is configured to: obtain the difference parameter between the frequency conversion control signal at the current moment and the operating frequency control signal at the previous moment; if the absolute value of the difference is greater than the preset frequency change rate limit threshold, then limit the increase or decrease of the operating frequency control signal to the frequency change rate limit threshold. If the absolute value of the difference is less than or equal to the frequency change rate limit threshold, the operating frequency control signal is updated directly according to the difference. The system also includes a resistance coefficient correction module, which is used to obtain the actual outlet pressure and update the preset comprehensive coefficient in the pipeline resistance model based on the average deviation between the actual outlet pressure and the target outlet pressure value within a preset time window and the preset step size. The system includes an atmospheric pressure buffer water supply device and a frequency converter booster device in the actuator section; the atmospheric pressure buffer water supply device corresponds to the buffer water tank control module, the water tank is an atmospheric pressure water storage tank, the mechanical float valve is set at the water inlet end of the atmospheric pressure water storage tank, and the water inlet solenoid valve is set in series at the front end of the mechanical float valve; The variable frequency booster device corresponds to the variable frequency adjustment module. The booster pump draws water from the atmospheric pressure water storage tank. The frequency converter drives the booster pump. Two nozzles are connected to the roof and are adjustable nozzles.

[0022] The two sprinklers on the roof of the industrial plant are supplied with water by the same booster pump. During operation, if one sprinkler continues to spray while the other suddenly shuts off, and the booster pump is driven in the conventional constant output mode, the water pressure on the side with the remaining open sprinkler will deviate from the required range. Therefore, the frequency converter module is equipped with a target pressure calculation unit, a frequency conversion unit, and a ramp adjustment unit, and works in conjunction with a resistance coefficient correction module to correct for pipeline changes. The target pressure calculation unit reads the nozzle status given by the open / closed status detection device, only counts the instantaneous flow rate corresponding to the nozzle currently in the open state, and calculates the total instantaneous flow rate of the nozzles; combined with the preset comprehensive coefficient and the basic dynamic pressure, it forms the target outlet pressure value required for the current cycle; The determination method of the basic dynamic pressure is further defined. The basic dynamic pressure is predetermined based on the nozzle installation height and spray distance. It is used to reflect the basic pressure required for the nozzle to achieve the expected spraying effect under the given installation conditions. On this basis, the product of the preset comprehensive coefficient and the sum of the instantaneous flow rate of the nozzle is added to obtain the target outlet pressure value. When both nozzles are open at the same time, the target outlet pressure value corresponds to the total flow rate when both nozzles are running; when one nozzle is closed, the target outlet pressure value is redefined as the current total flow rate changes. If the nozzle opening / closing status signal is missing in the current cycle, the target pressure calculation unit can continue to use the opening status and corresponding total flow rate confirmed in the previous cycle, and update it after the status signal is restored, so as to ensure the continuity of the calculation chain. After receiving the target outlet pressure value, the frequency conversion unit converts it into the frequency converter control signal corresponding to the booster pump. To avoid the conversion process from pressure to frequency converter signal becoming an implicit mapping process lacking a clear analytical relationship, the frequency conversion unit is configured to execute defined algebraic calculation rules: Using the equipment's factory-standard operating frequency required to maintain the base dynamic pressure as a baseline, the target outlet pressure value is subtracted from the base dynamic pressure to obtain the required additional pressure increment. This pressure increment is then multiplied by a pre-set pressure-frequency conversion constant, which characterizes the pressure increment per unit of pressure. The specific number of Hertz required to increase the export pressure is multiplied by the product and added to the reference operating frequency to determine the frequency setpoint value down to the Hertz unit, which is then used as the frequency conversion control signal. The frequency converter control signal is first sent to the ramp adjustment unit at the current moment to prevent the frequency converter output from being changed directly according to the latest target value when the nozzle is suddenly closed, which would cause the pump speed change rate to exceed the limit threshold and create fluctuations in the pipeline. Therefore, the ramp adjustment unit is configured to obtain the difference parameter between the frequency conversion control signal at the current moment and the operating frequency control signal at the previous moment, and to perform the restriction in a certain manner. The preset frequency change rate limit threshold is determined by a mathematical mapping formula to constrain the rate of change of frequency modulation and thus avoid mechanical shock and pipe wall rupture. The specific mapping formula is: Frequency change rate limit threshold: In the formula, This represents the maximum permissible transient electromagnetic torque output of the booster pump motor. This represents the steady-state resistance torque of the pipeline under full-load hydraulic conditions. This refers to the total mechanical rotational inertia of the booster pump motor and impeller assembly. For the system's control execution cycle, The preset pole-log transformation constant for mapping mechanical angular velocity to electrical frequency: If the absolute value of the difference is greater than the preset frequency change rate limit threshold, the increase or decrease of the operating frequency control signal will be limited to the frequency change rate limit threshold. Meanwhile, to compensate for the severe lag in the response of the upper computer's 1-second communication cycle to the millisecond-level transient impact of water hammer, the frequency converter control module adjusts the hardware deceleration time parameters at the bottom layer of the frequency converter. Forced takeover and locking within 0.1s: The inverter's insulated gate bipolar transistor hardware drive layer directly absorbs the back electromotive force and transient pressure wave of the pipeline caused by the sudden shut-off of the nozzle; the software ramp unit is only responsible for the smooth transition of the subsequent steady-state target frequency. If the absolute value of the difference is less than or equal to the frequency change rate limit threshold, the operating frequency control signal is updated directly according to the difference. The operating frequency control signal after the ramp processing is then sent to the frequency converter to drive the booster pump to adjust the output; if the operating frequency control signal of the previous moment is unavailable, the frequency converter control signal of the current moment can be used as the initial comparison reference, and the difference limiting process will begin from the next moment. The resistance coefficient correction module is used to handle changes in pipeline conditions during long-term operation. If only the preset comprehensive coefficient is used, there may be a continuous deviation between the target outlet pressure value and the actual outlet pressure when the hose is bent, the nozzle usage status changes, or the local resistance of the pipeline gradually changes. The resistance coefficient correction module obtains the actual outlet pressure, calculates the residual between the actual outlet pressure and the target outlet pressure value, and calculates the average value of the residual within a preset time window. The average value is multiplied by a preset step size and then superimposed on the preset comprehensive coefficient to update the preset comprehensive coefficient in the pipeline resistance model. The updated preset comprehensive coefficients are retained for direct use by subsequent target pressure calculation units, thereby reducing the need for repeated calibration; Assuming the preset time window includes Each sampling period, with the preset initial value of the comprehensive coefficient. The basic dynamic pressure is The preset step size is set to ; To ensure strict self-consistency of the physical dimensions on both sides of the equation in this correction step, the preset step size here is not a purely dimensionless numerical constant, but rather a conversion coefficient that incorporates the adaptive adjustment gain of the control system and the reciprocal of the current reference flow rate. Its dimensions are explicitly configured as follows: ; The initial value of the preset comprehensive coefficient is obtained by calibration based on the full flow friction resistance test data after the initial pipeline network is laid; The preset step size is a preset attenuation constant configured to achieve smooth correction, preventing fluctuations in the pipeline resistance model that exceed the set range due to single or short-term pressure measurement anomalies. Here Within each cycle, the nozzle remains in a stable open state, and the total instantaneous flow rate remains constant. According to the calculation logic of the target export pressure value, the target export pressure value is always... ; Because a slight deformation in the pipeline causes a change in actual resistance, the sensor then collects this data. The actual export pressure within each cycle is respectively , , , , ; The drag coefficient correction module calculates the residual between the actual outlet pressure and the target outlet pressure, i.e., the target outlet pressure minus the actual outlet pressure. , , , , The average value of the residuals within the preset time window was calculated to be... ; Multiply the average value by the preset step size, i.e. This yields a correction term whose dimensions perfectly match the original drag coefficient, which is then added to the current preset comprehensive coefficient. The updated preset comprehensive coefficient becomes... ; The system can achieve long-term adaptive correction of the pipeline resistance model without relying on complex feedback control formulas; The arrangement of the actuator is as follows: the atmospheric pressure buffer water supply device uses an atmospheric pressure water storage tank as an intermediate water supply unit, a mechanical float valve is set at the water inlet of the atmospheric pressure water storage tank, and a water inlet solenoid valve is set in series at the front end of the mechanical float valve. The two work together to complete the water replenishment control. In the variable frequency booster device, the booster pump draws water from the atmospheric pressure water storage tank, the frequency converter drives the booster pump to run, and two adjustable nozzles are connected to the roof cleaning position. The water replenishment device is responsible for maintaining the water supply conditions of the water tank, and the frequency converter is responsible for providing the outlet pressure that matches the current flow state to the open nozzle. The two parts execute their respective control signals. For situations requiring simultaneous cleaning by two people on the roof, single-person operation with a pause on another branch, and alternating switching between two nozzles, the system can adjust the operating frequency of the booster pump while maintaining constant water pressure in the water tank.

[0023] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A secondary pressurization cleaning system for rooftop photovoltaic modules, characterized in that, include: The system includes a water tank, a mechanical float valve, an inlet solenoid valve, a booster pump, a frequency converter, two nozzles, and an opening / closing status detection device connected to each of the two nozzles, as well as: The hydraulic data acquisition module is used to acquire data collected by multiple hydraulic sensors to form parameter data characterizing the hydraulic state. The parameter data includes at least inlet pressure, liquid level, instantaneous flow rate data, and dynamic pressure data. The buffer tank control module is used to determine the state of the water tank based on the inlet pressure and the liquid level, and the opening and closing state of the mechanical float valve, and generate an inlet solenoid valve control signal to control the opening and closing of the inlet solenoid valve. The resistance mutation identification module is used to calculate the rate of change of the instantaneous flow rate data and the dynamic pressure data to obtain the flow rate change rate and the pressure rate change rate, and extract the resistance mutation signal based on the flow rate change rate and the pressure rate change rate; The variable frequency control module is used to calculate the target outlet pressure value according to the preset pipeline resistance model after receiving the resistance change signal, and convert it into a variable frequency control signal corresponding to the booster pump and send it to the frequency converter.

2. The secondary pressurization cleaning system for rooftop photovoltaic modules according to claim 1, characterized in that, The resistance mutation identification module includes: The rate of change calculation unit is used to calculate the rate of change of the instantaneous flow rate data and the dynamic pressure data to obtain the flow rate of change and the pressure rate of change; The feature extraction unit is used to output the resistance change signal when the flow rate change rate and the pressure change rate are respectively greater than the corresponding warning thresholds.

3. The secondary pressurization cleaning system for rooftop photovoltaic modules according to claim 2, characterized in that, The parameter data also includes ambient temperature parameters and the dynamic pressure parameters at the outlet of the booster pump; The instantaneous flow rate data includes the instantaneous flow rate parameters of the first nozzle and the instantaneous flow rate parameters of the second nozzle; The warning thresholds include traffic warning thresholds and pressure warning thresholds.

4. The secondary pressurization cleaning system for rooftop photovoltaic modules according to claim 1, characterized in that, The buffer tank control module includes: The state threshold judgment unit is used to judge the relationship between the inlet pressure and the preset inlet safety pressure threshold, the liquid level height and the preset lower limit safety water level threshold and upper limit water level threshold, respectively. The valve control unit is used to generate the control signal for the water inlet solenoid valve based on the judgment result of the state threshold judgment unit and in combination with the opening and closing state of the mechanical float valve.

5. The secondary pressurization cleaning system for rooftop photovoltaic modules according to claim 4, characterized in that, The valve control unit is configured as follows: When the liquid level is less than the lower limit safe water level threshold and the inlet pressure is greater than the inlet safe pressure threshold, a control signal is generated to open the inlet solenoid valve. When the liquid level is greater than or equal to the upper limit water level threshold, or when the mechanical float valve is closed, a control signal is generated to close the inlet solenoid valve. In other states, a control signal is generated to maintain the current state of the water inlet solenoid valve.

6. The secondary pressurization cleaning system for rooftop photovoltaic modules according to claim 1, characterized in that, The frequency conversion adjustment module includes: The target pressure calculation unit is used to obtain the total instantaneous flow of the nozzle currently in the open state based on the detection results of the open / closed state detection device, and determine the target outlet pressure value by combining the preset comprehensive coefficient and the preset basic dynamic pressure. A frequency conversion unit is used to generate the frequency conversion control signal based on the target outlet pressure value; The ramp adjustment unit is used to limit the ramp of the frequency conversion control signal to obtain the operating frequency control signal sent to the frequency converter.

7. The secondary pressurization cleaning system for rooftop photovoltaic modules according to claim 6, characterized in that, The basic dynamic pressure is a pressure value predetermined based on the nozzle installation height and spray distance; The target outlet pressure value is determined based on the positive correlation between the base dynamic pressure, the preset comprehensive coefficient, and the sum of the instantaneous flow rates of the nozzle.

8. The secondary pressurization cleaning system for rooftop photovoltaic modules according to claim 6, characterized in that, The ramp adjustment unit is configured as follows: Obtain the difference parameter between the frequency conversion control signal at the current moment and the operating frequency control signal at the previous moment. If the absolute value of the difference is greater than the preset frequency change rate limit threshold, then limit the increase or decrease of the operating frequency control signal to the frequency change rate limit threshold. If the absolute value of the difference is less than or equal to the frequency change rate limit threshold, then the operating frequency control signal is directly updated according to the difference.

9. The secondary pressurization cleaning system for rooftop photovoltaic modules according to claim 6, characterized in that, The system also includes a resistance coefficient correction module, which is used to obtain the actual outlet pressure and update the preset comprehensive coefficient in the pipeline resistance model based on the average deviation between the actual outlet pressure and the target outlet pressure value within a preset time window and a preset step size.

10. The secondary pressurization cleaning system for rooftop photovoltaic modules according to claim 1, characterized in that, The system includes an atmospheric pressure buffer water supply device and a variable frequency booster device in the actuator section; The atmospheric pressure buffer water supply device corresponds to the buffer water tank control module. The water tank is an atmospheric pressure water storage tank. The mechanical float valve is located at the water inlet of the atmospheric pressure water storage tank. The water inlet solenoid valve is connected in series at the front end of the mechanical float valve. The variable frequency booster device corresponds to the variable frequency adjustment module. The booster pump draws water from the atmospheric pressure water storage tank. The frequency converter drives the booster pump. The two nozzles are connected to the roof and are adjustable nozzles.

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