Photovoltaic power station equipment insulation monitoring system and method for uneven foundation

Abstract

The invention relates to the field of photovoltaic insulation monitoring, and discloses a photovoltaic power station equipment insulation monitoring system for a non-uniform foundation, and the system comprises an insulation monitoring terminal which is used for collecting, processing and analyzing the voltage and leakage current data of photovoltaic power station equipment, and achieves the fault detection and warning. The invention also discloses a photovoltaic power station equipment insulation monitoring method for the non-uniform foundation, and the method comprises the following steps: S1, after the system is started, the fling-cut switches K1 and K2 are initialized, and the collection module carries out the signal conditioning and sampling of the high voltage of the DC bus. Through combination of a bridge detection method and a differential current detection method, the problems of switching switch loss and accident potential caused by frequent resistance switching in a single bridge method are solved, real-time fault early warning and fault position display are realized by using a high-sensitivity non-contact direct current leakage current sensor, and meanwhile, a power line communication technology is adopted, so that the fault detection accuracy is improved. Electric leakage data transmission of the distributed photovoltaic power generation system is realized, and a communication channel does not need to be specially erected.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic insulation monitoring, and in particular to a photovoltaic power station equipment insulation monitoring system and method for uneven foundations. Background Art

[0002] With the large-scale promotion of photovoltaic power generation technology, the safe operation of distributed photovoltaic power stations is of vital importance. Since there are many types of devices in each link of distributed photovoltaic power stations from solar photovoltaic cell arrays to grid-connected inverters, the wiring of various types is very complicated. The battery components are input to the inverter after being merged by the combiner box and the DC cabinet. There are many lines and they are widely distributed, which is prone to poor insulation. Most of the cables are laid in the open air, and the working environment is very harsh. In long-term operation, line insulation leakage faults are prone to occur. In reality, it is very necessary to use insulation monitoring devices to monitor the insulation condition of the system in the photovoltaic DC grounding system.

[0003] There is an essential difference between photovoltaic insulation monitoring and photovoltaic insulation detection. Photovoltaic insulation detection technology mainly focuses on using specific technical solutions to test the combiner box, string or solar panel when the inverter trips or detects a potential grounding fault to determine whether there is a grounding fault. This method is more inclined to post-maintenance. Relatively speaking, photovoltaic insulation monitoring uses a variety of monitoring methods such as video, environment, and electrical signals to grasp the insulation status of photovoltaic projects in real time, and promptly discover phenomena that may lead to grounding faults, such as abnormally high operating temperature of solar panels and abnormally low string insulation, so as to intervene in operation and maintenance in advance to prevent faults and accidents. Even in the event of sudden failures, monitoring data can assist in troubleshooting and repair work. Therefore, photovoltaic insulation monitoring is a pre-emptive prevention mechanism.

[0004] At present, photovoltaic insulation monitoring technology mostly adopts the bridge method as an implementation plan. Although the specific implementation details of each scheme are different, the core principle is based on changing the resistance of the upper and lower bridge arms to the ground. A notable feature of the bridge detection method is that it can estimate the insulation impedance to the ground in the bus. However, the presence of photovoltaic inverters in the DC system of photovoltaic power stations cannot be ignored, and it will cause voltage fluctuations in the DC bus system. In this case, two different unbalanced resistance switching operations are performed, and the sampled values ​​obtained will have different degrees of errors, which are difficult to eliminate. In addition, the DC bus voltage is generally high, and frequent resistance switching operations will not only increase the switching switch loss, but once the switch is damaged, it may cause serious accidents; at the same time, switching resistance will also cause significant fluctuations in the common-mode voltage to the ground, which will have an adverse effect on other equipment in the DC system. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a system and method for insulation monitoring of photovoltaic power station equipment on uneven foundations, which solves the problem of real-time monitoring and early warning of poor insulation and leakage faults caused by complex wiring and harsh environment in distributed photovoltaic power stations.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions: A photovoltaic power station equipment insulation monitoring system for uneven foundations, comprising:

[0007] Insulation monitoring terminal, which is responsible for collecting, processing and analyzing the voltage and leakage current data of photovoltaic power station equipment, and realizing fault detection and warning;

[0008] The insulation monitoring terminal includes a collection module, a central processing module, a control switch module and a sensor module. The collection module is used to sample the high voltage of the DC bus. The central processing module is used to process the voltage data collected by the collection module. The control switch module is connected to the central processing module. The control switch module is used to manage the switching switch and the sound and light warning device. The sensor module is connected to the central processing module. The sensor module is used to measure the branch leakage current.

[0009] The central processing module includes a data processing unit, an STM32 single-chip microcomputer, a signal transmission unit and an insulation impedance calculation unit. The data processing unit is responsible for processing the voltage data collected by the acquisition module; the STM32 single-chip microcomputer is used as a main controller to perform circuit control and voltage sampling, the signal transmission unit is used to transmit the processed data to the host computer, and the insulation impedance calculation unit is used to calculate the insulation impedance RX+ and PX- of the positive and negative bridge arms to the ground by measuring the voltages U1+, U1- and U2+, U2- of the positive and negative bridge arms to the ground;

[0010] The host computer is connected to the central processing module and is responsible for receiving, storing and displaying the data transmitted by the insulation monitoring terminal, and providing historical query and fault alarm functions.

[0011] Preferably, the acquisition module includes:

[0012] Conditioning circuit, which is used for signal conditioning and preliminary processing;

[0013] A collection circuit, which is used to collect the voltage signal of the DC bus high voltage;

[0014] Bridge detection method, which is used to detect the voltage difference of the DC bus;

[0015] The differential current detection method is used to detect the current difference of the bridge arm;

[0016] A voltage sensor is used to convert a strong current analog signal into a weak current analog signal.

[0017] Preferably, the control switch module includes:

[0018] Switches K1 and K2 are used to control the switching operation of the resistor;

[0019] An audible and visual warning device is used to issue a warning signal when a ground fault is detected.

[0020] Preferably, the sensor module comprises:

[0021] A leakage current sensor, which is used to measure the leakage current of the branch;

[0022] A signal amplifying circuit, which amplifies the weak current collected by the sensor;

[0023] DSP signal processing unit, which is used to perform digital signal processing on sensor signals;

[0024] A coupling circuit is used to couple a signal to a low voltage power line for transmission.

[0025] Preferably, the calculation formula involved in the insulation impedance calculation unit is:

[0026] Where I is the current.

[0027] A method for monitoring insulation of photovoltaic power station equipment on uneven foundations comprises the following steps:

[0028] S1, after starting the system, initialize the switching switches K1 and K2, and the acquisition module performs signal conditioning and sampling on the high voltage of the DC bus, and transmits the voltage signal to the central processing module;

[0029] S2, the central processing module receives the data transmitted by the acquisition module, collects the positive and negative bridge arm voltages U+ and U-, and detects whether the voltage difference |U+-U-| is less than the set threshold value θ;

[0030] S3. If |U+-U-| is less than the set threshold value θ, continue monitoring; otherwise, disconnect K1 and K2 separately, collect the voltage of the positive and negative bridge arms respectively, and calculate the insulation impedance RX+ and RX- of the positive and negative bridge arms;

[0031] S4, the central processing module determines whether the calculated insulation impedance RX+ and RX- are lower than the alarm value, and if so, sends a signal to the control switch module to trigger the sound and light warning device to sound an alarm;

[0032] S5, start the branch inspection, the sensor module measures the leakage current of each branch, and transmits the processed signal to the central processing module for further analysis;

[0033] S6. The host computer receives and stores the data from the central processing module, plots it into a voltage curve, and generates an alarm event when the alarm condition is reached, displaying the fault location;

[0034] S7. The host computer provides historical voltage and fault location records to assist operation and maintenance personnel in troubleshooting and analysis.

[0035] Preferably, the step S1 specifically includes the following steps:

[0036] S1.1. After the system is started, initialize the switching switches K1 and K2 to ensure that the switches are in the initial state;

[0037] S1.2, the acquisition module performs signal conditioning on the high voltage of the DC bus, and uses a conditioning circuit to filter and amplify the signal;

[0038] S1.3, the acquisition circuit collects the conditioned high voltage signal and converts it into a digital signal;

[0039] S1.4, transmitting the collected voltage signal to the central processing module for further processing.

[0040] Preferably, the step S2 specifically includes the following steps:

[0041] S2.1, the central processing module receives the digital voltage signal transmitted by the acquisition module;

[0042] S2.2, collecting the voltages U+ and U- of the positive and negative bridge arms;

[0043] S2.3, calculate the voltage difference |U+-U-|;

[0044] S2.4. Compare the calculated result with the set threshold value θ to determine whether it is less than the threshold value.

[0045] Preferably, the step S3 specifically includes the following steps:

[0046] S3.1, if |U+-U-| is less than the set threshold θ, the system continues to monitor without further operation;

[0047] S3.2, if |U+-U-| is not less than the set threshold value θ, the central processing module controls to disconnect K1 and K2 separately;

[0048] S3.3, respectively collect the voltages U1+, U1- and U2+, U2- of the positive and negative bridge arms;

[0049] S3.4. Use the formula to calculate the insulation resistance RX+ and RX- of the positive and negative bridge arms.

[0050] The present invention provides a photovoltaic power station equipment insulation monitoring system and method for uneven foundations. It has the following beneficial effects:

[0051] 1. By combining the bridge detection method and the differential current detection method, the acquisition module of the present invention can accurately collect the voltage and current difference information of the DC bus, overcoming the problem that the frequent resistance switching operations using the single bridge method lead to increased switching losses and cause hidden dangers of serious accidents. The insulation impedance calculation unit measures the voltage of the positive and negative bridge arms to the ground and accurately calculates the insulation impedance of the positive and negative bridge arms to the ground, thereby ensuring the accuracy of the detection results.

[0052] 2. The present invention measures the leakage current of each branch by utilizing a highly sensitive non-contact DC leakage current sensor, performs digital signal processing, and couples the signal to the low-voltage power line for transmission, thereby realizing automated monitoring and intelligent analysis. The system can automatically generate alarm events and display the fault location, reducing the workload and errors of manual inspections.

[0053] 3. Through comprehensive insulation monitoring and timely fault alarm, the system of the present invention provides key information for photovoltaic operation and maintenance management personnel, assisting them in completing efficient operation and maintenance work, reducing fault handling time, and improving the operating efficiency and safety of photovoltaic power stations.

[0054] 4. The present invention realizes the leakage data transmission of distributed photovoltaic power generation system by adopting power line communication technology, which does not require the establishment of special communication channels and has the advantages of small investment, flexible and convenient installation, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 It is a framework diagram of the system of the present invention;

[0056] Figure 2 It is a schematic diagram of the detection principle of the present invention;

[0057] Figure 3 This is the insulation monitoring flow chart of the present invention;

[0058] Figure 4 It is a framework diagram of the acquisition module of the present invention;

[0059] Figure 5 It is a framework diagram of the central processing module of the present invention;

[0060] Figure 6 This is a framework diagram of a control switch module of the present invention;

[0061] Figure 7 is a framework diagram of the sensor module of the present invention;

[0062] Figure 8 Flow chart of the method of the present invention. DETAILED DESCRIPTION

[0063] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0064] Please refer to the attached Figure 1 -Attached Figure 2 The embodiment of the present invention provides an insulation monitoring system for photovoltaic power station equipment on uneven foundation, comprising:

[0065] Insulation monitoring terminal, which is responsible for collecting, processing and analyzing the voltage and leakage current data of photovoltaic power station equipment, and realizing fault detection and warning;

[0066] The insulation monitoring terminal includes an acquisition module, a central processing module, a control switch module and a sensor module. The acquisition module is used to sample the high voltage of the DC bus. The central processing module is used to process the voltage data collected by the acquisition module. The control switch module is connected to the central processing module. The control switch module is used to manage the switching switch and the sound and light warning device. The sensor module is connected to the central processing module. The sensor module is used to measure the branch leakage current.

[0067] The host computer is connected to the central processing module and is responsible for receiving, storing and displaying the data transmitted by the insulation monitoring terminal, and providing historical query and fault alarm functions.

[0068] Specifically, the present invention solves multiple problems in the prior art by providing an insulation monitoring system for photovoltaic power station equipment on uneven foundations, and significantly improves the insulation monitoring accuracy and safety of photovoltaic power station equipment. The specific contents are as follows:

[0069] 1. Improve detection accuracy and real-time monitoring capabilities: By combining the bridge detection method and the differential current detection method, the acquisition module can accurately collect the voltage and current difference information of the DC bus. The central processing module accurately calculates the insulation impedance of the positive and negative bridge arms to the ground through the insulation impedance calculation unit to ensure the accuracy of the detection results. At the same time, the system can monitor the insulation status of photovoltaic power station equipment in real time, promptly detect and handle potential grounding faults, and avoid accidents.

[0070] 2. Automatic and intelligent monitoring: The sensor module measures the leakage current of each branch through the leakage current sensor, performs digital signal processing, and couples the signal to the low-voltage power line for transmission, realizing automatic monitoring and intelligent analysis. The system can automatically generate alarm events and display the fault location, reducing the workload and errors of manual inspections and improving operation and maintenance efficiency.

[0071] 3. Data storage and analysis function: The host computer has powerful data storage and analysis functions, which can draw the collected data into a voltage curve and store it in the database. Operation and maintenance personnel can use the historical query function of the host computer to view past voltage and fault location records, conduct fault troubleshooting and analysis, and improve the efficiency and accuracy of fault handling.

[0072] 4. Communication method adapted to complex environments: The system adopts DC power line communication, coupling the information of each photovoltaic cell leakage sensor to the DC cable through coupling inductance, and finally transmitting it to the DC distribution cabinet and integrated into the photovoltaic power station monitoring system, adapting to the needs of uneven foundation and complex communication wiring, ensuring the reliable transmission of monitoring data.

[0073] The present invention mainly solves the following problems in the prior art:

[0074] 1. Low insulation monitoring accuracy:

[0075] Specific solutions: By combining the bridge detection method and the differential current detection method in the acquisition module, the voltage and current difference information of the DC bus can be collected and analyzed more accurately. The central processing module uses the insulation impedance calculation unit to measure the voltage of the positive and negative bridge arms to the ground and calculate the insulation impedance of the positive and negative bridge arms to the ground, which significantly improves the detection accuracy.

[0076] 2. Lack of real-time monitoring and early warning capabilities:

[0077] Specific solutions: The system can monitor the insulation status of photovoltaic power station equipment in real time. When the central processing module detects abnormal voltage or current, it immediately sends a signal to the control switch module, triggering the sound and light warning device to issue a warning, and promptly remind the operation and maintenance personnel to handle it to prevent the fault from expanding.

[0078] 3. Low efficiency of manual inspection:

[0079] Specific solution: The sensor module measures the leakage current of each branch through the leakage current sensor and performs digital signal processing to achieve automatic monitoring and intelligent analysis. The system can automatically generate alarm events and display the fault location, reducing the workload and errors of manual inspections.

[0080] 4. Insufficient data management and analysis capabilities:

[0081] Specific solutions: The host computer has data storage and analysis functions, which can draw the collected data into voltage curves and store them in the database. The host computer provides a historical query function, which allows operation and maintenance personnel to view and analyze past voltage and fault location records, improving the efficiency and accuracy of fault handling.

[0082] 5. The communication method is not suitable for complex environments:

[0083] Specific solution: The system uses DC power line communication to couple the information of each photovoltaic cell leakage sensor to the DC cable line through coupling inductance, ensuring reliable transmission of monitoring data and adapting to the needs of uneven foundations and complex communication wiring.

[0084] Please refer to the attached Figure 4 , the acquisition module includes:

[0085] Conditioning circuit, which is used for signal conditioning and preliminary processing;

[0086] A collection circuit, which is used to collect the voltage signal of the DC bus high voltage;

[0087] Bridge detection method, which is used to detect the voltage difference of the DC bus;

[0088] The differential current detection method is used to detect the current difference of the bridge arm;

[0089] A voltage sensor is used to convert a strong current analog signal into a weak current analog signal.

[0090] Specifically, the acquisition module plays a vital role in the insulation monitoring system of photovoltaic power station equipment. It combines the functions of conditioning circuit, acquisition circuit, bridge detection method, differential current detection method and voltage sensor, and can accurately collect and process the high-voltage voltage signal of the DC bus, thereby improving the detection accuracy and reliability of the system. The specific beneficial effects are as follows:

[0091] 1. Improve signal quality: The conditioning circuit performs preliminary processing on the high-voltage signal to ensure the quality and stability of the signal.

[0092] 2. Accurate acquisition: The acquisition circuit can efficiently collect the high-voltage voltage signal of the DC bus to ensure the accuracy of the data.

[0093] 3. High detection accuracy: The combination of bridge detection method and differential current detection method can accurately detect the difference between voltage and current and improve detection accuracy.

[0094] 4. Signal conversion: The voltage sensor converts the strong current analog signal into the weak current analog signal for subsequent processing.

[0095] The main function of the acquisition module is to sample and process the high voltage of the DC bus and provide accurate voltage and current data for the central processing module. These data are the basis for calculating insulation impedance and detecting voltage and current anomalies, and directly affect the monitoring accuracy and fault detection capability of the system.

[0096] Conditioning circuit: The conditioning circuit is responsible for the preliminary processing of the collected high voltage signal to ensure the quality and stability of the signal. This includes filtering and amplification to remove noise and enhance signal strength.

[0097] The conditioning circuit uses filter and amplifier components to filter and amplify the collected high-voltage signal. The filter is used to remove high-frequency noise, and the amplifier is used to enhance the signal strength to ensure the stability and quality of the signal.

[0098] Acquisition circuit: The acquisition circuit collects the conditioned high voltage signal and converts it into an electrical signal that can be processed. The high precision of the acquisition circuit ensures the accuracy of the data.

[0099] The acquisition circuit is composed of a high-precision analog-to-digital converter (ADC), which converts the conditioned analog signal into a digital signal. The accuracy and sampling rate of the ADC determine the accuracy and real-time nature of the acquired data.

[0100] Bridge detection method: The bridge detection method is used to detect the voltage difference of the DC bus. Its basic principle is to compare the voltages at both ends of the bridge arm through a bridge circuit. When the voltage difference exceeds the set threshold, the system will detect an abnormality.

[0101] The bridge detection circuit includes resistors, capacitors and amplifiers. By adjusting the resistance value in the bridge circuit, the output voltage is zero in the balanced state. When the voltage of the DC bus changes, the bridge circuit will generate a voltage difference, which is amplified by the amplifier and transmitted to the central processing module.

[0102] Bridge detection formula:

[0103]

[0104] Among them, U bridge is the bridge output voltage, U in is the input voltage, R1, R2, R3, R4 are the resistances of each arm of the bridge.

[0105] Differential current detection method: The differential current detection method is used to detect the current difference of the bridge arm. It compares the current values ​​of the bridge arm to determine whether there is abnormal flow, thereby detecting the fault.

[0106] The differential current detection circuit consists of a high-precision current sensor and an amplifier. The current sensor measures the bridge arm current, the amplifier amplifies the measurement signal, and transmits the differential current signal to the central processing module.

[0107] Voltage sensor: The voltage sensor converts the collected strong current analog signal into weak current analog signal for subsequent digital processing and analysis. Its high precision and sensitivity ensure the accuracy of signal conversion.

[0108] The voltage sensor includes a high-precision voltage divider and an amplifier. The voltage divider reduces the high-voltage signal to a safe range, and the amplifier amplifies and conditions the reduced signal to ensure the accuracy and processability of the signal.

[0109] Please refer to the attached Figure 5 The central processing module includes a data processing unit, an STM32 single-chip microcomputer, a signal transmission unit and an insulation impedance calculation unit. The data processing unit is responsible for processing the voltage data collected by the acquisition module; the STM32 single-chip microcomputer is used as a main controller for circuit control and voltage sampling, the signal transmission unit is used to transmit the processed data to the host computer, and the insulation impedance calculation unit is used to calculate the insulation impedance RX+ and PX- of the positive and negative bridge arms to the ground by measuring the voltages U1+, U1- and U2+, U2- of the positive and negative bridge arms to the ground;

[0110] The calculation formula involved in the insulation resistance calculation unit is:

[0111] Where I is the current.

[0112] Specifically, the central processing module plays a core role in the insulation monitoring system of photovoltaic power station equipment. It integrates the data processing unit, STM32 microcontroller, signal transmission unit and insulation impedance calculation unit, and can efficiently process the collected voltage data, perform accurate insulation impedance calculation, and transmit the results to the host computer. The specific beneficial effects are as follows:

[0113] 1. Efficient data processing: The data processing unit quickly processes the collected voltage data, improving the response speed of the system.

[0114] 2. Precise control: As the main controller, the STM32 microcontroller can accurately control the circuit and voltage sampling to ensure the accuracy of the data.

[0115] 3. Reliable data transmission: The signal transmission unit ensures that the processed data can be reliably transmitted to the host computer, making it convenient for operation and maintenance personnel to view and analyze.

[0116] 4. Accurate calculation: The insulation impedance calculation unit calculates the insulation impedance of the positive and negative bridge arms to the ground by accurately measuring the voltage, providing high-precision test results.

[0117] The main function of the central processing module is to receive and process the voltage data transmitted by the acquisition module, perform accurate insulation impedance calculations, and transmit the processing results to the host computer for storage and analysis. Its core functions include data processing, control, calculation, and data transmission.

[0118] Data processing unit: Receives the voltage data transmitted by the acquisition module and performs preliminary processing, including filtering, denoising and data format conversion, to ensure the accuracy and reliability of the data.

[0119] The data processing unit consists of a high-performance processor and a filter. The processor is responsible for receiving and processing the voltage data transmitted by the acquisition module, and the filter is used to remove noise to ensure the accuracy and stability of the data.

[0120] STM32 MCU: As the main controller of the system, it is responsible for circuit control and voltage sampling. The STM32 MCU can realize the control and data collection of the bridge detection method and the differential current detection method through programming.

[0121] The STM32 microcontroller achieves comprehensive control of the system through programming. It is responsible for controlling the bridge detection method and the differential current detection method, collecting voltage and current data, and performing preliminary processing.

[0122] Signal transmission unit: The processed data is transmitted to the host computer through the signal transmission unit. This unit adopts a reliable communication protocol to ensure the integrity and accuracy of the data during the transmission process.

[0123] The signal transmission unit uses a serial communication protocol (such as UART or SPI) to ensure the integrity and accuracy of the data during transmission. It packages the processed data and transmits it to the host computer through the communication interface.

[0124] Insulation impedance calculation unit: By measuring the voltage U1+, U1- and U2+, U2- of the positive and negative bridge arms to the ground, the insulation impedance RX+ and RX- of the positive and negative bridge arms to the ground are calculated.

[0125] The insulation impedance calculation unit collects the ground voltages U1+, U1- and U2+, U2- of the positive and negative bridge arms through a high-precision ADC. The calculation process is as follows:

[0126] Measure the positive and negative bridge arm voltages U1+, U1- and U2+, U2- when the switching switches K1 and K2 are closed and opened.

[0127] The insulation resistance of the positive and negative bridge arms is calculated by the formula: Where I is the current. By accurately measuring the current and voltage, the insulation resistance is calculated to ensure the high accuracy and reliability of the test results.

[0128] These formulas are used to calculate the insulation impedance of the positive and negative bridge arms to the ground, and are closely related to the voltage and current detection principles in the technical solution. Through these calculations, the system can accurately detect and analyze the insulation status of photovoltaic power station equipment, providing reliable data support for subsequent fault detection and early warning.

[0129] Please refer to the attached Figure 6 , the control switch module includes:

[0130] Switches K1 and K2 are used to control the switching operation of the resistor;

[0131] An audible and visual warning device is used to issue a warning signal when a ground fault is detected.

[0132] Specifically, the control switch module plays a key role in the insulation monitoring system of photovoltaic power station equipment. Through the switching switches K1, K2 and the sound and light warning device, it can quickly respond and issue a warning signal when a ground fault is detected. The specific beneficial effects are as follows:

[0133] 1. Fast fault response: The switching switches K1 and K2 can quickly switch the resistors, detect and respond to faults in time, and prevent the faults from expanding.

[0134] 2. Clear warning: The sound and light warning device sends out a warning signal when a grounding fault is detected, which can promptly remind the operation and maintenance personnel to handle it and ensure the safety of the system.

[0135] 3. High reliability: The module design is simple and reliable, ensuring the stable operation of the system in various complex environments.

[0136] The main function of the control switch module is to realize the switching operation of the resistor through the switching switches K1 and K2, cooperate with the detection circuit to perform insulation detection, and when a grounding fault is detected, send out a warning signal through the sound and light warning device to remind the operation and maintenance personnel to deal with the fault in time and ensure the safe operation of the system.

[0137] Switches K1 and K2: Switches are used to control the connection and disconnection of resistors. By switching resistors, the impedance in the bridge circuit can be changed to perform insulation detection. The voltage difference detected by the bridge circuit is calculated by the central processing module to obtain the insulation impedance.

[0138] The switching switch is composed of high-performance relays or solid-state switches. The central processing module controls the connection and disconnection of K1 and K2 according to the detected voltage and current data. The specific operations are as follows:

[0139] During the detection process, the unbalanced resistance is connected to the circuit by controlling the switching switches K1 and K2, thereby changing the impedance in the bridge circuit and performing voltage sampling.

[0140] The status of the switching switches K1 and K2 is adjusted in real time by the central processing module according to the detection results to ensure the accuracy and reliability of the detection.

[0141] Sound and light warning device: The sound and light warning device is connected to the central processing module. When a grounding fault is detected, the central processing module sends a signal to trigger the sound and light warning device, which issues a sound and light warning to remind the operation and maintenance personnel to handle it in time.

[0142] The sound and light warning device consists of a buzzer and an LED indicator light, which are connected to the central processing module. When a ground fault is detected, the central processing module sends a signal to trigger the sound and light warning device. The specific operation is as follows:

[0143] When the insulation resistance calculated by the central processing module is lower than the set threshold, it is determined to be a ground fault.

[0144] The central processing module sends a signal to trigger the sound and light warning device, the buzzer sounds, and the LED indicator flashes, reminding the operation and maintenance personnel to deal with the fault in time.

[0145] Please see attached Figure 7 , the sensor module includes:

[0146] A leakage current sensor, which is used to measure the leakage current of the branch;

[0147] A signal amplifying circuit, which amplifies the weak current collected by the sensor;

[0148] DSP signal processing unit, which is used to perform digital signal processing on sensor signals;

[0149] A coupling circuit is used to couple a signal to a low voltage power line for transmission.

[0150] Specifically, the sensor module plays a key role in the insulation monitoring system of photovoltaic power station equipment. It ensures the accuracy and stability of data by measuring the leakage current of the branch circuit and performing signal amplification and digital processing. The specific beneficial effects are as follows:

[0151] 1. Accurate leakage current measurement: The leakage current sensor can measure the leakage current of the branch with high precision to ensure the accuracy of the data.

[0152] 2. Signal enhancement: The signal amplification circuit amplifies the weak current signal to improve the signal quality and facilitate subsequent processing.

[0153] 3. Efficient signal processing: DSP signal processing unit performs efficient digital signal processing to ensure the accuracy and real-time performance of data processing.

[0154] 4. Reliable signal transmission: The coupling circuit couples the processed signal to the low-voltage power line for transmission, ensuring reliable signal transmission in complex environments.

[0155] The main function of the sensor module is to measure the leakage current of each branch, amplify and digitally process the collected weak signals, and finally transmit the processed signals to the central processing module through the coupling circuit for further analysis. These functions ensure that the system can monitor the insulation status of photovoltaic power station equipment in real time and detect and handle potential faults in time.

[0156] Leakage current sensor: used to measure the leakage current of each branch, and can support the monitoring of up to 64 branches. The leakage current sensor can sense tiny current changes and convert them into voltage signals. By analyzing the polarity and magnitude of the leakage current sensor output voltage, the system can determine the polarity of the branch grounding and whether there is a fault

[0157] Leakage current sensors usually use Hall effect sensors or current transformers. Hall effect sensors can directly sense current changes and output corresponding voltage signals. The specific operation is as follows:

[0158] The leakage current sensor is installed on the current channel of each branch to measure the leakage current passing through in real time.

[0159] The voltage signal output by the sensor is proportional to the leakage current and is transmitted to the signal amplification circuit.

[0160] Leakage current sensing formula:

[0161] V out = k·I leak

[0162] Among them, V iut is the sensor output voltage, I leak is the measured leakage current, and k is the conversion factor of the sensor.

[0163] Signal amplifier circuit: amplifies the weak current signal collected by the leakage current sensor and enhances the signal strength to a processable level. The amplifier circuit is usually composed of a high-gain operational amplifier.

[0164] The signal amplification circuit is composed of a high-gain operational amplifier. The specific operation is as follows:

[0165] The amplifier amplifies the weak voltage signal output by the sensor to enhance the signal strength.

[0166] The amplified signal level meets the input requirement of the DSP signal processing unit, ensuring the accuracy of signal processing.

[0167] Signal amplification formula:

[0168] V amp =A·V out

[0169] Among them, V amp is the amplified signal voltage, A is the amplifier gain, V out is the sensor output voltage.

[0170] DSP signal processing unit: performs digital signal processing on the amplified signal, including filtering, denoising and data format conversion, to ensure the accuracy and real-time performance of the signal. DSP (digital signal processor) implements complex signal processing algorithms through programming.

[0171] The DSP signal processing unit uses a high-performance digital signal processor, and the specific operations are as follows:

[0172] The DSP receives the amplified signal and performs filtering and denoising to remove high-frequency noise and interference signals.

[0173] DSP digitizes the processed signal and converts it into a standard data format for easy transmission and analysis.

[0174] Signal processing formula:

[0175] V digital =f(V amp )

[0176] Among them, V digital is the digitized signal, f is the DSP signal processing function, V amp is the amplified signal voltage.

[0177] Coupling circuit: couples the processed signal to the low-voltage power line for transmission. The coupling circuit is usually composed of coupling capacitors or coupling transformers to ensure stable transmission of the signal in the power line.

[0178] The coupling circuit is composed of a coupling capacitor or a coupling transformer, and the specific operation is as follows:

[0179] The coupling capacitor is used to couple the signal from the DSP output to the low-voltage power line to ensure stable signal transmission.

[0180] The coupling transformer is used to isolate the high-voltage power line from the low-voltage signal circuit to protect the safety of the signal processing unit.

[0181] Please refer to the attached Figure 3 and attached Figure 8 , a method for monitoring insulation of photovoltaic power station equipment on uneven foundation, comprising the following steps:

[0182] S1, after starting the system, initialize the switching switches K1 and K2, and the acquisition module performs signal conditioning and sampling on the high voltage of the DC bus, and transmits the voltage signal to the central processing module;

[0183] S2, the central processing module receives the data transmitted by the acquisition module, collects the positive and negative bridge arm voltages U+ and U-, and detects whether the voltage difference |U+-U-| is less than the set threshold value θ;

[0184] S3. If |U+-U-| is less than the set threshold value θ, continue monitoring; otherwise, disconnect K1 and K2 separately, collect the voltage of the positive and negative bridge arms respectively, and calculate the insulation impedance RX+ and RX- of the positive and negative bridge arms;

[0185] S4, the central processing module determines whether the calculated insulation impedance RX+ and RX- are lower than the alarm value, and if so, sends a signal to the control switch module to trigger the sound and light warning device to sound an alarm;

[0186] S5, start the branch inspection, the sensor module measures the leakage current of each branch, and transmits the processed signal to the central processing module for further analysis;

[0187] S6. The host computer receives and stores the data from the central processing module, plots it into a voltage curve, and generates an alarm event when the alarm condition is reached, displaying the fault location;

[0188] S7. The host computer provides historical voltage and fault location records to assist operation and maintenance personnel in troubleshooting and analysis.

[0189] The S1 step specifically includes the following steps:

[0190] S1.1. After the system is started, initialize the switching switches K1 and K2 to ensure that the switches are in the initial state;

[0191] S1.2, the acquisition module performs signal conditioning on the high voltage of the DC bus, and uses a conditioning circuit to filter and amplify the signal;

[0192] S1.3, the acquisition circuit collects the conditioned high voltage signal and converts it into a digital signal;

[0193] S1.4, transmitting the collected voltage signal to the central processing module for further processing.

[0194] The S2 step specifically includes the following steps:

[0195] S2.1, the central processing module receives the digital voltage signal transmitted by the acquisition module;

[0196] S2.2, collecting the voltages U+ and U- of the positive and negative bridge arms;

[0197] S2.3, calculate the voltage difference |U+-U-|;

[0198] S2.4. Compare the calculated result with the set threshold value θ to determine whether it is less than the threshold value.

[0199] The S3 step specifically includes the following steps:

[0200] S3.1, if |U+-U-| is less than the set threshold θ, the system continues to monitor without further operation;

[0201] S3.2, if |U+-U-| is not less than the set threshold value θ, the central processing module controls to disconnect K1 and K2 separately;

[0202] S3.3, respectively collect the voltages U1+, U1- and U2+, U2- of the positive and negative bridge arms;

[0203] S3.4. Use the formula to calculate the insulation resistance RX+ and RX- of the positive and negative bridge arms.

[0204] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A photovoltaic power station equipment insulation monitoring system for uneven foundations, characterized in that: include: Insulation monitoring terminal, which is responsible for collecting, processing and analyzing the voltage and leakage current data of photovoltaic power station equipment, and realizing fault detection and warning; The insulation monitoring terminal includes a collection module, a central processing module, a control switch module and a sensor module. The collection module is used to sample the high voltage of the DC bus. The central processing module is used to process the voltage data collected by the collection module. The control switch module is connected to the central processing module. The control switch module is used to manage the switching switch and the sound and light warning device. The sensor module is connected to the central processing module. The sensor module is used to measure the branch leakage current. The central processing module includes a data processing unit, an STM32 single-chip microcomputer, a signal transmission unit and an insulation impedance calculation unit. The data processing unit is responsible for processing the voltage data collected by the acquisition module; the STM32 single-chip microcomputer is used as a main controller to perform circuit control and voltage sampling, the signal transmission unit is used to transmit the processed data to the host computer, and the insulation impedance calculation unit is used to calculate the insulation impedance RX+ and PX- of the positive and negative bridge arms to the ground by measuring the voltages U1+, U1- and U2+, U2- of the positive and negative bridge arms to the ground; The host computer is connected to the central processing module and is responsible for receiving, storing and displaying the data transmitted by the insulation monitoring terminal, and providing historical query and fault alarm functions.

2. The insulation monitoring system for photovoltaic power station equipment on uneven foundation according to claim 1, characterized in that: The acquisition module comprises: Conditioning circuit, which is used for signal conditioning and preliminary processing; A collection circuit, which is used to collect the voltage signal of the DC bus high voltage; Bridge detection method, which is used to detect the voltage difference of the DC bus; The differential current detection method is used to detect the current difference of the bridge arm; A voltage sensor is used to convert a strong current analog signal into a weak current analog signal.

3. The insulation monitoring system for photovoltaic power station equipment on uneven foundation according to claim 1, characterized in that: The control switch module comprises: Switches K1 and K2 are used to control the switching operation of the resistor; An audible and visual warning device is used to issue a warning signal when a ground fault is detected.

4. The insulation monitoring system for photovoltaic power station equipment on uneven foundation according to claim 1, characterized in that: The sensor module comprises: A leakage current sensor, which is used to measure the leakage current of the branch; A signal amplifying circuit, which amplifies the weak current collected by the sensor; DSP signal processing unit, which is used to perform digital signal processing on sensor signals; A coupling circuit is used to couple a signal to a low voltage power line for transmission.

5. The insulation monitoring system for photovoltaic power station equipment on uneven foundation according to claim 1, characterized in that: The calculation formula involved in the insulation resistance calculation unit is: Where I is the current.

6. A method for monitoring insulation of photovoltaic power station equipment on uneven foundation, characterized in that: The use of a photovoltaic power station equipment insulation monitoring system for uneven foundation according to any one of claims 1 to 5 comprises the following steps: S1, after starting the system, initialize the switching switches K1 and K2, and the acquisition module performs signal conditioning and sampling on the high voltage of the DC bus, and transmits the voltage signal to the central processing module; S2, the central processing module receives the data transmitted by the acquisition module, collects the positive and negative bridge arm voltages U+ and U-, and detects whether the voltage difference |U+-U-| is less than the set threshold value θ; S3. If |U+-U-| is less than the set threshold value θ, continue monitoring; otherwise, disconnect K1 and K2 separately, collect the voltage of the positive and negative bridge arms respectively, and calculate the insulation impedance RX+ and RX- of the positive and negative bridge arms; S4, the central processing module determines whether the calculated insulation impedance RX+ and RX- are lower than the alarm value, and if so, sends a signal to the control switch module to trigger the sound and light warning device to sound an alarm; S5, start the branch inspection, the sensor module measures the leakage current of each branch, and transmits the processed signal to the central processing module for further analysis; S6. The host computer receives and stores the data from the central processing module, plots it into a voltage curve, and generates an alarm event when the alarm condition is reached, displaying the fault location; S7. The host computer provides historical voltage and fault location records to assist operation and maintenance personnel in troubleshooting and analysis.

7. A method for monitoring insulation of photovoltaic power station equipment on uneven foundation according to claim 6, characterized in that: The S1 step specifically includes the following steps: S1.

1. After the system is started, initialize the switching switches K1 and K2 to ensure that the switches are in the initial state; S1.2, the acquisition module performs signal conditioning on the high voltage of the DC bus, and uses a conditioning circuit to filter and amplify the signal; S1.3, the acquisition circuit collects the conditioned high voltage signal and converts it into a digital signal; S1.4, transmitting the collected voltage signal to the central processing module for further processing.

8. The method for monitoring insulation of photovoltaic power station equipment on uneven foundation according to claim 6, characterized in that: The S2 step specifically includes the following steps: S2.1, the central processing module receives the digital voltage signal transmitted by the acquisition module; S2.2, collecting the voltages U+ and U- of the positive and negative bridge arms; S2.3, calculate the voltage difference |U+-U-|; S2.

4. Compare the calculated result with the set threshold value θ to determine whether it is less than the threshold value.

9. A method for monitoring insulation of photovoltaic power station equipment on uneven foundation according to claim 6, characterized in that: The S3 step specifically includes the following steps: S3.1, if |U+-U-| is less than the set threshold θ, the system continues to monitor without further operation; S3.2, if |U+-U-| is not less than the set threshold value θ, the central processing module controls to disconnect K1 and K2 separately; S3.3, respectively collect the voltages U1+, U1- and U2+, U2- of the positive and negative bridge arms; S3.

4. Use the formula to calculate the insulation resistance RX+ and RX- of the positive and negative bridge arms.

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