Insulation impedance detection circuit, abnormality detection method, and photovoltaic system

Abstract

The application belongs to the technical field of intelligent household appliances, and particularly relates to an insulation impedance detection circuit, an abnormality detection method and a photovoltaic system. The detection circuit is connected between an output positive electrode and an output negative electrode of a photovoltaic module, and comprises a voltage detection branch, a first bridge arm branch, a second bridge arm branch and a switching component circuit. The method obtains a positive electrode voltage value of the photovoltaic module; obtains a first voltage value of a voltage sampling point in a case where a working state of the switching component is in a closed state, and obtains a second voltage value of the voltage sampling point in a case where the working state of the switching component is in an open state; determines a resistance value of ground insulation impedance of the photovoltaic module based on the first voltage value and the second voltage value; and determines that the ground insulation impedance of the photovoltaic module is abnormal in a case where the resistance value of the ground insulation impedance is less than a preset impedance threshold. The method simplifies a resistance network in the detection circuit, and improves detection efficiency and system stability.

Description

Technical Field

[0001] This application belongs to the field of smart home appliance technology, specifically relating to an insulation impedance detection circuit, an anomaly detection method, and a photovoltaic system. Background Technology

[0002] A photovoltaic water heater system is a device that converts solar energy into thermal energy. Its core consists of photovoltaic modules, a control system, and a thermal energy conversion module. The photovoltaic modules output electrical energy to drive a water pump or heating element. It is widely used in scenarios such as household hot water supply.

[0003] Because photovoltaic modules are exposed to the outdoor environment for extended periods, their insulation performance gradually deteriorates due to factors such as temperature changes, humidity, and dust corrosion, leading to a decrease in their insulation impedance to ground. In existing technologies, the detection of the insulation impedance of photovoltaic modules to ground is typically based on the principle of resistive voltage division. This involves constructing a measurement circuit containing multiple fixed resistors and controllable switches, and calculating the insulation impedance value using voltage sampling.

[0004] However, existing detection methods typically rely on complex measurement circuits and control logic, resulting in low detection efficiency for insulation resistance to ground. Summary of the Invention

[0005] This application provides an insulation impedance detection circuit, an anomaly detection method, and a photovoltaic system to solve the technical problem that existing detection methods typically rely on complex measurement circuits and control logic, resulting in low detection efficiency of insulation impedance to ground.

[0006] In a first aspect, this application provides an insulation resistance detection circuit, which is connected between the output positive terminal and the output negative terminal of a photovoltaic module. The detection circuit includes: a voltage detection branch, a first bridge arm branch, a second bridge arm branch, and a switching assembly.

[0007] The first bridge arm branch and the second bridge arm branch are connected in parallel between the positive and negative output terminals of the photovoltaic module, respectively.

[0008] The first bridge arm branch is equipped with a first node and a second node; the voltage detection branch is connected in parallel between the first node and the second node;

[0009] The second bridge arm branch road is equipped with a third node and a fourth node;

[0010] The switching assembly is connected in parallel between the third and fourth nodes to switch the equivalent resistance of the second bridge arm branch;

[0011] The second and fourth nodes are connected to the same electrical connection node as the output negative terminal of the photovoltaic module.

[0012] In one possible implementation, the first bridge arm branch includes a positive ground insulation impedance and a negative ground insulation impedance;

[0013] The positive-to-ground insulation resistance is connected in series with the negative-to-ground insulation resistance;

[0014] The electrical connection nodes at both ends of the negative ground insulation impedance are the first node and the second node, respectively.

[0015] In one possible implementation, the second bridge arm branch includes: a first reference resistor, a second reference resistor, and a third reference resistor;

[0016] A fifth node is also set on the second bridge arm branch, and the fifth node is electrically connected to the output positive pole of the photovoltaic module.

[0017] The first reference resistor is set between the third node and the fifth node;

[0018] The second reference resistor is set between the third and fourth nodes;

[0019] The third reference resistor is set between the third node and the first node.

[0020] In one possible implementation, the voltage detection branch includes a first sampling resistor and a second sampling resistor; a voltage sampling point is provided on the voltage detection branch.

[0021] The first sampling resistor is connected in series with the second sampling resistor through the voltage sampling point;

[0022] The voltage detection branch is used to characterize the voltage divider detection circuit that detects the potential of the negative-to-ground insulation impedance.

[0023] In one possible implementation, the detection circuit further includes a sampling unit;

[0024] The sampling unit is electrically connected to the voltage detection branch through the voltage sampling point;

[0025] The sampling unit is used to acquire the potential signal at the voltage sampling point.

[0026] In one possible implementation, the detection circuit further includes: the operating state of the switching component includes a closed state and an open state; the equivalent resistance of the second bridge arm branch includes a first equivalent resistance and a second equivalent resistance;

[0027] When the switching assembly is in the closed state, the second reference resistor is short-circuited to switch the equivalent resistance of the second bridge arm branch to the first equivalent resistance.

[0028] When the switching assembly is in the off state, the second reference resistor is connected to the second bridge arm branch to switch the equivalent resistance of the second bridge arm branch to the second equivalent resistance.

[0029] In one possible implementation, the resistance values ​​of the first reference resistor and the second reference resistor are equal; the resistance value of the first reference resistor is a preset positive integer multiple of the resistance value of the third reference resistor.

[0030] Secondly, this application provides a method for detecting abnormal insulation resistance, applied to a photovoltaic system, the method comprising:

[0031] Obtain the positive electrode voltage value of the photovoltaic module. The positive electrode voltage value is used to represent the potential signal of the output positive electrode of the photovoltaic module.

[0032] When the switching component is in the closed state, the first voltage value of the voltage sampling point is obtained, and when the switching component is in the open state, the second voltage value of the voltage sampling point is obtained.

[0033] Based on the first voltage value and the second voltage value, the resistance value of the photovoltaic module's insulation impedance to ground is determined;

[0034] If the resistance to ground is less than a preset impedance threshold, the photovoltaic module is determined to have an abnormal ground insulation impedance.

[0035] In one possible implementation, the ground insulation impedance includes positive ground insulation impedance and negative ground insulation impedance; the method further includes:

[0036] Based on the positive voltage value, the first sampled voltage value, the positive-to-ground insulation impedance, the negative-to-ground insulation impedance, the first reference resistance, and the third reference resistance, a first equivalent equation is constructed. The first sampled voltage value is used to characterize the potential signal of the voltage sampling point when the working state of the switching component is closed.

[0037] Based on the positive voltage value, the second sampling voltage value, the positive-to-ground insulation impedance, the negative-to-ground insulation impedance, the first reference resistance, the second reference resistance, and the third reference resistance, a second equivalent equation is constructed. The second sampling voltage value is used to characterize the potential signal at the voltage sampling point when the switching component is in the off state.

[0038] Based on the first voltage value and the second voltage value, the resistance value of the photovoltaic module's insulation resistance to ground is determined, including:

[0039] The first sampled voltage value is updated based on the first voltage value;

[0040] The second sampled voltage value is updated based on the second voltage value;

[0041] Solve the first and second equivalent equations simultaneously to obtain the resistance values ​​of the positive-to-ground insulation impedance and the negative-to-ground insulation impedance of the photovoltaic module.

[0042] Thirdly, this application provides an insulation resistance anomaly detection device, comprising:

[0043] The acquisition module is used to acquire the positive voltage value of the photovoltaic module, which represents the potential signal of the output positive terminal of the photovoltaic module.

[0044] The acquisition module is also used to acquire a first voltage value of the voltage sampling point when the operating state of the switching component is closed, and to acquire a second voltage value of the voltage sampling point when the operating state of the switching component is open.

[0045] The processing module is used to determine the resistance value of the photovoltaic module's insulation impedance to ground based on the first voltage value and the second voltage value.

[0046] The processing module is also used to determine if the ground insulation impedance of the photovoltaic module is abnormal when the resistance value of the ground insulation impedance is less than a preset impedance threshold.

[0047] In one possible implementation, the processing module is further configured to construct a first equivalent equation based on the positive voltage value, the first sampled voltage value, the positive-to-ground insulation impedance, the negative-to-ground insulation impedance, the first reference resistance, and the third reference resistance. The first sampled voltage value is used to characterize the potential signal at the voltage sampling point when the switching component is in the closed state.

[0048] The processing module is also used to construct a second equivalent equation based on the positive voltage value, the second sampled voltage value, the positive-to-ground insulation impedance, the negative-to-ground insulation impedance, the first reference resistor, the second reference resistor, and the third reference resistor. The second sampled voltage value is used to characterize the potential signal of the voltage sampling point when the switching component is in the off state.

[0049] The processing module is also used to update the first sampled voltage value based on the first voltage value.

[0050] The processing module is also used to update the second sampled voltage value based on the second voltage value.

[0051] The processing module is also used to solve the first and second equivalent equations simultaneously to obtain the resistance values ​​of the positive-to-ground insulation impedance and the negative-to-ground insulation impedance of the photovoltaic module.

[0052] Fourthly, this application provides a photovoltaic system, including a photovoltaic module, a control unit, and an insulation impedance detection circuit as described in the first aspect and various possible implementations of the first aspect.

[0053] The control unit is used to control the operating state of the switching assembly;

[0054] The insulation resistance detection circuit is used to detect the resistance value of the photovoltaic module's insulation resistance to ground.

[0055] Fifthly, this application provides an electronic device, comprising:

[0056] The processor, and the memory that is in communication with the processor;

[0057] The memory stores the instructions that the computer executes;

[0058] The processor executes computer execution instructions stored in memory to implement the insulation impedance anomaly detection method as described in the second aspect and various possible implementations of the second aspect above.

[0059] Sixthly, this application provides a computer storage medium storing computer execution instructions, which are executed by a processor to implement the insulation impedance anomaly detection method as described in the second aspect and various possible implementations of the second aspect above.

[0060] In a seventh aspect, this application provides a computer program product, including a computer program that, when executed by a processor, implements an abnormal detection method for insulation impedance as described in the second aspect and various possible implementations of the second aspect above.

[0061] This application provides an insulation impedance detection circuit and an abnormal insulation impedance detection method. The detection circuit is connected between the positive and negative output terminals of a photovoltaic module and includes: a voltage detection branch, a first bridge arm branch, a second bridge arm branch, and a switching component circuit. The method obtains the positive terminal voltage value of the photovoltaic module; when the switching component is in a closed state, it obtains a first voltage value at the voltage sampling point, and when the switching component is in an open state, it obtains a second voltage value at the voltage sampling point; based on the first and second voltage values, it determines the insulation impedance to ground of the photovoltaic module; if the insulation impedance to ground is less than a preset impedance threshold, it determines that the insulation impedance to ground of the photovoltaic module is abnormal. This method simplifies the resistor network in the detection circuit, improving not only detection efficiency and system stability but also the user experience. Attached Figure Description

[0062] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0063] Figure 1 This is a schematic diagram of the insulation resistance detection circuit provided in this application. Figure 1 ;

[0064] Figure 2 This is a schematic diagram of the insulation resistance detection circuit provided in this application. Figure 2 ;

[0065] Figure 3 This is a schematic diagram of the insulation resistance detection circuit provided in this application. Figure 3 ;

[0066] Figure 4 This is a flowchart illustrating the abnormal detection method for insulation impedance provided in this application;

[0067] Figure 5 This is a schematic diagram of the structure of the insulation resistance anomaly detection device provided in this application;

[0068] Figure 6 This is a schematic diagram of the structure of the electronic device provided in this application.

[0069] Figure label:

[0070] 101 - Voltage detection branch;

[0071] 102 - First Bridge Arm Branch Road;

[0072] 103 - Second Bridge Arm Branch Road;

[0073] Q - First node;

[0074] O - Second node;

[0075] M - Third node;

[0076] N - Fourth node;

[0077] P - Fifth node;

[0078] PE - Voltage sampling point.

[0079] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0080] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0081] The terms "first," "second," "third," "fourth," etc. (if present) in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention described herein can be implemented, for example, in orders other than those illustrated or described herein.

[0082] In this application, the terms "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0083] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties. Furthermore, the collection, use and processing of the relevant data must comply with relevant laws, regulations and standards, and corresponding operation entry points are provided for users to choose to authorize or refuse.

[0084] First, the terms used in this application will be explained.

[0085] Nodal current conservation: also known as Kirchhoff's current law, is one of the fundamental laws in circuit analysis. Its core content is: in a lumped parameter circuit, at any time, for any circuit node, the sum of the currents flowing into the node is equal to the sum of the currents flowing out of the node; if the current flowing into the node is defined as positive and the current flowing out is negative, it can be equivalently stated as: at any time, the algebraic sum of the currents in all branches flowing through a certain node of the circuit is equal to zero.

[0086] Voltage divider balance principle: This is a fundamental characteristic of series resistor circuits. Its core content is that in a circuit composed of multiple resistors connected in series, the power supply voltage will be distributed across each series resistor according to the resistance value of each resistor; the voltage across each resistor is proportional to its resistance value.

[0087] A photovoltaic water heater system is a device that converts solar energy into thermal energy. Its core consists of photovoltaic modules, a control system, and a thermal energy conversion module. The photovoltaic modules output electrical energy through a DC bus (positive PV+ and negative PV-) to drive a water pump or heating element. It is widely used in scenarios such as household hot water supply.

[0088] Because photovoltaic panels are exposed to the outdoor environment for extended periods, their insulation performance gradually deteriorates due to factors such as temperature changes, humidity, and dust corrosion, leading to a decrease in their insulation resistance to ground. When the insulation resistance falls below a safe threshold, the positive and negative terminals of the photovoltaic system may form a leakage circuit through damp ground or metal conductors, posing a risk of electric shock. The probability of leakage accidents increases significantly, especially in humid weather or when water accumulates on the surface of the photovoltaic panels. Therefore, photovoltaic water heaters require real-time monitoring of the insulation resistance to ground of the photovoltaic modules. If an abnormality is detected, an alarm should be triggered immediately and operation should cease to ensure user safety.

[0089] In existing technologies, the detection of the insulation impedance of photovoltaic modules to ground is usually based on the principle of resistive voltage division. This involves constructing a measurement circuit that includes multiple fixed resistors and controllable switches, and using voltage sampling to calculate the insulation impedance value.

[0090] However, existing detection methods typically rely on complex measurement circuits and control logic, resulting in high hardware costs and complex detection logic. This makes it difficult to meet the requirements of photovoltaic water heaters for low cost and high reliability, and also easily leads to low detection efficiency of insulation resistance to ground.

[0091] In addition, frequent switching may accelerate component aging and further affect the stability of the photovoltaic system.

[0092] To address the aforementioned issues, this application provides an insulation impedance detection circuit and a method for detecting insulation impedance anomalies. This detection circuit, through the switching of a single relay between closed and open states, combined with a specific resistance ratio and equivalent circuit transformation, derives the photovoltaic system's insulation impedance to ground by measuring the difference between two voltage sampling values. Based on the principles of node current conservation and voltage division balance, a circuit balance equation is constructed, simplifying the resistor network in the detection circuit, improving detection efficiency and system stability. Furthermore, the single-switch action reduces frequent relay switching, extending hardware lifespan and avoiding the risk of failures due to mechanical wear. This method determines whether the photovoltaic system's insulation impedance to ground is abnormal by detecting the insulation impedance to ground using the insulation impedance detection circuit. By detecting insulation impedance anomalies in real time and triggering alarms, this method effectively prevents leakage accidents, ensures user safety, and improves the user experience.

[0093] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0094] Figure 1 This is a schematic diagram of the insulation resistance detection circuit provided in this application. Figure 1 ; Figure 2This is a schematic diagram of the insulation resistance detection circuit provided in this application. Figure 2 ; Figure 3 This is a schematic diagram of the insulation resistance detection circuit provided in this application. Figure 3 .

[0095] See attached document Figure 1 To be continued Figure 3 This application provides an insulation resistance detection circuit, which is connected between the positive output terminal PV+ and the negative output terminal PV- of a photovoltaic module. The detection circuit includes a voltage detection branch 101, a first bridge arm branch 102, a second bridge arm branch 103, and a switching component K.

[0096] The first bridge arm branch 102 and the second bridge arm branch 103 are connected in parallel between the positive output terminal PV+ and the negative output terminal PV- of the photovoltaic module, respectively. The first bridge arm branch 102 is provided with a first node Q and a second node O. The voltage detection branch 101 is connected in parallel between the first node Q and the second node O. The second bridge arm branch 103 is provided with a third node M and a fourth node N. The switching component K is connected in parallel between the third node M and the fourth node N and is used to switch the equivalent resistance of the second bridge arm branch 103. The second node O and the fourth node N are connected to the same electrical connection node as the negative output terminal PV- of the photovoltaic module.

[0097] Understandably, voltage detection branch 101 refers to a voltage divider circuit set between the first node Q and the second node O, which detects the insulation resistance to ground by the voltage division relationship of the sampling resistors; first bridge arm branch 101 refers to a circuit branch connected in parallel between the output positive terminal PV+ and the output negative terminal PV- of the photovoltaic module, which includes a series structure of positive insulation resistance to ground and negative insulation resistance to ground; second bridge arm branch 103 refers to a circuit branch connected in parallel between the output positive terminal PV+ and the output negative terminal PV- of the photovoltaic module, which includes a reference resistor network, which can be composed of multiple reference resistors connected in series or in parallel to form a voltage divider path.

[0098] The switching component K refers to a device that can switch the circuit connection state. The switching component K is connected in parallel between the third node M and the fourth node N of the second bridge arm branch 103, thereby changing the number of resistors in the second bridge arm branch 103 that participate in the equivalent resistance calculation.

[0099] In this embodiment, the insulation impedance detection circuit utilizes the principles of node current conservation and voltage division balance to construct corresponding circuit balance equations for different on / off states of the switch component K. The voltage detection branch 101 detects the voltage values ​​at corresponding sampling points in different states of the switch component K. These values ​​are then combined with the circuit balance equations for the corresponding on / off states to solve the corresponding ground insulation impedance values. This enables real-time detection of insulation impedance anomalies, effectively preventing leakage accidents, ensuring user safety, and improving the user experience.

[0100] For example, the switching component K can be a relay or an electronic switch for closing or opening a specific resistor in the second bridge arm branch.

[0101] In one possible implementation, the first bridge arm branch 102 includes a ground-to-ground insulation impedance. and negative insulation resistance to ground .

[0102] Among them, the insulation resistance to ground Negative insulation resistance to ground Series connection; negative insulation resistance to ground The two electrical connection nodes at the two ends are the first node Q and the second node O, respectively.

[0103] Understandable, ground insulation resistance This refers to the insulation resistance between the positive electrode of a photovoltaic module and the ground, and is a key parameter for measuring the positive electrode-to-ground insulation performance of a photovoltaic system; negative electrode-to-ground insulation resistance... It refers to the insulation resistance between the negative electrode side of the photovoltaic module and the ground, and is a key parameter for measuring the insulation performance of the negative electrode to the ground of the system.

[0104] In this embodiment, the first node Q is the insulation resistance to ground. and negative insulation resistance to ground The serial node is also the floating point Earth in the detection circuit.

[0105] In one possible implementation, the second bridge arm branch 103 includes: a first reference resistor. Second reference resistor and the third reference resistor .

[0106] Among them, a fifth node P is also set on the second bridge arm branch 103, and the fifth node P and the output positive terminal PV+ of the photovoltaic module are the same electrical connection node; the first reference resistor The second reference resistor is positioned between the third node M and the fifth node P. The third reference resistor is positioned between the third node M and the fourth node N. It is set between the third node M and the first node Q.

[0107] Understandable, the first reference resistor Second reference resistor Series connection, and the first reference resistor The other end is connected to the fifth node P, which is also connected to the positive output terminal PV+ of the photovoltaic module; the second reference resistor The other end is connected to the fourth node N, which is also connected to the negative output terminal PV- of the photovoltaic module; the third reference resistor This is a bridging resistor set between the first bridge arm branch 102 and the second bridge arm branch 103.

[0108] Insulation resistance to ground Negative insulation resistance to ground Series connection, and insulation resistance to ground The other end is connected to the fifth node P, which is also connected to the positive output terminal PV+ of the photovoltaic module; negative insulation resistance to ground. The other end is connected to the second node O, and the second node O is the grounding point.

[0109] In this embodiment, the equivalent resistance of the second bridge arm branch 103 is determined by the first reference resistor. Second reference resistor Series configuration, third reference resistor The bridging resistors for the first bridge arm branch 102 and the second bridge arm branch 103 are used to achieve potential coupling or signal bridging between the two branches.

[0110] In one possible implementation, the voltage detection branch 101 includes a first sampling resistor. Second sampling resistor A voltage sampling point PE is installed on the voltage detection branch 101.

[0111] Among them, the first sampling resistor The voltage sampling point PE is connected in series with the second sampling resistor. Voltage detection branch 101 is used to characterize the insulation resistance to negative ground. A voltage divider detection circuit for potential detection.

[0112] Understandably, voltage detection branch 101 is the detection point for this insulation impedance, used to collect the negative-to-ground insulation impedance, and is used to calculate the positive-to-ground insulation impedance. and negative insulation resistance to ground The sampling circuit; the first sampling resistor Second sampling resistor This is the voltage divider resistor in the sampling circuit.

[0113] In this embodiment, the first sampling resistor The resistance value is much larger than that of the second sampling resistor. And much greater than the insulation resistance to ground. Negative insulation resistance to ground First reference resistor Second reference resistor and the third reference resistor Therefore, when acquiring the potential signal of the voltage sampling point PE, the potential signal of PE can be used as the potential signal of the floating point Earth. Since the floating point Earth and the first node Q are equipotential points, and the second node O is a ground point, the potential signal of the voltage sampling point PE can be used as the negative ground insulation impedance. The potential difference between the two ends is used to assist in the corresponding insulation resistance to ground. and negative insulation resistance to ground The calculation.

[0114] In one possible implementation, the detection circuit further includes a sampling unit (not shown in the figure).

[0115] The sampling unit is electrically connected to the voltage detection branch 101 through the voltage sampling point PE; the sampling unit is used to collect the potential signal of the voltage sampling point PE.

[0116] For example, the sampling unit can be the microcontroller's ADC module (Analog-to-Digital Converter Module) or a stand-alone voltage acquisition module.

[0117] In one possible implementation, the detection circuit further includes: the operating state of the switch component K includes a closed state and an open state; the equivalent resistance of the second bridge arm branch 103 includes a first equivalent resistance and a second equivalent resistance.

[0118] The equivalent resistance of the second bridge arm branch 103 refers to the combined resistance value of all resistors involved in the equivalent resistance calculation when the switching component K is in different operating states.

[0119] In this embodiment, the equivalent resistance of the second bridge arm branch 103 is calculated solely from the first reference resistor. Second reference resistor The specific resistance value of the equivalent resistance of the second bridge arm branch 103 is adjusted according to the on / off state of the switching component K.

[0120] When the switching component K is in the closed state, the second reference resistor Short-circuited, used to switch the equivalent resistance of the second bridge arm branch 103 to the first equivalent resistance; when the switching component K is in the off state, the second reference resistor Connect to the second bridge arm branch 103 to switch the equivalent resistance of the second bridge arm branch 103 to the second equivalent resistance.

[0121] In other words, the switching assembly K is connected in parallel between the third node M and the fourth node N; when the switching assembly K is open, the second bridge arm branch 103 (from the fifth node P to the fourth node N) includes the first reference resistor. Second reference resistor Both are involved in the equivalent resistance calculation; when the switching component K is closed, the second reference resistor... Shorted, only the first reference resistor It participates in the equivalent resistance calculation; thereby, by changing the working state of the switching component K, the number of resistors participating in the equivalent resistance calculation in the second bridge arm branch 103 can be changed.

[0122] In this embodiment of the application, when the switching component K is in the open state, the insulation resistance to ground is... First reference resistor Second reference resistor A triangular resistor network is constructed, which is then transformed into an equivalent star resistor network using Kirchhoff's laws. This simplifies the resistor network in the detection circuit, making it easier to calculate the equivalent impedance of the branches, reducing the algorithm complexity of the detection module, and avoiding interference from complex loops in the triangular network topology on the sampling signal, thereby improving the accuracy and stability of the insulation impedance detection results.

[0123] Furthermore, by using a single switch, the frequent switching of relays is reduced, extending the lifespan of the hardware, avoiding the risk of failure due to mechanical wear, and improving detection efficiency and system stability.

[0124] For example, Figure 1 This is a schematic diagram of the insulation resistance detection circuit when the switching component K is in the closed state. Figure 2 This is a schematic diagram of the insulation resistance detection circuit when the switching component K is in the off state. Figure 3 This is a schematic diagram of the equivalent transformation of the insulation resistance detection circuit when the switching component K is in the open state; wherein, the insulation resistance to ground is... First reference resistor Second reference resistor The star-shaped resistor network is obtained by equivalent transformation of the triangular resistor network. The resistors in the star-shaped resistor network include... , , The specific equivalent calculation is shown in Formula 1 below:

[0125]

[0126] in, The third reference resistor The resistance value.

[0127] In one possible implementation, the first reference resistor With the second reference resistor The resistance values ​​are equal; the first reference resistor The resistance value is the third reference resistor. The resistance value is a preset positive integer multiple.

[0128] Understandable, the first reference resistor Second reference resistor and the third reference resistor The resistance values ​​satisfy a specific proportional relationship, where the preset positive integer multiple can be, for example, 2 times, meaning the first reference resistor... With the second reference resistor The resistance values ​​are all third reference resistors. It is twice the resistance value.

[0129] This application also provides a photovoltaic system, including a photovoltaic module, a control unit, and an insulation impedance detection circuit as described in any of the foregoing embodiments;

[0130] The control unit is used to control the operating state of the switching assembly;

[0131] The insulation resistance detection circuit is used to detect the resistance value of the photovoltaic module's insulation resistance to ground.

[0132] Figure 4 This is a schematic flowchart illustrating the abnormal insulation resistance detection method provided in this embodiment. The executing entity in this embodiment can be, for example, the control unit of a photovoltaic system. Figure 4 As shown, the insulation resistance anomaly detection method provided in this embodiment includes:

[0133] S401: Obtain the positive voltage value of the photovoltaic module.

[0134] S402: When the switching component is in the closed state, acquire the first voltage value of the voltage sampling point, and when the switching component is in the open state, acquire the second voltage value of the voltage sampling point.

[0135] As is understandable, a photovoltaic (PV) module refers to a power generation unit composed of several PV cells connected in series and parallel. It is the core power generation component of a PV system, and its output voltage varies with factors such as light intensity and ambient temperature. The positive voltage value refers to the potential value of the positive output terminal of the PV module relative to the PV system reference ground (usually the negative terminal of the system's DC bus or the earth). The positive voltage value is a fundamental electrical parameter used to characterize the power generation state of the PV module and can be denoted as... .

[0136] The first voltage value and the second voltage value refer to the potential values ​​of the voltage sampling point PE relative to the reference ground when the switching component K is in the closed and open states, respectively, and are denoted as follows: (Closed state) and (Disconnected state) is the core sampling parameter for calculating insulation impedance.

[0137] S403: Determine the resistance value of the photovoltaic module's insulation resistance to ground based on the first voltage value and the second voltage value.

[0138] For the insulation impedance detection circuit, the principle of node current conservation and voltage division balance is used to construct the corresponding circuit balance equations for different on and off states of switch component K. The voltage detection branch 101 is used to detect the voltage value (i.e., the first voltage value and the second voltage value) of the corresponding sampling point in different states of switch component K. The circuit balance equations for the corresponding on and off states are combined and solved to obtain the resistance value of the corresponding ground insulation impedance.

[0139] Understandably, the second bridge arm branch 103 is connected to the first reference resistor. Second reference resistor and the third reference resistor First reference resistor The second reference resistor is connected between the third node M and the positive output terminal PV+ of the photovoltaic module. The third reference resistor is connected between the fourth node N and the negative output terminal PV- of the photovoltaic module. Connected between the first node Q and the third node M; when the switching component K is in the closed state, the second reference resistor When short-circuited, it forms the first equivalent resistance; when the switching component K is open, the second reference resistance... It is connected to the circuit to form a second equivalent resistance; by switching the equivalent resistance twice, the voltage divider path of the voltage detection branch 101 changes, and the sampling unit calculates the insulation impedance by the difference between the two voltage measurements.

[0140] In one possible implementation, the insulation resistance to ground includes the insulation resistance to ground. Negative insulation resistance to ground Based on the positive voltage value, the first sampled voltage value, and the insulation resistance to ground. Negative insulation resistance to ground First reference resistor and the third reference resistor Construct the first equivalent equation; based on the positive voltage value, the second sampled voltage value, and the insulation impedance to ground. Negative insulation resistance to ground First reference resistor Second reference resistor and the third reference resistor A second equivalent equation is constructed; the first sampled voltage value is updated based on the first voltage value; the second sampled voltage value is updated based on the second voltage value; the first and second equivalent equations are solved simultaneously to obtain the forward-to-ground insulation impedance of the photovoltaic module. The resistance value and negative insulation resistance to ground The resistance value.

[0141] The first sampling voltage value refers to the potential detection value of the voltage sampling point PE when the switching component K is in the closed state, and the potential detection value of the voltage sampling point PE when the switching component K is in the open state.

[0142] For example, the first equivalent equation is shown in Formula 2 below:

[0143]

[0144] The second equivalent equation is shown in Formula 3 below:

[0145]

[0146] Solving the system of equations 1 and 2 simultaneously, we get...

[0147]

[0148]

[0149] in, When switch component K is closed, the voltage at voltage sampling point PE is recorded as follows: , When the switching component K is open, the voltage at the voltage sampling point PE is recorded as follows: , .

[0150] Combined with the first voltage value acquired in real time Second voltage value Substituting the results from the simultaneous solution, the insulation resistance to ground can be calculated. The resistance value and negative insulation resistance to ground .

[0151] S404: If the resistance to ground is less than the preset impedance threshold, the photovoltaic module is determined to have an abnormal ground insulation impedance.

[0152] In this embodiment of the application, the insulation resistance to ground includes the insulation resistance to ground. The resistance value and negative insulation resistance to ground Therefore, in determining whether an abnormality in the ground insulation impedance of a photovoltaic module is abnormal, the ground insulation impedance is crucial. The resistance value and negative insulation resistance to ground If any of the photovoltaic modules exhibits an abnormal ground insulation impedance, then the photovoltaic module's ground insulation impedance is abnormal.

[0153] The preset impedance threshold is dynamically adjusted based on the DC rated voltage of the photovoltaic system, denoted as . This application does not impose any special restrictions on the preset impedance threshold.

[0154] The insulation impedance anomaly detection method provided in this embodiment obtains the positive electrode voltage value of the photovoltaic module; when the switching component is in the closed state, it obtains a first voltage value at the voltage sampling point, and when the switching component is in the open state, it obtains a second voltage value at the voltage sampling point; based on the first and second voltage values, it determines the ground insulation impedance of the photovoltaic module, and if the ground insulation impedance is less than a preset impedance threshold, it determines that the ground insulation impedance of the photovoltaic module is abnormal. This method solves the problem of missed detection caused by the limited probe installation position, achieves high-precision detection of water leakage events, reduces the false judgment rate of water leakage faults, and not only improves detection efficiency but also enhances the user experience.

[0155] Figure 5 This is a schematic diagram of the insulation resistance anomaly detection device provided in this application. Figure 5 As shown, this application provides an insulation resistance anomaly detection device 500, which includes:

[0156] The acquisition module 501 is used to acquire the positive voltage value of the photovoltaic module, which represents the potential signal of the output positive terminal of the photovoltaic module.

[0157] The acquisition module 501 is also used to acquire a first voltage value of the voltage sampling point when the working state of the switching component is closed, and to acquire a second voltage value of the voltage sampling point when the working state of the switching component is open.

[0158] The processing module 502 is used to determine the resistance value of the photovoltaic module's insulation impedance to ground based on the first voltage value and the second voltage value.

[0159] The processing module 502 is also used to determine that the ground insulation impedance of the photovoltaic module is abnormal when the resistance value of the ground insulation impedance is less than a preset impedance threshold.

[0160] In one possible implementation, the processing module 502 is further configured to construct a first equivalent equation based on the positive voltage value, the first sampled voltage value, the positive-to-ground insulation impedance, the negative-to-ground insulation impedance, the first reference resistance, and the third reference resistance. The first sampled voltage value is used to characterize the potential signal at the voltage sampling point when the switching component is in the closed state.

[0161] The processing module 502 is also used to construct a second equivalent equation based on the positive voltage value, the second sampled voltage value, the positive to ground insulation impedance, the negative to ground insulation impedance, the first reference resistor, the second reference resistor, and the third reference resistor. The second sampled voltage value is used to characterize the potential signal of the voltage sampling point when the working state of the switching component is in the off state.

[0162] The processing module 502 is also used to update the first sampled voltage value based on the first voltage value.

[0163] The processing module 502 is also used to update the second sampled voltage value based on the second voltage value.

[0164] The processing module 502 is also used to solve the first equivalent equation and the second equivalent equation simultaneously to obtain the resistance value of the positive-to-ground insulation impedance and the resistance value of the negative-to-ground insulation impedance of the photovoltaic module.

[0165] Figure 6 A schematic diagram of the structure of the electronic device provided in this application. Figure 6 As shown, this application provides an electronic device 600, which includes: a receiver 601, a transmitter 602, a processor 603, and a memory 604.

[0166] Receiver 601 is used to receive instructions and data;

[0167] Transmitter 602 is used to send commands and data;

[0168] Memory 604 is used to store instructions executed by the computer;

[0169] The processor 603 is used to execute computer execution instructions stored in the memory 604 to implement the various steps of the insulation impedance anomaly detection method in the above embodiments. For details, please refer to the relevant descriptions in the foregoing embodiments of the insulation impedance anomaly detection method.

[0170] Optionally, the memory 604 can be either standalone or integrated with the processor 603.

[0171] When the memory 604 is set up independently, the electronic device also includes a bus for connecting the memory 604 and the processor 603.

[0172] This application also provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement an abnormal insulation impedance detection method as described above in the electronic device.

[0173] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the method for detecting abnormal insulation impedance of any of the foregoing embodiments.

[0174] It will be understood by those skilled in the art that all or some of the steps, systems, or apparatuses disclosed above, and their functional modules / units, can be implemented as software, firmware, hardware, or suitable combinations thereof. In hardware implementations, the division between functional modules / units mentioned in the above description does not necessarily correspond to the division of physical components; for example, a physical component may have multiple functions, or a function or step may be performed collaboratively by several physical components. Some or all physical components may be implemented as software executed by a processor, such as a central processing unit, digital signal processor, or microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit (ASIC). Such software may be distributed on a computer-readable medium, which may include computer storage media (or non-transitory media) and communication media (or transient media). As is known to those skilled in the art, the term computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disc (DVD) or other optical disc storage, magnetic cartridges, magnetic tape, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and can be accessed by a computer. Furthermore, it is well known to those skilled in the art that communication media typically contain computer-readable instructions, data structures, program modules, or other data in modulated data signals such as carrier waves or other transmission mechanisms, and may include any information delivery medium.

[0175] The technical solutions of this application have been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it is readily understood by those skilled in the art that the scope of protection of this application is obviously not limited to these specific embodiments. The above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. An insulation resistance detection circuit, characterized in that, The detection circuit is connected between the positive and negative output terminals of the photovoltaic module. The detection circuit includes: a voltage detection branch, a first bridge arm branch, a second bridge arm branch, and a switching assembly. The first bridge arm branch and the second bridge arm branch are respectively connected in parallel between the positive and negative output terminals of the photovoltaic module; The first bridge arm branch is provided with a first node and a second node; the voltage detection branch is connected in parallel between the first node and the second node. The second bridge arm branch is equipped with a third node and a fourth node; The switching assembly is connected in parallel between the third node and the fourth node to switch the equivalent resistance of the second bridge arm branch; The second node, the fourth node, and the output negative terminal of the photovoltaic module are connected to the same electrical node.

2. The detection circuit according to claim 1, characterized in that, The first bridge arm branch includes positive ground insulation resistance and negative ground insulation resistance; The positive ground insulation impedance is connected in series with the negative ground insulation impedance; The electrical connection nodes at both ends of the negative ground insulation impedance are the first node and the second node, respectively.

3. The detection circuit according to claim 1, characterized in that, The second bridge arm branch includes: a first reference resistor, a second reference resistor, and a third reference resistor; A fifth node is also provided on the second bridge arm branch, and the fifth node is electrically connected to the output positive pole of the photovoltaic module; The first reference resistor is disposed between the third node and the fifth node; The second reference resistor is disposed between the third node and the fourth node; The third reference resistor is positioned between the third node and the first node.

4. The detection circuit according to claim 2, characterized in that, The voltage detection branch includes a first sampling resistor and a second sampling resistor; a voltage sampling point is provided on the voltage detection branch. The first sampling resistor is connected in series with the second sampling resistor through the voltage sampling point; The voltage detection branch is used to characterize the voltage divider detection circuit that detects the potential of the negative ground insulation impedance.

5. The detection circuit according to claim 4, characterized in that, The detection circuit further includes: a sampling unit; The sampling unit is electrically connected to the voltage detection branch through the voltage sampling point; The sampling unit is used to collect the potential signal of the voltage sampling point.

6. The detection circuit according to claim 3, characterized in that, The detection circuit further includes: the working state of the switching assembly includes a closed state and an open state; the equivalent resistance of the second bridge arm branch includes a first equivalent resistance and a second equivalent resistance; When the switching assembly is in the closed state, the second reference resistor is short-circuited to switch the equivalent resistance of the second bridge arm branch to the first equivalent resistance. When the switching assembly is in the off state, the second reference resistor is connected to the second bridge arm branch to switch the equivalent resistance of the second bridge arm branch to the second equivalent resistance.

7. The detection circuit according to claim 3, characterized in that, The first reference resistor has the same resistance value as the second reference resistor; the resistance value of the first reference resistor is a preset positive integer multiple of the resistance value of the third reference resistor.

8. A photovoltaic system, characterized in that, Includes photovoltaic modules, a control unit, and an insulation resistance detection circuit as described in any one of claims 1-7; The control unit is used to control the operating state of the switching assembly; The insulation impedance detection circuit is used to detect the resistance value of the photovoltaic module's insulation impedance to ground.

9. A method for detecting abnormal insulation resistance, characterized in that, Applied to photovoltaic systems, the method includes: The positive electrode voltage value of the photovoltaic module is obtained, and the positive electrode voltage value is used to represent the potential signal of the output positive electrode of the photovoltaic module; When the switching component is in the closed state, a first voltage value of the voltage sampling point is acquired, and when the switching component is in the open state, a second voltage value of the voltage sampling point is acquired. Based on the first voltage value and the second voltage value, the resistance value of the photovoltaic module's insulation impedance to ground is determined; If the resistance value of the ground insulation impedance is less than a preset impedance threshold, the ground insulation impedance of the photovoltaic module is determined to be abnormal.

10. The method according to claim 9, characterized in that, The ground insulation resistance includes positive ground insulation resistance and negative ground insulation resistance; the method further includes: Based on the positive voltage value, the first sampled voltage value, the positive-to-ground insulation impedance, the negative-to-ground insulation impedance, the first reference resistance, and the third reference resistance, a first equivalent equation is constructed. The first sampled voltage value is used to characterize the potential signal of the voltage sampling point when the working state of the switching component is the closed state. Based on the positive voltage value, the second sampling voltage value, the positive-to-ground insulation impedance, the negative-to-ground insulation impedance, the first reference resistor, the second reference resistor, and the third reference resistor, a second equivalent equation is constructed. The second sampling voltage value is used to characterize the potential signal of the voltage sampling point when the working state of the switching component is in the open state. Determining the ground insulation impedance of the photovoltaic module based on the first voltage value and the second voltage value includes: The first sampled voltage value is updated based on the first voltage value; The second sampled voltage value is updated based on the second voltage value; Solve the first and second equivalent equations simultaneously to obtain the resistance values ​​of the positive-to-ground insulation impedance and the negative-to-ground insulation impedance of the photovoltaic module.

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