Relay fault detection method and device, inverter system and storage medium

Abstract

The invention relates to the technical field of new energy, and mainly provides a relay fault detection method and device, an inverter system and a storage medium, and the method comprises the steps: receiving a control signal; the three-phase relay is controlled to be closed according to the control signal, and three-phase current output by the three-phase inverter is collected; obtaining a current instruction, and calculating a difference value between the three-phase current and the current instruction; when the difference value is greater than a preset current threshold value, obtaining a reactive power instruction, and controlling the three-phase inverter to work according to the reactive power instruction so as to obtain the actual reactive power of the three-phase inverter; and calculating the deviation between the reactive power instruction and the actual reactive power, and outputting a turn-off signal to the three-phase relay when the deviation is greater than a preset power threshold value so as to control the three-phase relay to be turned off. On the basis, the situation of misjudgment is avoided through double threshold value judgment of the current and the power, then the reliability of the inverter system is improved, the inverter is controlled to stop working when the relay breaks down, and resource waste is effectively avoided.

Description

Technical Field

[0001] This invention relates to the field of new energy technology, and in particular to a relay fault detection method, device, inverter system, and storage medium. Background Technology

[0002] In new energy power generation systems such as photovoltaics and energy storage, the inverter, as the core equipment for power conversion, needs to interact with the power grid through a grid-connected path at its AC output end. The grid-connected contactor (a key relay) connected in series on this path is a core component that ensures power switching control and electrical safety isolation. The reliable operation of this grid-connected contactor directly determines the grid-connected stability of the system. If it becomes open-circuited due to faults such as mechanical jamming, contact burning, or abnormal coil drive, it will directly block the feed channel of the inverter's output power to the grid, causing the system to shut down and stop power generation.

[0003] Currently, inverter systems generally employ an open-loop detection mechanism based on drive signals for monitoring the status of grid-connected contactors. This means that the operating status is indirectly inferred by determining whether a relay energizing command has been issued, without directly detecting the actual contactor contact continuity. This monitoring method has significant limitations: when scenarios arise where the command status ("drive signal issued but contacts not closed due to physical fault" or "contacts abnormally open during operation") differs from the actual status, the system cannot effectively identify open-circuit faults in the grid-connected contactor. Due to the lack of diagnostic capabilities for the actual relay continuity, the system cannot promptly detect open-circuit faults or trigger corresponding alarms or protection actions, resulting in the inverter remaining in an abnormal grid-connected state. This leads to reduced system reliability, increased maintenance costs, and reduced power generation efficiency. Summary of the Invention

[0004] The present invention provides a relay fault detection method, device, inverter system and storage medium, which mainly solves the technical problems of low reliability, high cost and low utilization rate of inverter systems in the prior art.

[0005] To solve the above-mentioned technical problems, one technical solution adopted in this invention is: providing a relay fault detection method applied to an inverter system, the inverter system including a three-phase inverter and a three-phase relay connected to the three-phase inverter, wherein the three-phase inverter is used to output three-phase power to the power grid through the three-phase relay; the method includes: Receive control signals; The control signal is used to control the three-phase relays to close, and the three-phase currents output by the three-phase inverter are collected respectively. Obtain the current command and calculate the difference between the three-phase current and the current command; When the difference is greater than a preset current threshold, a reactive power command is obtained, and the three-phase inverter is controlled to work according to the reactive power command to obtain the actual reactive power of the three-phase inverter. The deviation between the reactive power command and the actual reactive power is calculated, and when the deviation is greater than a preset power threshold, a shutdown signal is output to the three-phase relay to control the three-phase relay to disconnect.

[0006] Optionally, the step of acquiring the current command and calculating the difference between the three-phase current and the current command includes: Obtain the current command, wherein the current command includes a first current command, a second current command, and a third current command; The first current command, the second current command, and the third current command are subjected to coordinate transformation to obtain the d-axis DC component and the q-axis DC component of the current command. The three-phase currents are subjected to coordinate transformation to obtain the d-axis DC component and the q-axis DC component of the three-phase currents. Calculate the difference between the d-axis DC component of the current command and the d-axis command component of the three-phase current, and the difference between the q-axis DC component of the current command and the q-axis DC component of the three-phase current.

[0007] Optionally, when the difference is greater than the preset current threshold, the method further includes: Obtain the duration for which the difference is greater than the preset current threshold; If the duration is greater than the first preset time, then the reactive power command is obtained; If the duration is less than the first preset time, then the acquisition of the reactive power command is stopped, and it is determined that the three-phase relay has not malfunctioned.

[0008] Optionally, after calculating the difference between the d-axis DC component of the current command and the d-axis command component of the three-phase current, and the difference between the q-axis DC component of the current command and the q-axis DC component of the three-phase current, the method further includes: The d-axis voltage command and q-axis voltage command are obtained based on the difference between the current command and the d-axis component and the q-axis component of the three-phase current; The d-axis voltage command and the q-axis voltage command are subjected to inverse coordinate transformation to obtain the three-phase voltage command; The three-phase voltage command is modulated by PWM and output to the three-phase inverter to update the three-phase current output by the three-phase inverter.

[0009] Optionally, calculating the deviation between the reactive power command and the actual reactive power includes: Collect the three-phase line voltages output by the three-phase inverter; Calculate the actual reactive power based on the three-phase line voltage, and calculate the average reactive power based on the actual reactive power; Based on the average reactive power, the deviation between the reactive power command and the average reactive power is calculated, and the three-phase relay is determined to be faulty based on the difference.

[0010] Optionally, the formula for calculating the reactive power is: ; Among them, Q 实 Vab, Vbc, and Vac are the actual reactive power of the three-phase inverter, Vab, Vbc, and Vac are the three-phase line voltages output by the three-phase inverter, and ia, ib, and ic are the three-phase currents output by the three-phase inverter. The formula for calculating the average reactive power is as follows: ; Where Q is the average reactive power and T is the integral time of the three-phase inverter.

[0011] Optionally, the method further includes: When the deviation between the reactive power command and the actual reactive power is less than a preset power threshold, it is determined that the three-phase relay has not malfunctioned.

[0012] To solve the above-mentioned technical problems, another technical solution adopted in this invention is: providing a relay fault detection device applied to an inverter system, the inverter system including a three-phase inverter and a three-phase relay connected to the three-phase inverter, wherein the three-phase inverter is used to output three-phase power to the power grid through the three-phase relay; the device includes: The receiving module is used to receive control signals; The acquisition module is used to control the three-phase relay to close according to the control signal, and to acquire the three-phase current output by the three-phase inverter respectively; The calculation module is used to acquire the current command and calculate the difference between the three-phase current and the current command; The acquisition module is used to acquire a reactive power command when the difference is greater than a preset current threshold, and control the three-phase inverter to work according to the reactive power command in order to acquire the actual reactive power of the three-phase inverter. The control module is used to calculate the deviation between the reactive power command and the actual reactive power, and when the deviation is greater than a preset power threshold, output a shutdown signal to the three-phase relay to control the three-phase relay to disconnect.

[0013] To solve the above-mentioned technical problems, another technical solution adopted in the embodiments of the present invention is: to provide an inverter system, the inverter system comprising: Three-phase inverter; A three-phase relay, the three-phase relay being connected to the three-phase inverter; and A controller, connected to both the three-phase inverter and the three-phase relay; wherein the controller includes at least one processor; and, A memory communicatively connected to the at least one processor; wherein, The memory stores instructions that can be executed by the at least one processor to enable the at least one processor to perform the method as described above.

[0014] To solve the above-mentioned technical problems, another technical solution adopted in the embodiments of the present invention is to provide a non-transitory computer-readable storage medium, wherein the non-transitory computer-readable storage medium stores computer-executable instructions, the computer-executable instructions being used to cause a computer to perform the method described above.

[0015] Unlike related technologies, this invention provides a relay fault detection method, device, inverter system, and storage medium. The method is applied to an inverter system, which includes a three-phase inverter and a three-phase relay connected to the three-phase inverter. The three-phase inverter outputs three-phase electricity to the power grid through the three-phase relay. The method includes: receiving a control signal; controlling the three-phase relay to close according to the control signal and collecting the three-phase current output by the three-phase inverter; obtaining a current command and calculating the difference between the three-phase current and the current command; when the difference is greater than a preset current threshold, obtaining a reactive power command and controlling the three-phase inverter to operate according to the reactive power command to obtain the actual reactive power of the three-phase inverter; calculating the deviation between the reactive power command and the actual reactive power, and when the deviation is greater than a preset power threshold, outputting a shutdown signal to the three-phase relay to control the three-phase relay to open. Based on this, by using dual thresholds for current and power, misjudgments are avoided, thereby improving the reliability of the inverter system. Furthermore, when a relay malfunctions, the relay is disconnected, and the inverter stops working, thus avoiding resource waste. Attached Figure Description

[0016] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements having the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0017] Figure 1 This is a schematic diagram of an application scenario of an inverter system provided by an embodiment of the present invention; Figure 2 This is a circuit diagram of an inverter system provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of a controller provided in an embodiment of the present invention; Figure 4 This is a flowchart of a fault detection method provided in an embodiment of the present invention; Figure 5 This is a structural block diagram of a relay fault detection device provided in an embodiment of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0019] It should be noted that, unless otherwise specified, the various features in the embodiments of the present invention can be combined with each other, and all are within the protection scope of the present invention. Furthermore, although functional modules are divided in the device schematic diagram and a logical order is shown in the flowchart, in some cases, the steps shown or described may be performed in a different module division or in a different order than that shown in the device schematic diagram or the flowchart.

[0020] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used in this specification includes any and all combinations of one or more of the associated listed items.

[0021] Please see Figure 1 , Figure 1 This is a schematic diagram illustrating an application scenario of an inverter system provided in an embodiment of the present invention, such as... Figure 1 As shown, this application scenario 1 includes an inverter system 100 and a power grid 200; the inverter system 100 is connected to the power grid 200, and the inverter system 100 is used to supply power to the power grid 200.

[0022] Among them, such as Figure 1As shown, the inverter system 100 includes a three-phase inverter 10, a three-phase relay 20, and a controller 30. The three-phase inverter 10 is connected to the three-phase relay 20, and the three-phase relay 20 is connected to the power grid 200. The controller 30 is connected to both the three-phase inverter 10 and the three-phase relay 20. When the inverter system 100 starts working, the controller 30 controls the three-phase relay 20 to close. When the three-phase relay 20 is closed, the three-phase inverter 10 outputs three-phase AC power to the power grid 200 through the three-phase relay 20, thereby achieving grid connection and improving energy utilization. It should be noted that the controller 30 outputs a control signal to the three-phase relay 20 so that the three-phase relay 20 engages according to the control signal. When the three-phase relay 20 malfunctions (e.g., due to relay contact burning, abnormal coil drive, or other reasons causing the relay to open), a path is not formed between the three-phase inverter 10 and the power grid 200. In this case, the three-phase AC power output by the three-phase inverter 10 cannot be accurately input to the power grid 200, leading to resource waste. Therefore, to improve resource utilization, this application provides a relay fault detection method. This method detects the operating status of the three-phase relay 20 and, upon detecting a fault in the three-phase relay 20, controls the three-phase relay 20 to disconnect and simultaneously controls the three-phase inverter 10 to stop working, thereby avoiding resource waste and improving the reliability of the inverter system 100.

[0023] In yet another embodiment, please refer to Figure 2 , Figure 2 This is a circuit diagram of an inverter system provided in an embodiment of the present invention, such as... Figure 2 As shown, the inverter system 100 includes three-phase inverter inductors (La1, Lb1, Lc1), filter capacitors (C1, C2, C3), grid-side filter inductors (La2, Lb2, Lc2), and three-phase relays (Sa, Sb, Sc) connected in series in each phase output circuit of the three-phase inverter 10. Wherein, ia, ib, and ic are the three-phase currents output by the three-phase inverter 10, Vsa, Vsb, and Vsc are the three-phase voltages output by the three-phase inverter 10, and Vab, Vbc, and Vac are the three-phase line voltages output by the three-phase inverter 10.

[0024] When the three-phase inverter (DC / AC) outputs three-phase AC power, the grid-side filter inductor filters the three-phase current to suppress abrupt changes in current, thus converting the three-phase current output by the inverter into a pulsating current. Simultaneously, the controller 30 outputs control signals to control the closing of the three-phase relays (Sa, Sb, Sc). When the three-phase relays are closed, the pulsating current output by the three-phase inverter is filtered by the filter capacitor and the grid-side filter inductor before being connected to the power grid 200. The grid-side filter inductor blocks high-frequency current from entering the power grid 200, and the filter capacitor provides a low-impedance bypass for high-frequency noise. The grid-side filter inductor and the filter capacitor effectively prevent high-frequency noise from entering the power grid 200, thereby improving the reliability of the inverter system 100. It should be noted that when determining whether a three-phase relay has malfunctioned, the controller 30 collects the three-phase current output by the three-phase inverter inductor to determine whether the three-phase relay has malfunctioned based on this three-phase current. The current sampling point is located after the three-phase inverter inductor and before the three-phase relay.

[0025] Please see Figure 3 , Figure 3 This is a schematic diagram of the structure of a controller provided in an embodiment of the present invention, such as... Figure 3 As shown, the controller 30 includes: at least one processor 31, Figure 3 Taking a processor 31 as an example; the at least one processor 31 is communicatively connected to a memory 32, Figure 3 Taking the example of a connection between China and Israel via a bus.

[0026] The memory 32 stores instructions that can be executed by the at least one processor 31, which are executed by the at least one processor 31 to enable the at least one processor 31 to perform the following relay fault detection method.

[0027] The memory 32, as a non-volatile computer-readable storage medium, can be used to store non-volatile software programs, non-volatile computer-executable programs, and modules, such as the program instructions / modules corresponding to the relay fault detection method in the embodiments of the present invention. The processor 31 executes various functional applications and data processing of the electronic device 30 by running the non-volatile software programs, instructions, and modules stored in the memory 32, thereby implementing the relay fault detection method in the following method embodiments.

[0028] The memory 32 may include a program storage area and a data storage area, wherein the program storage area may store the operating system and application programs required for at least one function. Furthermore, the memory 32 may include high-speed random access memory and may also include non-volatile memory. For example, it may include at least one disk storage device, flash memory device, or other non-volatile solid-state storage device. In some embodiments, the memory 32 may optionally include memory remotely located relative to the processor 31.

[0029] The one or more modules are stored in the memory 32. When executed by the one or more processors 31, they perform the relay fault detection method in any of the following method embodiments, for example, performing the following described... Figure 4 The methods and steps in the text.

[0030] The controller described above can execute the methods provided in the embodiments of the present invention and has corresponding functional modules for executing the methods. Technical details not described in detail in this embodiment can be found in the methods provided in the embodiments of the present invention.

[0031] In some embodiments, please refer to Figure 4 , Figure 4 This is a flowchart of a fault detection method provided in an embodiment of the present invention, such as... Figure 4 As shown, the method includes: S01, Receive control signals.

[0032] Specifically, when the inverter system starts working, the controller outputs the control signal to control the three-phase relay to close.

[0033] S02. Control the three-phase relays to close according to the control signal, and collect the three-phase current output by the three-phase inverter respectively.

[0034] When the three-phase relay closes, the three-phase current of the three-phase inverter is output to the power grid through the relay, thereby supplying power to the grid. During the transmission of the three-phase current by the relay, the controller collects the three-phase current (pulsating current) output by the three-phase inverter inductor. It should be noted that at the instant the three-phase relay closes, the phase difference between the three-phase inverter and the power grid may be inconsistent, resulting in a momentary potential difference and a momentary inrush current. If the three-phase current is collected at this time, it may lead to relay detection errors. Therefore, after controlling the three-phase relay to close according to the control signal, the controller waits for a second preset time to allow the three-phase relay to stabilize before collecting the three-phase current output by the inverter inductor. This avoids interference from the inrush current and improves the accuracy of the inverter system.

[0035] S03. Obtain the current command and calculate the difference between the three-phase current and the current command.

[0036] Specifically, after acquiring the three-phase current, the controller also obtains current commands, including a first current command, a second current command, and a third current command. After obtaining the current commands, coordinate transformations are performed on the first, second, and third current commands to obtain the d-axis DC component and the q-axis DC component of the current commands. Simultaneously, coordinate transformations are performed on the three-phase currents to obtain their d-axis DC components and q-axis DC components. After obtaining the d-axis DC components and q-axis DC components of the current commands, as well as the d-axis DC components and q-axis DC components of the three-phase currents, the differences between the d-axis DC components and the d-axis DC components of the three-phase currents, and the differences between the q-axis DC components and the q-axis DC components of the three-phase currents, are calculated. Based on this, the difference between the three-phase currents and the current commands can be obtained.

[0037] S04. When the difference is greater than the preset current threshold, obtain the reactive power command and control the three-phase inverter to work according to the reactive power command to obtain the actual reactive power of the three-phase inverter.

[0038] After obtaining the differences in the d-axis and q-axis components, the controller determines whether these differences exceed a preset current threshold. If the differences exceed the threshold, the controller acquires the duration for which the differences exceed the threshold and determines whether this duration exceeds a first preset time. If the duration exceeds the first preset time, the three-phase relay is considered to be faulty. At this time, the controller acquires a reactive power command and adjusts the operating state of the three-phase inverter based on the command, enabling the inverter to operate according to the command. After the inverter operates according to the command, the controller calculates the actual reactive power of the inverter to determine whether the relay is faulty based on the actual reactive power and the command.

[0039] It should be noted that during the acquisition of the three-phase current, signal interference and other factors may lead to significant errors in the acquired three-phase current, resulting in a difference between the three-phase current and the current command exceeding a preset current threshold. If the operating state of the three-phase inverter is directly adjusted based on the reactive power command in this case, it may cause operational errors in the inverter system. Therefore, to improve the reliability and accuracy of the inverter system, after determining that the difference between the three-phase current and the current command is greater than the preset current threshold, it is also necessary to determine whether the duration of this difference exceeding the preset current threshold is greater than a first preset time. If it is greater, the three-phase relay is suspected of being faulty. In this case, the reactive power command is increased to adjust the operating state of the three-phase inverter according to the reactive power command, thereby further determining whether the three-phase relay is faulty. If the duration is less than the first preset time, the three-phase relay is considered not to be faulty.

[0040] In some embodiments, if the difference is less than the preset current threshold, it is considered that the three-phase relay has not malfunctioned, and the three-phase inverter will correctly transmit the three-phase current to the power grid through the three-phase relay.

[0041] In another embodiment, after calculating the difference between the d-axis DC component of the current command and the d-axis command component of the three-phase current, and the difference between the q-axis DC component of the current command and the q-axis DC component of the three-phase current, the controller further obtains d-axis voltage commands and q-axis voltage commands based on the differences between the current command and the d-axis and q-axis components of the three-phase current, and performs an inverse coordinate transformation on the d-axis voltage commands and the q-axis voltage commands to obtain the three-phase voltage commands. After determining the three-phase voltage commands, the controller performs PWM modulation on the three-phase voltage commands to obtain pulse signals, and outputs the pulse signals to the three-phase inverter, so that the three-phase inverter starts working according to the pulse signals, thereby updating the three-phase current output by the three-phase inverter. Based on this, the three-phase current output by the three-phase inverter can be adjusted in real time according to the deviation, thereby regulating the three-phase current fed into the power grid.

[0042] In some embodiments, the reactive power command may be a power boost command output by the controller, or a reactive power command input to the three-phase inverter in the form of reactive power current, harmonic current of a specific frequency, or a specific current vector, etc., and its specific form is not limited.

[0043] S05. Calculate the deviation between the reactive power command and the actual reactive power, and when the deviation is greater than a preset power threshold, output a shutdown signal to the three-phase relay to control the three-phase relay to disconnect.

[0044] Specifically, after the three-phase inverter adjusts its operating state according to the reactive power command, the controller also collects the three-phase line voltages output by the three-phase inverter and calculates the actual reactive power of the three-phase inverter based on the three-phase line voltages. After obtaining the actual reactive power, the controller calculates the average reactive power of the three-phase inverter based on the actual reactive power and the formula, and calculates the difference between the reactive power command and the average reactive power based on the average reactive power to obtain the deviation between the average reactive power and the reactive power command. Based on the difference, the controller determines whether the three-phase relay has malfunctioned.

[0045] The formula for calculating reactive power is as follows: ; Among them, Q 实 Vab, Vbc, and Vac are the actual reactive power of the three-phase inverter, Vab, Vbc, and Vac are the three-phase line voltages output by the three-phase inverter, and ia, ib, and ic are the three-phase currents output by the three-phase inverter. The formula for calculating the average reactive power is as follows: ; Where Q is the average reactive power and T is the integral time of the three-phase inverter.

[0046] Based on the above formula, the reactive power of the three-phase inverter can be obtained in real time after adjusting the working state of the three-phase inverter according to the reactive power command.

[0047] In some embodiments, after obtaining the deviation between the reactive power command and the average reactive power, if the deviation is greater than a preset power threshold, the three-phase relay is considered to have failed. In this case, the controller outputs a shutdown signal to the three-phase relay to control its shutdown, and simultaneously controls the three-phase inverter to stop operating. Based on this, when a three-phase relay failure is determined, the inverter system can be controlled to stop operating, thereby improving the reliability of the inverter system while avoiding resource waste.

[0048] If the deviation is less than the preset power threshold, it is considered that the three-phase inverter is unable to output normally due to other limiting conditions, while the three-phase relay is in the normal closed state. At this time, the controller does not operate, and the three-phase relay continues to transmit the three-phase current to the power grid.

[0049] It is understood that the preset current threshold and the preset power threshold can be dynamically adjusted according to the real-time operating power of the three-phase inverter, the grid voltage level and the ambient temperature, and their specific values ​​are not limited here.

[0050] In some embodiments, when the three-phase relays are not detected to be fault-free, the three-phase inverter continuously outputs three-phase power to the grid through the three-phase relays. After the three-phase inverter is connected to the grid, the controller checks the three-phase relays for faults every third preset time interval. If a fault is detected, the controller shuts off the three-phase relays and controls the three-phase inverter to stop operating. This improves the reliability of the inverter system.

[0051] In another embodiment, when the three-phase relay fails, the controller further determines whether this is the first time the three-phase relay has failed. If it is not the first time, the controller shuts off the three-phase relay and stops the three-phase inverter. If it is the first time, the controller shuts off the three-phase relay and then reopens it to eliminate momentary interference. If the fault persists after reopening, the three-phase relay is confirmed to be faulty, and the controller shuts off the three-phase relay and stops the three-phase inverter.

[0052] This application provides a relay fault detection method, comprising: receiving a control signal; controlling the three-phase relay to close according to the control signal, and respectively collecting the three-phase current output by the three-phase inverter; acquiring a current command and calculating the difference between the three-phase current and the current command; when the difference is greater than a preset current threshold, acquiring a reactive power command and controlling the three-phase inverter to operate according to the reactive power command to obtain the actual reactive power of the three-phase inverter; calculating the deviation between the reactive power command and the actual reactive power, and when the deviation is greater than a preset power threshold, outputting a shutdown signal to the three-phase relay to control the three-phase relay to open. Based on this, by using dual threshold judgments of current and power, misjudgments are avoided, thereby improving the reliability of the inverter system. Furthermore, when a relay fault occurs, controlling the relay to open and simultaneously controlling the inverter to stop working avoids resource waste.

[0053] In some other embodiments, please refer to Figure 5 , Figure 5 This is a structural block diagram of a relay fault detection device provided in an embodiment of the present invention, as shown below. Figure 5 As shown, the relay fault detection device 40 includes a receiving module 41, a data acquisition module 42, a calculation module 43, an acquisition module 44, and a control module 45; The receiving module 41 is used to receive control signals.

[0054] The acquisition module 42 is used to control the three-phase relay to close according to the control signal, and to acquire the three-phase current output by the three-phase inverter respectively.

[0055] The calculation module 43 is used to acquire the current command and calculate the difference between the three-phase current and the current command.

[0056] The acquisition module 44 is used to acquire a reactive power command when the difference is greater than a preset current threshold, and control the three-phase inverter to work according to the reactive power command in order to acquire the actual reactive power of the three-phase inverter.

[0057] The control module 45 is used to calculate the deviation between the reactive power command and the actual reactive power, and when the deviation is greater than a preset power threshold, it outputs a shutdown signal to the three-phase relay to control the three-phase relay to disconnect.

[0058] It should be noted that the above-described relay fault detection device can execute the relay fault detection method provided in the embodiments of the present invention, and has the corresponding functional modules and beneficial effects of the method. Technical details not described in detail in the embodiments of the relay fault detection device can be found in the relay fault detection method provided in the embodiments of the present invention.

[0059] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0060] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented using software and a general-purpose hardware platform, or of course, using hardware. Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), or random access memory (RAM), etc.

[0061] This invention also provides a non-volatile computer-readable storage medium storing computer-executable instructions that are executed by one or more processors, for example, to perform the operations described above. Figure 4 The method and steps to achieve Figure 5 The functions of each module in the program.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; under the concept of the present invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of the present invention as described above, which are not provided in detail for the sake of brevity; although the present invention 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 of the technical features; and 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 the present invention.

Claims

1. A relay fault detection method, characterized in that, The method is applied to an inverter system, the inverter system including a three-phase inverter and a three-phase relay connected to the three-phase inverter, wherein the three-phase inverter is used to output three-phase power to the power grid through the three-phase relay; the method includes: Receive control signals; The control signal is used to control the three-phase relays to close, and the three-phase currents output by the three-phase inverter are collected respectively. Obtain the current command and calculate the difference between the three-phase current and the current command; When the difference is greater than a preset current threshold, a reactive power command is obtained, and the three-phase inverter is controlled to work according to the reactive power command to obtain the actual reactive power of the three-phase inverter. The deviation between the reactive power command and the actual reactive power is calculated, and when the deviation is greater than a preset power threshold, a shutdown signal is output to the three-phase relay to control the three-phase relay to disconnect.

2. The relay fault detection method according to claim 1, characterized in that, The process of acquiring the current command and calculating the difference between the three-phase current and the current command includes: Obtain the current command, wherein the current command includes a first current command, a second current command, and a third current command; The first current command, the second current command, and the third current command are subjected to coordinate transformation to obtain the d-axis DC component and the q-axis DC component of the current command. The three-phase currents are subjected to coordinate transformation to obtain the d-axis DC component and the q-axis DC component of the three-phase currents. Calculate the difference between the d-axis DC component of the current command and the d-axis command component of the three-phase current, and the difference between the q-axis DC component of the current command and the q-axis DC component of the three-phase current.

3. The relay fault detection method according to claim 2, characterized in that, When the difference is greater than the preset current threshold, the method further includes: Obtain the duration for which the difference is greater than the preset current threshold; If the duration is greater than the first preset time, then the reactive power command is obtained; If the duration is less than the first preset time, then the acquisition of the reactive power command is stopped, and it is determined that the three-phase relay has not malfunctioned.

4. The relay fault detection method according to claim 2 or 3, characterized in that, After calculating the difference between the d-axis DC component of the current command and the d-axis command component of the three-phase current, and the difference between the q-axis DC component of the current command and the q-axis DC component of the three-phase current, the method further includes: The d-axis voltage command and q-axis voltage command are obtained based on the difference between the current command and the d-axis component and the q-axis component of the three-phase current; The d-axis voltage command and the q-axis voltage command are subjected to inverse coordinate transformation to obtain the three-phase voltage command; The three-phase voltage command is modulated by PWM and output to the three-phase inverter to update the three-phase current output by the three-phase inverter.

5. The relay fault detection method according to claim 1, characterized in that, The calculation of the deviation between the reactive power command and the actual reactive power includes: Collect the three-phase line voltages output by the three-phase inverter; Calculate the actual reactive power based on the three-phase line voltage, and calculate the average reactive power based on the actual reactive power; Based on the average reactive power, the deviation between the reactive power command and the average reactive power is calculated, and the three-phase relay is determined to be faulty based on the difference.

6. The relay fault detection method according to claim 5, characterized in that, The formula for calculating the reactive power is: ； Among them, Q 实 Vab, Vbc, and Vac are the actual reactive power of the three-phase inverter, Vab, Vbc, and Vac are the three-phase line voltages output by the three-phase inverter, and ia, ib, and ic are the three-phase currents output by the three-phase inverter. The formula for calculating the average reactive power is as follows: ； Where Q is the average reactive power and T is the integral time of the three-phase inverter.

7. The relay fault detection method according to claim 5 or 6, characterized in that, The method further includes: When the deviation between the reactive power command and the actual reactive power is less than a preset power threshold, it is determined that the three-phase relay has not malfunctioned.

8. A relay fault detection device, characterized in that, An inverter system is used, the inverter system including a three-phase inverter and a three-phase relay connected to the three-phase inverter, wherein the three-phase inverter is used to output three-phase power to the power grid through the three-phase relay; the device includes: The receiving module is used to receive control signals; The acquisition module is used to control the three-phase relay to close according to the control signal, and to acquire the three-phase current output by the three-phase inverter respectively; The calculation module is used to acquire the current command and calculate the difference between the three-phase current and the current command; The acquisition module is used to acquire a reactive power command when the difference is greater than a preset current threshold, and control the three-phase inverter to work according to the reactive power command in order to acquire the actual reactive power of the three-phase inverter. The control module is used to calculate the deviation between the reactive power command and the actual reactive power, and when the deviation is greater than a preset power threshold, output a shutdown signal to the three-phase relay to control the three-phase relay to disconnect.

9. An inverter system, characterized in that, The inverter system includes: Three-phase inverter; A three-phase relay, the three-phase relay being connected to the three-phase inverter; and A controller, connected to both the three-phase inverter and the three-phase relay; wherein the controller includes at least one processor; and, A memory communicatively connected to the at least one processor; wherein, The memory stores instructions that can be executed by the at least one processor to enable the at least one processor to perform the method according to any one of claims 1-7.

10. A non-transitory computer-readable storage medium, characterized in that, The non-transitory computer-readable storage medium stores computer-executable instructions for causing a computer to perform the method as described in any one of claims 1-7.

Images