Portable loop resistance tester

Abstract

The invention relates to the technical field of resistance test equipment, in particular to a portable loop resistance tester, which comprises a test and acquisition module used for acquiring current and voltage signal data of a tested product, analyzing a loop contact state and calculating a loop resistance value and impedance characteristic parameters; the control and output module is used for performing high-precision constant-current output and self-adaptive adjustment; the interaction and printing module is used for receiving a user operation instruction and displaying current and voltage signal data and a resistance value of a tested product, and meanwhile, printing is performed through a built-in thermal printer according to the user instruction; the power supply module is used for stably supplying power to equipment; and the intelligent diagnosis module is in butt joint with the cloud case library, automatically diagnoses related defect types influencing the loop resistance test, and generates a health assessment report. Therefore, the problems of small current output, insufficient sampling precision, single operation mode and the like in the prior art are solved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of resistance testing equipment, in particular to a portable loop resistance tester. BACKGROUND

[0002] The loop resistance tester is a key device for detecting the contact resistance of a circuit breaker in a power system. The circuit breaker is a core protection device of the power system, and the stability of the contact resistance of the circuit breaker directly affects the safety and reliability of power transmission. In long-term operation, the circuit breaker generates heat due to the continuous passage of a large current, and the instantaneous strong current during short-circuit breaking is more likely to cause wear or oxidation of the contact part, thereby increasing the loop resistance and causing equipment failure. Therefore, regular loop resistance testing of the circuit breaker is a necessary link to ensure the stable operation of the power system, and the test data needs to be accurate and traceable to provide a basis for equipment maintenance.

[0003] The loop resistance testing equipment on the market has obvious limitations: most desktop devices have comprehensive functions, but are bulky, heavy, and rely on 220V AC power supply, which makes it difficult to meet the mobile testing needs of complex sites such as substations and outdoor lines; a few handheld devices achieve portability, but often sacrifice key functions, especially the lack of built-in printing function - the data after on-site testing needs to be processed through an external printer or exported to other devices, which not only is cumbersome, but also may affect the timeliness and accuracy of the record due to data transmission delay or loss. This "portable and functional" situation has become the main bottleneck restricting the efficiency of on-site testing. SUMMARY

[0004] The application provides a portable loop resistance tester to solve the problems of small current output, insufficient sampling precision and single operation mode in the prior art.

[0005] The embodiment of the application provides a portable loop resistance tester, which comprises a test and collection module, a control and output module, an interaction and printing module, a power supply module and an intelligent diagnosis module; wherein the test and collection module is used for arranging a sensing unit in a test loop, collecting current and voltage signal data of a tested product, analyzing a loop contact state through a deep neural network algorithm, and simultaneously calculating loop resistance and impedance characteristic parameters; the control and output module is used for high-precision constant current output and self-adaptive adjustment, and when the impedance characteristic of the tested product changes, a three-stage self-adaptive constant current control strategy is used to automatically switch three-stage output currents; the interaction and printing module is used for receiving user operation instructions and displaying the current and voltage signal data of the tested product and the resistance value, and simultaneously printing according to user instructions through a built-in thermal printer; the power supply module is used for stable power supply through intelligent power management and voltage conversion circuit; and the intelligent diagnosis module is connected to a cloud case library, and through a multi-feature weighted random forest algorithm, automatically diagnoses defect types related to loop resistance testing, and generates a health assessment report.

[0006] Preferably, the test and collection module comprises an ADC chip and a signal processing unit, wherein the ADC chip is used for collecting current and voltage signals of a tested product, and through 24-bit sigma-delta modulation, converts the signals into digital signals, and simultaneously uses a deep neural network algorithm to analyze a loop contact state; and the signal processing unit is used for receiving the digital signals, and through Ohm's law and impedance spectrum analysis algorithm, calculates loop resistance and impedance characteristic parameters.

[0007] Preferably, the control and output module comprises a single-chip microcomputer and a constant current generation circuit board, wherein the single-chip microcomputer is used for running a three-stage self-adaptive constant current control strategy, generating and sending adjustment instructions to the constant current generation circuit board based on real-time impedance characteristic parameters, and controlling the constant current generation circuit board to automatically switch three-stage output currents of micro-current, standard current and large current; and the constant current generation circuit board is used for outputting currents with different amplitudes according to the adjustment instructions.

[0008] Preferably, the interaction and printing module comprises an interaction driving unit and a printer driving unit, wherein the interaction driving unit is used for receiving instructions sent by a user through touch and key operation, analyzing and processing the instructions through a lookup table method and a finite state machine, and transmitting the instructions to corresponding modules; and the printer driving unit is used for format conversion and processing of test data information, and driving a built-in printer to complete a printing action.

[0009] Preferably, the power supply module comprises a charge-discharge protection unit and a voltage conversion unit, wherein the charge-discharge protection unit is used to monitor the charge-discharge process of the lithium battery, trigger overvoltage protection to cut off the circuit if overcharge occurs, trigger undervoltage protection to cut off discharge if overdischarge occurs, and use a protection circuit to quickly disconnect the total power supply if a short circuit occurs; the voltage conversion unit is used to convert the voltage of the lithium battery into an adaptive voltage required by each component inside the device.

[0010] Preferably, the intelligent diagnosis module comprises a data interaction unit, a diagnosis unit and a report generation unit, wherein the data interaction unit is used to interface with the cloud case library and interact the test data with the historical data and standard parameters in the cloud case library; the diagnosis unit is used to diagnose the test data and the case library data through a multi-feature weighted random forest algorithm, and automatically identify the defect type related to the loop resistance test of the tested product; the report generation unit is used to generate a health assessment report of the tested product according to the defect type, and display the report on the device.

[0011] Preferably, the impedance spectrum analysis algorithm formula is: ; ; wherein, represents impedance; represents resistance; represents an imaginary unit; represents reactance; represents the speed of change of an alternating signal; represents inductance; represents capacitance.

[0012] Preferably, the three-level adaptive constant current control strategy refers to a control method that dynamically adjusts control parameters in three levels to maintain stable current and automatically adapts to working conditions, and the formula is: ; ; wherein, represents output current; represents impedance of the measured product; represents a first-level impedance threshold of 100 mu omega; represents a second-level impedance threshold of 200 mu omega; represents a first-level preset constant current value; represents a second-level preset constant current value; represents a third-level preset constant current value; represents current adjustment amount; represents current target of the current gear; represents feedback current; denotes time; denotes a proportionality coefficient; denotes a differential coefficient; denotes a differential sign.

[0013] Preferably, the multi-feature weighted random forest algorithm formula is: ; ; ; wherein, denotes the weight of the i-th feature; denotes the total number of features; denotes the judgment criterion for selecting the feature that can best distinguish the defect types; denotes a maximum function; denotes the weighted information gain of the feature ; denotes a sample data set; denotes a specific feature; denotes the final predicted defect type; denotes a defect category; denotes the total number of decision trees in the random forest; denotes an optimal parameter function; denotes the weight of the i-th decision tree; denotes an indicator function; denotes the prediction result of the i-th decision tree. Preferably, the test and collection module is bidirectionally connected with the intelligent diagnosis module, the intelligent diagnosis module is bidirectionally connected with the control and output module and the interaction and printing module, and the power supply module supplies power for all the modules.

[0014] Thus, the present application includes the following beneficial effects:

[0015] ​​​The test and collection module is used for collecting the current and voltage signals of the tested product by using a 24-bit sigma-delta modulation ADC chip, analyzing the loop contact state by combining a deep neural network algorithm, calculating the loop resistance value and impedance characteristic parameters by using Ohm's law and impedance spectrum analysis algorithm, and performing data collection and accurate analysis; with the aid of the control and output module, the single-chip microcomputer runs a three-stage adaptive constant current control strategy to control the automatic switching of the micro-current file, the standard file and the large-current file of the constant current generation circuit board, and performs high-precision constant current output and adaptive adjustment; the interactive and printing module receives touch and key operation instructions through the interactive driving unit, transmits the instructions to the corresponding module after analysis and processing, and drives the built-in thermal printer to complete printing through the printer driving unit, thereby realizing diversified operation and data recording; the power supply module monitors and protects the charging and discharging process of the lithium battery through the charge and discharge protection unit, converts and adapts the voltage through the voltage conversion unit, and realizes stable power supply guarantee; the intelligent diagnosis module connects the cloud case library through the data interaction unit, the diagnosis unit identifies the defect type by using a multi-feature weighted random forest algorithm, the report generation unit generates a health assessment report, and intelligent diagnosis and evaluation are realized. Therefore, the problems of small current output, insufficient sampling precision and single operation mode in the prior art are solved.

[0016] Additional aspects and advantages of the application will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following and / or can be learned by practice of the application. BRIEF DESCRIPTION OF DRAWINGS

[0017] The above and / or additional aspects and advantages of the application will become apparent and be readily appreciated from the following description, taken in conjunction with the accompanying drawings, in which: Figure 1 A structural schematic diagram of a portable loop resistance tester according to an embodiment of the application is provided. Figure 2 A structural schematic diagram of a test and collection module according to an embodiment of the application is provided. Figure 3 An example diagram of data collection and analysis of a tester according to an embodiment of the application is provided. Figure 4 A structural schematic diagram of a control and output module according to an embodiment of the application is provided. Figure 5 An example diagram of control current output of a tester according to an embodiment of the application is provided. Figure 6 An interactive and printing module according to an embodiment of the application is provided. Figure 7 A structural schematic diagram of a power supply module according to an embodiment of the application is provided. Figure 8A schematic diagram of an intelligent diagnosis module provided according to an embodiment of the present application; Figure 9 A use schematic diagram of a portable loop resistance tester provided according to an embodiment of the present application. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0019] A portable loop resistance tester according to an embodiment of the present application is described below with reference to the drawings. In view of the insufficient sampling accuracy mentioned in the background art, the present application provides a portable loop resistance tester. In the loop resistance tester, a test and collection module is used to collect current and voltage signals of a tested product by using a 24-bit sigma-delta modulation ADC chip, a deep neural network algorithm is used to analyze a loop contact state, an ohm law and an impedance spectrum analysis algorithm are used to calculate loop resistance values and impedance characteristic parameters, and data collection and accurate analysis are performed. A control and output module is used to control a constant current generation circuit board to automatically switch a micro-current range, a standard range and a large-current range by running a three-stage adaptive constant current control strategy by a single-chip microcomputer, high-precision constant current output and adaptive adjustment are performed. An interactive and printing module is used to receive touch and key operation instructions by an interactive driving unit, the instructions are transmitted to corresponding modules after analysis and processing, a printer driving unit drives a built-in thermal printer to complete printing, and diversified operations and data recording are performed. A power supply module is used to monitor and protect a lithium battery charging and discharging process by a charging and discharging protection unit, a voltage conversion unit converts and adapts voltage, and stable power supply is ensured. An intelligent diagnosis module is used to connect a cloud case library by a data interaction unit, a diagnosis unit is used to identify a defect type by using a multi-feature weighted random forest algorithm, a report generation unit is used to generate a health assessment report, and intelligent diagnosis and evaluation are performed. Thus, the problems of small current output, insufficient sampling accuracy and single operation mode in the prior art are solved.

[0020] Figure 1 A structural schematic diagram of a portable loop resistance tester provided according to an embodiment of the present application.

[0021] The present application provides a portable loop resistance tester, which comprises: A test and collection module 100, a control and output module 200, an interactive and printing module 300, a power supply module 400 and an intelligent diagnosis module 500.

[0022] The test and collection module 100 is used to arrange a sensing unit in a test loop, collect current and voltage signal data of a tested product, analyze a loop contact state through a deep neural network algorithm, and calculate a loop resistance value and impedance characteristic parameters; the control and output module 200 is used for high-precision constant current output and adaptive adjustment, and when the impedance characteristic of the tested product changes, a three-stage adaptive constant current control strategy is used to automatically switch three output current levels; the interaction and printing module 300 is used to receive user operation instructions and display the current, voltage signal data and resistance value of the tested product, and print according to the user instructions through a built-in thermal printer; the power supply module 400 is used to stably supply power through intelligent power management and voltage conversion circuit; and the intelligent diagnosis module 500 is connected to a cloud case library, and through a multi-feature weighted random forest algorithm, automatically diagnoses defect types related to loop resistance testing, and generates a health assessment report.

[0023] It can be understood that in the embodiments of the present application, through the test and collection module, the 24-bit sigma-delta modulation ADC chip is used to collect the current and voltage signals of the tested product, the deep neural network algorithm is used to analyze the loop contact state, the Ohm's law and impedance spectrum analysis algorithm are used to calculate the loop resistance value and impedance characteristic parameters, data collection and accurate analysis are performed; with the help of the control and output module, the single-chip microcomputer runs the three-stage adaptive constant current control strategy, the constant current generation circuit board is automatically switched to the micro-current level, the standard level and the large current level, high-precision constant current output and adaptive adjustment are performed; the interaction and printing module receives touch and key operation instructions through the interaction driving unit, transmits them to the corresponding module after analysis and processing, the printer driving unit drives the built-in thermal printer to complete printing, and diversified operations and data recording are performed; the power supply module monitors and protects the charging and discharging process of the lithium battery through the charge and discharge protection unit, the voltage conversion unit converts and adapts the voltage, and stably supplies power; the intelligent diagnosis module is connected to the cloud case library through the data interaction unit, the diagnosis unit identifies the defect type by using the multi-feature weighted random forest algorithm, the report generation unit generates the health assessment report, and intelligent diagnosis and evaluation are performed. Thus, the problems of small current output, insufficient sampling precision and single operation mode in the prior art are solved.

[0024] In the embodiments of the present application, the test and collection module 100 further comprises: as shown in Figure 2 the ADC chip 101, the signal processing unit 102.

[0025] The ADC chip is used to collect the current and voltage signals of the tested product, and through 24-bit sigma-delta modulation, converts them into digital signals, and at the same time, uses a deep neural network algorithm to analyze the loop contact state; the signal processing unit is used to receive the digital signals, calculate the loop resistance value and impedance characteristic parameters through the Ohm's law and impedance spectrum analysis algorithm.

[0026] It should be noted that 24-bit sigma-delta modulation refers to a high-precision analog-to-digital conversion method that converts an analog signal into a 24-bit digital signal through sampling and noise shaping technology, and the formula is: ; ; wherein, represents a complex variable; represents the frequency domain characteristic of the error in the discrete time system; represents the preliminary digitalization of the signal; represents the z-transform of the current or voltage analog signal of the tested product after preprocessing; represents the effect of the internal integrator of the ADC; represents the ratio of signal power to noise power; represents that the base quantizer is 1 bit; represents the oversampling rate; represents the order of the internal integrator of the ADC; represents the logarithmic function.

[0027] The deep neural network algorithm is a computational model based on a multi-layer neural network structure, and the formula is: ; ; ; ; ; wherein, represents the intermediate result obtained after comprehensive processing of the current and voltage signal characteristics; represents the weight matrix; represents the features obtained after preprocessing the collected signals; represents the bias vector; represents a certain intermediate judgment feature of the contact state; represents the activation function; represents the difference between the predicted result of the contact state of the circuit and the actual contact state of the circuit; represents the loss function; represents the predicted contact state of the circuit output by the network; represents the actual contact state of the circuit; represents the learning rate; represents the gradient of the loss function with respect to the weight; represents the gradient of the loss function with respect to the bias.

[0028] The formula of Ohm's law is: ; wherein, represents the current; represents the voltage; represents the resistance.

[0029] It can be understood that in the embodiments of the present application, the sensing unit in the test loop is arranged, the current and voltage signals of the tested product are collected by using the ADC chip, and are converted into digital signals through 24-bit sigma-delta modulation, and the contact state of the loop is analyzed by means of a deep neural network algorithm; at the same time, after the signal processing unit receives the digital signals, the loop resistance value and impedance characteristic parameters are calculated through Ohm's law and impedance spectrum analysis algorithm. The accuracy of current and voltage signal collection and the accuracy of loop contact state analysis are improved, and the loop resistance value and impedance characteristic parameters are obtained, which provides a reliable data basis for subsequent testing and diagnosis.

[0030] For example, as Figure 3As shown, when testing the loop resistance of a certain 110 kV disconnecting switch, the ADC chip and signal processing unit of the test and collection module exhibit high-precision data collection and analysis capabilities. After the ADC chip is connected to the test loop of the disconnecting switch, it immediately starts collecting current and voltage signals. The 24-bit sigma-delta modulation technology used by the ADC chip can convert analog signals into digital signals with high precision. During this process, the quantization error is strictly controlled at a very low level. For example, with a 5V range, the quantization error can be controlled within 0.000018V. With this high-precision conversion capability, the ADC chip effectively suppresses the 0.1Hz-10kHz wide frequency noise in the test environment, including mechanical vibration noise generated by the device in operation, electromagnetic interference from surrounding power equipment, etc., so that the collected current signal is stable at 200A±0.0008A and the voltage signal is stable at 0.25V±0.00003V. After completing signal collection and conversion, the deep neural network algorithm analyzes these digital signals in depth. The algorithm compares and calculates the signal characteristics collected at present with the feature maps of different loop contact states (such as good contact, contact point oxidation, insufficient contact pressure, etc.) in a large amount of historical test data, and finally accurately determines that the loop contact state of the disconnecting switch is "slight oxidation of contact point", providing an important preliminary judgment basis for subsequent diagnosis. After receiving the digital signals transmitted by the ADC chip, the signal processing unit starts calculating the loop resistance value and impedance characteristic parameters. First, according to Ohm's law (I=U / R), the collected current 200A and voltage 0.25V are substituted into the formula to calculate the loop resistance value as 1.25mΩ. Then, the impedance spectrum analysis algorithm (Z=R+jX) is used to further calculate the impedance characteristic parameters. Combined with the angular frequency ω=314 rad / s of the AC signal in the test and the inductance L and capacitance C obtained through signal characteristic analysis, the reactance X=0.06mΩ is calculated, and then the impedance Z=1.25+j0.06mΩ is obtained. Through a series of work of the test and collection module, the error of the final output resistance value and impedance characteristic parameters is controlled within ±0.4%, providing high-precision and reliable data support for the evaluation of the disconnecting switch loop state. Compared with traditional test equipment, the data accuracy and stability have been significantly improved, which can more timely and accurately reflect the actual operating state of the equipment, providing strong technical support for the maintenance and repair of the equipment.

[0031] In the embodiment of the present application, the impedance spectrum analysis algorithm formula is: ; ; Among them, represents impedance; represents resistance; represents the imaginary unit; represents the reactance; represents the degree of rapidity of the AC signal change; represents the inductance; represents the capacitance.

[0032] It can be understood that, in the embodiments of the present application, the impedance characteristic parameters of the loop are calculated by the impedance spectrum analysis algorithm, the electrical influence caused by the inductance and capacitance characteristics of the tested product is comprehensively captured, the overall impedance characteristics of the loop under the AC environment are revealed, and the comprehensiveness and accuracy of the evaluation of the electrical characteristics of the loop are improved.

[0033] In the embodiments of the present application, as shown in Figure 4 The control and output module 200 includes a single-chip microcomputer 201 and a constant-current generation circuit board 202.

[0034] The single-chip microcomputer is configured to run a three-stage adaptive constant-current control strategy, generate an adjustment instruction based on real-time impedance characteristic parameters, and send the adjustment instruction to the constant-current generation circuit board to control the constant-current generation circuit board to automatically switch the micro-current, standard-current and large-current three-stage output currents; and the constant-current generation circuit board is configured to output currents with different amplitudes according to the adjustment instruction.

[0035] It can be understood that, in the embodiments of the present application, the single-chip microcomputer runs a three-stage adaptive constant-current control strategy, generates an adjustment signal according to real-time impedance characteristic parameters, and controls the constant-current generation circuit board to automatically switch the micro-current, standard-current and large-current three-stage output currents; and the constant-current generation circuit board outputs currents with different amplitudes according to the control instruction. High-precision constant-current output and adaptive adjustment are performed, so that the tested product can automatically adapt to the appropriate current gear when the impedance characteristic of the tested product changes, the stability and adaptability of the current output in the test process are ensured, good conditions are created for the test and collection module to accurately collect data, and the adaptability of the tester to tested products with different impedance characteristics is improved.

[0036] For example, as shown in Figure 5As shown, during the loop resistance test of a disconnector switch in a substation, the control and output module demonstrated precise adaptive adjustment capabilities. Initially, the circuit breaker was in a cold state, and the initial impedance characteristic parameters acquired by the test and acquisition module were low. The microcontroller of the control and output module immediately implemented a three-level adaptive constant current control strategy. Based on this parameter, it determined that the impedance Z of the tested component was less than or equal to the first-level impedance threshold Z1, and then sent an adjustment signal to the constant current generating circuit board, controlling it to switch to the high-current range and output 150A of current. During this process, the constant current generating circuit board strictly followed the control instructions to stably output current, providing a reliable current input for the test and acquisition module to acquire high-precision current and voltage signals. As the test continued, the circuit breaker generated heat due to energization, and the impedance characteristics gradually increased. When the real-time impedance parameter transmitted by the test and acquisition module showed that Z exceeded the first-level impedance threshold Z1 but did not exceed the second-level impedance threshold Z2, the microcontroller responded quickly, recalculated the adjustment signal, and controlled the constant current generating circuit board to switch to the standard range, adjusting the output current to 50A. At this point, the microcontroller calculates the current adjustment ∆I using the proportional coefficient Kp and the derivative coefficient Kd to ensure the stability of the output current and avoid current fluctuations caused by impedance changes affecting test accuracy. Later in the test, the circuit breaker's impedance characteristics further increased and exceeded the secondary impedance threshold Z2. The microcontroller again made a judgment based on real-time parameters, controlling the constant current generator circuit board to switch to the micro-current range, outputting an 8A current. Throughout this process, the constant current generator circuit board consistently and accurately responded to the microcontroller's adjustment signals, ensuring the accuracy of the current output at different ranges. This enabled the test and acquisition module to collect effective data under different impedance states of the circuit breaker, laying a solid foundation for the subsequent signal processing unit to calculate the loop resistance value and impedance characteristic parameters. Throughout the testing process, the control and output module, through a three-level adaptive constant current control strategy, automatically switched the current level according to the impedance characteristics of the device under test. This ensured that a large current was output at low impedance to reduce measurement errors, while switching to a small current at high impedance to avoid overloading the device under test. This fully demonstrated its high-precision constant current output and adaptive adjustment capabilities, effectively ensuring the accuracy and safety of the test, and providing reliable test data support for the subsequent defect diagnosis of the intelligent diagnostic module.

[0037] In this embodiment, the three-level adaptive constant current control strategy refers to a control method that dynamically adjusts control parameters in three levels to maintain current stability and can automatically adapt to operating conditions. The formula is as follows: ; ; in, Indicates the output current; Indicates the impedance of the measured object; This indicates a first-order impedance threshold of 100μΩ; represents a secondary preset constant current value; represents a primary preset constant current value; represents a secondary preset constant current value; represents a tertiary preset constant current value; represents a current adjustment amount; represents a current adjustment amount; represents a current adjustment amount; represents a current adjustment amount; represents a current adjustment amount; represents a current adjustment amount; represents a current adjustment amount.

[0038] It should be noted that when the impedance of the measured product is high, the micro-current gear is used based on the primary preset constant current value, and the current is less than or equal to 10A; when the impedance of the measured product is medium, the standard gear is used based on the secondary preset constant current value, and the current is greater than 10A and less than or equal to 100A; and when the impedance of the measured product is low, the large-current gear is used based on the tertiary preset constant current value, and the current is greater than 100A and less than or equal to 200A.

[0039] It can be understood that the embodiments of the present application dynamically adjust the control parameters in three stages, determine the output current gear based on the real-time impedance characteristic parameters, output the tertiary preset constant current value when the impedance of the measured product is less than or equal to the primary impedance threshold value, output the secondary preset constant current value when the impedance is greater than the primary impedance threshold value and less than or equal to the secondary impedance threshold value, and output the primary preset constant current value when the impedance is greater than the secondary impedance threshold value, and dynamically adjust by calculating the current adjustment amount. When the impedance characteristic of the measured product changes, the appropriate current gear can be automatically switched, the stability and adaptability of the current output in the test process are ensured, good conditions are created for the test and collection module to accurately collect data, and the adaptability of the test instrument to different impedance characteristic measured products is improved.

[0040] In the embodiments of the present application, the interaction and printing module 300 includes: as shown in Figure 6 the interaction driving unit 301 and the printer driving unit 302.

[0041] The interaction driving unit is used to receive instructions issued by the user through touch and key operations, analyze and process the instructions by using the table lookup method and the finite state machine, and transmit the instructions to the corresponding module; the printer driving unit is used to format and process the test data information, and drive the built-in printer to complete the printing action.

[0042] It should be noted that the table lookup method refers to a method of constructing a table containing the input and corresponding output relationship in advance, directly looking up and obtaining the required result from the table according to the input value in actual application, and quickly completing data matching, calculation or logical judgment.

[0043] The finite state machine refers to a model for describing the ordered conversion of an object between different states according to input through a state set, an input set and a state transition function.

[0044] It can be understood that the embodiments of the present application receive the instructions issued by the user through touch and key operation by the interactive driving unit, and transmit the instructions to the corresponding module after analyzing and processing the instructions by using the lookup table method and the finite state machine; the printer driving unit performs format conversion and processing on the test data information, and drives the built-in printer to complete the printing action, so that the user can intuitively issue operation instructions to the equipment and obtain the current, voltage, resistance and other data of the tested product, thereby improving the convenience of human-computer interaction, printing the test data by the built-in thermal printer for subsequent analysis, recording and archiving, and enhancing the practicality and operation efficiency of the equipment.

[0045] For example, when testing the loop resistance of a low-voltage distribution cabinet of a certain enterprise, the tester first starts the test program through the touch screen and physical buttons of the device. Under the support of the interactive driving unit, the "start test" instruction issued by the touch operation is quickly received, and the button operation is used to select the test mode (such as regular detection or deep detection). The interactive driving unit immediately matches the function code corresponding to the instruction by using the lookup table method, and then judges the current device state (such as whether it is in standby mode and whether the power supply is stable) by using the finite state machine. After confirming that there is no error, the processed instruction is transmitted to the test and collection module to trigger the test process. During the test process, the display interface of the interaction and printing module is refreshed in real time with the current, voltage signal data of the tested distribution cabinet and the resistance value calculated therefrom. When the tester finds that the resistance value of a certain loop fluctuates abnormally, the "pause test" instruction is issued by pressing the button, the interactive driving unit quickly analyzes the instruction and transmits it to the control and output module, so that the constant current generation circuit board temporarily stops outputting current, facilitating the tester to check whether the wiring is loose. After the troubleshooting is completed, the "continue test" instruction is issued again by the touch operation, and the device seamlessly resumes the test process. The whole interactive process responds quickly and the operation logic is clear. After the test is completed, the tester needs to keep the data for subsequent archiving. At this time, the "print report" function is selected by pressing the button, and the printer driving unit immediately starts working: first, the test data (including the current value, voltage value, resistance value, test time, etc. of each loop) is converted in format, and then arranged into a standard table according to the preset report template, and then the built-in thermal printer is driven to run. The printer quickly completes the data printing, and the output paper report clearly lists the specific values of each test item and the judgment result of whether it meets the standard range. The tester can hand over the paper report to the person in charge of the enterprise for signature and archiving, and at the same time, the electronic data is stored in the device locally by selecting "save data" through the touch operation, realizing the double backup of data. In addition, when the tester needs to call the historical test data for comparison and analysis, the "query history" function key of the touch screen is used, the interactive driving unit receives the instruction, and the test records of the distribution cabinet in the past three times are called from the device storage and displayed on the screen in pages. The tester switches the pages by pressing the button to clearly view the resistance change trend at different time points, which provides an intuitive basis for judging the aging degree of the distribution cabinet. During the whole process, the efficient interaction capability and convenient printing function of the interaction and printing module not only simplify the operation process, but also ensure the traceability of the test data, and greatly improve the work efficiency of the on-site test.

[0046] In the embodiment of the present application, the power supply module 400 includes, as shown in Figure 7 a charge and discharge protection unit 401 and a voltage conversion unit 402.

[0047] The charging and discharging protection unit is used for monitoring the charging and discharging process of the lithium battery. If overcharging occurs, overvoltage protection is triggered to cut off the circuit. If overdischarging occurs, undervoltage protection is triggered to cut off the discharging. If short circuit occurs, the protection circuit is used to quickly disconnect the total power supply. The voltage conversion unit is used for converting the voltage of the lithium battery into an adaptive voltage required by each component inside the device.

[0048] It can be understood that, by means of the charging and discharging protection unit, the application pays attention to the charging and discharging state of the lithium battery, so as to avoid damage to the device caused by abnormal state of the battery. By means of the voltage conversion unit, the voltage of the lithium battery is converted into an adaptive voltage required by each component inside the device, so as to ensure that the test process will not be interrupted due to power supply problems, and at the same time, the voltage requirements of different components are adapted. The device is jointly provided with stable power support, and the reliability and safety of the device are improved.

[0049] For example, when the loop resistance of the cable joint of a certain transformer substation is tested, the staff enables the lithium battery power supply of the tester, and the charging and discharging protection unit of the power supply module immediately starts to monitor the battery state. When the lithium battery is charged with low power, the charging and discharging protection unit tracks the voltage change in real time. Once the voltage reaches the overcharge threshold, the overvoltage protection is triggered quickly to cut off the charging circuit, so as to avoid damage to the battery due to overcharging. During the test process, as each module continues to run, the voltage of the lithium battery gradually decreases. When the voltage approaches the undervoltage threshold, the charging and discharging protection unit starts the undervoltage protection mechanism to timely cut off the discharging circuit, so as to prevent the battery from affecting the service life due to overdischarging, and at the same time, prevent the tester from being suddenly shut down due to insufficient voltage, thereby causing the test to be interrupted. During the test, the tester accidentally occurs short circuit, and the charging and discharging protection unit responds within milliseconds, and quickly disconnects the total power supply by means of the protection circuit, so as to effectively protect the single-chip microcomputer, ADC chip and other precise components inside the device from the impact of short circuit current. At the same time, the voltage conversion unit continuously works to convert the 3.7V voltage of the lithium battery into different adaptive voltages required by the test and acquisition module, such as 5V, and the control and output module, such as 12V, so as to ensure that each module can stably run under the rated voltage. For example, a stable 12V voltage is provided for the constant current generation circuit board, so that it can accurately output currents of different gears; a 5V voltage is provided for the touch screen of the interactive and printing module, so as to ensure the normal display and touch response of the operation interface. During the whole test process, the power supply module cooperates with the charging and discharging protection unit and the voltage conversion unit, so as to not only ensure the safe use of the lithium battery, but also provide stable and adaptive power support for each module of the tester, thereby ensuring the smooth completion of the loop resistance test of the cable joint, and fully embodying the important role of the power supply module in the safe operation of the device and the continuity of the test.

[0050] In the embodiment of the application, the intelligent diagnosis module 500, as shown in Figure 8 , includes a data interaction unit 501, a diagnosis unit 502 and a report generation unit 503.

[0051] The data interaction unit is configured to interact the test data with historical data and standard parameters in the cloud case library. The diagnosis unit is configured to diagnose the test data and the case library data by using the multi-feature weighted random forest algorithm, and automatically identify the defect type of the tested product affecting the loop resistance test. The report generation unit is configured to generate a health assessment report of the tested product according to the defect type, and display the health assessment report on the device.

[0052] It can be understood that, in the embodiments of the present application, the data interaction unit is configured to interact the test data with historical data and standard parameters in the cloud case library, so that the test data can be compared with rich historical cases and standards to provide more comprehensive reference basis. The diagnosis unit is configured to diagnose the test data and the case library data by using the multi-feature weighted random forest algorithm, and automatically identify the defect type of the tested product affecting the loop resistance test, thereby improving the accuracy and efficiency of defect identification. The report generation unit is configured to generate a health assessment report of the tested product according to the defect type, and display the health assessment report on the device, so that the user can intuitively understand the health status of the tested product, and a clear guide is provided for equipment maintenance. The intelligent level of the test and the diagnostic accuracy are improved together, and strong support is provided for equipment maintenance.

[0053] For example, after the loop resistance test of a high-voltage switch cabinet of an enterprise is completed, the data interaction unit of the intelligent diagnosis module immediately interfaces with the cloud case library, compares and interacts the current, voltage, resistance and other data obtained in this test with the historical test data and industry standard parameters of the switch cabinet of this type in the case library, the diagnosis unit then starts the multi-feature weighted random forest algorithm, combines the data obtained through the interaction, and comprehensively analyzes the loop contact state, resistance value fluctuation and other features of the switch cabinet, thereby automatically identifying that the switch cabinet has a defect type of contact oxidation leading to poor contact, which is a key factor affecting the abnormal test result of the loop resistance. The report generation unit automatically generates a health assessment report containing the defect position, severity and maintenance suggestions according to the diagnosed defect type, and clearly presents the health assessment report on the display interface of the tester. The tester can quickly master the health status of the switch cabinet through the report, and timely arrange targeted maintenance work, thereby effectively avoiding possible equipment failure due to defects not being timely processed. The whole process does not require manual intervention, greatly improves the diagnostic efficiency and accuracy, and fully reflects the practical value of the intelligent diagnosis module in equipment state evaluation and maintenance.

[0054] In the embodiments of the present application, the weighted random forest algorithm is as follows: ; ; ; in, Indicates the first The weights of each feature; Indicates the total number of features; This indicates the selection of the judgment criteria that best distinguishes the characteristics of defect types; Represents the maximum value function; Representation of features Weighted information gain; Represents the sample dataset; Indicates specific characteristics; Indicates the final predicted defect type; Indicates the defect category; This represents the total number of decision trees in the random forest; Represents the optimal parameter function; Indicates the first The weights of each decision tree; Indicates an indicator function; Indicates the first The prediction results of the decision tree.

[0055] It is understood that the embodiments of this application use a multi-feature weighted random forest algorithm to diagnose test data and historical data and standard parameters in the cloud case library, identify the types of defects related to the circuit resistance test of the tested product, improve the accuracy of defect type identification, improve diagnostic efficiency, adapt to the complex data situation of different tested products under different operating conditions, and provide a basis for generating health assessment reports.

[0056] The following will illustrate a portable loop resistance tester through a specific embodiment, such as... Figure 9 As shown, it includes: When conducting loop resistance testing on a low-voltage distribution cabinet in a factory, staff arrived on site with a portable loop resistance tester. After turning on the tester, the power supply module indicator light showed that the lithium battery was fully charged. The charge / discharge protection unit completed its self-test and entered standby mode, enabling rapid response in case of overcharging, over-discharging, or short circuit. The voltage conversion unit was initialized and ready to convert the 3.7V lithium battery voltage to the appropriate voltage for each module. Specifically, the test and acquisition module requires 5V, the microcontroller of the control and output module requires 3.3V, and the constant current generator circuit board requires 12V, ensuring that each component operates at its rated voltage.

[0057] Before the test starts, the staff selects the "low-voltage loop test" mode through interaction with the touch screen of the printing module. The interaction driving unit matches the corresponding test parameters using a lookup table, confirms that the device is in standby state through a finite state machine, and then transmits instructions to the control and output module and the test and collection module, so that they enter the working preparation state. The screen synchronously displays the test mode, the expected duration, and safety prompts. The staff confirms that there is no error and presses the "start test" button, and the test is officially started. The single-chip microcomputer of the control and output module immediately sends an adjustment signal to the constant-current generation circuit board, so that it outputs a 50A standard-grade current. The current flows through the main loop of the power distribution cabinet through a special test line, forming a complete test loop, and the loop current is captured in real time by the test and collection module.

[0058] The ADC chip of the test and collection module monitors the loop current and voltage signals in real time, converts the analog signals into digital signals using 24-bit sigma-delta modulation technology, effectively reduces noise interference, and ensures that small signal changes can also be accurately captured. After the digital signals are transmitted to the signal processing unit through the internal bus, the signal processing unit immediately starts the Ohm's law and impedance spectrum analysis algorithm: according to the Ohm's law formula I=U / R, combined with the collected current and voltage data, the loop resistance value is quickly calculated, and the initial test display is 85μΩ, which is within the normal range; at the same time, through the impedance spectrum analysis algorithm formula Z=R+jX and the extended formula, the impedance characteristic parameters such as resistance R, reactance X, inductance L and capacitance C are analyzed. The deep neural network algorithm compares a large amount of historical data and standard models to evaluate the loop contact state and determine whether the contacts have potential problems such as oxidation and looseness. These real-time calculated resistance values, impedance characteristic parameters, and contact state analysis results are transmitted to the interaction and printing module, and the touch screen presents the current, voltage, and resistance values in digital form and dynamically displays the impedance characteristic curve in graphical form, making it easy for the staff to observe intuitively. During this period, the staff found that the resistance value had a slight fluctuation, issued a "data freeze" instruction through the button, the interaction driving unit quickly analyzed the instruction to keep the data static, which was convenient for recording and analysis, and then issued a "continue test" instruction, and the device immediately resumed real-time data display. The entire interaction process responds quickly.

[0059] As the test progresses, the power distribution cabinet loop temperature rises due to continuous current flow, and the impedance characteristics change. The test and collection module captures the impedance value from the initial 100 μΩ to 150 μΩ in real time. These real-time impedance characteristic parameters are transferred to the single-chip microcomputer of the control and output module through the intelligent diagnosis module. The single-chip microcomputer runs a three-stage adaptive constant current control strategy. According to the preset impedance threshold value, when the impedance value exceeds the second threshold Z2 (120 μΩ), an adjustment signal is generated and sent to the constant current generation circuit board, causing it to switch the output current from the standard 50 A to the large current 100 A within 200 ms, ensuring test continuity and accuracy, and avoiding data distortion caused by impedance changes. After the switch is completed, the screen displays that the current gear has been switched and updates the current value, making it easy for staff to monitor the equipment status. At the same time, the data interaction unit of the intelligent diagnosis module interfaces with the cloud case library through a wireless network, uploading real-time test data, impedance characteristic parameters, current and voltage change curves, and other information, and comparing and interacting with the past five years of test data, common defect cases, and industry standard parameters stored in the cloud. Similar historical cases and related standards are selected. The diagnosis unit uses a multi-feature weighted random forest algorithm, taking the resistance value change rate, impedance spectrum characteristics, temperature coefficient, and other 12 characteristic parameters as input, and automatically identifies the defect type affecting the loop resistance test by algorithm model calculation and analysis. It is determined that the power distribution cabinet has a potential defect of contact oxidation, which is consistent with the phenomenon of abnormal increase in resistance value with temperature rise.

[0060] The report generation unit of the intelligent diagnosis module automatically generates a health assessment report based on the diagnosed defect type, detailing the test time, environmental temperature, initial resistance value, impedance characteristic parameters, defect type, defect level, and maintenance recommendations. It clearly recommends "cleaning and polishing the contacts and retesting after treatment." The report also displays the resistance value change curve over time and impedance spectrum analysis results through charts, making it easy for staff to intuitively understand the equipment health status. The generated report is clearly presented on the device display interface, and staff can view it by sliding the screen. After the test is completed, the staff issues a "print report" instruction through the interaction and printing module. The printer drive unit immediately formats the test data information, converting numbers and charts into a format suitable for thermal printing, and compressing and optimizing the data to ensure clear printing and save consumables. Subsequently, the built-in thermal printer starts, and the print head quickly heats up, completing the test report printing within 15 seconds. After the staff checks the report content and finds no errors, they archive it as an important basis for power distribution cabinet maintenance. During the entire test process, the modules work together to accurately and efficiently complete the loop resistance test and defect diagnosis of the low-voltage power distribution cabinet, providing a scientific basis for equipment maintenance.

[0061] In summary, through the cooperative work of each module of the portable circuit resistance tester, in the test of the low-voltage power distribution cabinet, the power supply module guarantees stable and safe power support, ensuring the continuous operation of the equipment; the test and collection module accurately collects and processes signals to provide reliable data for analysis; the control and output module adaptively adjusts the current according to the impedance change to ensure the test accuracy; the interaction and printing module realizes convenient human-computer interaction and data recording; the intelligent diagnosis module automatically identifies defects and generates reports through cloud data interaction and algorithm diagnosis. The whole realizes efficient and accurate testing and diagnosis of the tested product, provides a scientific basis for equipment maintenance, improves the intelligent level, accuracy and efficiency of the test, and guarantees the safe operation of the power equipment.

[0062] In the description of the present specification, the description referring to the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms is not necessarily directed to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, the person skilled in the art can combine and combine the different embodiments or examples described in the present specification and the features of the different embodiments or examples without contradiction.

[0063] In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise specifically limited.

[0064] Any process or method descriptions in flow charts or described elsewhere herein can be understood as representing code modules, segments, or portions of code that include one or more executable instructions for implementing specific logic functions (or steps) in the process, and the preferred embodiments of the present application include additional implementations in which the order of steps can differ from those shown or discussed, including a step can occur at other times, including as recited in the description, and additional functions can be added or performed at a same or different time, including according to the application's description. It is understood that the terms "module", "section", and "portion" are used in the description of the preferred embodiments of the present application to represent software modules, segments, or portions of code that include one or more executable instructions for implementing specific logic functions (or steps) in the process, and the scope of the preferred embodiments of the present application includes additional implementations in which the order of steps can differ from those shown or discussed, including a step can occur at other times, including as recited in the description, and additional functions can be added or performed at a same or different time, including according to the application's description. It is understood that the terms "module", "section", and "portion" are used in the description of the preferred embodiments of the present application to represent software modules, segments, or portions of code that include one or more executable instructions for implementing specific logic functions (or steps) in the process, and the scope of the preferred embodiments of the present application includes additional implementations in which the order of steps can differ from those shown or discussed, including a step can occur at other times, including as recited in the description, and additional functions can be added or performed at a same or different time, including according to the application's description.

[0065] It should be understood that portions of the present application can be realized with a hardware, software, firmware or a combination thereof. In the above-described embodiments, a plurality of steps or methods can be realized with software or firmware stored in a memory and executed by a suitable instruction execution system. As such, if realized with hardware and in another embodiment, any one or a combination of the following technologies known in the art can be used: discrete logic circuit having logic gates for implementing logic functions on data signals, application specific integrated circuits having appropriate combinational logic gates, programmable gate arrays (PGA), field programmable gate arrays (FPGA), etc.

[0066] Those skilled in the art of the present technology can understand that all or part of the steps carried out by the above-mentioned embodiment methods can be completed by programs instructing related hardware, and the programs can be stored in a computer readable storage medium. When the program is executed, it includes one of the steps of the method embodiment or a combination thereof.

[0067] Although the embodiments of the present application have been shown and described above, it should be understood that the above-described embodiments are exemplary and cannot be understood as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above-described embodiments within the scope of the present application.

Claims

1. A portable loop resistance tester characterized by, The application relates to a test and collection module, a control and output module, an interaction and printing module, a power supply module and an intelligent diagnosis module. The test and collection module is used for arranging a sensing unit in a test loop, collecting current and voltage signal data of a tested product, analyzing a loop contact state through a deep neural network algorithm, and simultaneously calculating loop resistance and impedance characteristic parameters. The control and output module is used for high-precision constant current output and self-adaptive adjustment, automatically switching three-grade output currents by using a three-grade self-adaptive constant current control strategy when the impedance characteristic of the tested product changes. The interaction and printing module is used for receiving user operation instructions and displaying the current and voltage signal data of the tested product and the resistance value, and simultaneously printing according to the user instructions through a built-in thermal printer. The power supply module is used for stable power supply through intelligent power management and voltage conversion circuit. The intelligent diagnosis module is connected to a cloud case library, and automatically diagnoses defect types affecting loop resistance test through a multi-feature weighted random forest algorithm, and generates a health assessment report. The test and collection module comprises an ADC chip and a signal processing unit, wherein the ADC chip is used for collecting current and voltage signals of a tested product, and converting the signals into digital signals through 24-bit sigma-delta modulation, and simultaneously analyzing a loop contact state through a deep neural network algorithm; and the signal processing unit is used for receiving the digital signals, calculating loop resistance and impedance characteristic parameters through Ohm's law and impedance spectrum analysis algorithm.

2. The portable loop resistance tester of claim 1, wherein, The control and output module comprises a single-chip microcomputer and a constant current generation circuit board, wherein the single-chip microcomputer is used for running a three-grade self-adaptive constant current control strategy, generating and sending adjustment instructions to the constant current generation circuit board based on real-time impedance characteristic parameters, and controlling the constant current generation circuit board to automatically switch three-grade output currents of micro-current, standard current and large current; and the constant current generation circuit board is used for outputting currents with different amplitudes according to the adjustment instructions.

3. The portable loop resistance tester of claim 1, wherein, The interaction and printing module comprises an interaction driving unit and a printer driving unit, wherein the interaction driving unit is used for receiving instructions sent by a user through touch and key operation, analyzing and processing the instructions through a lookup table method and a finite state machine, and transmitting the instructions to corresponding modules; and the printer driving unit is used for format conversion and processing of test data information, and driving a built-in printer to complete a printing action.

4. The portable loop resistance tester of claim 1, wherein, The power supply module comprises a charge and discharge protection unit and a voltage conversion unit, wherein the charge and discharge protection unit is used for monitoring the charge and discharge process of a lithium battery, triggering overvoltage protection to cut off the loop if overcharge occurs, triggering undervoltage protection to cut off discharge if overdischarge occurs, and rapidly disconnecting the total power supply through a protection circuit if a short circuit occurs; and the voltage conversion unit is used for converting the voltage of the lithium battery into adaptive voltages required by internal components of the equipment.

5. The portable loop resistance tester of claim 1, wherein, ​ 6. The portable loop resistance tester of claim 1, wherein, The intelligent diagnosis module comprises a data interaction unit, a diagnosis unit and a report generation unit, wherein the data interaction unit is used for interfacing with a cloud case library and interacting test data with historical data and standard parameters in the cloud case library; the diagnosis unit is used for diagnosing test data and case library data through a multi-feature weighted random forest algorithm, automatically identifying a defect type related to a loop resistance test of a tested product; and the report generation unit is used for generating a health assessment report of the tested product according to the defect type and displaying the report on a device.

7. The portable loop resistance tester of claim 2, wherein, The impedance spectrum analysis algorithm formula is: ； ； wherein, represents impedance; represents resistance; represents imaginary unit; represents reactance; represents the speed of AC signal change; represents inductance; represents capacitance.

8. The portable loop resistance tester of claim 1, wherein, The three-stage adaptive constant current control strategy refers to a control method of dynamically adjusting control parameters in three stages to maintain current stability and automatically adapt to working conditions, and the formula is: ； ； wherein, represents an output current; represents an impedance of a measured product; represents a 100 μΩ first impedance threshold value; represents a 200 μΩ second impedance threshold value; represents a first preset constant current value; represents a second preset constant current value; represents a third preset constant current value; represents a current regulation amount; represents a current gear target current; represents a feedback current; represents time; represents a proportional coefficient; represents a differential coefficient; represents a differential sign.

9. The portable loop resistance tester of claim 1, wherein, The multi-feature weighted random forest algorithm formula is: ； ； ； wherein, represents the weight of the th feature; represents the total number of features; represents the criterion for selecting the features that best distinguish between defect types; represents the maximum function; represents the weighted information gain of a feature ; represents the sample data set; represents a specific feature; represents the final predicted defect type; represents the defect class; represents the total number of decision trees in the random forest; represents the optimal parameter function; represents the weight of the th decision tree; represents the indicator function; represents the prediction result of the th decision tree.

10. The portable loop resistance tester of claim 1, wherein, The test and collection module is bidirectionally connected with the intelligent diagnosis module, the intelligent diagnosis module is bidirectionally connected with the control and output module and the interaction and printing module, and the power supply module supplies power to all the modules.

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