Fault detection system and method for electrical system

Abstract

The invention relates to a fault detection method for an electrical system, and the method comprises the steps: operating a data collection oscilloscope in the electrical system under the condition that the electrical system is not started, carrying out the collection to obtain an initial waveform, and verifying whether the electrical system works normally or not; detailed information of the tested equipment is obtained, an electrical system is started, and a real-time waveform of the data acquisition oscilloscope is obtained; and performing corresponding fault detection on the tested equipment according to the detailed information of the tested equipment to obtain a test waveform. According to the invention, the fault detection result information of the tested equipment can be determined according to the obtained real-time waveform and the obtained test waveform. Meanwhile, interference data can be discarded according to the influence of electromagnetic interference generated during operation of each device in the electrical system on test data, so that the accuracy of the data is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of fault diagnosis, and in particular to a fault detection system and method for an electrical system. Background Art

[0002] The fault detection of the electrical system is mainly formulated according to the requirements of the standard, so that the test procedure must meet the requirements of the standard. At the same time, the SCPD (short-circuit protection device) used in the speed control system has the characteristics of fast breaking speed and small breaking current, but the current sensor accuracy is not high, and it is easy to be triggered by mistake or not triggered, resulting in test failure, which is easy to cause the protection program to be completed and the data not to be collected. The short-circuit test is a destructive test, and there is a possibility of non-repeatability, which will cause unnecessary losses to the company and also cause the problem of low detection efficiency. Because the electromagnetic interference is large when the speed control system is working, there are high-frequency harmonics, which will also cause the collected waveform to be distorted, affecting the measurement of the test data and the accuracy of the data. Therefore, how to eliminate interference and collect waveforms is the most important problem to be solved in this study. If this can be done, it will improve the work efficiency of the detection and the accuracy of the data.

[0003] Through the study of the short-circuit test and component breakdown test requirements in the speed control electrical transmission system standard GB12668.501, a complete set of reasonable related test processes were developed, and the factors affecting the test data results were found and solved, including: 1. The sensor accuracy is not high, and it is easy to cause false triggering or non-triggering; 2. The electromagnetic interference is large during operation, and the presence of high-frequency harmonics will also cause the collected waveform to be distorted, affecting the measurement of the test data and the accuracy of the data. Finally, the detection test details are formed.

[0004] The SCPD (short circuit protection device) used in the speed control system has an extremely fast breaking speed, generally less than 1ms, and the breaking current is also very small, sometimes only tens of amperes to hundreds of amperes. The existing short circuit test acquisition system is prone to false triggering during the acquisition process, which will result in the inability to collect the test waveform. Secondly, when the speed control system is working, the electromagnetic interference is large, causing harmonics to appear in the waveform collected by the acquisition system, resulting in waveform distortion.

[0005] In the short - circuit test and component breakdown test of a speed - regulated electrical drive system, there are many auxiliary devices and sampling points. The devices include rectifier devices, inverters, frequency converters, motors, load devices, etc.; the sampling positions include input - side voltage monitoring, input - side current monitoring, output - side voltage monitoring, short - circuit current monitoring at the output - side short - circuit point, contactor coil voltage monitoring for triggering the short - circuit, and two - way low - voltage signal monitoring, etc. When this entire set of systems is running, electromagnetic interference may be generated by each device. It is necessary to analyze which devices have a greater impact on the electromagnetic interference of the acquisition system; the SCPD (short - circuit protection device) used in the speed - regulated electrical drive system has the characteristics of extremely fast breaking speed and small breaking current. The sensors used in the existing short - circuit test acquisition system have low accuracy, and it is easy to have false triggering or non - triggering situations during actual acquisition, resulting in the problem that the test waveform is not collected. How to accurately measure needs to be solved; through experimental verification, find out the factors affecting the detection accuracy and solutions, propose an improved solution to solve the problem and verify the detection effect. Summary of the Invention

[0006] The purpose of the present invention is to overcome the deficiencies of the prior art and propose a fault detection system and method for an electrical system, which can eliminate interference data according to the electromagnetic interference generated when each device in the electrical system operates, thereby improving the accuracy of the data.

[0007] The present invention solves its technical problems by adopting the following technical solutions:

[0008] A fault detection system and method for an electrical system includes the following steps:

[0009] Step 1: When the electrical system is not started, run the data acquisition oscilloscope in the electrical system, collect the initial waveform, and verify whether the electrical system works normally;

[0010] Step 2: Obtain the detailed information of the device under test, start the electrical system, and obtain the real - time waveform of the data acquisition oscilloscope;

[0011] Step 3: Perform corresponding fault detection on the device under test according to the detailed information of the device under test in Step 2 to obtain the test waveform;

[0012] Step 4: Determine the fault detection result information of the device under test according to the real - time waveform obtained in Step 2 and the test waveform obtained in Step 3.

[0013] Moreover, Step 1 includes the following steps:

[0014] Step 1.1: When the electrical system is not started, run the data acquisition oscilloscope in the electrical system to collect the initial waveform;

[0015] Step 1.2: Based on the initial waveform obtained in Step 1.1, determine whether the data acquisition oscilloscope is operating normally. If it is operating normally, proceed to Step 2; otherwise, generate an abnormal operation message for the oscilloscope and send the abnormal operation message of the oscilloscope to the target terminal device for display.

[0016] Moreover, in Step 1.1, the data acquisition oscilloscope includes a short-circuit data acquisition oscilloscope and a component breakdown data acquisition oscilloscope. The short-circuit data acquisition oscilloscope is fixed to the wire to be tested through the clip part of the current probe, and the component breakdown data acquisition oscilloscope is connected to the node that needs to measure the voltage in the circuit under test through the probe of the high-voltage probe. Among them, the short-circuit data acquisition oscilloscope is used to collect the short-circuit initial waveform and the short-circuit real-time waveform, and the component breakdown data acquisition oscilloscope is used to collect the component breakdown initial waveform and the component breakdown real-time waveform.

[0017] Moreover, Step 2 includes the following steps:

[0018] Step 2.1: In the case of normal operation, start the electrical system and obtain the real-time waveform through the data acquisition oscilloscope.

[0019] Step 2.2: According to the device model of the device under test in the electrical system, obtain the detailed device information of the device under test.

[0020] Moreover, the specific implementation method of Step 2.2 is: divide the devices under test into a component breakdown test group and a short-circuit test group. Among them, the component breakdown test group includes at least two devices under test, the short-circuit test group includes at least two devices under test, and the device test information includes component breakdown test information and short-circuit test information.

[0021] Moreover, the fault detection in Step 3 includes short-circuit fault detection and component breakdown test fault detection.

[0022] Moreover, the specific implementation method of the short-circuit fault detection is: set different types of short-circuit fault detection scenarios for the electrical system. Among them, different types of short-circuit fault detection scenarios include three-phase short-circuit fault detection scenarios and two-phase short-circuit fault detection scenarios; use the detection device to measure the real-time operation parameter information of the electrical system at the moment of short circuit; based on the real-time operation parameter information, generate a feedback signal and transmit the feedback signal to the control device of the electrical system.

[0023] Moreover, the specific implementation method of the component breakdown test fault detection is: set a component breakdown test fault detection scenario for the key components in the electrical system, apply high voltage to the key components using high-voltage equipment, and obtain the leakage current of each key component and the breakdown voltage corresponding to each key component when different voltages are applied; based on the leakage current and the breakdown voltage, generate a feedback signal and transmit the feedback signal to the control device of the electrical system.

[0024] Moreover, the specific implementation method of step 4 is as follows: Under normal operation, select the probe corresponding to the data acquisition oscilloscope, connect the probe of the probe to the signal output terminal to be measured in the electrical system, and connect the ground clip of the probe to the ground of the circuit; Turn on the data acquisition oscilloscope, confirm that the power indicator light is on, and enter the initialization interface; Set the basic parameters of the data acquisition oscilloscope; When a trigger operation for starting scanning is detected, the data acquisition oscilloscope samples and processes the input signal, and displays the waveform of the signal on the screen in real time, and uses the waveform as the real-time waveform.

[0025] The advantages and positive effects of the present invention are:

[0026] The present invention operates the data acquisition oscilloscope in the electrical system when the electrical system is not started, acquires the initial waveform, and verifies whether the electrical system works normally; obtains the detailed information of the device under test, starts the electrical system, and obtains the real-time waveform of the data acquisition oscilloscope; performs corresponding fault detection on the device under test according to the detailed information of the device under test to obtain the test waveform. The present invention can determine the fault detection result information of the device under test according to the obtained real-time waveform and the obtained test waveform. At the same time, according to the electromagnetic interference generated when each device in the electrical system operates and its influence on the test data, the present invention can eliminate the interference data, thereby improving the accuracy of the data. Brief Description of the Drawings

[0027] Figure 1 is a flowchart of the present invention. Detailed Embodiments

[0028] The following further describes the present invention in detail with reference to the drawings.

[0029] A fault detection system and method for an electrical system, as Figure 1 shown, includes the following steps:

[0030] Step 1, when the electrical system is not started, operate the data acquisition oscilloscope in the electrical system, acquire the initial waveform, and verify whether the electrical system works normally.

[0031] The electrical system detected by the present invention includes: a power supply, a speed regulating device, a motor, a control device, and multiple sensors; the power supply is used to provide electrical energy for the electrical system, wherein the power supply includes an AC power supply or a DC power supply; the speed regulating device is used to adjust the speed of the motor; the motor is used to convert electrical energy into mechanical energy to drive the load to operate; the control device is used to control the speed regulating device and the motor, thereby controlling the speed regulation and operation of the electrical system; the multiple sensors are used to detect the operating parameters of the electrical system, wherein the operating parameters include the speed, current, and voltage of the motor; based on the operating parameters, a feedback signal is generated and transmitted to the control device.

[0032] Step 1 includes the following steps:

[0033] Step 1.1: When the electrical system is not started, operate the data acquisition oscilloscope in the electrical system to collect the initial waveform.

[0034] In Step 1.1, the data acquisition oscilloscope includes a short-circuit data acquisition oscilloscope and a component breakdown data acquisition oscilloscope. The short-circuit data acquisition oscilloscope is fixed on the wire to be tested through the clip part of the current probe, and the component breakdown data acquisition oscilloscope is connected to the node that needs to measure the voltage in the circuit under test through the probe of the high-voltage probe. The short-circuit data acquisition oscilloscope is used to collect the short-circuit initial waveform and the short-circuit real-time waveform, and the component breakdown data acquisition oscilloscope is used to collect the component breakdown initial waveform and the component breakdown real-time waveform. The short-circuit data acquisition oscilloscope often uses a current probe to measure the short-circuit current according to the characteristics and measurement requirements of the circuit under test. The current probe needs to have a high current measurement range and a low internal resistance to avoid affecting the circuit under test. At the same time, it is also necessary to select a suitable voltage probe to measure the voltage change during short circuit. Fix the clip part of the current probe on the wire to be tested to ensure that the clip is in close contact with the wire to accurately measure the short-circuit current. Connect the plug of the oscilloscope current probe to the corresponding channel on the oscilloscope, and adjust the vertical and horizontal scales of the oscilloscope as needed to correctly display the current waveform. At the same time, ensure that the oscilloscope and the circuit are well grounded to avoid noise interference caused by ground loops; the component breakdown data acquisition oscilloscope selects a probe suitable for measuring the breakdown voltage or current of the component. For high-voltage measurements, a high-voltage probe may be required; for large-current measurements, a current transformer or Rogowski coil, etc. may be required. Before connecting the probe, it may be necessary to perform some pre-processing on the signal, such as voltage division, current division, filtering, etc., to ensure that the signal input to the oscilloscope is within its measurement range; connect the processed signal to the corresponding channel of the oscilloscope, and set parameters such as the vertical and horizontal scales and sampling rate of the oscilloscope to obtain a clear breakdown waveform. When setting the trigger condition, usually use the characteristic signal at the moment of component breakdown as the trigger source, such as voltage mutation, current mutation, etc., so as to accurately capture the moment of component breakdown.

[0035] Step 1.2: Based on the initial waveform obtained in Step 1.1, determine whether the data acquisition oscilloscope is operating normally. If it is operating normally, proceed to Step 2. Otherwise, generate an abnormal operation message for the oscilloscope and send the abnormal operation message of the oscilloscope to the target terminal device for display.

[0036] Step 2: Obtain the detailed information of the device under test, start the electrical system, and obtain the real-time waveform of the data acquisition oscilloscope.

[0037] Step 2 includes the following steps:

[0038] Step 2.1: Under normal operation, start the electrical system and obtain the real-time waveform through the data acquisition oscilloscope;

[0039] Step 2.2: According to the device model of the device under test in the electrical system, obtain the detailed device information of the device under test.

[0040] Under normal operation, select the probe corresponding to the data acquisition oscilloscope, connect the probe tip of the probe to the signal output terminal to be measured in the electrical system, and connect the ground clip of the probe to the ground of the circuit; turn on the data acquisition oscilloscope, confirm that the power indicator light is on, and enter the initialization interface; set the basic parameters of the data acquisition oscilloscope; when a trigger operation for starting the scan is detected, the data acquisition oscilloscope samples and processes the input signal, and the waveform of the signal is displayed in real time on the screen, and the waveform is used as the real-time waveform.

[0041] As an example, select a probe adapted to the signal to be measured, connect the probe tip of the probe to the signal output terminal to be measured in the electrical system, and connect the ground clip of the probe to the ground (GND) of the circuit to ensure good grounding and avoid errors caused by ground loops; turn on the data acquisition oscilloscope, confirm that the power indicator light is on, and enter the initialization interface. Set the basic parameters of the oscilloscope, including trigger settings, time base (horizontal axis), vertical gain (vertical axis), and trigger level; press the start scan button, and the oscilloscope starts to sample and process the input signal, and the waveform of the signal is displayed in real time on the screen. If the waveform is unstable or not clear, the trigger settings, time base, and vertical gain and other parameters can be further adjusted until a satisfactory waveform is obtained.

[0042] The devices under test are divided into a component breakdown test group and a short-circuit test group. Among them, the component breakdown test group includes at least two devices under test, the short-circuit test group includes at least two devices under test, and the device test information includes component breakdown test information and short-circuit test information.

[0043] Step 3: Perform corresponding fault detection on the device under test according to the detailed information of the device under test in Step 2 to obtain the test waveform.

[0044] The fault detection in step 3 includes short - circuit fault detection and component breakdown test fault detection.

[0045] The specific implementation method of short - circuit fault detection is as follows: Set different types of short - circuit fault detection scenarios for the electrical system. Among them, different types of short - circuit fault detection scenarios include three - phase short - circuit fault detection scenarios and two - phase short - circuit fault detection scenarios; Use detection equipment to measure the real - time operating parameter information of the electrical system at the moment of short - circuit; Based on the real - time operating parameter information, generate a feedback signal and transmit the feedback signal to the control device of the electrical system.

[0046] The specific implementation method of component breakdown test fault detection is as follows: Set component breakdown test fault detection scenarios for key components in the electrical system. The key components include motor windings, transformers, and capacitors. Use high - voltage equipment to apply high voltage to the key components, and obtain the leakage current of each key component and the breakdown voltage corresponding to each key component when different voltages are applied; Based on the leakage current and breakdown voltage, generate a feedback signal and transmit the feedback signal to the control device of the electrical system.

[0047] Step 4: Determine the fault detection result information of the device under test according to the real - time waveform obtained in step 2 and the test waveform obtained in step 3.

[0048] According to the above - mentioned fault detection system and method for an electrical system, certain electrical systems are tested to verify the effect of the present invention.

[0049] The electrical system used in this embodiment includes a power source, sensors, a controller, protection device - type equipment, and data acquisition equipment;

[0050] Among them, the power source includes motors, frequency converters, and DC speed regulators; The motor is the power output device of the speed - regulating system. During operation, it will generate a magnetic field, etc., which may cause electromagnetic interference to other devices. At the same time, it may also be affected by other devices, interfering with its normal operation and the accuracy of test data; The frequency converter and DC speed regulator are used to control the speed of the motor and are the core control components of the speed - regulating system. They will generate a large amount of electromagnetic interference during operation. Especially the frequency converter, which realizes speed regulation by changing the power frequency, and will generate electromagnetic interference components such as high - frequency harmonics during this process. Moreover, their normal operation may also be affected by electromagnetic interference emitted by other devices. For example, their control circuits may malfunction due to external interference, thereby affecting the speed - regulating effect of the motor and the accuracy of test data.

[0051] The sensors include a rotational speed sensor, a current sensor, and a temperature sensor; the rotational speed sensor is used to monitor the rotational speed of the motor in real time and convert the rotational speed signal into an electrical signal for feedback to devices such as the controller. The current sensor is responsible for monitoring the current situation during the operation of the motor and will also convert the current signal into an electrical signal for transmission. The temperature sensor is mainly used to monitor the temperatures of key components such as the motor and the controller.

[0052] The controller includes a main controller and an auxiliary controller; the main controller, such as a PLC, combines relevant control programs and issues control commands to the motor driver according to the set speed requirements and various parameters (such as rotational speed, current, temperature, etc.) fed back by the sensors to achieve precise control of the rotational speed of the motor. The auxiliary controller is a small controller for specific function control, such as a controller for special control during the motor startup process. These auxiliary controllers are also vulnerable to electromagnetic interference, and their normal operation also has an important impact on the test effect and data accuracy of the entire speed regulation system.

[0053] The device of the protection device category, SCPD, includes short-circuit protection devices such as fuses and circuit breakers. When a short-circuit fault occurs in the system, these devices will quickly cut off the circuit to protect the safety of the entire speed regulation system. The main function of SCPD (Short Circuit Protective Device) is to quickly detect the abnormally increased current when a short-circuit fault occurs in the circuit and cut off the circuit in time, thereby protecting other electrical devices, lines, and the entire electrical system in the circuit from damage caused by excessive short-circuit current. For example, it can prevent electrical components from being burned out and line insulation from being damaged. SCPD (short-circuit protection device) has the characteristics of fast breaking speed and small breaking current.

[0054] The data acquisition equipment includes a data acquisition instrument and an oscilloscope; the data acquisition instrument is responsible for acquiring the signals (such as rotational speed, current, temperature, etc.) fed back by various sensors and converting these signals into digital signals for subsequent analysis and processing. It needs to accurately acquire the original and undisturbed signals. Otherwise, if the acquired waveform is distorted, it will be impossible to accurately analyze the operating state of the speed regulation system. Since its working principle involves the processing of weak signals, it is extremely sensitive to the electromagnetic environment and is easily affected by electromagnetic interference generated by other devices. The oscilloscope is used to perform waveform analysis on the various acquired signals and observe the characteristics of the signal such as the change law, frequency, and amplitude. It also requires a clear and accurate original waveform for effective analysis. If it is affected by electromagnetic interference and the acquired waveform is distorted, it will be impossible to accurately judge the operating conditions of each part in the speed regulation system, affecting the accuracy of the test data.

[0055] The electrical system can also use a speed - regulating electrical drive system. A data acquisition oscilloscope is an instrument specifically used to accurately acquire and analyze relevant electrical signal data (such as voltage and current waveforms, etc.) when an electrical fault occurs. The above - mentioned initial waveform can include signals fed back by various sensors (such as rotational speed, current, temperature, etc.). These fed - back signals are the relevant electrical signal data (such as voltage and current waveforms, etc.). Therefore, the initial waveform can include information such as voltage and current waveforms.

[0056] According to the initial waveform, check whether there are problems affecting detection interference. If there are no problems, determine that the data acquisition oscilloscope is operating normally; when the data acquisition oscilloscope is operating normally, start the electrical system, and obtain the real - time waveform through the data acquisition oscilloscope; according to the real - time waveform, check whether there is detection interference and the change of the interference degree.

[0057] A circuit data acquisition oscilloscope is an instrument specifically used to accurately acquire and analyze relevant electrical signal data when a short - circuit electrical fault occurs; it obtains the electrical signals in the circuit through a probe, converts them into processable analog or digital signals, and then performs operations such as amplification, processing, storage, and display inside the oscilloscope. When a short - circuit occurs, parameters such as voltage and current in the circuit will change sharply. The probe of the oscilloscope is connected to the measured circuit and can capture these mutated electrical signals in real time. For example, at the moment of short - circuit, the current will increase rapidly and the voltage may drop sharply. The oscilloscope can record a series of current and voltage waveform changes from before the short - circuit occurs to during and after the occurrence, providing an intuitive data basis for analyzing the short - circuit characteristics.

[0058] The component breakdown data acquisition oscilloscope is based on the basic architecture of an ordinary oscilloscope but is optimized for the characteristics of component breakdown tests. In component breakdown tests, when a high voltage is gradually applied to a component until its insulation is broken down, electrical signals such as voltage and current in the circuit will change significantly. The oscilloscope is connected to the circuit where the measured component is located through a probe to obtain these changing electrical signals in real time. The probe transmits the electrical signals to the inside of the oscilloscope. After a series of processing steps such as amplification and analog - to - digital conversion, they are converted into digital signals available for analysis and display, so as to be able to record the whole process of voltage and current waveform changes from the start of voltage application to the moment of component breakdown and for some time after breakdown, providing an intuitive and accurate data basis for in - depth study of component breakdown characteristics.

[0059] The device under test can be a DC speed control device DCM, and the device models can be DCM 850A and DCM 2600A; the device details information of the device under test DCM 850A can be armature power supply: 3AC, 400V; field power supply: 2AC, 400V; rated output current: 850ADC (light load is sufficient during the test); the device details information of the device under test DCM 2600A can be armature power supply: 3AC, 690V; field power supply: 2AC, 480V; rated output current: 2600ADC (light load is sufficient during the test). Selecting the target device to be tested from the devices under test can be a random selection, and several devices of the same model are selected from a batch of devices for testing; the target devices to be tested in the component breakdown test group and the short-circuit test group are respectively used for component breakdown tests and short-circuit tests. The above device test information can be the information of the voltage and current applied to the device under test.

[0060] Test the following two EUTs (DC speed control device DCM), and the device information data is shown in Table 1

[0061] Table 1 EUT device information data

[0062]

[0063] The signal acquisition during the test includes: monitoring the voltage on the input side of the EUT; monitoring the current on the input side of the EUT; monitoring the voltage on the output side of the EUT; monitoring the short-circuit current at the short-circuit point on the output side of the EUT (the peak current is relatively large, about 1kA - 100kA); monitoring the coil voltage of the contactor that triggers the short circuit (the contactor is used to connect the short-circuit loop); monitoring 2 low-voltage signals.

[0064] The test conditions are shown in Table 2.

[0065] Table 2 Test conditions

[0066]

[0067] Fault detection includes short-circuit tests and component breakdown tests. According to the pre-determined device test information, corresponding fault detections are performed on each target device to be tested in turn, and then different fault detections correspond to different data acquisition oscilloscopes to obtain the test waveforms corresponding to each target device to be tested, and a set of test waveforms is obtained.

[0068] According to each test waveform in the set of test waveforms and the real-time waveform, determine the fault detection result information corresponding to each target device to be tested in each of the target devices to be tested.

[0069] Select a suitable test standard according to the type of speed control electrical drive system (such as DC speed control system, AC speed control system, etc.), application scenarios (industrial production, transportation, etc.), and relevant regulatory requirements of the region or industry. The test standard is the requirements for short-circuit test and component breakdown test in the speed control electrical drive system standard GB12668.501; Set the short-circuit switch: used to artificially create short-circuit conditions during the test, which should have sufficient on-off capacity, be able to withstand the large short-circuit current that may occur during the test, and have reliable and rapid operation. A suitable specification of short-circuit switch can be selected according to parameters such as the rated current of the system. Determine a suitable short-circuit point. Generally speaking, a short-circuit point can be set at both ends of the motor winding, between the controller output end and the motor input end, a certain part of the cable, etc. However, it should be noted that when selecting the short-circuit point, the degree of damage to the system should be considered as small as possible, and it should be convenient for measuring and analyzing relevant data. For example, when studying the short-circuit characteristics of the motor, the short-circuit point is often set at both ends of the motor winding, so that the current, voltage, etc. of the motor in the short-circuit state can be directly observed.

[0070] Connect the ammeter in series in the short-circuit circuit to accurately measure the short-circuit current. Adjust the range of the ammeter according to the expected magnitude of the short-circuit current to ensure that the change of the short-circuit current can be completely and accurately recorded. Connect the voltmeter in parallel across the short-circuit point or other relevant parts (such as both ends of the motor winding, controller output end, etc.) to measure the voltage value of the corresponding part. Similarly, adjust the range of the voltmeter according to the expected voltage value of the measurement part to make it accurately reflect the voltage change. After completing all the preparatory work, create a short-circuit condition by operating the short-circuit switch. When operating the short-circuit switch, ensure rapid and accurate operation to simulate a more realistic short-circuit situation. At the same time, start equipment such as an oscilloscope to start recording the current and voltage waveform changes during the short-circuit instant and process. If an oscilloscope is used to record the current and voltage waveform changes, carefully observe these waveforms. Analyze the characteristics of the waveforms such as shape, amplitude, frequency, etc. For example, by observing the rising edge, peak value, falling edge, etc. of the short-circuit current waveform, understand the dynamic characteristics of the short-circuit process; by observing the change of the voltage waveform, judge the influence of the short-circuit point and the surrounding environment on the voltage. The short-circuit characteristics of the system can be further analyzed based on the waveform changes, such as whether there are components such as inductance and capacitance affecting the short-circuit process. According to the test standard and analysis results, judge the short-circuit test results of the speed control electrical drive system. If the data and characteristics shown by the system during the short-circuit test meet the requirements specified in the test standard and no abnormal situations that seriously affect the system performance (such as component burnout, system out-of-control, etc.) occur, it can be determined that the system has passed the short-circuit test.

[0071] Select appropriate test standards according to the specific types of components in the speed-regulating electric drive system (such as motors, controllers, cables, capacitors, resistors, etc.), application scenarios, and relevant regulatory requirements in the region or industry. The test standards are the requirements for short-circuit tests and component breakdown tests in the speed-regulating electric drive system standard GB12668.501; select representative component samples from the speed-regulating electric drive system for testing. The number of samples usually needs to meet the requirements of statistical analysis, generally not less than 3, in order to more accurately evaluate the overall performance of the components. Set parameters such as the initial output voltage value and voltage rise rate of the high-voltage power supply according to the test standards and the characteristics of the components. For example, for some electrical insulation components, the initial voltage can be set to about 10% of the rated voltage of the component, and the voltage rise rate can be set to 1 kV per second or other appropriate rates specified by the standard. Set parameters such as the measurement range and accuracy of the measuring instrument to ensure that it can accurately record the changes in voltage and current during the test.

[0072] Start the high-voltage power supply and gradually apply voltage to the component at the set voltage rise rate. During the voltage application process, closely monitor the readings of the voltmeter and ammeter, and record the current values passing through the component at different voltage values to analyze the insulation characteristics and current change trends of the component. For example, when the voltage gradually rises from the initial value to 5 kV, record the current value passing through the component at this time as 0.01 A; when the voltage rises to 10 kV, record the corresponding current value as 0.02 A, and so on. If it is observed during the test that the component has reached the breakdown state (such as the above abnormal phenomena occur and the current suddenly increases), record the voltage value at this time, and this voltage value is the breakdown voltage of the component. For example, in the above test, when the component smokes and the current increases from 0.05 A to 10 A, the recorded voltage value is 30 kV, then 30 kV is the breakdown voltage of the component. Organize and analyze the voltage and current data recorded during the test, and draw a voltage-current curve to more intuitively understand the insulation characteristics and breakdown process of the component. By analyzing the characteristics such as the trend and slope of the curve, it is possible to judge the insulation quality of the component and whether there are weak links. Determine the test results of the component according to the test standards and analysis results. If the breakdown voltage of the component reaches or exceeds the minimum requirements specified by the standard, and no other serious difficulties affecting the performance of the component occur during the test, generally it can be determined that the component has passed the breakdown test and its insulation performance meets the requirements.

[0073] According to Clause 5.2.3.6 of the GB 12668.501-2013 standard, study the problems generated during short-circuit tests and component breakdown tests. Conduct tests under full load or light load conditions of the speed-regulating drive system; use a cross-sectional area of at least 2.5 mm 2A cable and appropriate switching devices are used to apply a short circuit; for the short-circuit test, a short circuit is introduced at the output under test; for the component breakdown test, the component is short-circuited or open-circuited, one component at a time; the speed control drive system is operated until one or more of the following results are obtained: (1) the electronic short-circuit protection circuit operates; (2) a short-circuit protection device opens; (3) a steady-state temperature is reached after at least 10 minutes.

[0074] Simulate different types of short-circuit faults, such as three-phase short circuit, two-phase short circuit, etc. This can be achieved by connecting a short-circuit reactor in the system or using short-circuit test equipment; measure parameters such as current and voltage at the moment of short circuit, and record data such as the peak value and duration of the short-circuit current; observe whether the protection device of the system can act in time to cut off the short-circuit current and protect the system from damage. Determine the magnitude of the short-circuit current of the system through the above steps to reasonably select the protection device and determine the short-circuit capacity of the system; test the protection performance and tolerance of the speed control electrical drive system under short-circuit faults; verify the action accuracy and reliability of the short-circuit protection devices (such as fuses, circuit breakers, etc.) of the system.

[0075] Perform a withstand voltage test on key components in the system, such as motor windings, transformers, capacitors, etc. Equipment such as a high-voltage generator can be used to apply a high voltage and gradually increase the voltage value until the component breaks down or reaches the specified test voltage; measure the leakage current of the component at different voltages and record the magnitudes of the breakdown voltage and leakage current; observe the appearance changes of the component during the test, such as whether there is a discharge phenomenon, whether there is an abnormal smell, etc. Detect the insulation performance and withstand voltage capacity of key components in the speed control electrical drive system through the above steps; determine whether the component will break down under high voltage to ensure the safe operation of the system; verify the quality and reliability of the component and provide a basis for the design and selection of the system.

[0076] It should be emphasized that the embodiments described in the present invention are illustrative rather than restrictive. Therefore, the present invention includes but is not limited to the embodiments described in the specific implementation manners. Any other implementation manners obtained by those skilled in the art based on the technical solutions of the present invention also fall within the protection scope of the present invention.

Claims

1. A fault detection method for an electrical system, characterized in that: It includes the following steps: Step 1: When the electrical system is not started, run the data acquisition oscilloscope in the electrical system, collect the initial waveform, and verify whether the electrical system is working properly; Step 2: Obtain the detailed information of the device under test, start the electrical system, and obtain the real-time waveform of the data acquisition oscilloscope; Step 3: Perform corresponding fault detection on the device under test according to the detailed information of the device under test in Step 2 to obtain the test waveform; Step 4: Determine the fault detection result information of the device under test according to the real-time waveform obtained in Step 2 and the test waveform obtained in Step 3.

2. The fault detection method of an electrical system according to claim 1, characterized in that: The said Step 1 includes the following steps: Step 1.1: When the electrical system is not started, run the data acquisition oscilloscope in the electrical system to collect the initial waveform; Step 1.2: According to the initial waveform obtained in Step 1.1, judge whether the data acquisition oscilloscope is running normally. If it is running normally, proceed to Step 2. Otherwise, generate an oscilloscope operation abnormal information and send the oscilloscope operation abnormal information to the target terminal device for display.

3. A fault detection method for an electrical system according to claim 2, characterized in that: In the said Step 1.1, the data acquisition oscilloscope includes a short-circuit data acquisition oscilloscope and a component breakdown data acquisition oscilloscope. The short-circuit data acquisition oscilloscope is fixed on the wire to be tested through the clip part of the current probe, and the component breakdown data acquisition oscilloscope is connected to the node that needs to measure the voltage in the circuit under test through the probe of the high-voltage probe. Among them, the short-circuit data acquisition oscilloscope is used to collect the short-circuit initial waveform and the short-circuit real-time waveform, and the component breakdown data acquisition oscilloscope is used to collect the component breakdown initial waveform and the component breakdown real-time waveform.

4. The fault detection method of an electrical system according to claim 1, characterized in that: The said Step 2 includes the following steps: Step 2.1: When running normally, start the electrical system and obtain the real-time waveform through the data acquisition oscilloscope; Step 2.2: According to the device model of the device under test in the electrical system, obtain the detailed device information of the device under test.

5. A fault detection method for an electrical system according to claim 4, characterized in that: The specific implementation method of the said Step 2.2 is: Divide the device under test into a component breakdown test group and a short-circuit test group. Among them, the component breakdown test group includes at least two devices under test, and the short-circuit test group includes at least two devices under test. The device test information includes component breakdown test information and short-circuit test information.

6. The fault detection method for an electrical system according to claim 1, characterized in that: The fault detection in the said Step 3 includes short-circuit fault detection and component breakdown test fault detection.

7. A fault detection method for an electrical system according to claim 7, characterized in that: The specific implementation method of the said short-circuit fault detection is: Set different types of short-circuit fault detection scenarios for the electrical system. Among them, different types of short-circuit fault detection scenarios include three-phase short-circuit fault detection scenarios and two-phase short-circuit fault detection scenarios; Use the detection device to measure the real-time operation parameter information of the electrical system at the moment of short circuit; Based on the real-time operation parameter information, generate a feedback signal and transmit the feedback signal to the control device of the electrical system.

8. A fault detection method for an electrical system according to claim 7, characterized in that: The specific implementation method for the breakdown test fault detection of the component is as follows: Set up a breakdown test fault detection scenario for the key components in the electrical system, apply high voltage to the key components using high voltage equipment, and obtain the leakage current of each key component and the breakdown voltage corresponding to each key component when different voltages are applied; Based on the leakage current and the breakdown voltage, generate a feedback signal and transmit the feedback signal to the control device of the electrical system.

9. A fault detection method for an electrical system according to claim 1, characterized in that: The specific implementation method of step 4 is as follows: Under normal operation, select the probe corresponding to the data acquisition oscilloscope, connect the probe tip of the probe to the signal output end to be measured in the electrical system, and connect the ground clip of the probe to the ground of the circuit; Turn on the data acquisition oscilloscope, confirm that the power indicator light is on, and enter the initialization interface. Set the basic parameters of the data acquisition oscilloscope; When a trigger operation for starting the scan is detected, the data acquisition oscilloscope samples and processes the input signal, and displays the waveform of the signal on the screen in real time, and uses the waveform as the real-time waveform.

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