Handheld intelligent comprehensive tester for substation secondary circuit detection

Abstract

The application discloses a handheld intelligent comprehensive tester for detecting a substation secondary circuit, which comprises a handheld shell, a display screen, a test connecting line, a wiring terminal area and an intelligent comprehensive test circuit. The display screen is arranged above the handheld shell. The wiring terminal area is arranged on the handheld shell and below the display screen. The test connecting line is used for connecting the substation secondary circuit to be detected and the handheld intelligent comprehensive tester. The intelligent comprehensive test circuit is arranged in the handheld shell and connected with the display screen and the wiring terminal area. The comprehensive tester integrates the core test functions of the substation secondary circuit into the intelligent comprehensive test circuit, realizes the rapid detection of the parameters of the substation secondary circuit by cooperating with the selection of the wiring terminal area, solves the pain points of the dispersion and complexity of the traditional test methods, improves the accuracy and safety of the test of the substation secondary circuit, reduces the operation and maintenance cost and guarantees the stable operation of the power system.

Description

Technical Field

[0001] This invention relates to the field of substation secondary circuit operation and maintenance technology, and in particular to a handheld intelligent integrated tester for substation secondary circuit testing. Background Technology

[0002] As the core hub for power transmission and distribution in a power system, substations play a crucial role in secondary circuits, undertaking critical tasks such as control command transmission, protection action triggering, and operational status monitoring. They serve as the "nerve center" for ensuring the safe and stable operation of the power system. The insulation performance, electrical parameter accuracy, and connection reliability of the secondary circuits directly determine the operating status of substation equipment. Problems such as insulation aging, abnormal parameters, or line breaks can trigger malfunctions or failures to operate protection devices, leading to widespread power outages, damage to main equipment, and resulting in huge economic losses and adverse social impacts. However, current substation secondary circuit operation and maintenance testing methods have significant shortcomings: they rely on various specialized instruments such as insulation resistance meters and multimeters, which are heavy to carry on-site, requiring frequent equipment switching and rewiring, increasing the workload of maintenance personnel; different instruments have different operating logics and interface standards, requiring maintenance personnel to master the use of multiple devices, resulting in high learning costs and increasing the risk of safety hazards due to operational errors. Summary of the Invention

[0003] To overcome the above problems, the purpose of this invention is to provide a handheld intelligent integrated tester for substation secondary circuit testing. This integrated tester integrates the core testing functions of substation secondary circuit testing into an intelligent integrated test circuit. With the selection of corresponding terminal blocks, it enables rapid detection of substation secondary circuit parameters, solving the pain points of the dispersion and complexity of traditional testing methods, improving the accuracy and safety of substation secondary circuit testing, providing a one-stop solution for on-site operation and maintenance, reducing operation and maintenance costs, and ensuring the stable operation of the power system.

[0004] The technical solution adopted in this invention is:

[0005] A handheld intelligent integrated tester for substation secondary circuit testing includes a handheld housing, a display screen, test connection cables, a terminal block area, and an intelligent integrated test circuit. The display screen is mounted on top of the handheld housing, and the terminal block area is located on the handheld housing below the display screen. The test connection cables connect the substation secondary circuit to be tested to the handheld intelligent integrated tester. The intelligent integrated test circuit is located inside the handheld housing and connects to the display screen and the terminal block area.

[0006] The intelligent integrated test circuit includes a control module, a secondary circuit insulation resistance detection module, a DC resistance detection module, a conductor polarity detection module, a multi-point grounding test module, a switching module, and a power supply module. The control module uses an STM32 microcontroller. The input terminals of the secondary circuit insulation resistance detection module, DC resistance detection module, conductor polarity detection module, and multi-point grounding test module are each connected to one output of the STM32 microcontroller. The outputs of the secondary circuit insulation resistance detection module, DC resistance detection module, conductor polarity detection module, and multi-point grounding test module are connected to a display screen. The switching module is used for switching between the various detection modules and is connected to the STM32 microcontroller. The power supply module provides power to the intelligent integrated test circuit.

[0007] As a further description of the present invention, the terminal block area includes a detection switch, a first test connection interface, a second test connection interface, a comprehensive test button, and an independent test area. The detection switch is located on the lower left side of the display screen, the first test connection interface and the second test connection interface are located below the detection switch, the comprehensive test button is located on the right side of the detection switch, and the independent test area is located below the comprehensive test button.

[0008] As a further description of the present invention, the independent test area includes an insulation resistance button, a DC resistance button, a wire polarity button, and a multi-point grounding button, wherein the insulation resistance button and the DC resistance button are located above the wire polarity button and the multi-point grounding button.

[0009] As a further description of the present invention, the secondary circuit insulation resistance detection module includes a high voltage generating circuit and a voltage and current measurement sampling circuit. The high voltage generating circuit generates the high voltage required for detection, and the voltage and current measurement sampling circuit measures the weak leakage current generated in the circuit when the high voltage is applied, and calculates the resistance value.

[0010] As a further description of the present invention, the DC resistance detection module includes a high-precision constant current source unit, a four-terminal measurement circuit unit, a signal conditioning and AD conversion unit, and an automatic protection and discharge circuit unit;

[0011] The high-precision constant current source unit outputs a stable and adjustable DC current;

[0012] The four-terminal measurement circuit unit consists of a set of current output lines and a set of voltage sampling lines. The current lines inject a constant current into the transformer windings, and the voltage lines independently sample the voltage at both ends of the transformer windings.

[0013] The signal conditioning and analog-to-digital conversion unit filters out ripple and interference noise in the circuit, amplifies the acquired weak voltage signal, and converts it into a digital signal.

[0014] The automatic protection and discharge circuit unit quickly and safely releases the energy stored in the transformer windings.

[0015] As a further description of the present invention, the wire core polarity detection module includes a signal processing circuit and a polarity discrimination circuit. The signal processing circuit includes a high-voltage side signal processing circuit and a low-voltage side signal processing circuit. The high-voltage side signal processing circuit attenuates the input signal and converts the AC signal into a DC signal through a resistor voltage divider network. The low-voltage side signal processing circuit attenuates or amplifies the low-voltage side signal. The polarity discrimination circuit converts the AC voltage signals of the high-voltage side and the low-voltage side into two pulse signals respectively, and detects the phase relationship of the two pulses through an XOR gate circuit.

[0016] As a further description of the present invention, the multi-point grounding test module includes a current sensor, a signal conditioning and filtering unit, and an intelligent diagnosis and control unit. The current sensor is a high-precision through-hole sensor. The signal conditioning and filtering unit processes the measured grounding current and sends it to the intelligent diagnosis and control unit. The intelligent diagnosis and control unit analyzes the data, identifies faults, and controls the output.

[0017] As a further description of the present invention, the input terminal of the switching module is connected to the output of the STM32, and connected to an optocoupler through R14. The output is connected to a transistor through R10 and R9. The output of the transistor is connected to a relay. A diode protection circuit is also connected to the output terminal of the transistor. The output of the relay is the detection circuit after the final switching.

[0018] As a further description of the present invention, the STM32 output terminal connection switching module controls the corresponding detection module through four output pins.

[0019] As a further description of the invention, the handheld housing is made of fiberglass.

[0020] The beneficial effects of this invention are:

[0021] This invention relates to a handheld intelligent integrated tester for substation secondary circuit testing. The tester's intelligent integrated testing circuit integrates a secondary circuit insulation resistance testing module, a DC resistance testing module, a conductor polarity testing module, and a multi-point grounding test module into a single handheld device. A switching module enables the orderly switching of each testing function. The entire testing process requires only the use of this handheld intelligent integrated tester. The test connection wires are connected to the transformer's secondary circuit, and the buttons in the terminal block area are used for one-button measurement. The measurement results are directly displayed on the screen, allowing maintenance personnel to quickly and accurately obtain measurement results, improving the efficiency of power grid operation and maintenance, reducing maintenance costs, and ensuring the stable operation of the power system. Furthermore, the integrated design of the handheld intelligent integrated tester allows on-site testing personnel to complete multiple testing tasks with just one instrument, eliminating the need for frequent equipment and wiring changes. Testing time is reduced by more than 60% compared to traditional methods, significantly improving on-site operation and maintenance efficiency.

[0022] This invention relates to a handheld intelligent integrated tester for substation secondary circuit testing. The integrated test button in the terminal block area measures all parameters of the substation secondary circuit. Independent test areas correspond to various test items. During actual substation secondary circuit testing, selection can be made according to measurement needs. The switching module uses a combination of optocouplers and relays, with an STM32 microcontroller controlling four output pins to drive the corresponding test modules. The optocouplers provide electrical isolation between the control signals and the test circuit, effectively preventing damage to the control module during high-voltage testing. The relay contact capacity meets the switching requirements of each module, with low contact resistance and reliable operation. Users can initiate full-process automatic testing via the integrated test button or initiate individual tests via the insulation resistance, DC resistance, wire polarity, and multi-point grounding buttons in the independent test areas, meeting the needs of different application scenarios such as on-site segmented testing and fault diagnosis. This switching structure is simple and compact, with good isolation performance, clear switching logic, and flexible operation.

[0023] This invention relates to a handheld intelligent integrated tester for substation secondary circuit testing. The handheld casing is made of fiberglass, offering excellent insulation, high mechanical strength, and lightweight construction, with the entire unit weighing less than 1.2 kg, facilitating one-handed operation and portability. Silicone corner protectors around the casing provide drop resistance. The display uses a high-brightness color touchscreen, supporting visibility under strong outdoor light and operation with gloves, making it suitable for the complex and harsh working environments of substations. Attached Figure Description

[0024] Figure 1 This is a front structural diagram of the handheld intelligent integrated tester for substation secondary circuit testing proposed in this invention.

[0025] Figure 2This is a schematic diagram of the intelligent integrated test circuit structure of the handheld intelligent integrated tester for substation secondary circuit testing proposed in this invention.

[0026] Figure 3 This is a circuit diagram of the secondary circuit insulation resistance detection module in an embodiment of the handheld intelligent integrated tester for substation secondary circuit testing proposed in this invention.

[0027] Figure 4 This is a circuit diagram of the DC resistance detection module in an embodiment of the handheld intelligent integrated tester for substation secondary circuit testing proposed in this invention.

[0028] Figure 5 This is a circuit diagram of the core polarity detection module in an embodiment of the handheld intelligent integrated tester for substation secondary circuit testing proposed in this invention.

[0029] Figure 6 This is a circuit diagram of the multi-point grounding test module in an embodiment of the handheld intelligent integrated tester for substation secondary circuit testing proposed in this invention.

[0030] Figure 7 This is a circuit diagram of the switching module in an embodiment of the handheld intelligent integrated tester for substation secondary circuit testing proposed in this invention.

[0031] Explanation of reference numerals in the attached figures:

[0032] 1- Handheld casing;

[0033] 2-Display screen;

[0034] 3-Terminal block area, 31-Detection switch, 32-First test connection interface, 33-Second test connection interface, 34-Comprehensive test button, 35-Independent test area, 351-Insulation resistance button, 352-DC resistance button, 353-Wire polarity button, 354-Multi-point grounding button;

[0035] 4-Intelligent integrated test circuit, 41-Control module, 42-Secondary circuit insulation resistance detection module, 43-DC resistance detection module, 44-Core polarity detection module, 45-Multi-point grounding test module, 46-Switching module, 47-Power supply module. Detailed Implementation

[0036] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0037] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0038] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0039] This invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of this invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not adhering to the usual scale. Furthermore, the schematic diagrams are merely examples and should not be construed as limiting the scope of protection of this invention. In actual fabrication, the three-dimensional spatial dimensions of length, width, and depth should be included.

[0040] Furthermore, in the description of this invention, it should be noted that the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used solely for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. In addition, the terms "first," "second," or "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0041] Unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" in this invention should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; similarly, they can refer to mechanical connections, electrical connections, or direct connections, or indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0042] like Figure 1-7 As shown, it illustrates a specific embodiment of the present invention:

[0043] Example 1:

[0044] A handheld intelligent integrated tester for testing secondary circuits in substations includes a handheld housing 1, a display screen 2, test connection cables, a terminal block area 3, and an intelligent integrated test circuit 4. The display screen 2 is mounted on top of the handheld housing 1, and the terminal block area 3 is located on the handheld housing 1 below the display screen 2. The test connection cables are used to connect the secondary circuit of the substation to be tested to the handheld intelligent integrated tester. The intelligent integrated test circuit 4 is located inside the handheld housing 1 and connects the display screen 2 and the terminal block area 3.

[0045] Specifically, the terminal block area 3 includes a detection switch 31, a first test connection interface 32, a second test connection interface 33, a comprehensive test button 34, and an independent test area 35. The detection switch 31 is located on the lower left side of the display screen 2. The first test connection interface 32 and the second test connection interface 33 are located below the detection switch 31. The comprehensive test button 34 is located on the right side of the detection switch 31. The independent test area 35 is located below the comprehensive test button 34.

[0046] Specifically, the independent test area 35 includes an insulation resistance button 351, a DC resistance button 352, a wire polarity button 353, and a multi-point grounding button 354. The insulation resistance button 351 and the DC resistance button 352 are located above the wire polarity button 353 and the multi-point grounding button 354.

[0047] In this embodiment, the detection switch 31 is the main power switch, located on the lower left side of the display screen 2, used to control the power supply of the entire machine. The first test connection interface 32 and the second test connection interface 33 are arranged side by side below the detection switch 31, used to connect the red and black test connection lines respectively, corresponding to the high potential end and low potential end of the test circuit. The comprehensive test button 34 is located to the right of the detection switch 31. When pressed, the control module 41 will sequentially call the insulation resistance test, DC resistance test, wire polarity test, and multi-point grounding test modules according to a preset order, realizing one-button fully automatic comprehensive testing. The independent test area 35 is located below the comprehensive test button 34, including the insulation resistance button 351, DC resistance button 352, wire polarity button 353, and multi-point grounding button 354 arranged in two rows and two columns. The user can press any button individually according to the actual testing needs, and the control module 41 will call the corresponding function module for specific testing, making the operation flexible and convenient.

[0048] Display screen 2 is mounted on top of the handheld housing 1. It is a 4.3-inch TFT color touchscreen with a resolution of 800×480 and a brightness of ≥400cd / m², supporting visibility under strong outdoor light. The touchscreen uses capacitive multi-touch and supports operation with gloves, meeting the needs of field use in winter. Display screen 2 is used to display test parameters, real-time test results, historical data curves, operation prompts, and fault alarm information.

[0049] Terminal block 3 is located below display screen 2. Test connection cable 3 is used to connect the secondary circuit of the substation under test to this tester. The test connection cable uses silicone insulated high-voltage wire with a withstand voltage rating of 3kV, a wire diameter of 2.5mm², and a length of 2m. The end is equipped with both 4mm banana plugs and alligator clips to accommodate different wiring methods.

[0050] In this embodiment, the terminal block area 3 further integrates human-machine interaction and signal access functions. The detection switch 31 is a waterproof self-locking push-button switch with a rated current of 3A, used to control the power-on and power-off of the entire machine. When pressed, the indicator light illuminates, indicating that the system is powered on. The first test connection cable interface 32 and the second test connection cable interface 33 are used to connect the positive and negative terminals of the test cables, respectively. The interfaces use 4mm safety jacks with internal spring sheets to ensure reliable contact. Insulating sleeves are installed around the jacks to prevent accidental contact. The comprehensive test button 34 is a yellow circular button used to start the one-button comprehensive test process. The four buttons in the independent test area 35 are all blue square buttons, used to individually start each test function to meet the needs of on-site segmented testing. All buttons use waterproof membrane switches with a protection level of IP67.

[0051] Specifically, the handheld casing 1 is made of fiberglass.

[0052] In this embodiment, the handheld housing 1 is made of fiberglass reinforced plastic (FRP), specifically epoxy fiberglass laminate with a thickness of 3mm. It features good insulation performance (insulation resistance greater than 1000MΩ), high mechanical strength (tensile strength ≥300MPa), and light weight (total weight ≤1.2kg), making it suitable for on-site carrying and high-altitude operations. Silicone corner protectors are provided around the housing to enhance drop resistance.

[0053] Example 2:

[0054] The intelligent integrated test circuit 4 includes a control module 41, a secondary circuit insulation resistance detection module 42, a DC resistance detection module 43, a conductor polarity detection module 44, a multi-point grounding test module 45, a switching module 46, and a power supply module 47. The control module 41 uses an STM32 microcontroller. The input terminals of the secondary circuit insulation resistance detection module 42, DC resistance detection module 43, conductor polarity detection module 44, and multi-point grounding test module 45 are respectively connected to one output of the STM32. The outputs of the secondary circuit insulation resistance detection module 42, DC resistance detection module 43, conductor polarity detection module 44, and multi-point grounding test module 45 are connected to the display screen 2. The switching module 46 is used for switching between the various detection modules and is connected to the STM32. The power supply module 47 provides power to the intelligent integrated test circuit 4.

[0055] In this embodiment, the control module 41 uses an STM32 series microcontroller, specifically the STM32F407ZGT6. This chip has powerful digital signal processing capabilities, which can meet the requirements of parallel control and data processing of multiple modules. The control module 41 also has an external W25Q128 Flash chip (16MB) for storing historical test data and device configuration parameters; and an external DS3231 high-precision real-time clock chip for adding timestamps to the test data.

[0056] The power module 47 is powered by a rechargeable lithium battery pack. The battery pack consists of three lithium-ion batteries connected in series, each with a capacity of 3400mAh, forming a 6600mAh battery pack with a rated voltage of 12V. It has a built-in battery management system with overcharge protection, over-discharge protection, overcurrent protection, and short-circuit protection. Internally, the power module 47 provides the required operating voltage to each module through a multi-channel DC-DC converter.

[0057] The LM2596-5.0 step-down switching power supply chip is used to output 5V / 2A to power the display screen 2, control module 41 and peripheral circuits;

[0058] It uses the LM2596-12 boost switching power supply chip, which outputs 12V / 1A to power relays and high voltage generating circuits.

[0059] It uses the ICL7660 charge pump chip, which outputs -5V / 100mA to supply the negative power supply for the operational amplifier;

[0060] An AMS1117-3.3 linear regulator is used, with an output of 3.3V / 500mA, to provide the reference voltage for the STM32 and ADC.

[0061] The power module 47 is also equipped with a voltage detection circuit, which uses a resistor voltage divider to divide the battery voltage and then sends it to the STM32's ADC channel to monitor the battery level in real time. The remaining battery level is displayed as an icon in the upper right corner of the display screen, and an audible and visual alarm is issued when the battery level is below 10%.

[0062] Specifically, the secondary circuit insulation resistance detection module 42 includes a high voltage generating circuit and a voltage and current measurement sampling circuit. The high voltage generating circuit generates the high voltage required for detection. When the high voltage is applied, the voltage and current measurement sampling circuit measures the weak leakage current generated in the circuit and calculates the resistance value.

[0063] In this embodiment, the secondary circuit insulation resistance detection module 42 is used to detect the insulation performance of the secondary circuit to ground and between circuits. The high-voltage generation circuit adopts a flyback boost topology, controlled by the control module via PWM signals to boost the battery voltage (e.g., 12V) to a preset test voltage (e.g., 500V, 1000V, or 2500V) and apply it to both ends of the secondary circuit under test. The voltage and current measurement sampling circuit includes a high-precision sampling resistor and an operational amplifier conditioning circuit. During the high-voltage application, the sampling resistor collects the weak leakage current (nanoampere to milliampere level) generated in the circuit, which is then converted by IV, filtered, and amplified before being sent to the ADC interface of the STM32. The STM32 calculates the insulation resistance value according to Ohm's law (R = U / I) and displays the result on the display screen 2 in real time.

[0064] Specifically, the DC resistance detection module 43 includes a high-precision constant current source unit, a four-terminal measurement circuit unit, a signal conditioning and AD conversion unit, and an automatic protection and discharge circuit unit;

[0065] The high-precision constant current source unit outputs a stable and adjustable DC current;

[0066] The four-terminal measurement circuit unit consists of a set of current output lines and a set of voltage sampling lines. The current lines inject a constant current into the transformer windings, and the voltage lines independently sample the voltage at both ends of the transformer windings.

[0067] The signal conditioning and analog-to-digital conversion unit filters out ripple and interference noise in the circuit, amplifies the acquired weak voltage signal, and converts it into a digital signal.

[0068] The automatic protection and discharge circuit unit quickly and safely releases the energy stored in the transformer windings.

[0069] In this embodiment, the high-precision constant current source unit adopts a linear constant current source design, capable of outputting a stable and adjustable DC current within the range of 10mA to 10A. The four-terminal measurement circuit unit adopts a Kelvin four-wire connection method, that is, a constant current is injected into the winding under test through the current output lines in the first test connection interface 32 and the second test connection interface 33, while the voltage is accurately collected at both ends of the winding through an independent voltage sampling line, eliminating the influence of wire resistance and contact resistance on the measurement results. The signal conditioning and AD conversion unit includes an instrumentation amplifier and a 24-bit high-precision ADC, used to filter out ripple noise in the circuit and convert the collected weak voltage signal into a digital quantity. The automatic protection and discharge circuit unit consists of a high-power discharge resistor and a MOSFET switch. When the test is completed or interrupted, the control module 41 controls the MOSFET to turn on, quickly and safely releasing the electromagnetic energy stored in the inductive load through the discharge resistor, preventing back electromotive force from damaging the test instrument or endangering the safety of the operator.

[0070] Specifically, the wire core polarity detection module 44 includes a signal processing circuit and a polarity discrimination circuit. The signal processing circuit includes a high-voltage side signal processing circuit and a low-voltage side signal processing circuit. The high-voltage side signal processing circuit attenuates the input signal and converts the AC signal into a DC signal through a resistor voltage divider network. The low-voltage side signal processing circuit attenuates or amplifies the low-voltage side signal. The polarity discrimination circuit converts the AC voltage signals of the high-voltage side and the low-voltage side into two pulse signals respectively, and detects the phase relationship between the two pulses through an XOR gate circuit.

[0071] In this embodiment, the core polarity detection module 44 is used to distinguish between the same-name and opposite-name terminals of the transformer, current transformer, or voltage transformer windings. The high-voltage side signal processing circuit attenuates the AC voltage signal input from the high-voltage side to a low-voltage signal range through a resistor divider network, and then converts it to DC level through a precision rectifier circuit; the low-voltage side signal processing circuit adaptively attenuates or amplifies the input signal amplitude through a programmable gain amplifier (PGA), so that both signals are adjusted to a level range that can be processed by subsequent circuits. The polarity discrimination circuit uses a zero-crossing comparator to shape the sinusoidal AC signals from the high-voltage side and the low-voltage side into square wave pulse signals of the same frequency, and then inputs the two pulse signals to an XOR gate logic circuit. If the XOR gate output is low, it indicates that the two pulses are in phase, and the polarity is determined to be "subtractive polarity" or "same polarity"; if the XOR gate output is high, it indicates that the two pulses are out of phase, and the polarity is determined to be "additive polarity" or "opposite polarity". The discrimination result is read by the control module and displayed on the display screen.

[0072] Specifically, the multi-point grounding test module 45 includes a current sensor, a signal conditioning and filtering unit, and an intelligent diagnosis and control unit. The current sensor is a high-precision through-hole sensor. The signal conditioning and filtering unit processes the measured grounding current and sends it to the intelligent diagnosis and control unit. The intelligent diagnosis and control unit analyzes the data, identifies faults, and controls the output.

[0073] In this embodiment, the multi-point grounding test module 45 is used to detect whether there is a multi-point grounding fault in the secondary circuit of the substation. The current sensor is a high-precision through-hole Hall current sensor with a range of 1mA to 1A, covering the power frequency and harmonic components. During testing, it is clamped to the grounding wire connecting the protection chamber and the cable shield. The signal conditioning and filtering unit consists of an instrumentation amplifier and a bandpass filter, which accurately amplifies the grounding current signal and filters out high-frequency interference and DC offset. The intelligent diagnostic and control unit is integrated into the STM32 control module. It runs a grounding fault diagnosis algorithm, analyzes the amplitude, frequency characteristics, and trend of the grounding current, and compares it with a preset fault threshold. If a multi-point grounding fault is detected, the control module drives the display screen to show alarm information and can control the output relay to issue an audible and visual alarm signal.

[0074] Specifically, the input of the switching module 46 is connected to the output of the STM32, and then connected to an optocoupler via R14. The output is connected to a transistor via R10 and R9. The output of the transistor is connected to a relay. A diode protection circuit is also connected to the output of the transistor. The output of the relay is the detection circuit after the final switching.

[0075] Specifically, the STM32 output terminal connected to the switching module 46 controls the corresponding detection module through four output pins.

[0076] In this embodiment, the intelligent integrated test circuit 4 is built into the handheld housing 1 and is the core functional unit of the tester. This circuit uses an STM32 series microcontroller; in this embodiment, an STM32F407 is used as the control module 41. It is electrically connected to the secondary circuit insulation resistance detection module 42, DC resistance detection module 43, wire polarity detection module 44, multi-point grounding test module 45, switching module 46, power supply module 47, and display screen 2 via an internal bus.

[0077] The input terminal of the switching module 46 is connected to the output pin of the STM32. The STM32 controls the access and de-access of the insulation resistance detection, DC resistance detection, wire polarity detection, and multi-point grounding test modules through four independent output pins. Specifically, the output pin of the STM32 is connected to the input terminal of the optocoupler through a current-limiting resistor R14 to achieve electrical isolation between the control signal and the test circuit. The output terminal of the optocoupler is connected to the base of an NPN transistor through resistors R10 and R9, with the transistor acting as a switch to drive the relay coil. A freewheeling diode is connected in parallel between the transistor collector and the power supply to absorb the reverse induced electromotive force generated when the relay coil is de-energized, protecting the drive circuit. The normally open contacts of the relays are connected in series in the signal output circuits of each detection module. By controlling the activation and deactivation of the relays, the physical switching of different detection circuits is achieved, ensuring that only the currently selected module is connected to the measurement port during each test.

[0078] The switching module 46 is used for switching between the various detection modules and connects the STM32 to each detection module. The switching module adopts a four-channel independent relay switching circuit, with each channel having the same circuit structure. The first channel will be used as an example for explanation.

[0079] The PA0 pin of the STM32 microcontroller serves as the control output, connected to input pin 1 of the optocoupler U1 via a current-limiting resistor R14. Input pin 2 of the optocoupler is grounded. When PA0 outputs a high level, the internal LED of the optocoupler conducts, and the output-side phototransistor is saturated and conducting. Output pin 4 of the optocoupler is connected to a pull-up resistor R10 to a 5V power supply, and pin 3 is grounded. The optocoupler output signal is pulled up by R10 and then connected to the base of the NPN transistor Q1. A pull-down resistor R9 is connected in parallel between the base and emitter to prevent false triggering. The collector of the transistor is connected to the negative terminal of the relay K1 coil, and the positive terminal of the coil is connected to a 12V power supply. A freewheeling diode D1 is connected in parallel between the collector and emitter of the transistor to absorb the reverse induced electromotive force generated when the relay coil is turned off, protecting the transistor from breakdown.

[0080] When PA0 outputs a high level, the optocoupler conducts, the base of Q1 receives a high level, Q1 saturates and conducts, the coil of relay K1 is energized, the normally open contact closes, and the test circuit of the corresponding detection module is connected. When PA0 outputs a low level, the optocoupler is cut off, the base of Q1 is low, Q1 is cut off, the coil of relay K1 is de-energized, the normally open contact opens, and the corresponding detection module is isolated from the test circuit.

[0081] The relay contacts are signal relays with a contact capacity of 2A / 30VDC, contact resistance ≤50mΩ, and operating time ≤3ms, meeting the switching requirements of each detection module. The STM32 controls the four relays through four output pins (PA0, PA1, PA2, PA3) to achieve independent and combined switching of the four detection modules.

[0082] Example 3:

[0083] This embodiment specifically illustrates the usage of the handheld intelligent integrated tester. In practical application, the operator first inserts the test connection cable into the first test connection cable interface 32 and the second test connection cable interface 33 respectively, and reliably connects the other end to the designated test point of the secondary circuit under test. Then, the detection switch 31 is turned on, and the system powers on and performs a self-test. If the operator presses the "Integrated Test Button 34," the control module 41 will sequentially control the switching module 46, automatically switching the test circuit in the order of "insulation resistance → DC resistance → wire core polarity → multi-point grounding," and calling the corresponding detection module to complete the test. After each module test is completed, the control module stores the test data in its internal memory and displays the results on the display screen 2. If a test result exceeds the standard range, the display screen 2 will automatically highlight it and emit a prompt sound. If the operator presses any button in the independent test area (such as the "insulation resistance button"), the control module 41 will only switch to the insulation resistance detection module and execute that test alone. After the test is completed, all data can be exported to the background management system via the USB interface or wireless communication module for easy generation of a test report.

[0084] In summary, this invention provides a compact, comprehensive, easy-to-operate, accurate, and reliable handheld intelligent integrated tester for substation secondary circuits. This highly integrated tester combines insulation resistance testing, DC resistance testing, conductor polarity testing, and multi-point grounding testing into a single handheld device, replacing multiple traditional single-function testers. This significantly reduces the number of instruments carried on-site and improves work efficiency. Furthermore, the one-button integrated testing function allows users to automatically complete all test items and generate reports simply by connecting the test cables and pressing the integrated test button, eliminating the need for manual wiring and parameter settings, thus reducing operational difficulty and the risk of misoperation. The multi-point grounding test module features intelligent diagnostic capabilities, automatically analyzing the grounding current spectrum to determine the fault type and severity. The polarity discrimination module automatically identifies the fault and provides voice prompts, eliminating the need for manual waveform interpretation.

[0085] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

[0086] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

[0087] Many other changes and modifications can be made without departing from the concept and scope of this invention. It should be understood that this invention is not limited to the specific embodiments, and the scope of this invention is defined by the appended claims.

Claims

1. A handheld intelligent integrated tester for testing secondary circuits in substations, characterized in that, The device includes a handheld housing (1), a display screen (2), test connection cables, a terminal block area (3), and an intelligent integrated test circuit (4). The display screen (2) is mounted on top of the handheld housing (1). The terminal block area (3) is located on the handheld housing (1) and below the display screen (2). The test connection cables are used to connect the secondary circuit of the substation to be tested to the handheld intelligent integrated tester. The intelligent integrated test circuit (4) is located inside the handheld housing (1) and connects the display screen (2) and the terminal block area (3). The intelligent integrated test circuit (4) includes a control module (41), a secondary circuit insulation resistance detection module (42), a DC resistance detection module (43), a wire core polarity detection module (44), a multi-point grounding test module (45), a switching module (46), and a power supply module (47). The control module (41) uses an STM32. The input terminals of the secondary circuit insulation resistance detection module (42), the DC resistance detection module (43), the wire core polarity detection module (44), and the multi-point grounding test module (45) are respectively connected to one output of the STM32. The outputs of the secondary circuit insulation resistance detection module (42), the DC resistance detection module (43), the wire core polarity detection module (44), and the multi-point grounding test module (45) are connected to a display screen. The switching module (46) is used to switch between the detection modules and is connected to the STM32. The power supply module (47) provides power to the intelligent integrated test circuit (4).

2. The handheld intelligent integrated tester for substation secondary circuit testing according to claim 1, characterized in that, The terminal block area (3) includes a detection switch (31), a first test connection interface (32), a second test connection interface (33), a comprehensive test button (34), and an independent test area (35). The detection switch (31) is located on the lower left side of the display screen (2). The first test connection interface (32) and the second test connection interface (33) are located below the detection switch (31). The comprehensive test button (34) is located on the right side of the detection switch (31). The independent test area (35) is located below the comprehensive test button (34).

3. The handheld intelligent integrated tester for substation secondary circuit testing according to claim 2, characterized in that, The independent test area (35) includes an insulation resistance button (351), a DC resistance button (352), a wire polarity button (353), and a multi-point grounding button (354). The insulation resistance button (351) and the DC resistance button (352) are located above the wire polarity button (353) and the multi-point grounding button (354).

4. The handheld intelligent integrated tester for substation secondary circuit testing according to claim 1, characterized in that, The secondary circuit insulation resistance detection module (42) includes a high voltage generating circuit and a voltage and current measurement sampling circuit. The high voltage generating circuit generates the high voltage required for detection. When the high voltage is applied, the voltage and current measurement sampling circuit measures the weak leakage current generated in the circuit and calculates the resistance value.

5. The handheld intelligent integrated tester for substation secondary circuit testing according to claim 1, characterized in that, The DC resistance detection module (43) includes a high-precision constant current source unit, a four-terminal measurement circuit unit, a signal conditioning and AD conversion unit, and an automatic protection and discharge circuit unit; The high-precision constant current source unit outputs a stable and adjustable DC current; The four-terminal measurement circuit unit consists of a set of current output lines and a set of voltage sampling lines. The current lines inject a constant current into the transformer windings, and the voltage lines independently sample the voltage at both ends of the transformer windings. The signal conditioning and analog-to-digital conversion unit filters out ripple and interference noise in the circuit, amplifies the acquired weak voltage signal, and converts it into a digital signal. The automatic protection and discharge circuit unit quickly and safely releases the energy stored in the transformer windings.

6. The handheld intelligent integrated tester for substation secondary circuit testing according to claim 1, characterized in that, The wire core polarity detection module (44) includes a signal processing circuit and a polarity discrimination circuit. The signal processing circuit includes a high-voltage side signal processing circuit and a low-voltage side signal processing circuit. The high-voltage side signal processing circuit attenuates the input signal and converts the AC signal into a DC signal through a resistor voltage divider network. The low-voltage side signal processing circuit attenuates or amplifies the low-voltage side signal. The polarity discrimination circuit converts the AC voltage signals of the high-voltage side and the low-voltage side into two pulse signals respectively, and detects the phase relationship of the two pulses through an XOR gate circuit.

7. The handheld intelligent integrated tester for substation secondary circuit testing according to claim 1, characterized in that, The multi-point grounding test module (45) includes a current sensor, a signal conditioning and filtering unit, and an intelligent diagnosis and control unit. The current sensor is a high-precision through-hole sensor. The signal conditioning and filtering unit processes the measured grounding current and sends it to the intelligent diagnosis and control unit. The intelligent diagnosis and control unit analyzes the data, identifies faults, and controls the output.

8. The handheld intelligent integrated tester for substation secondary circuit testing according to claim 1, characterized in that, The input of the switching module (46) is connected to the output of the STM32, and is connected to the optocoupler through R14. The output is connected to the transistor through R10 and R9. The output of the transistor is connected to the relay. A diode protection circuit is also connected to the output of the transistor. The output of the relay is the detection circuit after the final switching.

9. The handheld intelligent integrated tester for substation secondary circuit testing according to claim 8, characterized in that, The STM32 output terminal connection switching module (46) controls the corresponding detection module through four output pins.

10. The handheld intelligent integrated tester for substation secondary circuit testing according to claim 1, characterized in that, The handheld housing (1) is made of fiberglass.

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