Intelligent high-voltage capacitor bank test system and test method

Abstract

The invention discloses an intelligent high-voltage capacitor bank test system and test method. The system comprises a current acquisition module, an intelligent measurement and control module and a tester host. The current acquisition module is used for sensing the lead current of the capacitor in a non-contact manner; the intelligent measurement and control module is used for controlling the current sensor to act and collecting and processing a current signal; the tester host is used for outputting a test voltage, collecting a voltage signal and calculating the capacity of the capacitor; the current acquisition module comprises a three-side integrated magnetic core, a modularized independent magnetic core, a multi-wire-slot compensation structure and an automatic opening and closing mechanism; the modularized independent magnetic core is located on the opening side of the three-side-integrated magnetic core so as to be matched with the three-side-integrated magnetic core to form a closed magnetic circuit. The multi-slot compensation structures are arranged on two side edges of the three-side integrated magnetic core and are used for compensating magnetic resistance imbalance; the automatic opening and closing mechanism is used for controlling the modularized independent magnetic core to ascend and descend to achieve opening and closing of the jaw. The method has the advantages of high detection efficiency, high detection precision and the like.

Description

Technical Field

[0001] This invention mainly relates to the field of power equipment testing technology, specifically to an intelligent high-voltage capacitor bank testing system and testing method. Background Technology

[0002] To reduce reactive power losses, power systems typically use parallel capacitor banks to improve the power factor. To meet the requirements of automatic tracking and real-time compensation in power systems, reactive power compensation devices inevitably need to frequently switch on and off these capacitor banks. However, these switching operations generate current and overvoltage surges, which can damage the capacitors. To ensure the normal operation of equipment, it is crucial to regularly inspect the capacitors to detect defects early and prevent further escalation. However, in the field, capacitors are usually connected in parallel groups, so using a standard capacitance meter requires disconnecting the leads before measurement, which is labor-intensive and prone to wiring errors and capacitor damage.

[0003] To address the need for on-site testing of capacitor banks, the industry has developed two relatively mature technical solutions. However, these solutions still have significant shortcomings in practical applications and fail to fully resolve the pain points of on-site testing. Specifically: (I) Manual Capacitance and Inductance Testing Techniques This technical solution is a widely used traditional approach in on-site testing. Its core principle is to manually operate a dedicated capacitance and inductance tester to test each individual capacitor in a capacitor bank. The specific operating procedure is as follows: First, the tester carries the large and heavy tester to the site; second, by manually climbing (as the capacitor bank is typically installed at a height of 3-5 meters, and even higher in some scenarios), the current sampling clamps are installed onto the leads of each capacitor under test; subsequently, the tester manually records the capacitance and other test data displayed for each individual capacitor; after all capacitors have been tested, the capacitance deviation value of each capacitor is manually calculated to determine if any defects exist.

[0004] The main shortcomings of this technical solution are reflected in the following four aspects: Extremely low work efficiency: Since capacitor banks are usually composed of dozens or even hundreds of small capacitors connected in parallel, testers need to frequently climb to switch the capacitors under test, install and remove current clamps, and it often takes several hours to complete the test of a capacitor bank, which cannot meet the needs of large-scale, high-efficiency operation and maintenance.

[0005] High labor costs and safety risks: Working at height requires strict adherence to safety regulations, and the process must be repeated for each capacitor tested. This not only increases the workload for testing personnel but also poses safety hazards such as falls from heights and electric shocks. Furthermore, human error can easily lead to misinterpretations of data during manual calculation of deviation values, affecting the accuracy of the test results. Additionally, the existing clamp-on current sensor requires considerable gripping force to open its jaws, making continuous testing of hundreds of capacitors difficult, tiring, and unfriendly to operators, resulting in poor human-machine interaction.

[0006] Poor portability and ease of operation of the equipment: Traditional test instrument main unit uses power frequency transformer, which is large and heavy, making it inconvenient to move and carry on site; in addition, the current sampling clamp is connected to the main unit through a cable, and the main unit needs to be moved frequently during the test to adapt to the installation position of the current clamp, which not only increases the workload, but the connecting cable is also easy to get tangled with other electrical equipment on site, which may cause equipment damage or cause safety accidents such as short circuits.

[0007] The solution is not adaptable to on-site conditions: It relies on manual operation throughout the process and is greatly affected by environmental factors such as on-site space, lighting, and weather. In narrow spaces or in bad weather, the difficulty of operation is further increased, and the detection efficiency and safety will be significantly reduced.

[0008] (II) Voltage and Current Testing Technology Scheme Based on Simultaneous Clock System without Disconnection To address the issues of low efficiency and the need for wire removal in traditional manual testing methods, the industry has gradually developed a wire-free testing technology. Its core idea is to achieve online testing of capacitor banks using a "simultaneous clock system voltage-current method," eliminating the need to remove capacitor leads. The principle of this solution is as follows: under the synchronous control of the same clock signal, the terminal voltage signal and total current signal of the capacitor bank are simultaneously acquired via wired connection. Then, an algorithm is used to separate the current signal of individual capacitors, thereby calculating the capacitance parameters of each individual capacitor, achieving wire-free testing.

[0009] While this technical solution solves the problem of needing to disconnect wires in traditional solutions, it still has key technical drawbacks: it can only be tested via wired connection, requiring a relatively long cable. It is susceptible to electromagnetic interference (such as magnetic field interference from transformers and reactors) or voltage fluctuations in the field, which can cause significant deviations in the calculated capacitance of individual capacitors, making it impossible to accurately determine the actual condition of the capacitors. Furthermore, this solution still requires manual installation and placement of sampling sensors. In scenarios involving capacitor banks at high installation heights, it cannot avoid the safety risks and cumbersome operations associated with working at heights, failing to fundamentally improve the convenience and safety of on-site testing.

[0010] The two existing similar technical solutions both have insurmountable defects and cannot simultaneously meet the requirements of high efficiency, high safety, high accuracy and portability for on-site testing of capacitor banks. Therefore, developing a new intelligent capacitor bank testing technology that can solve the above pain points has become an urgent need in the field of power system operation and maintenance. Summary of the Invention

[0011] To address the technical problems existing in the prior art, this invention provides an intelligent high-voltage capacitor bank testing system and method with high detection efficiency and high detection accuracy.

[0012] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows: A smart high-voltage capacitor bank testing system includes a current acquisition module, an intelligent measurement and control module, and a test instrument host. The current acquisition module is used for non-contact sensing of capacitor lead current. The intelligent measurement and control module is connected to the current sensor and is used to control the operation of the current sensor, acquire and process current signals. The test instrument host is wirelessly connected to the intelligent measurement and control module and is used to output test voltage, acquire voltage signals, and calculate capacitor capacity. The current acquisition module includes a three-sided integrated magnetic core, a modular independent magnetic core, a multi-slot compensation structure, and an automatic opening and closing mechanism. The three-sided integrated magnetic core is milled from permalloy into a C-shape, with an induction coil wound on the middle side and the open side forming a jaw. The modular independent magnetic core is located on the open side of the three-sided integrated magnetic core to cooperate with the three-sided integrated magnetic core to form a closed magnetic circuit. The multi-slot compensation structure is located on both sides of the three-sided integrated magnetic core to compensate for magnetic reluctance imbalance. The automatic opening and closing mechanism is connected to the modular independent magnetic core and is used to control the up and down movement of the modular independent magnetic core to achieve jaw opening and closing.

[0013] Preferably, the multi-slot compensation structure includes multiple semi-circular microslots located on the upper and lower sides of the three-sided integrated magnetic core, with the number of semi-circular microslots on the upper side being the same as the number of semi-circular microslots on the lower side and their positions being symmetrical.

[0014] Preferably, the microgroove has a diameter of 0.15-0.25 mm, a depth of 0.1-0.2 mm, and a groove spacing of 3-6 mm.

[0015] Preferably, the automatic opening and closing mechanism includes a spring, a pull rope, a pulley, a DC motor, and a control circuit; the spring is located in a straight slot for mounting the modular independent magnetic core, and one end of the spring abuts against one end of the modular independent magnetic core; one end of the pull rope is connected to one end of the modular independent magnetic core, and the other end passes around the pulley and is wound around the output end of the DC motor; the control circuit is connected to the DC motor and is used to control the forward and reverse rotation of the DC motor to realize the opening and closing of the jaws.

[0016] Preferably, the control circuit includes a limit switch K and a diode D. The limit switch K includes a normally closed contact KC and a normally open contact K0. The normally closed contact KC is connected in series in the power supply circuit of the DC motor, and the normally open contact K0 is connected in series with the diode D and then in parallel with the normally closed contact KC.

[0017] Preferably, the intelligent measurement and control module includes a first MCU measurement and control unit, a lithium battery power supply module, an AI intelligent voice module, a first human-machine interaction module, a first memory, a first data communication module, a current sensor, a differential amplifier module, a first comparator, a wireless transmission module, and a motor drive IC; the AI ​​intelligent voice module, the first human-machine interaction module, the first memory, the first data communication module, the wireless transmission module, and the motor drive IC are all connected to the first MCU measurement and control unit; the current sensor is connected to the first MCU measurement and control unit via a differential amplifier circuit and a comparator.

[0018] Preferably, the main unit of the test instrument includes a second MCU control unit, a pure sine wave inverter module, a test voltage output module, a voltage transformer, a second comparator, a second memory, a second human-machine interaction module, a second data communication module, and a wireless receiving module; the pure sine wave inverter module, the second memory, the second human-machine interaction module, the second data communication module, and the wireless receiving module are all connected to the second MCU control unit; the pure sine wave inverter module is connected to the voltage transformer via the test voltage output module; and the voltage transformer is connected to the second MCU control unit via the second comparator.

[0019] Preferably, the pure sine wave inverter module includes four N-channel enhancement-mode MOSFETs, namely Q1, Q2, Q3, and Q4; Q1 and Q2 are upper arm switches, and Q3 and Q4 are lower arm switches; the sources of the upper arm switches Q1 and Q2 are connected to the drains of the lower arm switches Q3 and Q4 respectively, forming the midpoint of the two bridge arms, which serves as the AC output terminal; the sources of the lower arm switches Q3 and Q4 share a common ground, and the drains of the upper arm switches Q1 and Q2 are connected to the DC input voltage VDD; the diagonal switches Q1 and Q4, and Q2 and Q3 are driven by the same SPWM signal, and the signals of the upper and lower bridge arms are out of phase, so as to achieve a sinusoidal change in output voltage by controlling the conduction time difference of the switches.

[0020] Preferably, the system also includes a telescopic rod, with the current acquisition module installed at the telescopic end of the telescopic rod and the intelligent measurement and control module installed at the fixed end of the telescopic rod.

[0021] This invention also discloses a testing method based on the intelligent high-voltage capacitor bank testing system described above, comprising the following steps: The current in the lead wires of the inductive capacitor is acquired by the current acquisition module, and the voltage signal on the capacitor is acquired by the host of the test instrument. The MCU of the test instrument calculates the zero-crossing time difference between the current and voltage signals. The phase difference is obtained. f represents the test power supply frequency; The main unit MCU of the tester collects the effective voltage value U, the effective current value I, and the phase difference. Calculate the capacitive reactance, and then obtain the actual capacitance C of the capacitor under test; The capacitance deviation is calculated based on the actual capacitance C; if the capacitance deviation is less than the preset value, the capacitor is deemed qualified; otherwise, it is deemed defective.

[0022] Preferably, through the capacitive reactance formula Calculate the capacitive reactance, then substitute it into the capacitance formula. The actual capacitance C of the capacitor under test is obtained; then the deviation formula is used. Calculate capacity deviation; This is the standard capacity.

[0023] Compared with the prior art, the advantages of the present invention are as follows: This invention significantly improves the efficiency and safety of on-site testing of high-voltage capacitor banks by integrating a current acquisition module, an intelligent measurement and control module, and a testing instrument host, and employing non-contact current sensing, wireless communication, and an automatic opening and closing mechanism. Utilizing a telescopic pole and voice control enables operation without climbing, allowing testing personnel to deploy sensors without repeated ascents. The wireless signal transmission avoids the tangled cables and cumbersome handling of the host unit inherent in traditional wired connections, thus improving testing efficiency. Simultaneously, the automatic opening and closing jaw design reduces the intensity of manual operation, eliminates the risks of working at heights and electric shock, simplifies the overall workflow, and allows a single person to complete large-scale capacitor bank testing, significantly reducing labor and time costs, and enhancing adaptability and operational safety in complex field environments.

[0024] In terms of measurement accuracy and reliability, this invention employs a "three-sided integrated magnetic core + multi-slot compensation structure" design. Through semi-circular micro-slot processing and active reluctance compensation, it reduces reluctance deviation and effectively solves the problem of reluctance imbalance in asymmetrical magnetic cores, significantly improving the accuracy of current signal sensing. Combined with pure sine wave inverter voltage output, the system can accurately acquire voltage and current signals and calculate capacitor capacity, automatically completing deviation judgment and report generation, ensuring high accuracy and consistency of detection results. This provides reliable data support for power system operation and maintenance, overcoming the shortcomings of traditional methods that are affected by electromagnetic interference and human error. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the current acquisition module of the present invention in an embodiment.

[0026] Figure 2This is a schematic diagram of the communication between the intelligent measurement and control module and the test instrument host of the present invention.

[0027] Figure 3 This is a circuit block diagram of the intelligent measurement and control module of the present invention in an embodiment.

[0028] Figure 4 This is a circuit block diagram of the main unit of the tester according to an embodiment of the present invention.

[0029] Figure 5 This is a circuit diagram of the pure sine wave inverter module of the present invention in an embodiment.

[0030] Figure 6 This is an example diagram of a specific application of the testing method of the present invention.

[0031] Legend: 1. Three-sided integrated magnetic core; 101. Middle side; 102. Induction coil; 103. Side; 2. Modular independent magnetic core; 3. Multi-slot compensation structure; 301. Micro-slot; 4. Automatic opening and closing mechanism; 401. Spring; 402. Pull rope; 403. Pulley; 404. DC motor; 405. Control circuit; 406. Limit switch; 5. Telescopic rod. Detailed Implementation

[0032] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0033] The intelligent high-voltage capacitor bank testing system provided in this embodiment of the invention includes three parts: a non-climbing current acquisition module, an intelligent measurement and control module, and a testing instrument host. like Figure 1 As shown, the height-free current acquisition module includes a three-sided integrated magnetic core 1, a modular independent magnetic core 2, a multi-slot compensation structure, and an automatic opening and closing mechanism 4. The three-sided integrated magnetic core 1 is integrally milled from permalloy, with an induction coil 102 wound on the middle side 101. The modular independent magnetic core 2 cooperates with the three-sided integrated magnetic core 1 to form a closed magnetic circuit. The multi-slot compensation structure is located on both sides (non-working sections) of the three-sided integrated magnetic core 1 to compensate for magnetic resistance imbalance. The automatic opening and closing mechanism 4 is connected to the modular independent magnetic core 2 and is used to control the up and down movement of the modular independent magnetic core 2 to achieve jaw opening and closing.

[0034] Specifically, addressing the problem that traditional clamp sensors, which employ symmetrical magnetic core structures, struggle to achieve automatic separation and engagement, this invention utilizes a special C-type permalloy magnetic core structure, designing a combined structure of "three-sided integrated magnetic core 1 + modular independent magnetic core 2": the three-sided integrated magnetic core 1 is integrally milled from 1J85 / 1J50 permalloy (without seams), and ensures low magnetic resistance through hydrogen annealing and ultra-precision grinding (fitting surface Ra≤0.4μm). The middle side 101 is used to wind the induction coil 102, and the open side is adapted to the modular independent magnetic core 2; the modular independent magnetic core 2 is perfectly matched in size to the integrated magnetic core to complete the magnetic circuit.

[0035] To address the core problem of unbalanced magnetic reluctance between the integrated three-sided magnetic core 1 and the modular independent magnetic core 2 due to the asymmetrical magnetic circuit structure of an asymmetric magnetic core (three-sided integrated magnetic core 1 + modular independent magnetic core), which affects measurement accuracy and linearity, this invention proposes a "multi-slot compensation structure." The specific design details are as follows: In the non-working section of the integrated three-sided magnetic core 1 (i.e., the two sides 103 where the induction coil 102 is not wound), 3-5 semi-circular micro-slots 301 are uniformly machined along the magnetic circuit direction. The diameter of the micro-slots 301 is uniformly 0.2mm, and the slot spacing is set to 5mm. To accurately match the magnetic reluctance, multiple sets of samples with different depths are fabricated for actual measurement and calibration. The final depth of the micro-slots 301 is determined to be 0.15mm, ensuring that the deviation between the "total magnetic reluctance of the integrated three-sided magnetic core 1" and the "total magnetic reluctance of the modular independent magnetic core + air gap" is controlled within ≤0.4%. After the micro-slots 301 are machined, the integrated magnetic core undergoes a 600° rotation. The hydrogen annealing treatment at ℃ / 2h completely eliminates the internal stress generated by milling (avoiding stress-induced decrease in magnetic permeability). Subsequently, the surface of the microgroove 301 is polished using an ultra-precision grinding process to achieve a surface roughness Ra≤0.2μm, preventing abnormal increase in local magnetic reluctance at the groove opening due to excessive roughness. This structure breaks through the traditional design concept of relying on symmetrical dimensions to achieve magnetic reluctance balance. By introducing controllable magnetic reluctance into the integrated section of the asymmetrical magnetic core, it actively compensates for the magnetic reluctance difference caused by the independent section of the magnetic core and the air gap. It solves the problem of magnetic reluctance imbalance in asymmetrical structures from the root of the magnetic circuit, laying the foundation for accurate current signal sensing. It can reduce the measurement accuracy deviation caused by magnetic reluctance imbalance from ±1.2% before optimization to ±0.25%, while ensuring that the linear error within the 1-100A range is stable within ±0.3%, without affecting the core functional advantages of the asymmetrical magnetic core: "no wire removal required, easy to open and close".

[0036] Specifically, the automatic opening and closing mechanism 4 consists of a spring 401, a pull rope 402, a DC motor 404, a pulley 403, and a control circuit 405. The spring 401 is located in the straight groove where the modular independent magnetic core 2 is installed, with one end of the spring 401 abutting against one end of the modular independent magnetic core 2; one end of the pull rope 402 is connected to one end of the modular independent magnetic core 2, and the other end passes around the pulley 403 and is wound around the output end of the DC motor 404; the control circuit 405 is connected to the DC motor 404 and is used to control the forward and reverse rotation of the DC motor 404 to realize the opening and closing of the jaws.

[0037] Specifically, outside the C-shaped structure, the modular independent magnetic core 2 forms a closed magnetic circuit through a fixed straight groove and the elastic force of the spring 401. A limit block is set inside the modular independent magnetic core 2. When the DC motor 404 rotates clockwise, the motor shaft pulls the rope 402, which overcomes the pressure of the spring 401 and causes the modular independent magnetic core 2 to slide down. The current sensor jaws open. When the jaws are opened to the maximum position, the limit block will just touch the limit switch 406, disconnecting the power circuit of the DC motor 404. Similarly, when the DC motor 404 rotates counterclockwise, the modular independent magnetic core 2 will close with the C-shaped magnetic core under the pressure of the spring 401 to form a magnetic circuit, realizing the opening and closing of the electrically controlled jaws.

[0038] Specifically, the control circuit 405 includes a limit switch 406 and a diode D. The limit switch 406 includes a normally closed contact KC and a normally open contact KO. The normally closed contact KC is connected in series in the power supply circuit of the motor (electric motor), and the normally open contact KO is connected in series with the diode D and then in parallel with the normally closed contact KC.

[0039] Working principle of control circuit 405: This invention cleverly utilizes a limit switch 406 and a diode D to realize the sensor jaw opening limit and opening and closing control. When a positive current is applied to the motor, the current flows to the normally closed contact of the limit switch 406, forming a circuit. The DC motor 404 is energized in the positive direction, the motor rotates in the forward direction, the retraction rope is tightened, and the independent magnetic core moves downward against the tension of the spring 401, and the jaws open. When the jaws are opened to the maximum position, the limit block hits the limit switch 406, the normally closed contact of the limit switch 406 is opened, and the normally open contact is closed. Due to the presence of diode D, the positive current cannot flow through the DC motor 404, the DC motor 404 stops, and the current sensor jaws are opened to the maximum position. Conversely, when it is necessary to close the current sensor jaws, a reverse current is supplied to the motor. The current first flows through the normally open contact of the limit switch 406 and the diode circuit. After the jaws leave the limit switch 406, the current continues through the normally closed contact of the limit switch 406. The DC motor 404 reverses, releasing the rope. The independent magnetic core of the current sensor slowly closes under the pressure of the spring 401.

[0040] This invention utilizes a normally closed limit switch 406 to achieve jaw opening limit, and simultaneously connects a unidirectional conducting diode D in series to constrain the forward and reverse current direction of the motor. Compared with conventional circuits, this invention can save control components and improve circuit response speed.

[0041] The lower end of the entire clamp body is connected to the telescopic rod 5. The 4-core cable passes through the threaded port and through the inside of the telescopic rod 5, connecting to the connection and fixing seat on the grip, and making electrical connection with the intelligent measurement and control module.

[0042] like Figure 2 As shown, the intelligent measurement and control module is connected to the host of the test instrument, using 2.4G data communication and 315MHz voltage and current synchronization.

[0043] like Figure 3 As shown, the intelligent measurement and control module includes a first MCU measurement and control unit, a lithium battery power supply module, an AI intelligent voice module, a first human-machine interaction module, a first memory, a first data communication module, a current sensor, a differential amplifier module, a first comparator, a wireless transmission module, and a motor drive IC; the AI ​​intelligent voice module, the first human-machine interaction module, the first memory, the first data communication module, the wireless transmission module, and the motor drive IC are all connected to the first MCU measurement and control unit; the current sensor is connected to the first MCU measurement and control unit via a differential amplifier circuit and a comparator.

[0044] The first MCU measurement and control unit is the core of the module. It is responsible for receiving and processing various input signals (such as voice commands, current sensor signals, etc.), sending control commands to other units, coordinating the orderly operation of various parts within the module, and is the "command center" of the module. The lithium battery power supply module provides power support for the entire module, outputting 3.3V and 24V voltages to power the MCU measurement and control unit, motor drive IC and other units, ensuring the stable operation of each unit; AI intelligent voice module: Communicates with MCU measurement and control unit through IIC interface, supports operators to control the action of the height-free current sensor through voice commands (such as "open jaws", "close jaws"), and can also broadcast the module's working status feedback (such as "jaw action completed"), improving the convenience and intelligence of operation; The first human-machine interaction module connects to the MCU measurement and control unit via a TTL interface. It is used by operators to set module parameters, view working status, etc., to realize information interaction between humans and machines and make operation more flexible. First memory: Connected to the MCU measurement and control unit via the IIC interface, it is used to store the module's working parameters, historical control command records and other data, facilitating subsequent data retrieval and analysis; First data communication module (2.4G): Connects to the MCU measurement and control unit through the ISP interface, enabling wireless data transmission between the module and external devices (such as test instrument host, operation and maintenance terminal), facilitating remote data sharing and management.

[0045] Current sensor: Collects the current signal sensed by the non-climbing current sensor, providing raw data for subsequent analysis of capacitor current; Differential amplifier module: performs differential amplification on the signal output by the current sensor to enhance signal strength and improve signal quality, facilitating accurate detection by the subsequent MCU measurement and control unit; First comparator: Receives the differentially amplified current signal, compares it with the reference level, and outputs characteristic signals such as square waves. It can be used for current zero-crossing detection, and provides the basic signal for functions such as synchronous sampling of current and voltage. Wireless Transmitter Module (315MHz): Interacts with the MCU measurement and control unit through the I / O interface to wirelessly transmit processed current signals to the 315MHz wireless receiver module of the test instrument host, and works with the host to realize non-contact current signal acquisition and synchronization, providing support for accurate calculation of capacitor detection. Motor driver IC: Connects to the MCU measurement and control unit through the I / O interface. After receiving the control command from the MCU, it drives the motor in the height-free current sensor to run, realizing the automatic opening and closing of the current sensor jaws (such as opening or closing the jaws to put on or remove capacitor leads).

[0046] like Figure 4 As shown, the main unit of the test instrument includes a second MCU control unit, a pure sine wave inverter module, a test voltage output module, a voltage transformer, a second comparator, a second memory, a second human-machine interaction module, a second data communication module, and a wireless receiving module. The pure sine wave inverter module, the second memory, the second human-machine interaction module, the second data communication module, and the wireless receiving module are all connected to the second MCU control unit. The pure sine wave inverter module is connected to the voltage transformer via the test voltage output module. The voltage transformer is connected to the second MCU control unit via the second comparator.

[0047] The second MCU measurement and control unit is the core of the host, responsible for receiving and processing signals and sending control commands to various modules, coordinating the orderly operation of each part, and is the "brain" of the entire system.

[0048] The pure sine wave inverter module, as a voltage source, generates a standard pure sine wave test voltage, providing a stable voltage input for subsequent capacitor testing.

[0049] Test voltage output module: After conditioning the voltage generated by the pure sine wave inverter module, it outputs the voltage to the capacitor under test to simulate the actual working voltage environment and test the performance of the capacitor under that voltage.

[0050] Voltage transformer: It collects the voltage signal applied to the capacitor, converting the high voltage signal into a low voltage signal proportionally to facilitate safe and accurate detection by subsequent modules; on the other hand, it provides the raw signal for functions such as voltage zero-crossing detection.

[0051] The second comparator receives the voltage signal (Up, Un) output by the voltage transformer, compares it with the reference level, and outputs characteristic signals such as square waves. It can be used for voltage zero-crossing detection, provides basic signals for functions such as synchronous sampling of current and voltage, and ensures the accuracy of sampling.

[0052] Secondary memory: Connected to the MCU measurement and control unit via the IIC interface, it is used to store data generated during the test (such as capacitor capacitance, phase difference, etc.), system parameters, and historical test records, so as to facilitate subsequent data retrieval, analysis, and traceability.

[0053] The second human-machine interaction module communicates with the MCU measurement and control unit via a TTL interface. Operators can use this module to set test parameters (such as capacitor rated capacity, voltage, etc.), view test status and results, and realize information interaction between humans and machines, making operation more convenient and intuitive.

[0054] The second data communication module connects to the MCU measurement and control unit via the ISP interface, enabling wireless data transmission between the host and external devices (such as maintenance terminals, host computers, etc.), facilitating remote sharing, management, and analysis of test data, and improving the flexibility and convenience of data transmission.

[0055] Wireless receiving module: It interacts with the MCU measurement and control unit through the I / O interface to receive wireless signals (such as current signals collected by current sensors) sent from intelligent measurement and control modules, etc. It works with the wireless transmitting module to realize non-contact signal transmission and synchronization, and provides support for functions such as synchronous sampling of current and voltage.

[0056] ADC (Analog-to-Digital Converter): Converts the analog voltage signal output by the voltage transformer into a digital signal, which is then input to the MCU measurement and control unit. This allows the MCU to perform digital processing, analysis, and calculation of the voltage signal, providing digital basis for subsequent calculations of parameters such as capacitor capacity.

[0057] Working Principle: A pure sine wave inverter module is set up, which is connected to the test voltage output unit to output a pure sine wave test voltage. The test voltage output unit is connected to a voltage transformer. The voltage transformer outputs (Up) and (Un) to a second comparator. The output of the second comparator is connected to the (I / O) port of the second MCU measurement and control unit. On the other hand, it is connected to the second MCU measurement and control unit through an ADC. The pure sine wave inverter module is connected to the second MCU measurement and control unit through (I / O) to realize the MCU's control over its working state. The second memory is connected to the second MCU measurement and control unit through IIC to store test data. The second human-machine interaction module is connected to the second MCU measurement and control unit through TTL for human-machine information interaction. The second data communication module is connected to the second MCU measurement and control unit through ISP to realize wireless data transmission. The 315MHz wireless receiving module is connected to the second MCU measurement and control unit through (I / O) to receive external 315MHz frequency band wireless signals and current synchronization signals. All modules work together to complete the test task.

[0058] like Figure 5 As shown, the main power circuit design of the pure sine wave inverter module adopts a full-bridge topology, consisting of four N-channel enhancement-type MOSFETs (Q1 and Q2 are upper arm switches, and Q3 and Q4 are lower arm switches) forming an H-bridge inverter circuit: the sources (S) of the upper arm switches Q1 and Q2 are connected to the drains (D) of the lower arm switches Q3 and Q4 respectively, forming the midpoint of the two bridge arms, which serves as the AC output terminal; the sources (S) of the lower arm switches Q3 and Q4 share a common ground, and the drains (D) of the upper arm switches Q1 and Q2 are connected to the DC input voltage VDD; The diagonal switching transistors (Q1 and Q4, Q2 and Q3) are driven by the same SPWM signal, with the upper and lower bridge arm signals out of phase. The sinusoidal change of the output voltage is achieved by controlling the conduction time difference of the switching transistors. The output voltage is 0 at 0° / 180° (the conduction time of the upper and lower transistors is equal), and the output voltage reaches its peak at 90° / 270° (the conduction time difference of the upper and lower transistors is the largest).

[0059] Compared to unipolar SPWM, it eliminates the need for an additional phase inverter circuit. It achieves symmetrical output of the positive and negative half cycles through synchronous drive of the diagonal diode, reducing circuit complexity and avoiding interference caused by the reverse recovery of the freewheeling diode in the unipolar scheme.

[0060] This invention significantly improves the efficiency and safety of on-site testing of high-voltage capacitor banks by integrating a current acquisition module, an intelligent measurement and control module, and a testing instrument host, and employing non-contact current sensing, wireless communication, and an automatic opening and closing mechanism 4. The use of a telescopic pole 5 and voice control enables operation without climbing, allowing testing personnel to deploy sensors without repeated climbing. Combined with wireless signal transmission, it avoids the cumbersome cable entanglement and moving of the host unit inherent in traditional wired connections, thus improving testing efficiency. Simultaneously, the automatic opening and closing jaw design reduces the intensity of manual operation, eliminates the risk of working at heights and electric shock, simplifies the overall workflow, and allows a single person to complete the testing of large-scale capacitor banks, significantly reducing labor and time costs, and enhancing adaptability and operational safety in complex field environments.

[0061] In terms of measurement accuracy and reliability, this invention employs a "three-sided integrated magnetic core 1 + multi-slot compensation structure" design. Through the machining of semi-circular micro-slots 301 and active reluctance compensation, reluctance deviation is reduced, effectively solving the problem of reluctance imbalance in asymmetrical magnetic cores, thus significantly improving the accuracy of current signal sensing. Combined with a pure sine wave inverter voltage output, the system can accurately acquire voltage and current signals and calculate capacitor capacity, automatically completing deviation judgment and report generation, ensuring high accuracy and consistency of detection results. This provides reliable data support for power system operation and maintenance, overcoming the shortcomings of traditional methods that are affected by electromagnetic interference and human error.

[0062] like Figure 6 As shown, this embodiment of the invention also provides a testing method based on the intelligent high-voltage capacitor bank testing system described above, including the following steps: Preparation before testing: Place the main unit of the tester in a safe area below the capacitor bank (distance ≤ 5m), perform a self-test upon power-on, and set the test parameters (including capacitor rated capacity Cn, rated voltage Un, and capacity deviation threshold) through the human-machine interface module. (Typically set to ±5%)); The tester holds the telescopic rod 5 (connecting the non-climbing current sensor and the intelligent measurement and control module), and initiates the zero-point calibration of the current sensor via the voice command "sensor self-test" to ensure no signal drift in the initial state; Sensor positioning and jaw opening and closing: The tester holds the telescopic rod 5 with both hands and raises the current sensor to the lead of the first capacitor under test (height 3-5m). By controlling the DC motor 404 to rotate forward via the voice command "open jaw" or the human-machine interface, the pull rope 402 drives the modular independent magnetic core 2 to move downward, and the jaws open (the motor automatically stops after the limit switch 406 is triggered); After the lead is put into the jaw, the "close jaw" command is given, the motor rotates in reverse, the spring 401 pushes the modular independent magnetic core 2 to reset, and the magnetic circuit closes (air gap ≤ 5μm). Voltage output and signal synchronous acquisition: By issuing the "start test" instruction through the tester host, the pure sine wave inverter module outputs the test voltage Un, which is applied to the capacitor bank through the test voltage output unit and the voltage transformer; the voltage transformer divides the voltage signal into two paths, one path is converted into a square wave signal through a comparator and input into the host MCU measurement and control unit, and the other path is converted into a digital voltage signal through an ADC; at the same time, the current sensor senses the working current of the capacitor, outputs a current signal to the intelligent measurement and control module, and the module converts the current signal into a square wave and sends it to the tester host through the 315M wireless transmission module; The tester host MCU calculates the zero-crossing time difference between the current and voltage square waves through the dual-clock synchronization algorithm (calibrating the fixed time difference t0 of wireless transmission) , and obtains the phase difference (f is the test power frequency, taking 50Hz); Capacitance calculation and deviation determination: The host MCU calculates the capacitive reactance according to the collected voltage effective value U, current effective value I and phase difference , and then substitutes it into the capacitance formula to calculate the actual capacitance C of the measured capacitor; Subsequently, the capacitance deviation is calculated through the deviation formula ; if , it is determined that the capacitor is qualified; otherwise, it is determined as defective; Multi-capacitor switching detection: After the detection of the first capacitor is completed, issue the "open jaw" instruction, move the telescopic rod 5 to the next measured capacitor, and repeat the above steps until the detection of the entire group of capacitors is completed; Data processing after testing: The host automatically stores all data such as C of the capacitors, , test time, etc., generates a test report (including a list of qualified / defective capacitors, a capacitance distribution histogram), and supports export through the USB interface or wireless transmission to the operation and maintenance terminal.

[0063] The above is only the preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions falling within the concept of the present invention belong to the protection scope of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements should be regarded as the protection scope of the present invention.​

Claims

1. An intelligent high-voltage capacitor bank testing system, characterized in that, It includes a current acquisition module, an intelligent measurement and control module, and a test instrument host; the current acquisition module is used for non-contact sensing capacitor lead current; the intelligent measurement and control module is connected to the current sensor and is used to control the operation of the current sensor, acquire and process current signals; The main unit of the test instrument is wirelessly connected to the intelligent measurement and control module, and is used to output test voltage, acquire voltage signals, and calculate capacitor capacity. The current acquisition module includes a three-sided integrated magnetic core (1), a modular independent magnetic core (2), a multi-slot compensation structure (3), and an automatic opening and closing mechanism (4). The three-sided integrated magnetic core (1) is milled into a C-shape from permalloy, with an induction coil (102) wound on the middle side (101) and the open side forming a jaw. The modular independent magnetic core (2) is located on the open side of the three-sided integrated magnetic core (1) to cooperate with the three-sided integrated magnetic core (1) to form a closed magnetic circuit. The multi-slot compensation structure (3) is located on both sides (103) of the three-sided integrated magnetic core (1) to compensate for magnetic resistance imbalance. The automatic opening and closing mechanism (4) is connected to the modular independent magnetic core (2) and is used to control the modular independent magnetic core (2) to move up and down to realize the opening and closing of the jaw.

2. The intelligent high-voltage capacitor bank testing system according to claim 1, characterized in that, The multi-slot compensation structure (3) includes multiple semi-circular micro-slots (301) located on the upper and lower sides (103) of the three-sided integrated magnetic core (1). The number of semi-circular micro-slots (301) on the upper side is the same as that on the lower side, and their positions are symmetrical.

3. The intelligent high-voltage capacitor bank testing system according to claim 2, characterized in that, The microgroove (301) has a diameter of 0.15-0.25 mm, a depth of 0.1-0.2 mm, and a groove spacing of 3-6 mm.

4. The intelligent high-voltage capacitor bank testing system according to claim 1, 2, or 3, characterized in that, The automatic opening and closing mechanism (4) includes a spring (401), a pull rope (402), a pulley (403), a DC motor (404), and a control circuit (405). The spring (401) is located in the straight groove where the modular independent magnetic core (2) is installed, and one end of the spring (401) abuts against one end of the modular independent magnetic core (2). One end of the pull rope (402) is connected to one end of the modular independent magnetic core (2), and the other end passes around the pulley (403) and is wound around the output end of the DC motor (404). The control circuit (405) is connected to the DC motor (404) and is used to control the DC motor (404) to rotate forward and backward to realize the opening and closing of the jaws.

5. The intelligent high-voltage capacitor bank testing system according to claim 4, characterized in that, The control circuit (405) includes a limit switch (406) and a diode D. The limit switch (406) includes a normally closed contact KC and a normally open contact KO. The normally closed contact KC is connected in series in the power supply circuit of the DC motor (404), and the normally open contact KO is connected in series with the diode D and then in parallel with the normally closed contact KC.

6. The intelligent high-voltage capacitor bank testing system according to claim 1, 2, or 3, characterized in that, The intelligent measurement and control module includes a first MCU measurement and control unit, a lithium battery power supply module, an AI intelligent voice module, a first human-machine interaction module, a first memory, a first data communication module, a current sensor, a differential amplifier module, a first comparator, a wireless transmission module, and a motor drive IC; the AI ​​intelligent voice module, the first human-machine interaction module, the first memory, the first data communication module, the wireless transmission module, and the motor drive IC are all connected to the first MCU measurement and control unit; the current sensor is connected to the first MCU measurement and control unit via a differential amplifier circuit and a comparator.

7. The intelligent high-voltage capacitor bank testing system according to claim 1, 2, or 3, characterized in that, The main unit of the test instrument includes a second MCU control unit, a pure sine wave inverter module, a test voltage output module, a voltage transformer, a second comparator, a second memory, a second human-machine interaction module, a second data communication module, and a wireless receiving module. The pure sine wave inverter module, the second memory, the second human-machine interaction module, the second data communication module, and the wireless receiving module are all connected to the second MCU control unit. The pure sine wave inverter module is connected to the voltage transformer via the test voltage output module. The voltage transformer is connected to the second MCU control unit via the second comparator.

8. The intelligent high-voltage capacitor bank testing system according to claim 7, characterized in that, The pure sine wave inverter module includes four N-channel enhancement-mode MOSFETs, namely Q1, Q2, Q3, and Q4; Q1 and Q2 are upper arm switches, and Q3 and Q4 are lower arm switches; the sources of the upper arm switches Q1 and Q2 are connected to the drains of the lower arm switches Q3 and Q4 respectively, forming the midpoint of the two bridge arms, which serves as the AC output terminal; the sources of the lower arm switches Q3 and Q4 share a common ground, and the drains of the upper arm switches Q1 and Q2 are connected to the DC input voltage VDD; the diagonal switches Q1 and Q4, and Q2 and Q3 are driven by the same SPWM signal, with the signals of the upper and lower bridge arms out of phase, and the sinusoidal change of the output voltage is achieved by controlling the conduction time difference of the switches.

9. A test method based on the intelligent high-voltage capacitor bank test system according to any one of claims 1-8, characterized in that, Including the following steps: The current in the lead wires of the inductive capacitor is acquired by the current acquisition module, and the voltage signal on the capacitor is acquired by the host of the test instrument. The MCU of the test instrument calculates the zero-crossing time difference between the current and voltage signals. The phase difference is obtained. f represents the test power supply frequency; The main unit MCU of the tester collects the effective voltage value U, the effective current value I, and the phase difference. Calculate the capacitive reactance, and then obtain the actual capacitance C of the capacitor under test; The capacitance deviation is calculated based on the actual capacitance C; if the capacitance deviation is less than the preset value, the capacitor is deemed qualified. Otherwise, it is judged as a defect.

10. The test method according to claim 9, characterized in that, Using the capacitive formula Calculate the capacitive reactance, then substitute it into the capacitance formula. The actual capacitance C of the capacitor under test is obtained; then the deviation formula is used. Calculate capacity deviation; This is the standard capacity.

Images