Self-excitation method test system for capacitor voltage transformer without disconnecting wire

Abstract

The invention relates to the technical field of capacitive voltage transformers, in particular to a non-wire-removing self-excitation method test system for a capacitive voltage transformer, which comprises a capacitive voltage dividing unit, an electromagnetic unit, a measurement module and a dielectric loss meter, and is characterized in that the measurement module comprises a current detection unit and a control unit; a measurement module is arranged between a dielectric loss instrument and a capacitance voltage dividing unit and an electromagnetic unit, the measurement module comprises a current detection unit and a control unit, the current detection unit obtains the current of a capacitance voltage transformer, current signals are respectively connected to the control unit, the control unit processes the input current signals, and the input current signals are transmitted to the electromagnetic unit. And the processed data is output to the dielectric loss instrument, so that the test of the non-wire-removal self-excitation method on the capacitive voltage transformer is realized, a worker does not need to climb to the top of the capacitive voltage transformer to carry out complex wire removal and wiring work, and the convenience and safety of the whole test are remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of capacitive voltage transformers, and in particular to a capacitive voltage transformer self-excitation method testing system without disconnecting the wires. Background Art

[0002] The traditional CVT (capacitive voltage transformer) self-excitation method test is to detect whether the CVT can generate self-excitation oscillation through the voltage-dividing characteristics of its own capacitor and the coupling of the electromagnetic unit without the need for an additional power supply, and then test the performance of the CVT; in the traditional self-excitation method, by applying an appropriate excitation signal to the secondary winding of the CVT, the transformer is made to self-excite and stabilize at a certain frequency and amplitude, so as to judge the dynamic response and other performance indicators of the transformer; however, the above test has the following disadvantages:

[0003] (1) The wires need to be removed for testing: The traditional self-excitation method requires the secondary side of the CVT to be disconnected from the system before testing. This means that power needs to be cut off and wires need to be removed before testing, which increases the complexity of the operation and reduces the test efficiency.

[0004] (2) Stability of the excitation signal: The traditional self-excitation method has high requirements on the amplitude and frequency of the excitation signal. If the excitation signal is unstable, the test results may be inaccurate.

[0005] (3) Large interference to on-site equipment: Since the CVT wiring method needs to be switched during the test, it may cause certain electromagnetic interference and safety hazards to on-site equipment. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a capacitive voltage transformer self-excitation method testing system without disconnecting the wires, which can effectively solve the current collection problem and improve the measurement accuracy.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0008] A capacitive voltage transformer non-disconnection self-excitation method test system comprises a capacitive voltage divider unit, an electromagnetic unit, a measuring module and a dielectric loss meter, wherein the measuring module comprises a current detection unit and a control unit, wherein the current detection unit is electrically connected to the capacitive voltage divider unit, the electromagnetic unit and the control unit respectively, wherein the dielectric loss meter is electrically connected to the control unit and the electromagnetic unit respectively, wherein the capacitive voltage divider unit is electrically connected to the electromagnetic unit, and wherein the capacitive voltage divider unit is grounded.

[0009] Furthermore, the current detection unit includes a Hall sensor U4 and a Hall sensor U5, the models of the Hall sensor U4 and the Hall sensor U5 are both ACS712, the current sampling end of the Hall sensor U4 is electrically connected to the electromagnetic unit, the current sampling end of the Hall sensor U5 is electrically connected to the capacitive voltage divider unit, and the analog output signal end of the Hall sensor U4 and the analog output signal end of the Hall sensor U5 are both electrically connected to the control unit.

[0010] Furthermore, the current detection unit also includes a resistor R1, a resistor R2, a resistor R5 and a resistor R6, one end of the resistor R1 is electrically connected to the electromagnetic unit, the other end of the resistor R1 is electrically connected to one end of the resistor R2, the other end of the resistor R2 is electrically connected to the current sampling end of the Hall sensor U4, one end of the resistor R5 is electrically connected to the capacitive voltage divider unit, the other end of the resistor R5 is electrically connected to one end of the resistor R6, and the other end of the resistor R6 is electrically connected to the current sampling end of the Hall sensor U5.

[0011] Furthermore, the current detection unit also includes capacitor C1, capacitor C4, capacitor C5 and capacitor C6, one end of the capacitor C1 is electrically connected to the power supply terminal of the Hall sensor U4, the other end of the capacitor C1 is electrically connected to one end of the capacitor C4 and the ground terminal of the Hall sensor U4 respectively, and the other end of the capacitor C1, one end of the capacitor C4 and the ground terminal of the Hall sensor U4 are all grounded, the other end of the capacitor C4 is electrically connected to the analog output signal terminal of the Hall sensor U4 and the control unit respectively, one end of the capacitor C5 is electrically connected to the power supply terminal of the Hall sensor U5, the other end of the capacitor C5 is electrically connected to one end of the capacitor C6 and the ground terminal of the Hall sensor U5 respectively, and the other end of the capacitor C5, one end of the capacitor C6 and the ground terminal of the Hall sensor U5 are all grounded.

[0012] Furthermore, the capacitive voltage divider unit includes a capacitor C101 and a capacitor C201, one end of the capacitor C101 is grounded, the other end of the capacitor C101 is electrically connected to one end of the capacitor C201 and the electromagnetic unit respectively, and the other end of the capacitor C201 is electrically connected to the current detection unit.

[0013] Furthermore, the electromagnetic unit includes a transformer T1, one end of the main winding of the transformer T1 is electrically connected to the capacitor voltage divider unit, the other end of the main winding of the transformer T1 is electrically connected to the current detection unit, one end of the auxiliary winding of the transformer T1 is electrically connected to the current detection unit, and the other end of the auxiliary winding of the transformer T1 is electrically connected to the dielectric loss meter.

[0014] Furthermore, the measuring module also includes a display unit, and the display unit is electrically connected to the control unit.

[0015] Furthermore, the measurement module also includes a LORA wireless transmission unit, and the LORA wireless transmission unit is electrically connected to the control unit.

[0016] Furthermore, the measurement module also includes a DC overvoltage protection unit, and the DC overvoltage protection unit is electrically connected to the current detection unit and the control unit respectively.

[0017] Furthermore, the measurement module also includes a power supply unit, and the power supply unit is electrically connected to the DC overvoltage protection unit.

[0018] The beneficial effects of the present invention are:

[0019] This solution is provided with a capacitor voltage divider unit, an electromagnetic unit, a measuring module and a dielectric loss meter. The measuring module includes a current detection unit and a control unit. The current detection unit is electrically connected to the capacitor voltage divider unit, the electromagnetic unit and the control unit respectively. The dielectric loss meter is electrically connected to the control unit and the electromagnetic unit respectively. The capacitor voltage divider unit is electrically connected to the electromagnetic unit. The capacitor voltage divider unit is grounded. A measuring module is provided between the capacitor voltage divider unit and the electromagnetic unit. The measuring module includes a current detection unit and a control unit. The current of the capacitive voltage transformer is obtained through the current detection unit, and these current signals are respectively connected to the control unit. The control unit processes the input current signal and outputs the processed data to the dielectric loss meter. In this way, the self-excitation method test of the capacitive voltage transformer without removing the wires is realized. It can ensure that the dielectric loss and capacitance of the capacitor voltage divider unit can be measured more accurately and efficiently without disassembling the original wiring, so that the staff does not need to climb to the top of the capacitive voltage transformer to perform complicated wire removal and wiring work, which significantly improves the convenience and safety of the overall test. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a connection block diagram of the capacitive voltage transformer non-disconnection self-excitation method testing system of the present invention;

[0021] Figure 2 A circuit schematic diagram of a current detection unit of a capacitive voltage transformer self-excitation method test system without disconnecting the wires of the present invention;

[0022] Figure 3 A circuit schematic diagram of a power supply unit and a DC overvoltage protection unit of a capacitive voltage transformer self-excitation method test system without disconnecting the wires of the present invention;

[0023] Figure 4 A circuit schematic diagram of a control unit of a capacitive voltage transformer non-disconnection self-excitation method test system of the present invention;

[0024] Figure 5 A circuit schematic diagram of a clock crystal oscillator unit of a capacitive voltage transformer self-excitation method test system without disconnecting the wires of the present invention;

[0025] Figure 6 It is a circuit principle diagram of a reset unit and a debugging interface J1 of a capacitive voltage transformer self-excitation method test system without disconnecting the wires of the present invention;

[0026] Figure 7 A circuit schematic diagram of a display unit of a capacitive voltage transformer non-disconnection self-excitation method testing system of the present invention;

[0027] Figure 8 It is a circuit principle diagram of the LORA wireless transmission unit of the capacitive voltage transformer self-excitation method test system without disconnecting the wires of the present invention;

[0028] Description of labels:

[0029] 1. Capacitor voltage divider unit; 2. Electromagnetic unit; 3. Measurement module; 301. Current detection unit; 302. Control unit; 303. Display unit; 304. LORA wireless transmission unit; 305. DC overvoltage protection unit; 306. Power supply unit; 4. Dielectric loss meter. DETAILED DESCRIPTION

[0030] In order to explain the technical content, achieved objectives and effects of the present invention in detail, the following is an explanation in conjunction with the implementation modes and the accompanying drawings.

[0031] Please refer to Figure 1 , the technical solution adopted by the present invention is:

[0032] A capacitive voltage transformer non-disconnection self-excitation method test system comprises a capacitive voltage divider unit, an electromagnetic unit, a measuring module and a dielectric loss meter, wherein the measuring module comprises a current detection unit and a control unit, wherein the current detection unit is electrically connected to the capacitive voltage divider unit, the electromagnetic unit and the control unit respectively, wherein the dielectric loss meter is electrically connected to the control unit and the electromagnetic unit respectively, wherein the capacitive voltage divider unit is electrically connected to the electromagnetic unit, and wherein the capacitive voltage divider unit is grounded.

[0033] From the above description, it can be seen that the beneficial effects of the present invention are:

[0034] This solution is provided with a capacitor voltage divider unit, an electromagnetic unit, a measuring module and a dielectric loss meter. The measuring module includes a current detection unit and a control unit. The current detection unit is electrically connected to the capacitor voltage divider unit, the electromagnetic unit and the control unit respectively. The dielectric loss meter is electrically connected to the control unit and the electromagnetic unit respectively. The capacitor voltage divider unit is electrically connected to the electromagnetic unit. The capacitor voltage divider unit is grounded. A measuring module is provided between the capacitor voltage divider unit and the electromagnetic unit. The measuring module includes a current detection unit and a control unit. The current of the capacitive voltage transformer is obtained through the current detection unit, and these current signals are respectively connected to the control unit. The control unit processes the input current signal and outputs the processed data to the dielectric loss meter. In this way, the self-excitation method test of the capacitive voltage transformer without removing the wires is realized. It can ensure that the dielectric loss and capacitance of the capacitor voltage divider unit can be measured more accurately and efficiently without disassembling the original wiring, so that the staff does not need to climb to the top of the capacitive voltage transformer to perform complicated wire removal and wiring work, which significantly improves the convenience and safety of the overall test.

[0035] Furthermore, the current detection unit includes a Hall sensor U4 and a Hall sensor U5, the models of the Hall sensor U4 and the Hall sensor U5 are both ACS712, the current sampling end of the Hall sensor U4 is electrically connected to the electromagnetic unit, the current sampling end of the Hall sensor U5 is electrically connected to the capacitive voltage divider unit, and the analog output signal end of the Hall sensor U4 and the analog output signal end of the Hall sensor U5 are both electrically connected to the control unit.

[0036] Furthermore, the current detection unit also includes a resistor R1, a resistor R2, a resistor R5 and a resistor R6, one end of the resistor R1 is electrically connected to the electromagnetic unit, the other end of the resistor R1 is electrically connected to one end of the resistor R2, the other end of the resistor R2 is electrically connected to the current sampling end of the Hall sensor U4, one end of the resistor R5 is electrically connected to the capacitive voltage divider unit, the other end of the resistor R5 is electrically connected to one end of the resistor R6, and the other end of the resistor R6 is electrically connected to the current sampling end of the Hall sensor U5.

[0037] Furthermore, the current detection unit also includes capacitor C1, capacitor C4, capacitor C5 and capacitor C6, one end of the capacitor C1 is electrically connected to the power supply terminal of the Hall sensor U4, the other end of the capacitor C1 is electrically connected to one end of the capacitor C4 and the ground terminal of the Hall sensor U4 respectively, and the other end of the capacitor C1, one end of the capacitor C4 and the ground terminal of the Hall sensor U4 are all grounded, the other end of the capacitor C4 is electrically connected to the analog output signal terminal of the Hall sensor U4 and the control unit respectively, one end of the capacitor C5 is electrically connected to the power supply terminal of the Hall sensor U5, the other end of the capacitor C5 is electrically connected to one end of the capacitor C6 and the ground terminal of the Hall sensor U5 respectively, and the other end of the capacitor C5, one end of the capacitor C6 and the ground terminal of the Hall sensor U5 are all grounded.

[0038] Furthermore, the capacitive voltage divider unit includes a capacitor C101 and a capacitor C201, one end of the capacitor C101 is grounded, the other end of the capacitor C101 is electrically connected to one end of the capacitor C201 and the electromagnetic unit respectively, and the other end of the capacitor C201 is electrically connected to the current detection unit.

[0039] Furthermore, the electromagnetic unit includes a transformer T1, one end of the main winding of the transformer T1 is electrically connected to the capacitor voltage divider unit, the other end of the main winding of the transformer T1 is electrically connected to the current detection unit, one end of the auxiliary winding of the transformer T1 is electrically connected to the current detection unit, and the other end of the auxiliary winding of the transformer T1 is electrically connected to the dielectric loss meter.

[0040] Furthermore, the measuring module also includes a display unit, and the display unit is electrically connected to the control unit.

[0041] Furthermore, the measurement module also includes a LORA wireless transmission unit, and the LORA wireless transmission unit is electrically connected to the control unit.

[0042] Furthermore, the measurement module also includes a DC overvoltage protection unit, and the DC overvoltage protection unit is electrically connected to the current detection unit and the control unit respectively.

[0043] Furthermore, the measurement module also includes a power supply unit, and the power supply unit is electrically connected to the DC overvoltage protection unit.

[0044] Please refer to Figures 1 to 8 As shown, the first embodiment of the present invention is:

[0045] Please refer to Figure 1A capacitive voltage transformer non-disconnection self-excitation method test system includes a capacitive voltage divider unit 1, an electromagnetic unit 2, a measurement module 3 and a dielectric loss meter 4, the measurement module 3 includes a current detection unit 301 and a control unit 302, the current detection unit 301 is electrically connected to the capacitive voltage divider unit 1, the electromagnetic unit 2 and the control unit 302, the dielectric loss meter 4 is electrically connected to the control unit 302 and the electromagnetic unit 2, the capacitive voltage divider unit 1 is electrically connected to the electromagnetic unit 2, and the capacitive voltage divider unit 1 is grounded.

[0046] Please refer to Figure 2 The current detection unit 301 includes a Hall sensor U4 and a Hall sensor U5, the models of the Hall sensor U4 and the Hall sensor U5 are both ACS712, the current sampling end of the Hall sensor U4 is electrically connected to the electromagnetic unit 2, the current sampling end of the Hall sensor U5 is electrically connected to the capacitive voltage divider unit 1, and the analog output signal end of the Hall sensor U4 and the analog output signal end of the Hall sensor U5 are both electrically connected to the control unit 302.

[0047] Please refer to Figure 2 The current detection unit 301 also includes a resistor R1, a resistor R2, a resistor R5 and a resistor R6, one end of the resistor R1 is electrically connected to the electromagnetic unit 2, the other end of the resistor R1 is electrically connected to one end of the resistor R2, the other end of the resistor R2 is electrically connected to the current sampling end of the Hall sensor U4, one end of the resistor R5 is electrically connected to the capacitor voltage divider unit 1, the other end of the resistor R5 is electrically connected to one end of the resistor R6, and the other end of the resistor R6 is electrically connected to the current sampling end of the Hall sensor U5.

[0048] Please refer to Figure 2 The current detection unit 301 also includes a capacitor C1, a capacitor C4, a capacitor C5 and a capacitor C6, one end of the capacitor C1 is electrically connected to the power supply end of the Hall sensor U4, the other end of the capacitor C1 is electrically connected to one end of the capacitor C4 and the ground end of the Hall sensor U4 respectively, and the other end of the capacitor C1, one end of the capacitor C4 and the ground end of the Hall sensor U4 are all grounded, the other end of the capacitor C4 is electrically connected to the analog output signal end of the Hall sensor U4 and the control unit 302 respectively, one end of the capacitor C5 is electrically connected to the power supply end of the Hall sensor U5, the other end of the capacitor C5 is electrically connected to one end of the capacitor C6 and the ground end of the Hall sensor U5 respectively, and the other end of the capacitor C5, one end of the capacitor C6 and the ground end of the Hall sensor U5 are all grounded.

[0049] The current detection unit 301 adopts a Hall effect sensor of model ACS712 to achieve dual-channel high-precision current monitoring, which is suitable for real-time detection and analysis of current signals; the current detection unit 301 includes two input terminals: IXL+ / IXL- and IC+ / IC-, which are used for current input of two channels respectively; IXL+ and IXL- are the positive and negative input terminals of the first channel, connected to the positive and negative poles of the current loop to be measured; similarly, IC+ and IC- are the positive and negative input terminals of the second channel, connected to another current loop.

[0050] At the input end of each channel, a resistor divider network (such as resistor R1, resistor R2, resistor R5 and resistor R6) is designed to divide the input signal to ensure that the current remains within the safe detection range of the sensor and prevent excessive current from damaging the sensor or affecting the measurement accuracy; the divided current signal is transmitted to the input pins (IP+ and IP-) of the Hall effect sensor. The Hall effect sensor uses the Hall effect to convert the flowing current into a voltage signal proportional to the current size and output it from the OUT pin.

[0051] Decoupling capacitors (such as capacitor C1, capacitor C4, capacitor C5, capacitor C6, etc.) are used to filter the power supply voltage, reduce noise interference on the sensor, and ensure the stability of the output voltage signal; after the output end is filtered by the capacitor, it is connected to the PA1 interface and the PA2 interface respectively, and the PA1 interface and the PA2 interface output the converted voltage signal to the external circuit; since the voltage of the output signal is proportional to the input current, the subsequent circuit can collect and monitor the current size and direction of the two channels in real time through the PA1 interface and the PA2 interface.

[0052] Please refer to Figure 1 The capacitive voltage divider unit 1 includes a capacitor C101 and a capacitor C201, one end of the capacitor C101 is grounded, the other end of the capacitor C101 is electrically connected to one end of the capacitor C201 and the electromagnetic unit 2 respectively, and the other end of the capacitor C201 is electrically connected to the current detection unit 301.

[0053] Please refer to Figure 1 The electromagnetic unit 2 includes a transformer T1, one end of the main winding of the transformer T1 is electrically connected to the capacitor voltage divider unit 1, the other end of the main winding of the transformer T1 is electrically connected to the current detection unit 301, one end of the auxiliary winding of the transformer T1 is electrically connected to the current detection unit 301, and the other end of the auxiliary winding of the transformer T1 is electrically connected to the dielectric loss meter 4.

[0054] Please refer to Figure 7The measuring module 3 also includes a display unit 303, which is electrically connected to the control unit 302. The display unit 303 uses an OLED display screen (i.e., chip U2). SCL and SDA are I2C communication pins, which are connected to the CPU (i.e., chip U6) interface through the PC6 interface and the PC7 interface. The PC6 interface and the PC7 interface have their own I2C communication for the driving function module. The unit can display whether the current is overloaded. After the CPU processes the data, it displays I2C in real time through the OLED display screen. XL and I C201 In addition, the unit can also display the connection status of the LORA wireless transmission unit 304.

[0055] The measurement module 3 also includes a DC overvoltage protection unit 305, which is electrically connected to the current detection unit 301 and the control unit 302 respectively; the DC overvoltage protection unit 305 is composed of a lightning arrester and a capacitor control protector. The lightning arrester is a 400V zinc oxide lightning arrester, which operates in parallel with the capacitor control protector. When the applied voltage exceeds a certain amplitude, the lightning arrester always acts first, discharging a large amount of energy through itself, limiting overvoltage, and protecting the capacitor control protector.

[0056] Please refer to Figure 8 The measuring module 3 also includes a LORA wireless transmission unit 304, which is electrically connected to the control unit 302. The LORA wireless transmission unit 304 includes a chip U1 (model SX1278). The system uses the LORA wireless transmission unit for remote data transmission. The U3RX interface and U3TX interface of the unit are responsible for data reception and transmission respectively. The data is connected to the CPU through the PC13 interface and the PC14 interface. These two interfaces have the functions of data transmission and reception; the unit can remotely transmit and display I XL and I C201 The DC overvoltage protection unit 305 will intervene to prevent the device from being damaged if an overload occurs.

[0057] The measuring module 3 further includes a power supply unit 306 , and the power supply unit 306 is electrically connected to the DC overvoltage protection unit 305 .

[0058] The measuring module 3 further includes a clock crystal unit, a reset unit and a debugging interface J1.

[0059] Please refer to Figure 5The clock crystal oscillator unit has two crystal oscillator circuits. The main clock crystal oscillator X2 is connected to the main clock pins OSCIN and OSCOUT of chip U6 to form an internal clock circuit, and is matched with capacitors to stabilize the oscillation frequency, providing the main operating frequency for the system to control its core operating speed; the clock crystal oscillator X1 is similar to X2, connected to the RTC pins PC14 and PC15 of chip U6, providing RTC clock signals, and running independently of the main clock. Even if the main clock stops working or the system is in low power mode, the RTC can still time normally; in short, the clock frequency of the main clock crystal oscillator X2 is used to drive the CPU and most peripherals, so the frequency is higher and supports fast processing speed; the clock crystal oscillator X1 clock uses a lower frequency to record the date and time, so as to maintain the continuity of time when the system is restarted or in low power mode.

[0060] Please refer to Figure 6 The switch SW2 in the reset unit is a reset switch (model TS-103); capacitor C11 and resistor R8 form an RC delay circuit, which is used to generate a short delay during reset, ensuring the stability of the reset signal and preventing the system from falsely triggering reset; resistor R8 and capacitor C11 cooperate to control the charging and discharging speed of the capacitor, and determine the delay time of the reset signal; therefore, when we press switch SW2, the reset pin of chip U6 is pulled low, the system is reset, and restarts into a known initial state.

[0061] Please refer to Figure 6 The debugging interface J1 is used to connect a debugger for program downloading and debugging. The PA14 interface and the PA13 interface are the SWDIO (data input / output) and SWCLK (clock signal) pins of the chip U6, which are usually used for debugging via a serial debugging interface (SWD).

[0062] Please refer to Figure 3 The IN pin of the voltage regulating chip U3 (model TLV71333PQDBVRQ1) in the power supply unit 306 is connected to the external power supply, and the OUT pin outputs a stable 3.3V voltage to supply the entire circuit; the capacitor C2 is used to filter out the clutter and interference in the input power supply to protect the voltage regulating chip U3; the capacitor C3 is used to further stabilize the output voltage to prevent load changes or output voltage fluctuations; in short, the function of the power supply unit 306 is to adjust the external power supply to the 3.3V voltage required by the system, and at the same time reduce interference through the filtering capacitor to ensure power supply stability and system reliability.

[0063] The measurement module 3 of this solution is mainly composed of a current detection unit 301, a control unit 302, a display unit 303, a LORA wireless transmission unit 304, a DC overvoltage protection unit 305, a power supply unit 306, a clock crystal unit, a reset unit and a debugging interface. The problem that the bridge in the self-excitation method cannot directly collect the C101 current is solved by an indirect method; to ensure the reliability of the device, the power supply unit 306 is equipped with a filtering device to avoid interference from external electromagnetic fields; the measurement module 3 collects the X of the CVT through the current detection unit 301 L Terminal current I XL And the N-terminal current I C101 , which is specially suitable for calculating the capacitance based on the current amplitude and the dielectric loss value through the current phase. Different from the conventional self-excitation method, the primary low-voltage terminal X of the transformer T1 L After passing through the measurement module 3, it is grounded to form a loop and finally connected to the signal line Cx socket of the dielectric loss meter 4; at the same time, the low voltage end N of the voltage divider capacitor C201 collects I through the measurement module 3. C101 , and then connected to the high voltage output socket of the dielectric loss meter 4; according to Kirchhoff's current law, when the secondary winding of the CVT is excited and pressurized, there is I XL =I C101 +I C201 , so I C101 =I XL -I C201 , the measurement module 3 outputs I through the signal line Cx C101 Go to the dielectric loss meter 4 for reading and calculation; finally, the dielectric loss meter 4 can achieve bridge balance under the self-excitation method, and automatically calculate the dielectric loss and capacitance of the main capacitor C101 and the voltage-dividing capacitor C201. Its calculation process is consistent with the self-excitation method when the top of the CVT is not grounded, thereby effectively solving the current collection problem and improving the measurement accuracy.

[0064] Compared with the traditional self-excitation test of removing the primary wiring of the CVT, the measurement module 3 simplifies the experimental process and improves the safety of the operation; when conducting the experiment, only the primary low-voltage terminal X of the intermediate transformer T1 of the CVT is required. L The amplitude and phase of the primary current are collected, and the amplitude and phase information of the current from capacitor C201 are combined. The AC current bridge is used to calculate the amplitude and phase of the current of capacitor C101 independently to determine I C101 The value is then transmitted to the dielectric loss meter 4 to implement the self-excitation method test; this method greatly facilitates the operation and wiring, so that the staff does not need to climb to the top of the CVT to perform complicated wiring and wiring work, which significantly improves the convenience and safety of the overall test.

[0065] The CVT non-removal self-excitation test system is used to conduct a comprehensive test on the CVT dielectric loss and capacitance, and the measured data is compared with the factory report data to evaluate the equipment performance, ensure compliance with standards and achieve accurate measurement.

[0066] The specific test steps are as follows:

[0067] 1. Connecting equipment: There is no need to remove the primary side wiring. Connect the CVT self-excitation test system to the appropriate position of the CVT to ensure that the system is electrically insulated from the CVT to avoid interference with the normal operation of the power system.

[0068] 2. Apply excitation signal: Use the system to apply an excitation signal of appropriate frequency and amplitude to the CVT. The excitation signal should be able to put the CVT into a resonant state. Ensure that the signal meets the rated parameters of the CVT to avoid damage to the equipment or errors.

[0069] 3. Measure the dielectric loss tangent (tanδ): The system calculates the dielectric loss tangent (tanδ) by detecting the voltage and current response of the CVT. This is a key parameter reflecting the insulation dielectric loss and is used to evaluate whether the CVT insulation performance is good. The system will automatically record the loss angle value.

[0070] 4. Measure capacitance: The self-excitation method can calculate the capacitance through the excitation signal and the resonant response of the CVT. The capacitance is an important indicator reflecting the electrical performance of the CVT, especially its transmission performance. The measurement results can be automatically processed and output.

[0071] 5. Data analysis and comparison: Compare the dielectric loss and capacitance data obtained from the test with the factory report data of the CVT; focus on the following points: First, whether the dielectric loss tangent value is within the range of the factory report and whether there is a large fluctuation; if the test data is significantly higher than the factory value, it indicates that the insulation performance may be deteriorated and the insulation status of the CVT needs to be further checked; secondly, whether the capacitance is consistent with the factory data and whether there is a significant change; if the capacitance is significantly different from the factory data, it may be that the internal structure or electrical characteristics have changed, which may affect the normal operation of the CVT.

[0072] In summary, the present invention provides a capacitive voltage transformer non-removal self-excitation method test system, by setting a capacitor voltage divider unit, an electromagnetic unit, a measuring module and a dielectric loss meter, the measuring module includes a current detection unit and a control unit, the current detection unit is electrically connected to the capacitor voltage divider unit, the electromagnetic unit and the control unit respectively, the dielectric loss meter is electrically connected to the control unit and the electromagnetic unit respectively, the capacitor voltage divider unit is electrically connected to the electromagnetic unit, and the capacitor voltage divider unit is grounded, by setting a measuring module between the capacitor voltage divider unit and the electromagnetic unit, the measuring module includes a current detection unit and a control unit, the current of the capacitor voltage transformer is obtained through the current detection unit, and these current signals are respectively connected to the control unit, the control unit processes the input current signal, and the processed data is output to the dielectric loss meter, so as to realize the non-removal self-excitation method test of the capacitor voltage transformer, which can ensure that the dielectric loss and capacitance of the capacitor voltage divider unit are measured more accurately and efficiently without disassembling the original wiring, so that the staff does not need to climb to the top of the capacitor voltage transformer to perform complicated wire removal and wiring work, which significantly improves the convenience and safety of the overall test.

[0073] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention's specification and drawings, or directly or indirectly applied in related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A capacitive voltage transformer self-excitation test system without disconnecting the wire, characterized in that: It includes a capacitive voltage divider unit, an electromagnetic unit, a measuring module and a dielectric loss meter. The measuring module includes a current detection unit and a control unit. The current detection unit is electrically connected to the capacitive voltage divider unit, the electromagnetic unit and the control unit respectively. The dielectric loss meter is electrically connected to the control unit and the electromagnetic unit respectively. The capacitive voltage divider unit is electrically connected to the electromagnetic unit. The capacitive voltage divider unit is grounded.

2. The capacitive voltage transformer non-disconnection self-excitation method test system according to claim 1, characterized in that: The current detection unit includes a Hall sensor U4 and a Hall sensor U5, the models of the Hall sensor U4 and the Hall sensor U5 are both ACS712, the current sampling end of the Hall sensor U4 is electrically connected to the electromagnetic unit, the current sampling end of the Hall sensor U5 is electrically connected to the capacitive voltage divider unit, and the analog output signal end of the Hall sensor U4 and the analog output signal end of the Hall sensor U5 are both electrically connected to the control unit.

3. The capacitive voltage transformer non-disconnection self-excitation method test system according to claim 1, characterized in that: The current detection unit also includes a resistor R1, a resistor R2, a resistor R5 and a resistor R6, one end of the resistor R1 is electrically connected to the electromagnetic unit, the other end of the resistor R1 is electrically connected to one end of the resistor R2, the other end of the resistor R2 is electrically connected to the current sampling end of the Hall sensor U4, one end of the resistor R5 is electrically connected to the capacitive voltage divider unit, the other end of the resistor R5 is electrically connected to one end of the resistor R6, and the other end of the resistor R6 is electrically connected to the current sampling end of the Hall sensor U5.

4. The capacitive voltage transformer non-disconnection self-excitation method test system according to claim 1, characterized in that: The current detection unit also includes capacitors C1, C4, C5 and C6, one end of the capacitor C1 is electrically connected to the power supply terminal of the Hall sensor U4, the other end of the capacitor C1 is electrically connected to one end of the capacitor C4 and the ground terminal of the Hall sensor U4 respectively, and the other end of the capacitor C1, one end of the capacitor C4 and the ground terminal of the Hall sensor U4 are all grounded, the other end of the capacitor C4 is electrically connected to the analog output signal terminal of the Hall sensor U4 and the control unit respectively, one end of the capacitor C5 is electrically connected to the power supply terminal of the Hall sensor U5, the other end of the capacitor C5 is electrically connected to one end of the capacitor C6 and the ground terminal of the Hall sensor U5 respectively, and the other end of the capacitor C5, one end of the capacitor C6 and the ground terminal of the Hall sensor U5 are all grounded.

5. The capacitive voltage transformer self-excitation method test system without disconnecting the wire according to claim 1, characterized in that: The capacitive voltage divider unit includes a capacitor C101 and a capacitor C201. One end of the capacitor C101 is grounded, the other end of the capacitor C101 is electrically connected to one end of the capacitor C201 and the electromagnetic unit respectively, and the other end of the capacitor C201 is electrically connected to the current detection unit.

6. The capacitive voltage transformer non-disconnection self-excitation method test system according to claim 1, characterized in that: The electromagnetic unit includes a transformer T1, one end of the main winding of the transformer T1 is electrically connected to the capacitor voltage divider unit, the other end of the main winding of the transformer T1 is electrically connected to the current detection unit, one end of the auxiliary winding of the transformer T1 is electrically connected to the current detection unit, and the other end of the auxiliary winding of the transformer T1 is electrically connected to the dielectric loss meter.

7. The capacitive voltage transformer non-disconnection self-excitation method test system according to claim 1, characterized in that: The measuring module further comprises a display unit, and the display unit is electrically connected to the control unit.

8. The capacitive voltage transformer self-excitation method test system without disconnecting the wire according to claim 1, characterized in that: The measuring module also includes a LORA wireless transmission unit, and the LORA wireless transmission unit is electrically connected to the control unit.

9. The capacitive voltage transformer non-disconnection self-excitation method test system according to claim 1, characterized in that: The measurement module further comprises a DC overvoltage protection unit, and the DC overvoltage protection unit is electrically connected to the current detection unit and the control unit respectively.

10. The capacitive voltage transformer self-excitation method test system without disconnecting the wire according to claim 9, characterized in that: The measuring module further comprises a power supply unit, and the power supply unit is electrically connected to the DC overvoltage protection unit.

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