A partial discharge detection circuit for switchgear

Abstract

This invention discloses a partial discharge detection circuit for switchgear, relating to the field of current detection. The circuit includes a discharge detection module for detecting ground waves generated by partial discharge in the switchgear. These waves are converted into a stable voltage by a first capacitor to obtain a detection signal, which is then output to an isolation feedback module. Compared with existing technologies, the advantages of this invention are: This invention detects the presence of partial discharge in the switchgear by detecting ground waves, which can be performed even when the switchgear is energized, thus reducing limitations; the difficult-to-determine ground waves are converted into a stable voltage signal by the discharge detection module (first capacitor), allowing the discharge level of the partial discharge to be determined by a discharge digital indicator module and a discharge magnitude indicator module; the pressure relief control module and delay drive module work together to ensure timely pressure relief for the discharge detection module, preventing circuit damage; and the presence or absence of LED illumination can detect whether related modules are faulty.

Description

Technical Field

[0001] This invention relates to the field of current detection, specifically a partial discharge detection circuit for switchgear. Background Technology

[0002] Partial discharge in switchgear refers to electrical discharge caused by the breakdown of insulation components. It can occur near conductors or in other areas. Conventional non-withstand voltage and withstand voltage tests are unlikely to detect this type of insulation defect. Partial discharge can lead to a vicious cycle of insulation deterioration and defects in power equipment, and in severe cases, it can even cause insulation accidents. Therefore, it is necessary to detect partial discharge to prevent sudden insulation damage accidents in power equipment during operation.

[0003] Existing pulse current detection methods for detecting partial discharge in switchgear are generally used when the switchgear is powered off, and cannot be used when the switchgear is powered on normally, which is a significant limitation and needs to be improved. Summary of the Invention

[0004] The purpose of this invention is to provide a partial discharge detection circuit for switchgear to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A partial discharge detection circuit for switchgear, comprising:

[0007] The discharge detection module is used to detect the ground wave generated by partial discharge in the switchgear. It converts the ground wave into a stable voltage through the first capacitor to obtain a detection signal, which is then output to the isolation feedback module. The stronger the ground wave (the greater the intensity of partial discharge in the switchgear), the longer the discharge detection module outputs the detection signal to the isolation feedback module.

[0008] The isolation feedback module is used to charge the second capacitor when a detection signal is received. The voltage on the second capacitor varies depending on the charging time. Based on the voltage on the second capacitor, the module selects whether to drive the alarm module and the discharge magnitude indicator module.

[0009] The alarm module is used to alert the switchgear to partial discharge during operation.

[0010] The discharge magnitude indicator module is used to display the magnitude of partial discharge intensity of the switchgear by whether or not the LED is lit during operation;

[0011] A discharge digital indicator module is used to detect the voltage across the second capacitor;

[0012] The pressure relief control module is used to control the operation of the pressure relief module when all the LEDs of the discharge size indicator module are lit.

[0013] The delay drive module is used to directly drive the pressure relief control module to work when the alarm module's working time reaches a set value;

[0014] The pressure relief module is used to control the grounding and pressure relief of the first capacitor during operation.

[0015] The output of the discharge detection module is connected to the input of the isolation feedback module. The output of the isolation feedback module is connected to the input of the alarm module, the input of the discharge magnitude indicator module, and the input of the discharge digital indicator module. The output of the discharge magnitude indicator module is connected to the first input of the pressure relief control module. The output of the alarm module is connected to the input of the delay drive module. The output of the delay drive module is connected to the second input of the pressure relief control module. The output of the pressure relief control module is connected to the input of the pressure relief working module. The output of the pressure relief working module is connected to the input of the discharge detection module.

[0016] As a further embodiment of the present invention: the discharge detection module includes a detection head, a first resistor, a second resistor, a first transistor, a second transistor, a first diode, a first capacitor, and a second diode. The detection head is connected to the base of the first transistor, the collector of the first transistor is connected to one end of the first resistor, the other end of the first resistor is connected to the power supply voltage, the emitter of the first transistor is connected to the base of the second transistor, the collector of the second transistor is connected to one end of the second resistor, the other end of the second resistor is connected to the power supply voltage, the emitter of the second transistor is connected to the anode of the first diode, the cathode of the first diode is connected to one end of the first capacitor, the anode of the second diode, and the output terminal of the voltage relief module, the other end of the first capacitor is grounded, and the cathode of the second diode is connected to the input terminal of the isolation feedback module.

[0017] As a further embodiment of the present invention: the isolation feedback module includes a third resistor, an optocoupler, a fourth resistor, a fifth resistor, a third MOSFET, a seventh resistor, and a second capacitor. One end of the third resistor is connected to the output terminal of the discharge detection module, and another end of the third resistor is connected to the first terminal of the optocoupler. The second terminal of the optocoupler is grounded. The third terminal of the optocoupler is connected to one end of the fourth resistor and the gate (G) of the third MOSFET. The fourth terminal of the optocoupler is grounded. The other end of the fourth resistor is connected to the power supply voltage. The source (S) of the third MOSFET is connected to one end of the fifth resistor. The other end of the fifth resistor is connected to the power supply voltage. The drain (D) of the third MOSFET is connected to one end of the seventh resistor. The other end of the seventh resistor is connected to one end of the second capacitor, the input terminal of the alarm module, the input terminal of the discharge magnitude indicator module, and the input terminal of the discharge digital indicator module. The other end of the second capacitor is grounded.

[0018] As a further embodiment of the present invention: the alarm module includes a sixth resistor, a buzzer, a fourth transistor, and a third diode. One end of the sixth resistor is connected to the power supply voltage, and the other end of the sixth resistor is connected to one end of the buzzer. The other end of the buzzer is connected to the collector of the fourth transistor. The emitter of the fourth transistor is connected to the anode of the third diode. The cathode of the third diode is grounded. The base of the fourth transistor is connected to the output terminal of the isolation feedback module. The third diode is a light-emitting diode.

[0019] As a further aspect of the present invention: the discharge size indicator module includes multiple discharge size indicator units, which are connected in parallel.

[0020] As a further embodiment of the present invention: the discharge size indicator unit includes a fourth diode, an eighth resistor, a first Zener diode, and a seventh diode. The positive terminal of the fourth diode is connected to the output terminal of the isolation feedback module, the negative terminal of the fourth diode is connected to one end of the eighth resistor, the other end of the eighth resistor is connected to the negative terminal of the first Zener diode, the positive terminal of the first Zener diode is connected to the positive terminal of the seventh diode, and the negative terminal of the seventh diode is grounded. The rated voltage of the Zener diodes in different discharge size indicator units is different, and the seventh diode is a light-emitting diode.

[0021] As a further embodiment of the present invention: the discharge digital indicator module includes a tenth diode and a voltmeter. The positive terminal of the tenth diode is connected to the output terminal of the isolation feedback module, the negative terminal of the tenth diode is connected to one end of the voltmeter, and the other end of the voltmeter is grounded.

[0022] As a further embodiment of the present invention: the pressure relief control module includes an eleventh resistor, a first relay, an eleventh diode, and multiple transistors, which are phototransistors. The number of transistors corresponds to the discharge size indicator unit. The base of each transistor only receives light from the light-emitting diode of the corresponding discharge size indicator unit. The emitter of the previous transistor is connected to the collector of the next transistor.

[0023] One end of the eleventh resistor is connected to the power supply voltage, the other end of the eleventh resistor is connected to one end of the first relay and the negative terminal of the eleventh diode, the other end of the first relay is connected to the positive terminal of the eleventh diode, the output terminal of the delay drive module, and the collector of the first transistor, and the emitter of the last transistor is grounded.

[0024] As a further embodiment of the present invention: the delay driving module includes a twelfth resistor, a ninth transistor, a thirteenth resistor, a third capacitor, an eighth MOSFET, and a twelfth diode. One end of the twelfth resistor is connected to the power supply voltage, and the other end of the twelfth resistor is connected to the collector of the ninth transistor. The ninth transistor is a phototransistor. The base of the ninth transistor only receives light from the third diode. The emitter of the ninth transistor is connected to one end of the thirteenth resistor. The other end of the thirteenth resistor is connected to one end of the third capacitor and the gate (G) of the eighth MOSFET. The other end of the third capacitor is grounded. The drain (D) of the eighth MOSFET is connected to the second input terminal of the voltage relief control module. The source (S) of the eighth MOSFET is connected to the anode of the twelfth diode. The cathode of the twelfth diode is grounded. The twelfth diode is a light-emitting diode.

[0025] As a further embodiment of the present invention: the pressure relief working module includes a first switch and a second switch, one end of the first switch is connected to one end of the second switch and the input terminal of the discharge detection module, the other end of the first switch is grounded, and the other end of the second switch is grounded.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention detects the presence of partial discharge in the switchgear by means of ground waves, and the switchgear can be detected while it is energized, thus having fewer limitations; the difficult-to-determine ground waves are converted into a stable voltage signal by the discharge detection module (first capacitor), and the discharge level of the partial discharge in the switchgear can be determined by the discharge digital indicator module and the discharge magnitude indicator module; the pressure relief control module and the delay drive module work together to ensure that the discharge detection module can be depressurized in time to avoid damage to the circuit, and at the same time, whether the light-emitting tube is lit or not can be used to detect whether the related modules are faulty. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a partial discharge detection circuit for a switchgear.

[0028] Figure 2 This is a schematic diagram of the discharge size indicator module.

[0029] Figure 3 This is the circuit diagram for the discharge detection module, isolation feedback module, and alarm module.

[0030] Figure 4 This is a circuit diagram for the discharge magnitude indicator module.

[0031] Figure 5 This is the circuit diagram for the discharge digital indicator module.

[0032] Figure 6 This is a circuit diagram of the pressure relief control module and the delay drive module.

[0033] Figure 7 The circuit diagram is for the pressure relief module. Detailed Implementation

[0034] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0035] Please see Figure 1 A partial discharge detection circuit for switchgear, comprising:

[0036] The discharge detection module 1 is used to detect the ground wave generated by the partial discharge of the switchgear. It is converted into a stable voltage through the first capacitor C1 to obtain a detection signal, which is then output to the isolation feedback module 2. The stronger the ground wave (the greater the intensity of the partial discharge of the switchgear), the longer the discharge detection module 1 outputs the detection signal to the isolation feedback module 2.

[0037] The isolation feedback module 2 is used to charge the second capacitor C2 when a detection signal is received. The voltage on the second capacitor C2 varies depending on the charging time. Based on the voltage on the second capacitor C2, the module selects whether to drive the alarm module 3 and the discharge size indicator module 4.

[0038] Alarm module 3 is used to alert the switchgear to partial discharge during operation;

[0039] Discharge magnitude indicator module 4 is used to indicate the magnitude of partial discharge intensity of the switchgear by whether or not the light-emitting tube is lit during operation;

[0040] The discharge digital indicator module 5 is used to detect the voltage across the second capacitor C2.

[0041] The pressure relief control module 6 is used to control the operation of the pressure relief module 8 when all the LEDs of the discharge size indicator module 4 are lit.

[0042] The delay drive module 7 is used to directly drive the pressure relief control module 6 to work when the working time of the alarm module 3 reaches the set value;

[0043] The pressure relief module 8 is used to control the first capacitor C1 to ground and relieve pressure during operation.

[0044] The output of the discharge detection module 1 is connected to the input of the isolation feedback module 2. The output of the isolation feedback module 2 is connected to the input of the alarm module 3, the input of the discharge size indicator module 4, and the input of the discharge digital indicator module 5. The output of the discharge size indicator module 4 is connected to the first input of the pressure relief control module 6. The output of the alarm module 3 is connected to the input of the delay drive module 7. The output of the delay drive module 7 is connected to the second input of the pressure relief control module 6. The output of the pressure relief control module 6 is connected to the input of the pressure relief working module 8. The output of the pressure relief working module 8 is connected to the input of the discharge detection module 1.

[0045] In a specific embodiment: When partial discharge occurs in the insulation layer of the switchgear, electromagnetic waves are generated. Due to the shielding effect of the switchgear's metal casing, most of these electromagnetic waves are blocked. However, a small amount of electromagnetic waves still propagates through the seams of the metal casing or the gas-insulated switch gaskets, generating a ground wave that travels through the outer surface of the equipment's metal casing to the ground. This ground wave typically ranges from a few millivolts to a few volts and has an extremely short rise time. Therefore, the presence of partial discharge in the switchgear can be detected using this ground wave.

[0046] In this embodiment: Please refer to Figure 3 The discharge detection module 1 includes a detection head X, a first resistor R1, a second resistor R2, a first transistor V1, a second transistor V2, a first diode D1, a first capacitor C1, and a second diode D2. The detection head X is connected to the base of the first transistor V1. The collector of the first transistor V1 is connected to one end of the first resistor R1, and the other end of the first resistor R1 is connected to the power supply voltage VCC. The emitter of the first transistor V1 is connected to the base of the second transistor V2. The collector of the second transistor V2 is connected to one end of the second resistor R2, and the other end of the second resistor R2 is connected to the power supply voltage VCC. The emitter of the second transistor V2 is connected to the anode of the first diode D1. The cathode of the first diode D1 is connected to one end of the first capacitor C1, the anode of the second diode D2, and the output terminal of the voltage relief module 8. The other end of the first capacitor C1 is grounded. The cathode of the second diode D2 is connected to the input terminal of the isolation feedback module 2.

[0047] Since ground waves typically range from a few millivolts to a few volts and have an extremely short rise time, they need to be converted into a measurable voltage signal. Therefore, a discharge detection module 1 is designed. The detection head X is placed on the metal panel on the surface of the switch cabinet. Ground waves are introduced through the detection head X. Since ground waves can range from a few millivolts, a first transistor V1 and a second transistor V2 are designed for two-stage amplification to amplify the ground wave signal. After passing through the first diode D1, the signal is stored in the first capacitor C1. The first capacitor C1 stores the electrical energy of the amplified ground wave and outputs it through the second diode D2. The stronger the ground wave, the longer the voltage output time of the first capacitor C1 through the second diode D2; the weaker the ground wave, the shorter the voltage output time of the first capacitor C1 through the second diode D2. This allows the ground wave intensity to be measured.

[0048] In another embodiment: two transistors are used to amplify the ground wave signal, or an amplifier or other device can be used to amplify the ground wave signal.

[0049] In this embodiment: Please refer to Figure 3 The isolation feedback module 2 includes a third resistor R3, an optocoupler U1, a fourth resistor R4, a fifth resistor R5, a third MOSFET V3, a seventh resistor R7, and a second capacitor C2. One end of the third resistor R3 is connected to the output terminal of the discharge detection module 1, and another end of the third resistor R3 is connected to the first terminal of the optocoupler U1. The second terminal of the optocoupler U1 is grounded. The third terminal of the optocoupler U1 is connected to one end of the fourth resistor R4 and the gate (G) of the third MOSFET V3. The fourth terminal of the optocoupler U1 is grounded. The other end of the fourth resistor R4 is connected to the power supply voltage VCC. The source (S) of the third MOSFET V3 is connected to one end of the fifth resistor R5. The other end of the fifth resistor R5 is connected to the power supply voltage VCC. The drain (D) of the third MOSFET V3 is connected to one end of the seventh resistor R7. The other end of the seventh resistor R7 is connected to one end of the second capacitor C2, the input terminal of the alarm module 3, the input terminal of the discharge size indicator module 4, and the input terminal of the discharge digital indicator module 5. The other end of the second capacitor C2 is grounded.

[0050] When the first capacitor C1 outputs voltage through the second diode D2, it passes through the third resistor R3, causing the internal LED of the optocoupler U1 to light up. The internal phototransistor of the optocoupler U1 then conducts, causing the gate of the third MOSFET V3 (PMOS) to change from a high level to a low level. The third MOSFET V3 then conducts, and the supply voltage VCC charges the second capacitor C2 through the fifth resistor R5, the third MOSFET V3, and the seventh resistor R7. The stronger the ground wave, the longer the charging time of the second capacitor C2, and the greater the voltage on the second capacitor C2. Therefore, the magnitude of the voltage on the second capacitor C2 reflects the strength of the ground wave.

[0051] In another embodiment, optocoupler U1 can be omitted. Optocoupler U1 is set up for isolation, so that the output signal will not affect the input signal, thus ensuring the stability and independence of the signal.

[0052] In this embodiment: Please refer to Figure 3 The alarm module 3 includes a sixth resistor R6, a buzzer BUZZ, a fourth transistor V4, and a third diode D3. One end of the sixth resistor R6 is connected to the power supply voltage VCC, and the other end of the sixth resistor R6 is connected to one end of the buzzer BUZZ. The other end of the buzzer BUZZ is connected to the collector of the fourth transistor V4. The emitter of the fourth transistor V4 is connected to the anode of the third diode D3. The cathode of the third diode D3 is grounded. The base of the fourth transistor V4 is connected to the output terminal of the isolation feedback module 2. The third diode D3 is a light-emitting diode.

[0053] When the voltage across the second capacitor C2 is sufficient to turn on the fourth transistor V4, it indicates that there is a partial discharge in the current switch cabinet. After the fourth transistor V4 turns on, the buzzer BUZZ sounds as a warning, and the third diode D3 illuminates as an indicator.

[0054] In another embodiment, the buzzer can be replaced by a sound prompting device such as a voice chip.

[0055] In this embodiment: Please refer to Figure 2 and Figure 4 The discharge size indicator module 4 includes multiple discharge size indicator units 41, which are connected in parallel.

[0056] In this embodiment: Please refer to Figure 4 The discharge magnitude indicator unit 41 includes a fourth diode D4, an eighth resistor R8, a first Zener diode Z1, and a seventh diode D7. The positive terminal of the fourth diode D4 is connected to the output terminal of the isolation feedback module 2, the negative terminal of the fourth diode D4 is connected to one end of the eighth resistor R8, the other end of the eighth resistor R8 is connected to the negative terminal of the first Zener diode Z1, the positive terminal of the first Zener diode Z1 is connected to the positive terminal of the seventh diode D7, and the negative terminal of the seventh diode D7 is grounded. The rated voltages of the Zener diodes in different discharge magnitude indicator units 41 are different, and the seventh diode D7 is a light-emitting diode.

[0057] To clearly indicate the magnitude of the ground wave (the intensity of partial discharge in the switchgear), a discharge magnitude indicator module 4 is provided, which contains multiple discharge magnitude indicator units 41. Figure 2 , Figure 4The middle section contains three discharge magnitude indication units 41, which are used as an example here. It should be noted that the second capacitor C2 is directly connected to the base of the fourth transistor V4, so the alarm module 3 operates before the discharge magnitude indication units 41.

[0058] As the second capacitor C2 charges, its voltage gradually increases, leading to an increase in the voltage at the common point A1. Since the rated voltage of the first Zener diode Z1 is less than the rated voltage of the second Zener diode Z2, which is less than the rated voltage of the third Zener diode Z3, the first Zener diode Z1 will conduct first. As charging continues, the second Zener diode Z2 will then conduct, and finally, the third Zener diode Z3 will also conduct. After the Zener diodes conduct, the LEDs connected in series (the seventh diode D7, the eighth diode D8, and the ninth diode D9) will also emit light. Therefore, by observing the number of LEDs, the magnitude of the current ground wave can be determined.

[0059] In another embodiment: For example, three discharge size indicator units 41 are used, but the number of discharge size indicator units 41 is not limited in actual use.

[0060] In this embodiment: Please refer to Figure 5 The discharge digital indicator module 5 includes a tenth diode D10 and a voltmeter V. The positive terminal of the tenth diode D10 is connected to the output terminal of the isolation feedback module 2, and the negative terminal of the tenth diode D10 is connected to one end of the voltmeter V. The other end of the voltmeter V is grounded.

[0061] Similarly, in order to clearly indicate the magnitude of the ground wave (the intensity of partial discharge in the switchgear), a discharge digital indicator module 5 is set up. The magnitude of the ground wave can be observed by reading the pointer of the voltmeter V.

[0062] In another embodiment, the common point A1 can also be connected to a microcontroller, which is connected to a display screen. After the voltage signal of the common point A1 is processed by the microcontroller, a specific number is displayed on the display screen to show the magnitude of the ground wave, thereby replacing the voltmeter V.

[0063] In this embodiment: Please refer to Figure 6 The pressure relief control module 6 includes an eleventh resistor R11, a first relay J1, an eleventh diode D11, and multiple transistors. The transistors are phototransistors. The number of transistors corresponds to the discharge size indicator unit 41. The base of each transistor only receives light from the LED of the corresponding discharge size indicator unit 41 (unaffected by other LEDs). The emitter of the previous transistor is connected to the collector of the next transistor.

[0064] One end of the eleventh resistor R11 is connected to the power supply voltage VCC, and the other end of the eleventh resistor R11 is connected to one end of the first relay J1 and the negative terminal of the eleventh diode D11. The other end of the first relay J1 is connected to the positive terminal of the eleventh diode D11, the output terminal of the delay drive module 7, and the collector of the first transistor. The emitter of the last transistor is grounded.

[0065] The range of ground waves is usually between a few millivolts and a few volts, and the rise time is extremely short. Therefore, a two-stage discharge system with a first transistor V1 and a second transistor V2 is designed to ensure that the voltage on the first capacitor C1 is sufficient to drive the optocoupler U1 when the ground wave is a few millivolts. However, when the ground wave is large (a few volts), in order to ensure the acquisition of the ground wave, only a third resistor R3 is set on the output side of the first capacitor C1. When the voltage is continuously input, the power cannot be consumed in time, and there is a possibility that the voltage on the first capacitor C1 will accumulate to a large extent, which may damage the circuit.

[0066] Taking the discharge magnitude indicator unit 41 as an example again, when the first capacitor C1 continuously drives the optocoupler U1, causing the voltage of the second capacitor C2 to continuously rise, resulting in the seventh diode D7, the eighth diode D8, and the ninth diode D9 all emitting light (assuming that the voltage accumulation on the first capacitor C1 is large), the corresponding phototransistors (the fifth transistor V5, the sixth transistor V6, and the seventh transistor V7 in sequence) are all turned on. When all the LEDs of the discharge magnitude indicator unit 41 are lit, all the phototransistors of the voltage relief control module 6 are also turned on, the first relay J1 is energized and works, controlling the voltage relief module 8 to work, releasing the voltage on the first capacitor C1, and preventing the voltage accumulation on the first capacitor C1 from damaging the circuit.

[0067] In another embodiment: the supply voltage VCC is a stable voltage, which can be obtained through devices such as voltage regulators.

[0068] In this embodiment: Please refer to Figure 6The delay drive module 7 includes a twelfth resistor R12, a ninth transistor V9, a thirteenth resistor R13, a third capacitor C3, an eighth MOSFET V8, and a twelfth diode D12. One end of the twelfth resistor R12 is connected to the power supply voltage VCC, and the other end of the twelfth resistor R12 is connected to the collector of the ninth transistor V9. The ninth transistor V9 is a phototransistor, and its base only receives light from the third diode D3 (unaffected by other light-emitting diodes). The emitter of the ninth transistor V9 is connected to one end of the thirteenth resistor R13, and the other end of the thirteenth resistor R13 is connected to one end of the third capacitor C3 and the gate (G) of the eighth MOSFET V8. The other end of the third capacitor C3 is grounded. The drain (D) of the eighth MOSFET V8 is connected to the second input terminal of the voltage relief control module 6. The source (S) of the eighth MOSFET V8 is connected to the anode of the twelfth diode D12, and the cathode of the twelfth diode D12 is grounded. The twelfth diode D12 is a light-emitting diode.

[0069] Under normal conditions, when the accumulated voltage on the first capacitor C1 is too high, all the LEDs of the discharge size indicator unit 41 will light up, all the phototransistors of the pressure relief control module 6 will also be turned on, and the first relay J1 will be energized to relieve the voltage on the first capacitor C1. However, there is a possibility that the discharge size indicator unit 41 or the phototransistor of the pressure relief control module 6 may malfunction. At this time, the voltage on the first capacitor C1 will accumulate, which may damage the circuit. Therefore, the delay drive module 7 is set up.

[0070] When alarm module 3 is working, the third diode D3 illuminates, causing the ninth transistor V9 to conduct and charge the third capacitor C3. When the accumulated voltage on the first capacitor C1 is too high; under normal conditions (all the LEDs of the discharge size indicator unit 41 are illuminating, and all the phototransistors of the pressure relief control module 6 are also conducting), after the first relay J1 works, the first capacitor C1 discharges voltage, and when alarm module 3 is not working, the voltage on the third capacitor C3 is gradually consumed; under abnormal conditions (when at least one of the discharge size indicator unit 41 or the phototransistor of the pressure relief control module 6 fails), the third capacitor C3 continues to charge until it is charged enough to conduct the eighth MOS transistor V8 (NMOS). The first relay J1 forms a circuit through the eighth MOS transistor V8 and the twelfth diode D12, and the first relay J1 is energized and works, controlling the pressure relief module 8 to discharge the voltage of the first capacitor C1, thus providing protection.

[0071] In another embodiment: the twelfth diode D12 can be omitted. Here, the twelfth diode D12, the third diode D3, the seventh diode D7, the eighth diode D8, and the ninth diode D9 serve as indicators to facilitate the determination of whether there is a fault in the circuit.

[0072] When the accumulated voltage on the first capacitor C1 is normal, the third diode D3 lights up, and among the seventh diode D7, the eighth diode D8, and the ninth diode D9, at most the seventh diode D7 and the eighth diode D8 light up.

[0073] When the accumulated voltage on the first capacitor C1 is too high and it is working normally, the third diode D3 lights up, and the seventh diode D7, the eighth diode D8, and the ninth diode D9 also light up.

[0074] When the accumulated voltage on the first capacitor C1 is too high and it is working abnormally, the third diode D3 lights up, and the seventh diode D7, the eighth diode D8, and the ninth diode D9 do not all light up. At this time, the twelfth diode D12 lights up, which can indicate that the discharge size indicator unit 41 is faulty.

[0075] When the accumulated voltage on the first capacitor C1 is too high and it is working abnormally, the third diode D3 lights up, and the seventh diode D7, the eighth diode D8, and the ninth diode D9 all light up. At this time, the twelfth diode D12 lights up, which can indicate the fault of the phototransistor in the pressure relief control module 6.

[0076] The third diode D3 does not emit light, and one of the seventh diode D7, the eighth diode D8, and the ninth diode D9 emits light, indicating a fault in the alarm module 3. This allows for timely handling of the alarm module 3 and prevents the delay drive module 7 from failing to operate when at least one of the phototransistors in the discharge magnitude indicator unit 41 or the pressure relief control module 6 is faulty.

[0077] In this embodiment: Please refer to Figure 7 The pressure relief module 8 includes a first switch S1 and a second switch S2. One end of the first switch S1 is connected to one end of the second switch S2 and the input terminal of the discharge detection module 1. The other end of the first switch S1 is grounded, and the other end of the second switch S2 is grounded.

[0078] When the first relay J1 is working, the first switch S1 is closed, grounding the common point A2, and the first capacitor C1 is quickly discharged to prevent voltage accumulation from damaging the circuit. The second switch S2 is a manual switch, allowing the user to manually control the protection circuit.

[0079] In another embodiment: Here, the first capacitor C1 is automatically discharged by controlling whether the first switch S1 is closed by the first relay J1, or the first capacitor C1 can be discharged by controlling the switching transistor (transistor, MOSFET, IGBT, etc.) by an electrical signal.

[0080] The working principle of this invention is as follows: Discharge detection module 1 detects the ground wave generated by partial discharge in the switchgear, converts it into a stable voltage through the first capacitor C1, obtains a detection signal, and outputs it to the isolation feedback module 2; the stronger the ground wave (the greater the partial discharge intensity of the switchgear), the longer the discharge detection module 1 outputs the detection signal to the isolation feedback module 2; when the isolation feedback module 2 receives the detection signal, it charges the second capacitor C2. The voltage on the second capacitor C2 varies depending on the charging time; based on the voltage on the second capacitor C2, it selects whether to activate the alarm module 3 and discharge. The system includes: a magnitude indicator module 4; an alarm module 3 for alerting the switchgear to detect partial discharge during operation; a discharge magnitude indicator module 4 for displaying the intensity of partial discharge by observing whether the LEDs are lit; a discharge digital indicator module 5 for detecting the voltage across the second capacitor C2; a pressure relief control module 6 for controlling the pressure relief module 8 to operate when all LEDs in the discharge magnitude indicator module 4 are lit; a delay drive module 7 for directly driving the pressure relief control module 6 to operate when the alarm module 3's operating time reaches a set value; and a pressure relief module 8 for controlling the first capacitor C1 to ground and release pressure during operation.

[0081] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and not restrictive.

[0082] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A partial discharge detection circuit for switchgear, characterized in that, The partial discharge detection circuit of the switchgear includes: The discharge detection module is used to detect the ground wave generated by partial discharge in the switchgear. It converts the ground wave into a stable voltage through the first capacitor to obtain a detection signal, which is then output to the isolation feedback module. The stronger the ground wave, the longer the discharge detection module outputs the detection signal to the isolation feedback module. The isolation feedback module is used to charge the second capacitor when a detection signal is received. The voltage on the second capacitor varies depending on the charging time. Based on the voltage on the second capacitor, the module selects whether to drive the alarm module and the discharge magnitude indicator module. The alarm module is used to alert the switchgear to partial discharge during operation. The discharge magnitude indicator module is used to display the magnitude of partial discharge intensity of the switchgear by whether or not the LED is lit during operation; A discharge digital indicator module is used to detect the voltage across the second capacitor; The pressure relief control module is used to control the operation of the pressure relief module when all the LEDs of the discharge size indicator module are lit. The delay drive module is used to directly drive the pressure relief control module to work when the alarm module's working time reaches a set value; The pressure relief module is used to control the grounding and pressure relief of the first capacitor during operation. The output of the discharge detection module is connected to the input of the isolation feedback module. The output of the isolation feedback module is connected to the input of the alarm module, the input of the discharge size indicator module, and the input of the discharge digital indicator module. The output of the discharge size indicator module is connected to the first input of the pressure relief control module. The output of the alarm module is connected to the input of the delay drive module. The output of the delay drive module is connected to the second input of the pressure relief control module. The output of the pressure relief control module is connected to the input of the pressure relief working module. The output of the pressure relief working module is connected to the input of the discharge detection module. The discharge detection module includes a detection head, a first resistor, a second resistor, a first transistor, a second transistor, a first diode, a first capacitor, and a second diode. The detection head is connected to the base of the first transistor. The collector of the first transistor is connected to one end of the first resistor, and the other end of the first resistor is connected to the power supply voltage. The emitter of the first transistor is connected to the base of the second transistor. The collector of the second transistor is connected to one end of the second resistor, and the other end of the second resistor is connected to the power supply voltage. The emitter of the second transistor is connected to the anode of the first diode. The cathode of the first diode is connected to one end of the first capacitor, the anode of the second diode, and the output terminal of the voltage relief module. The other end of the first capacitor is grounded. The cathode of the second diode is connected to the input terminal of the isolation feedback module.

2. The partial discharge detection circuit for switchgear according to claim 1, characterized in that, The isolation feedback module includes a third resistor, an optocoupler, a fourth resistor, a fifth resistor, a third MOSFET, a seventh resistor, and a second capacitor. One end of the third resistor is connected to the output terminal of the discharge detection module, and another end of the third resistor is connected to the first terminal of the optocoupler. The second terminal of the optocoupler is grounded. The third terminal of the optocoupler is connected to one end of the fourth resistor and the gate (G) of the third MOSFET. The fourth terminal of the optocoupler is grounded. The other end of the fourth resistor is connected to the power supply voltage. The source (S) of the third MOSFET is connected to one end of the fifth resistor. The other end of the fifth resistor is connected to the power supply voltage. The drain (D) of the third MOSFET is connected to one end of the seventh resistor. The other end of the seventh resistor is connected to one end of the second capacitor, the input terminal of the alarm module, the input terminal of the discharge magnitude indicator module, and the input terminal of the discharge digital indicator module. The other end of the second capacitor is grounded.

3. The partial discharge detection circuit for switchgear according to claim 1, characterized in that, The alarm module includes a sixth resistor, a buzzer, a fourth transistor, and a third diode. One end of the sixth resistor is connected to the power supply voltage, and the other end of the sixth resistor is connected to one end of the buzzer. The other end of the buzzer is connected to the collector of the fourth transistor. The emitter of the fourth transistor is connected to the anode of the third diode. The cathode of the third diode is grounded. The base of the fourth transistor is connected to the output of the isolation feedback module. The third diode is a light-emitting diode.

4. The partial discharge detection circuit for switchgear according to any one of claims 1 to 3, characterized in that, The discharge size indication module includes multiple discharge size indication units, which are connected in parallel.

5. The partial discharge detection circuit for switchgear according to claim 4, characterized in that, The discharge magnitude indicator unit includes a fourth diode, an eighth resistor, a first Zener diode, and a seventh diode. The positive terminal of the fourth diode is connected to the output terminal of the isolation feedback module, the negative terminal of the fourth diode is connected to one end of the eighth resistor, the other end of the eighth resistor is connected to the negative terminal of the first Zener diode, the positive terminal of the first Zener diode is connected to the positive terminal of the seventh diode, and the negative terminal of the seventh diode is grounded. The rated voltage of the Zener diodes in different discharge magnitude indicator units is different, and the seventh diode is a light-emitting diode.

6. The partial discharge detection circuit for switchgear according to claim 1, characterized in that, The discharge digital indicator module includes a tenth diode and a voltmeter. The positive terminal of the tenth diode is connected to the output terminal of the isolation feedback module, the negative terminal of the tenth diode is connected to one end of the voltmeter, and the other end of the voltmeter is grounded.

7. The partial discharge detection circuit for switchgear according to claim 5, characterized in that, The pressure relief control module includes an eleventh resistor, a first relay, an eleventh diode, and multiple transistors. The transistors are phototransistors. The number of transistors corresponds to the discharge size indicator unit. The base of each transistor only receives light from the LED of the corresponding discharge size indicator unit. The emitter of the previous transistor is connected to the collector of the next transistor. One end of the eleventh resistor is connected to the power supply voltage, the other end of the eleventh resistor is connected to one end of the first relay and the negative terminal of the eleventh diode, the other end of the first relay is connected to the positive terminal of the eleventh diode, the output terminal of the delay drive module, and the collector of the first transistor, and the emitter of the last transistor is grounded.

8. The partial discharge detection circuit for switchgear according to claim 3, characterized in that, The delay drive module includes a twelfth resistor, a ninth transistor, a thirteenth resistor, a third capacitor, an eighth MOSFET, and a twelfth diode. One end of the twelfth resistor is connected to the power supply voltage, and the other end is connected to the collector of the ninth transistor (a phototransistor). The base of the ninth transistor only receives light from the third diode. The emitter of the ninth transistor is connected to one end of the thirteenth resistor, and the other end of the thirteenth resistor is connected to one end of the third capacitor and the gate (G) of the eighth MOSFET. The other end of the third capacitor is grounded. The drain (D) of the eighth MOSFET is connected to the second input terminal of the voltage relief control module. The source (S) of the eighth MOSFET is connected to the anode of the twelfth diode, and the cathode of the twelfth diode is grounded. The twelfth diode is a light-emitting diode.

9. The partial discharge detection circuit for switchgear according to claim 1, characterized in that, The pressure relief module includes a first switch and a second switch. One end of the first switch is connected to one end of the second switch and the input terminal of the discharge detection module. The other end of the first switch is grounded, and the other end of the second switch is grounded.

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