CN109932625A - Optical partial discharge sensing device and partial discharge detection method - Google Patents

Abstract

The invention provides an optical partial discharge sensing device and a partial discharge detection method. The optical partial discharge sensing device includes a light source, an optical current sensing probe and a signal processing display terminal; the optical current sensing probe includes an optical fiber collimator, a polarizer, a magneto-optical crystal, a polarization beam splitter and a dual optical fiber A coupler; the signal processing display terminal includes an adjustable optical attenuator, a balanced detector, a filter circuit, an amplifier circuit, a data acquisition card and a PC. Compared with the all-fiber current sensor, the optical current sensor based on the magneto-optical crystal in the present invention has the characteristics of high Verdet constant and low absorption coefficient, which is easy to realize high-sensitivity pulse current sensing, and also has the structure Simple and easy to miniaturize. By using the optical partial discharge sensing device of the present invention, partial discharge detection can be performed on cables or electrical equipment without power failure of the electrical equipment.

Description

Optical partial discharge sensing device and partial discharge detection method

technical field

The invention relates to the field of on-line monitoring of electric power and electrical equipment, in particular to an optical partial discharge sensing device and a partial discharge detection method.

Background technique

With the development of industry and social progress, the power system is developing in the direction of large capacity, ultra-high voltage and ultra-high voltage, and the requirements for system operation reliability are getting higher and higher. Partial discharge (referred to as partial discharge) is one of the important factors affecting the normal operation of power equipment. one. The detection of partial discharge can reflect the insulation status of power equipment in advance, detect internal insulation defects in time, and prevent latent and sudden accidents, which is of great significance to ensure the safe and stable operation of power systems. When partial discharge occurs in electrical equipment, it usually produces current pulses, electromagnetic radiation, ultrasonic waves, optical radiation, and decomposition to produce new substances, which can cause local overheating. Therefore, according to the different physical and chemical processes generated by partial discharge, the detection methods include pulse current method, radio frequency method, ultra-high frequency method, ultrasonic detection method, chemical detection method, infrared thermal imaging method and optical detection method which has emerged in recent years.

The pulse current method based on Rogowski coil detects the pulse current generated by the partial discharge through the coupling capacitor, thereby judging the intensity of the partial discharge, which is the most commonly used detection method. The radio frequency detection method uses radio frequency sensors to detect partial discharge, and excites electromagnetic signals in the frequency range of 1~30MHz, and obtains the partial discharge amount through subsequent circuit processing. These two methods can quantitatively detect partial discharge, but the anti-electromagnetic interference ability is poor, which is not suitable for online monitoring. The ultra-high frequency detection method uses the high-frequency signal of 300~3000MHz to detect partial discharge, and the ultrasonic detection method uses the ultrasonic signal generated when the ultrasonic sensor detects the partial discharge to detect the partial discharge. These two methods have the advantages of strong anti-electromagnetic interference ability and can locate the partial discharge source, but cannot calibrate the partial discharge quantity. The optical current sensor detection method has the advantages of fast response speed, large dynamic range, strong anti-electromagnetic interference ability, and reliable performance. Tianjin University, China University of Mining and Technology and other units have developed an all-fiber structure fiber optic current partial discharge sensor, but the sensitivity of the system needs to be further improved.

SUMMARY OF THE INVENTION

One of the objectives of the present invention is to provide an optical partial discharge sensing device, so as to improve the detection sensitivity of the optical fiber current partial discharge sensor with an all-fiber structure, and to realize high sensitivity, high reliability, high response speed, and anti-electromagnetic interference of partial discharge information. detection.

Another object of the present invention is to provide a method for detecting partial discharge using the above-mentioned optical partial discharge sensing device.

One of the objectives of the present invention is achieved as follows: an optical partial discharge sensing device, comprising a light source, an optical current sensing probe and a signal processing display terminal;

The optical current sensing probe includes a fiber collimator, a polarizer, a magneto-optical crystal, a polarization beam splitter and a double fiber coupler; the signal processing display terminal includes an adjustable optical attenuator, a balanced detector, and a filter circuit , amplifier circuit, data acquisition card and PC;

The light emitted by the light source is collimated by the optical fiber collimator and then incident on the polarizer. After passing through the polarizer, it becomes linearly polarized light. The linearly polarized light is incident on the magneto-optical crystal, and the The light emitted from the optical crystal passes through the polarization beam splitter into a beam 1 and a beam 2 whose vibration directions are perpendicular to each other, and the beam 1 and the beam 2 are transmitted to the signal processing display terminal through the double fiber coupler;

The output end of the double-fiber coupler is connected to the transmission fiber, and the light beam is connected to the balanced detector after passing through the double-fiber coupler and the transmission fiber; the second beam is connected to the balanced detector after passing through the double-fiber coupler, the transmission fiber and the adjustable optical attenuator; The balanced detector is used to convert the optical signal into a voltage signal. The balanced detector outputs two voltage signals and transmits them to the filter circuit through the coaxial cable. The signal output by the filter circuit is collected by the data acquisition card after being amplified by the circuit. , The data acquisition card transmits the collected data to the PC, and the PC performs signal processing and realizes the output display of the waveform and intensity of the partial discharge signal.

Preferably, the light source is a broadband light source, and its center wavelength is 1310 nm.

Preferably, the balanced detector, the filter circuit, the amplifying circuit and the data acquisition card are sequentially connected through a coaxial cable, and the impedance of the coaxial cable is 50 ohms.

The use of the optical partial discharge sensing device can perform partial discharge detection on cables or electrical equipment. During the detection, the optical current sensing probe is placed on the central axis of a helical coil, and the partial discharge generated by the partial discharge occurs in the cable or electrical equipment. A pulsed current is passed through the helical coil, which is connected to the ground lead.

The second purpose of the present invention is achieved in this way: a partial discharge detection method, comprising the following steps:

a. Wind the wire on a cylindrical surface, and then remove the cylindrical surface to form a spiral coil;

b. The optical current sensing probe is built into the central axis of the helical coil; the optical current sensing probe includes a fiber collimator, a polarizer, a magneto-optical crystal, a polarization beam splitter and a double fiber coupler;

A light source is arranged in front of the optical current sensing probe, and a signal processing display terminal is arranged behind the optical current sensing probe. The signal processing display terminal includes an adjustable optical attenuator, a balanced detector, a filter circuit, an amplifier circuit, Data acquisition card and PC;

c. One end of the spiral coil is connected to the grounding end of the cable or electrical equipment, and the other end is connected to the grounding lead; the pulse current generated by the partial discharge of the cable or electrical equipment will pass through the spiral coil;

d. The light emitted by the light source is collimated by the fiber collimator and then incident on the polarizer. After passing through the polarizer, it becomes linearly polarized light. The linearly polarized light is incident on the magneto-optical crystal. The polarization plane of the linearly polarized light of the magneto-optical crystal is deflected, and then becomes two beams of light whose vibration directions are perpendicular to each other through the polarization beam splitter; one of the two beams of light is directly connected to the balance detector through the double fiber coupler, and the other A beam of light is connected to a balanced detector through a dual fiber coupler and an adjustable optical attenuator; the balanced detector converts the optical signal into a voltage signal, and outputs two voltage signals to the filter circuit, and the signal output by the filter circuit is amplified After the circuit is collected by the data acquisition card, the data acquisition card transmits the collected data to the PC, and the PC performs signal processing and realizes the output display of the waveform and intensity of the partial discharge signal.

The optical current sensor (or optical current sensing probe) based on the magneto-optical crystal in the present invention, compared with the all-fiber current sensor, the magneto-optical crystal has the characteristics of high Verdet constant, low absorption coefficient, etc., and is easy to achieve high sensitivity Pulse current sensing also has the characteristics of simple structure and easy miniaturization.

The optical partial discharge sensing device provided by the present invention performs partial discharge sensing of the cable based on the detection principle of the pulse current method. The wires of the cable and the metal shielding layer are separated by an insulating layer to form a distributed capacitance, and the capacitance is only a few hundred picofarads. , it is a good conductor for high frequency signals. Therefore, the high-frequency partial discharge signal is transmitted by the distributed capacitance and the grounding lead. Installing an optical partial discharge sensing device on the shielded grounding wire at the cable joint can detect the discharge current pulse signal of the cable and determine the amount of partial discharge. value.

The partial discharge detection of electrical equipment such as high-voltage switch cabinets by the optical partial discharge sensing device can be detected based on the ground wave detection method or the pulse current method. The ground wave method uses capacitive probes to couple the electromagnetic waves generated by partial discharge, and the optical partial discharge sensing device obtains characteristic parameters such as the amplitude and number of pulses of the ground wave signal. The above parameters can be used to evaluate the partial discharge degree of electrical equipment such as high-voltage switch cabinets. . The pulse current method is similar to the partial discharge measurement of the above-mentioned cables. The partial discharge signal measurement is realized by monitoring the current of the ground wire of electrical equipment such as switch cabinets. When installing the optical partial discharge sensing device of the present invention, it is not necessary to power off the electrical equipment.

Compared with other existing devices, the present invention has the following advantages:

1) The magneto-optical crystal probe has high sensitivity, fast response speed, small size, flexible arrangement, and can go deep into the power equipment for detection without affecting its working state.

2) The optical fiber is used as the signal transmission carrier, and the anti-electromagnetic interference ability is strong.

3) The main material of the optical current sensor based on magneto-optical crystal is SiO ₂ , which has excellent insulation performance, and this advantage is particularly prominent in ultra-high voltage and ultra-high voltage power systems.

4) It is easy to realize digitization and connect to the smart grid.

Description of drawings

FIG. 1 is a schematic structural diagram of an optical partial discharge sensing device provided by the present invention.

FIG. 2 is a schematic diagram of detecting cable partial discharge based on the pulse current method using the optical partial discharge sensing device of the present invention.

3 is a schematic diagram of detecting partial discharge in a switch cabinet based on the pulse current method using the optical partial discharge sensing device of the present invention.

FIG. 4 is a schematic diagram of detecting the partial discharge of the switch cabinet by using the optical partial discharge sensing device of the present invention based on the ground wave method.

In the figure: 1. Fiber collimator; 2. Polarizer; 3. Magneto-optical crystal; 4. Polarizing beam splitter; 5. Double fiber coupler; 6. Optical current sensing probe; 7. Signal processing display terminal 8. Spiral coil; 9. Conductor; 10. Insulation layer; 11. Metal shielding layer; 12. Signal coupling capacitance detector.

Detailed ways

Embodiment 1, an optical partial discharge sensing device.

As shown in FIG. 1 , the optical partial discharge sensing device provided by the present invention includes a light source, an optical current sensing probe 6 , and a signal processing display terminal 7 . The light source, the optical current sensing probe 6 and the signal processing and display terminal 7 are arranged in sequence.

The light source is a broadband light source with a center wavelength of 1310nm. At this wavelength, the fiber transmission loss is low and the transmission distance is long.

The optical current sensing probe 6 includes a fiber collimator 1 , a polarizer 2 , a magneto-optical crystal 3 , a polarization beam splitter 4 and a double fiber coupler 5 . The light emitted by the light source is collimated by the fiber collimator 1 and then incident on the polarizer 2. The light beam passes through the polarizer 2 and becomes linearly polarized light. After passing through the polarization beam splitter 4, the vibration directions become beam 1 and beam 2, and the beam 1 and beam 2 are input to the balanced detector in the signal processing display terminal 7 through the double fiber coupler 5 and the transmission fiber.

The signal processing display terminal 7 includes a variable optical attenuator (VOA), a balanced detector, a filter circuit, an amplifier circuit, a data acquisition card (DAQ) and a PC. The balanced detector, filter circuit, amplifier circuit and data acquisition card are connected in sequence through coaxial cable, and the connection impedance of the coaxial cable is 50 ohms. The double-fiber coupler 5 is connected to the transmission fiber, and the first beam is directly connected to the balanced detector through the transmission fiber; the second beam is connected to the balanced detector through the transmission fiber and the adjustable optical attenuator. An adjustable optical attenuator is added to the optical path to adjust the optical power. The balanced detector converts the optical signal into a voltage signal, and the two voltage signals output by the balanced detector are transmitted to the filter circuit through the coaxial cable, and the filter circuit is used to filter out the signal outside the frequency range of partial discharge. Since the partial discharge current signal is relatively weak, an amplifier circuit is required to amplify the signal, and the amplified voltage signal is transmitted to the data acquisition card, which then transmits the data to the PC. The PC is based on LabVIEW software programming to filter and algorithmically process the measured voltage signal to reduce the influence of noise and light source power fluctuations, obtain information such as the waveform and discharge amount of the partial discharge signal, and finally display the partial discharge signal through the PC output.

In the cable, the conductor and the metal shield are separated by an insulating layer to form a distributed capacitance, which is generally only a few hundred picofarads and is a good conductor for high-frequency signals. The partial discharge signal caused by cable deterioration is a high-frequency signal, which is transmitted in a loop formed by distributed capacitance and grounding lead. By detecting the discharge current pulse signal on the shielded grounding wire at the cable joint, the partial discharge signal of the cable can be sensed and can be determined. The magnitude of the partial discharge. As shown in Figure 2, the conductor 9 of the cable and the metal shielding layer 11 are separated by an insulating layer 10 to form a distributed capacitance. The partial discharge signal generated by the cable discharge is transmitted in the loop formed by the distributed capacitance and the grounding lead. The spiral coil 8 Connecting the ground lead, the optical current sensing probe 6 is located on the inner central axis of the helical coil 8 .

The discharge signal caused by the insulation deterioration of electrical equipment such as switchgear is an instantaneous pulse current. The optical partial discharge sensing device is used to measure the pulse current signal of the ground wire of the equipment to realize the sensing of the partial discharge signal inside the electrical equipment, which has higher sensitivity , Strong anti-electromagnetic interference ability, can realize long-term on-site live detection. As shown in Figure 3, the wire is wound on the cylindrical surface to form a spiral coil 8, and the spiral coil 8 is connected to the ground lead. When the pulse current generated by the partial discharge in the high-voltage switch cabinet passes through the spiral coil 8, it will be in the space around the coil. generate a magnetic field. According to the analysis of the magnetic field strength of the energized helical coil 8 , the magnetic field strength is the largest at the center of the helical coil 8 , so the optical current sensing probe 6 is built in the central axis of the helical coil 8 . Under the action of the magnetic field, the polarization plane of the linearly polarized light passing through the magneto-optical crystal 3 is deflected, and the measurement frequency band of the magneto-optical crystal 3 can reach 2 GHz. The light carrying the current information passes through the polarization beam splitter 4 and the light intensity changes. After signal processing , obtain the discharge current intensity and waveform.

The partial discharge signal test system using optical partial discharge sensing devices for electrical equipment such as switch cabinets is shown in Figure 4. The partial discharge signal generated inside the switch cabinet and other electrical equipment is coupled to the transmission through the signal coupling capacitor detector 12. In the sensing loop, the optical partial discharge sensing device measures the current pulse signal in the loop, and realizes the measurement of the waveform and intensity of the partial discharge signal of electrical equipment such as switch cabinets.

Embodiment 2, a partial discharge detection method.

a. Wind the wire on a cylindrical surface, and then remove the cylindrical surface to form a spiral coil.

b. The optical current sensing probe is built into the central axis of the helical coil; the optical current sensing probe includes a fiber collimator, a polarizer, a magneto-optical crystal, a polarization beam splitter and a double fiber coupler. A light source is arranged in front of the optical current sensing probe, and a signal processing display terminal is arranged behind the optical current sensing probe. The signal processing display terminal includes an adjustable optical attenuator, a balanced detector, a filter circuit, an amplifier circuit, Data acquisition card and PC.

c. Connect one end of the spiral coil to the grounding end of the cable or electrical equipment, and the other end to the grounding lead; the pulse current generated by partial discharge of the cable or electrical equipment will pass through the spiral coil.

d. The light emitted by the light source is collimated by the fiber collimator and then incident on the polarizer. The beam becomes linearly polarized light after passing through the polarizer. The linearly polarized light is incident on the magneto-optical crystal. Under the action of the energized helical coil, The polarization plane of the linearly polarized light passing through the magneto-optical crystal is deflected, and then becomes two beams of light whose vibration directions are perpendicular to each other through the polarization beam splitter; one of the two beams of light is directly connected to the balance detector through the double fiber coupler, The other beam of light is connected to the balanced detector after passing through the double fiber coupler and the adjustable optical attenuator; the balanced detector converts the optical signal into a voltage signal, and outputs two voltage signals to the filter circuit, and the signal output by the filter circuit is passed through. After the amplification circuit is collected by the data acquisition card, the data acquisition card transmits the collected data to the PC, and the PC performs signal processing and realizes the output display of the waveform and intensity of the partial discharge signal.

Claims (7)

1. a kind of optical profile type shelf depreciation sensing device, characterized in that including light source, optical current sensing probe and signal processing Display terminal；

The optical current sensing probe includes optical fiber collimator, the polarizer, magneto-optical crystal, polarization beam apparatus and double fiber couplings Device；The signal processing display terminal includes adjustable optical attenuator, balanced detector, filter circuit, amplifying circuit, data acquisition Card and PC machine；

The light that the light source issues is incident to the polarizer after collimating by the optical fiber collimator, after the polarizer As linearly polarized light, linearly polarized light is incident to the magneto-optical crystal, and the light of the magneto-optical crystal outgoing is using the polarization point Beam device becomes the mutually perpendicular light beam one of direction of vibration and light beam two, light beam one and light beam two to be transmitted through double fiber couplers To the signal processing display terminal；

The output end of double fiber couplers connects transmission fiber, and light beam is connected to flat after double fiber couplers and transmission fiber Weigh detector；Light beam two is connected to balanced detector after double fiber coupler, transmission fiber and adjustable optical attenuators；It is described Balanced detector is for converting optical signals to voltage signal, and the balanced detector output two-way voltage signal is through coaxial cable It is transmitted to filter circuit, is acquired after amplifying circuit by data collecting card by the signal that the filter circuit exports, data acquisition The collected data of institute are transmitted to PC machine by card, and PC machine carries out signal processing and realizes that the waveform of local discharge signal and intensity are big Small output is shown.

2. optical profile type shelf depreciation sensing device according to claim 1, characterized in that the light source is wideband light source, The wherein a length of 1310nm of cardiac wave.

3. optical profile type shelf depreciation sensing device according to claim 1, characterized in that the balanced detector, described Filter circuit, the amplifying circuit and the data collecting card are sequentially connected by coaxial cable, the impedance of the coaxial cable It is 50 ohm.

4. optical profile type shelf depreciation sensing device according to claim 1, characterized in that use the optical profile type shelf depreciation Sensing device can carry out Partial Discharge Detection to cable or electrical equipment, and when detection makes optical current sensing probe be placed in a helical On the central axis of shape coil, and makes cable or electrical equipment that the pulse current that shelf depreciation generates occur and pass through the scroll line Circle, the helical coil connect ground lead.

5. a kind of detection method for local discharge, characterized in that include the following steps:

A, conducting wire is wrapped on a cylindrical surface, removes cylindrical surface later, form helical coil；

B, optical current sensing probe is built on the central axis of helical coil；The optical current sensing probe includes Optical fiber collimator, the polarizer, magneto-optical crystal, polarization beam apparatus and double fiber couplers；

It is provided with light source in front of optical current sensing probe, the rear of optical current sensing probe is provided with signal processing Display terminal, the signal processing display terminal include adjustable optical attenuator, balanced detector, filter circuit, amplifying circuit, number According to capture card and PC machine；

C, make helical coil one end connecting cable or electrical equipment grounding end, the other end connects ground lead；Cable is electrical The pulse current that shelf depreciation generates, which occurs, for equipment can pass through helical coil；

D, the light that light source issues is incident to the polarizer after collimating by optical fiber collimator, becomes linearly polarized light, line after the polarizer Polarised light is incident to magneto-optical crystal, under the action of the helical coil of energization, passes through the polarization of the linearly polarized light of magneto-optical crystal Face deflects, and becomes the mutually perpendicular two-beam of direction of vibration by polarization beam apparatus；Light beam in the two-beam is through double Fiber coupler is directly connected to balanced detector, and another light beam is connected to balance after double fiber couplers and adjustable optical attenuator Detector；Balanced detector converts optical signals to voltage signal, and exports two-way voltage signal to filter circuit, by filtered electrical The signal of road output is acquired after amplifying circuit by data collecting card, and collected data are transmitted to PC machine by data collecting card, PC machine carries out signal processing and realizes that the waveform of local discharge signal and the output of intensity size are shown.

6. detection method for local discharge according to claim 5, characterized in that the light source is wideband light source, center Wavelength is 1310nm.

7. detection method for local discharge according to claim 5, characterized in that the balanced detector, the filtered electrical Road, the amplifying circuit and the data collecting card are sequentially connected by coaxial cable, and the impedance of the coaxial cable is 50 Europe Nurse.