Weak electric signal transmission line for dry-type reactor turn-to-turn insulation detection

Abstract

The application discloses a weak electric signal transmission line for dry-type electric reactor turn-to-turn insulation detection, which comprises a transmission line bearing body, the outer surface of the transmission line bearing body is wound with a wire, the wire is periodically and repeatedly wound in an alternating and continuous mode of forward winding and reverse winding on the surface of the transmission line bearing body, and an insulation encapsulation layer is encapsulated on the outer surface of the transmission line after winding. The transmission line greatly reduces and offsets the induced voltage in a strong electromagnetic environment, the electromagnetic interference noise of the environment cannot affect the weak electric signal of the thermistor wire and the thermoelectric couple wire, meanwhile, the inductance characteristics of the spiral solenoid type structure can effectively filter out alternating current and high frequency signal interference, and further fundamentally ensure the signal transmission accuracy and stability of the transmission line. The application is suitable for the field of online monitoring low frequency (or direct current) and weak electric signal transmission of power grids and power systems under complex electromagnetic environments and with high reliability requirements.

Description

TECHNICAL FIELD

[0001] The present application relates to a signal transmission line, more particularly to a weak electric signal transmission line for dry-type reactor turn-to-turn insulation detection. BACKGROUND

[0002] Due to the construction of large-capacity power grids, dry-type reactors of 35kV or above power systems are generally operated outdoors, and their working conditions are harsh, being in a strong electromagnetic interference environment. In order to ensure the reliable operation of the equipment, on-line detection of parameters reflecting the operating state of turn-to-turn insulation (such as temperature, voltage, current, phase, etc.) is widely used for real-time monitoring.

[0003] Taking a temperature detection sensor as an example, the thermistor and thermocouple temperature sensing method (patent numbers CN105587679A and CN201464067U) utilizes the characteristics of thermistors and thermocouples to generate changes in the resistance and voltage of the loop to represent the temperature value and its change at the location. Near 100℃, the resistance change rate of the thermistor is about ~35Ω / ℃, the resistance change rate of pt100 is about 0.38Ω / ℃, and the potential (voltage) change range of the thermocouple is about ~0.04mV / ℃. Taking a 35kV dry-type air-core reactor as an example, the induced voltage at the transmission line port is about 0.3-3V. Therefore, in a high-voltage and strong electromagnetic environment, the weak electric signal generated by the sensor is inevitably strongly interfered and affected in the transmission process, thereby resulting in that the signal detection accuracy and reliability cannot be guaranteed.

[0004] Therefore, how to improve the anti-electromagnetic interference capability of the signal transmission device is a key technology for realizing the monitoring of the operating state of the power grid. The currently used methods mainly include two types: 1. Shielded cable: using an outer metal tube or mesh to shield electromagnetic interference, but due to the eddy current heating bringing high temperature and insulation failure, it is not suitable for strong electromagnetic environments; 2. Twisted pair: using differential to eliminate common-mode interference signals, but in a strong electromagnetic environment, the common-mode induced voltage sharply rises, which is easy to discharge and destroy the electrical insulation of the signal receiving device, affecting the reliability of signal transmission. SUMMARY

[0005] In order to solve the problems existing in the above-mentioned technologies, the present application provides a weak electric signal transmission line for dry-type reactor turn-to-turn insulation detection.

[0006] The application is realized by the following technical scheme: a weak electric signal transmission line for dry-type electric reactor turn-to-turn insulation detection, comprising a transmission line force body, the outer surface of the transmission line force body is wound with a wire, the wire is periodically wound in an alternating and continuous way of forward winding and reverse winding on the surface of the transmission line force body, the number of turns and the turn density of the forward winding and the reverse winding are the same, one forward winding section and one reverse winding section form a winding unit, and an insulation encapsulating layer is encapsulated on the outer surface of the transmission line after winding.

[0007] In the above scheme, the transmission line force body is a flexible insulation core wire, and the material of the flexible insulation core wire can be PVC wire, nylon wire, polytetrafluoroethylene wire, glass fiber bundle wire or pipe.

[0008] In the above scheme, the wire adopts double wires or multi-wires with an insulation layer and without magnetic conduction, and the double wires or multi-wires can be twisted wires or parallel wires.

[0009] In the above scheme, the material of the wire is copper or aluminum, and the diameter of the wire is 0.1mm-2mm.

[0010] In the above scheme, the turn density of the wire winding is 2-100 turns / cm.

[0011] In the above scheme, the total number of turns of the winding unit is 2-100 turns.

[0012] In the above scheme, the diameter of the flexible insulation core wire is 0.5-15mm.

[0013] In the above scheme, the material of the insulation encapsulating layer is a heat shrink tube, PVC, nylon, glass fiber bundle, polytetrafluoroethylene or other insulation sleeve, and the wall thickness of the insulation sleeve is 0.01-2mm.

[0014] Compared with the prior art, the weak electric signal transmission line for dry-type electric reactor turn-to-turn insulation detection has the following beneficial effects:

[0015] 1. The equal number of turns (similar number of turns) forward winding and reverse winding structure unit is periodically wound, the induced voltages generated by the transmission line body in the electromagnetic environment are offset to each other to realize the self-compensation effect of 0 induced voltage;

[0016] 2. The double wires are parallel wound or the twisted wires are parallel wound to form a self-difference form to eliminate external electromagnetic interference;

[0017] 3. The wire is wound in a solenoid way to filter out alternating current and high frequency signals by using the inductance characteristics of itself, so that the stable and reliable transmission of low frequency or direct current type weak electric signal can be realized.

[0018] 4. Compared with the conventional shielding line structure, the application has no eddy current effect and is suitable for weak electric signal transmission in a strong electromagnetic environment.

[0019] 5The application is more secure to signal back-end processing device without electromagnetic induction voltage compared with conventional twisted pair structure, and has good shielding and filtering effect on AC and high frequency signals. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is the structural diagram of the weak electric signal transmission line for turn-to-turn insulation detection of the dry-type electric reactor.

[0021] Figure 2 is the anti-electromagnetic interference experimental data diagram of the transmission line for air channel temperature measurement between dry-type air-core electric reactor enclosures.

[0022] Figure 3 is the anti-electromagnetic interference experimental data diagram of the transmission line for core upper yoke temperature measurement of dry-type core electric reactor.

[0023] In the figure: 1. Insulation encapsulation layer, 2. Transmission line force bearing body, 3. Forward winding wire, 4. Reverse winding wire, 5. Forward winding section, 6. Reverse winding section. DETAILED DESCRIPTION

[0024] The weak electric signal transmission line for turn-to-turn insulation detection of the dry-type electric reactor will be further described below in combination with the drawings and specific embodiments:

[0025] Figure 1 is the structural diagram of the weak electric signal transmission line for turn-to-turn insulation detection of the dry-type electric reactor. In the figure, the weak electric signal transmission line for turn-to-turn insulation detection of the dry-type electric reactor includes a transmission line force bearing body 2, the outer surface of which is wound with forward winding wires 3 and reverse winding wires 4. The wires are periodically and repeatedly wound in an alternating and continuous manner of forward winding and reverse winding on the surface of the transmission line force bearing body, and the number of turns and the turn density of the forward winding section 5 and the reverse winding section 6 are the same. One forward winding section 5 and one reverse winding section 6 form a winding unit, and the outer surface of the wound transmission line is encapsulated with an insulation encapsulation layer 1. The transmission line force bearing body 2 is a flexible insulation core wire, and the material of the flexible insulation core wire can be PVC wire, nylon wire, polytetrafluoroethylene wire, glass fiber bundle wire or pipe. The forward winding wires 3 and the reverse winding wires 4 are double wires or multi-wires with insulation layers and non-magnetic permeability. The double wires or multi-wires can be twisted wires or parallel wires.

[0026] Figure 1In the transmission line, the conductive wire adopts two parallel conductive wires or twisted wires with an insulating layer and non-magnetic property. The material of the conductive wire is enameled copper wire or insulated aluminum wire, and the diameter of the single conductive wire is Φ0.1mm-2mm. The transmission line is wound in the form of a solenoid structure, along the insulating core wire, with the same turn density, according to the principle of equal number of turns, and the forward winding section and the reverse winding section as a winding unit. The turn density is 2-100 turns / cm, and the number of turns of the forward winding section 5 and the reverse winding section 6 is selected as 2-100 turns. The insulating envelope layer 1 adopts commercial heat shrink tube, PVC, nylon, glass fiber bundle, polytetrafluoroethylene, etc. to package the wound transmission line, and the wall thickness is about 0.01-2mm. The insulating core wire adopts commercial flexible insulating organic wire or pipe material such as nylon, polytetrafluoroethylene, PVC, glass fiber bundle, polytetrafluoroethylene, etc., and the diameter is Φ0.5mm-15mm. As the winding fixing core and the force body of the signal transmission line.

[0027] The following is proved by two specific examples.

[0028] Example 1:

[0029] Figure 2 is the anti-electromagnetic interference experimental data diagram of the transmission line for the air duct temperature measurement between the packages of the dry-type air-core reactor. The voltage signal transmission of the thermocouple sensor for the air duct temperature measurement between the packages of the dry-type air-core reactor, the rated capacity of the reactor is 1000kvar, the rated voltage is 2100V, the rated current is 476A, the rated inductance is 14.04mH, and the working frequency is 50Hz. The signal transmission line adopts the parallel winding method of the film-coated copper conductive wire, the number of turns of the forward winding and the reverse winding of the transmission line unit is 100 respectively, the internal insulating core wire adopts glass fiber bundle (diameter 2mm), the outer covering insulating sleeve adopts high-temperature resistant heat shrink tube, and the length of the transmission line is 3.5m. The T-type thermocouple is connected to the signal input end of the transmission line as the temperature measurement sensor, and the output end of the transmission line is connected to the temperature detection module through the compensation conductive wire. The actual measured ground potential of the output end of the transmission line is about 0.3V, and the differential voltage of the output end is ≤0.005mV. Under the working temperature of 30℃, the T-type thermocouple measures the temperature, and the output potential of the transmission line is about 1.65mV. Even in the process of turning on and off the reactor, the temperature signal output can still remain stable, showing good anti-interference performance and reliability.

[0030] Example 2:

[0031] Figure 3It is the anti-electromagnetic interference experimental data diagram of transmission line for dry core reactor core yoke temperature measurement. It is used for the yoke temperature monitoring condition of 480kvar dry core reactor. The rated voltage of the reactor is 381kV, the rated current is 420A, the rated inductance is 2.89mH, and the working frequency is 50Hz. The temperature measurement of the upper yoke of the reactor uses a thermistor pt100 sensor, the test working current is direct current 0.3A, the signal transmission line uses a laminated copper wire parallel winding mode, the positive winding and reverse winding turns of the transmission line unit are 50 turns respectively, the wire diameter is 0.3mm, the turn density is 33 turns / cm, the internal insulation core wire uses a polytetrafluoroethylene wire (diameter 4mm), the outer wrapping insulating sleeve uses a glass fiber sleeve, and the transmission line length is 5.5m. The output end of the transmission line to ground potential is about 0.1V under the measured working condition, the output end differential voltage is less than or equal to 0.01mV, the temperature monitoring is carried out under the room temperature condition, the test is carried out under the variable load condition, and the temperature signal output can still remain stable in the strong electromagnetic interference environment, which shows good anti-interference performance and reliability.

[0032] The above is only the preferred embodiment of the present application, and does not limit the present application in any form. Although the present application has been disclosed as above, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to the above disclosed methods and technical contents without departing from the scope of the present application, and any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present application still belong to the scope of the present application.

Claims

1. A weak current signal transmission line for dry-type reactor inter-turn insulation detection, characterized by: The invention comprises a transmission line load-bearing body, wherein the outer surface of the transmission line load-bearing body is wound with a conductor, and the conductor is periodically and repeatedly wound on the surface of the transmission line load-bearing body in a forward winding and reverse winding alternating and continuous manner, and the number of turns and the turn density of the forward winding and the reverse winding are the same, a forward winding section and a reverse winding section constitute a winding unit, and an insulating encapsulation layer is encapsulated on the outer surface of the wound transmission line; the turn density of the conductor winding is 2 to 100 turns / cm; the total number of turns of the winding unit is 2 to 100 turns; the transmission line load-bearing body is a flexible insulating The material of the flexible insulating core wire is PVC wire, nylon wire, polytetrafluoroethylene wire, glass fiber bundle wire or tube; the conductor adopts a double wire or multiple wires with an insulating layer and non-magnetic conductivity, and the double wire or multiple wires are twisted wires or parallel wires; the material of the conductor is copper or aluminum, and the diameter of the conductor is 0.1mm~2mm; the diameter of the flexible insulating core wire is 0.5~15mm; the material of the insulating encapsulation layer is heat shrinkable tube, PVC, nylon, glass fiber bundle, polytetrafluoroethylene insulating sleeve, and the wall thickness of the insulating sleeve is 0.01~2mm.

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