Capacitive voltage transformer dielectric loss on-line monitoring device

Abstract

The utility model discloses a capacitor voltage transformer dielectric loss on-line monitoring device, which comprises a first electrode, a second electrode, a capacitor voltage transformer, a cross-core current transformer, a filter, an amplifier, a current detection unit and a signal processing unit, the first electrode and the second electrode are both sleeved on a supporting column of the capacitive voltage transformer, the cross-core current transformer is arranged on a low-voltage side of the capacitive voltage transformer, the filter is connected with the first electrode and the second electrode, and the amplifier is connected with the filter and the signal processing unit. The current detection unit is respectively connected with the straight-through current transformer and the signal processing unit; the capacitive voltage transformer dielectric loss on-line monitoring device provided by the utility model realizes accurate on-line monitoring of the dielectric loss of the capacitive voltage transformer, and improves the sensitivity and reliability of system fault detection.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the electric power equipment monitoring and diagnosis technical field, concretely relates to a kind of capacitive voltage transformer dielectric loss on-line monitoring device. BACKGROUND

[0002] Capacitance and vibration sound of capacitive voltage transformer are required to be tested and visited according to regulation, and the investment and manpower consumption are restricted to popularization and application due to the need of wiring in the way of bus comparison, in the process of conventional visit, the I vector sum of the ground current of N end and X end of low-voltage capacitor of capacitive voltage transformer is equal to the high-voltage side capacitor current, so the ground current of N and X end is obtained, the current and current ratio of high and low voltage capacitor can be obtained, and the capacitance is abnormal by comparing the change of secondary voltage, but the existing way needs secondary voltage collection, because secondary voltage involves electricity metering and protection, usually in safety consideration, secondary voltage is not allowed to be connected, which challenges the existing algorithm structure. SUMMARY

[0003] The utility model solves the technical problem to provide a kind of capacitive voltage transformer dielectric loss accurate on-line monitoring, improve the sensitivity and reliability of system fault detection capacitive voltage transformer dielectric loss on-line monitoring device.

[0004] The technical scheme of the utility model is as follows: a kind of capacitive voltage transformer dielectric loss on-line monitoring device, comprising: first electrode, second electrode, capacitive voltage transformer, through core current transformer, filter, amplifier, current detection unit and signal processing unit, the first electrode is located at the bottom of capacitive voltage transformer and is grounded by ground wire, the second electrode is fixed above the first electrode and is connected with signal processing unit, the first electrode is parallel with the second electrode, the first electrode and the second electrode are all sleeved on the support column of capacitive voltage transformer, the secondary terminal cable of capacitive voltage transformer is led to underground cable trench after passing through the hollow area of second electrode, the secondary terminal cable of capacitive voltage transformer does not pass through the hollow area of first electrode, the through core current transformer is arranged at the low-voltage side of capacitive voltage transformer, the filter is connected with the first electrode and the second electrode respectively, the amplifier is connected with filter and signal processing unit respectively, the current detection unit is connected with through core current transformer and signal processing unit respectively.

[0005] Further, the planar distance between the first electrode and the second electrode is not less than 10 cm.

[0006] Further, the second electrode is connected and fixed with the first electrode through insulating studs, and the second electrode is located above the terminal box of capacitive voltage transformer.

[0007] Further, the first electrode and the second electrode are connected with the filter through a voltage line.

[0008] Further, the low-voltage side lead wire of the capacitive voltage transformer passes through the hollow part of the through core current transformer, and the output side of the through core current transformer is connected with the current detection unit.

[0009] The beneficial effects of the utility model are as follows:

[0010] 1. Real-time online monitoring: the utility model realizes the online real-time monitoring of the dielectric loss of the capacitive voltage transformer through the through core current transformer and the signal processing unit, and can be completed without shutdown or disassembly of equipment, compared with traditional offline testing, the online monitoring can timely find potential faults, and the operation safety of equipment is improved.

[0011] 2. Reduce manual intervention and maintenance cost: the signal processing unit of the utility model can automatically send an alarm signal when detecting abnormal dielectric loss, without manual intervention, compared with manual periodic detection and maintenance, the manual workload and maintenance cost are greatly reduced, and the sensitivity and reliability of monitoring are ensured.

[0012] 3. Safety is improved: the first electrode and the second electrode are arranged in parallel with the supporting column of the capacitive voltage transformer and are fixed through insulating studs, so that the stability and safety of the device are ensured, the first electrode is grounded, the second electrode is connected with the signal processing unit, and the risk of electric shock of the operator is reduced.

[0013] 4. Strong environmental adaptability: the electrode and the transformer are sleeved on the supporting column of the capacitive voltage transformer and are connected with the underground cable channel, can adapt to various harsh environments in the power substation, such as high humidity and high temperature, improve the durability of the equipment, and reduce the equipment failure caused by environmental factors; the application of the filter and the amplifier effectively removes high-frequency noise interference, ensures the purity of the signal, improves the collection accuracy of the current and voltage signals, and enables the system to operate stably in a strong electromagnetic interference environment. BRIEF DESCRIPTION OF DRAWINGS

[0014] Fig. 1 It is a capacitive voltage transformer dielectric loss online monitoring device structure schematic view of the utility model.

[0015] Fig. 2 It is a capacitive voltage transformer dielectric loss online monitoring device structure schematic view of the utility model.

[0016] Fig. 3It is a kind of first electrode or second electrode structural diagram of the capacitive voltage transformer dielectric loss on-line monitoring device of the utility model. DETAILED DESCRIPTION

[0017] As Figs. 1-3 The utility model relates to a kind of capacitive voltage transformer dielectric loss on-line monitoring device, including: first electrode, second electrode, capacitive voltage transformer, through core current transformer, filter, amplifier, current detection unit and signal processing unit, the first electrode is located at capacitive voltage transformer bottom and is grounded by ground wire, the second electrode is fixed above first electrode and is connected with signal processing unit, the first electrode is parallel with second electrode, the first electrode and second electrode are both sleeved on the support column of capacitive voltage transformer, the secondary terminal cable of capacitive voltage transformer passes through the hollow area of second electrode after leading to underground cable channel, the secondary terminal cable of capacitive voltage transformer does not pass through the hollow area of first electrode, the through core current transformer is arranged at the low voltage side of capacitive voltage transformer, the filter is connected with first electrode and second electrode respectively, the amplifier is connected with filter and signal processing unit respectively, the current detection unit is connected with through core current transformer and signal processing unit respectively.

[0018] Preferably, the plane distance between the first electrode and the second electrode is not less than 10 cm.

[0019] Preferably, the second electrode is connected and fixed with the first electrode through insulating studs, and the second electrode is located above the terminal box of the capacitive voltage transformer.

[0020] Preferably, the first electrode and the second electrode are connected with the filter through voltage lines.

[0021] Preferably, the low voltage side lead of the capacitive voltage transformer passes through the hollow part of the through core current transformer, and the output side of the through core current transformer is connected with the current detection unit.

[0022] Working principle:

[0023] When the capacitive voltage transformer is in normal operation state, the monitoring device starts to continuously monitor: high voltage is added to the CVT (capacitive voltage transformer), the internal dielectric loss produces a slight electrical characteristic change under the specific power frequency signal environment, the change causes the slight change of the electric field distribution around the CVT, the change is picked up as a weak electric signal by the second electrode above, at the same time, the low-voltage side current transformer senses a weak current change, the first electrode is grounded to stabilize the reference potential and reduce external interference, after the irrelevant noise is removed by the filter, the signals are amplified by the amplifier, and then enter the signal processing unit, the signal processing unit analyzes the phase and amplitude of the electric field signal and the current signal, thereby calculating the dielectric loss factor or the related characteristic quantity, comparing the long-term collected data and performing trend analysis, once the dielectric loss is obviously increased or abnormally changed, an alarm or a maintenance personnel is prompted to perform in-depth inspection and maintenance.

[0024] In summary, the core working principle of the capacitive voltage transformer dielectric loss on-line monitoring device is to utilize the electrode structure and the through-type current transformer to realize the capture and amplification of the weak signal change caused by the CVT dielectric loss, the dielectric loss change which is originally difficult to directly observe on-line is converted into the detectable and quantifiable electrical signal, the dielectric health condition is judged through the precise signal processing, and the purpose of on-line monitoring and early warning is achieved.

[0025] The above specific embodiments further specifically explain the purpose, technical scheme and beneficial effects of the utility model, and it should be understood that the above description is only the specific embodiment of the utility model, and is not used to limit the protection scope of the utility model, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model should be included in the protection scope of the utility model.

Claims

1. A device for on-line monitoring of dielectric loss of a capacitive voltage transformer, characterized in that The utility model relates to a kind of voltage transformer and current transformer, including: First electrode, second electrode, capacitive voltage transformer, through core current transformer, filter, amplifier, current detection unit and signal processing unit, the first electrode is located at capacitive voltage transformer bottom and is grounded by ground wire, the second electrode is fixed above first electrode and is connected with signal processing unit, the first electrode is parallel with second electrode, the first electrode and second electrode are both sleeved on the support column of capacitive voltage transformer, the secondary terminal cable of capacitive voltage transformer passes through the hollow area of second electrode after leading to underground cable channel, the secondary terminal cable of capacitive voltage transformer does not pass through the hollow area of first electrode, the through core current transformer is arranged at the low voltage side of capacitive voltage transformer, the filter is connected with first electrode and second electrode respectively, the amplifier is connected with filter and signal processing unit respectively, the current detection unit is connected with through core current transformer and signal processing unit respectively.

2. The on-line monitoring device for dielectric loss of a capacitance voltage transformer according to claim 1, characterized in that, The planar distance between the first electrode and the second electrode is not less than 10 cm.

3. The on-line monitoring device for dielectric loss of a capacitance voltage transformer according to claim 1, characterized in that, The second electrode is connected to the first electrode by an insulating stud.

4. The on-line monitoring device for dielectric loss of a capacitance voltage transformer according to claim 1, characterized in that, The first electrode and the second electrode are connected to the filter by a voltage line.

5. The on-line monitoring device for dielectric loss of a capacitance voltage transformer according to claim 1, characterized in that, The low voltage side lead of the capacitive voltage transformer passes through the hollow part of the through core current transformer, and the output side of the through core current transformer is connected to the current detection unit.

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