JP2018189620A - Insulator remaining life measurement device by discharge amount detection of partial discharging, corona discharging, and creeping discharging (hereinafter, referred to as corona discharging) - Google Patents

Abstract

PROBLEM TO BE SOLVED: To learn the progression of corona discharging by continuously measuring a high frequency current generated from the corona discharging for a long term and to learn the deterioration conditions of electrical facility/cables and the repairing period thereof by estimating the remaining life based on a deteriorated bus-tub curve of an insulator.SOLUTION: A micro discharge current of the high frequency generated by the corona discharging is detected by the Rogowskii coil or high frequency detection coils CT6-1, 6-2, and 6-3, and the specific frequency band different in frequencies generated respectively from partial discharging, corona discharging and creeping discharging is always detected through a filter, and converted into a DC voltage and numerically recorded in a logger 8 over a long period so as to periodically display the record such as the logger in a display device 9 such as the PC, and assumes and learns the remaining life by comparing with the deterioration bus-tub from the increasing tendency from the actually measured voltage.SELECTED DRAWING: Figure 1

Description

The present invention detects weak high-frequency currents generated from corona discharge, etc., detects the deterioration of insulators in electrical equipment and cables at an early stage, predicts the repair time and remaining life of electrical / electronic equipment, and repairs them. To provide a detection and measurement device for corona discharge to prevent sudden accidents, breakdowns, power outages, fires and spillovers.

Some electrical devices and cables have deteriorated over time, and many of them have been in operation without being refurbished even after the end of their product life. Recently, this tendency is remarkable.
As a result, electrical equipment suddenly breaks down, leading to spillovers from accidents and breakdowns, and it has become obvious that human and economic losses due to major power outages and recovery take a long time. Since the power supply has been tight since the Great East Japan Earthquake, the problems of shipping and distribution have a great social impact, so the inspection work of electrical equipment management engineers has become more important.
As for the inspection contents of the electrical equipment defined in the current system, a method in which deterioration of the electrical equipment cannot be properly judged is repeated as before.
In addition, recently, there has been an imbalance between the number of qualified electric management technicians and the number of electrical facilities, and as a matter of fact, it is still impossible to conduct adequate performance inspections and inspections of electrical facilities. Including the increase in energy facilities and the complete liberalization of electricity in FY2020, the electrical equipment maintenance system itself may have collapsed.

Electrical equipment measuring instruments used in the current inspection work can easily measure corona discharge, etc., which causes deterioration of the insulation, and continuously measure electricity for a long period of time. At present, the remaining life is not predicted by grasping the above. There are no measuring instruments that can be measured.

There are several detection methods such as corona discharge for electrical equipment in operation, but none of them are continuously measured locally. In general, most inspection equipment is installed in factories or the like for continuous monitoring of important equipment. Accordingly, it is desired that discharge and the like can be detected in the applied state at the site.

Although some detectors such as portable corona discharge exist, this is a method of detecting “sound” generated by corona discharge or the like. It is a method to detect the change of "sound" due to electric discharges generated from electrical equipment and cables stored in the casing, and to directly contact the sensor with the protective casing. For the "sound" measurement, This is a measurement method for finding out the occurrence point from corona discharge or the like. In this method, the ambient noise level is high, the determination is very difficult, and continuous measurement is not possible. (Hereinafter, the electrical / electronic device storage box is referred to as a casing)

Inspecting electrical equipment and cables such as circuit breakers and transformers installed in the power receiving / transforming / distribution equipment, open the door of the panel and investigate whether there is any abnormality in the equipment. At this time, a sensor that can easily and quantitatively measure whether corona discharge or the like has occurred is desired.

None

In the above-described background art, regarding the conventional measurement of corona discharge or the like, since the measurement amount is displayed in units of coulombs, it has to be converted into “corona discharge current etc. × time” = coulomb amount. Therefore, it is necessary to integrate with a capacitor, but receiving with a capacitor directly results in the loss of important frequency characteristics, resulting in a decrease in measurement sensitivity and limitations such as power supply noise. difficult. The present invention measures the high-frequency current generated from corona discharge, etc. for a long period of time, grasps the progress of corona discharge, etc., and estimates the remaining life based on the deterioration bathtub curve of the insulator. It is to grasp the deterioration status of equipment / cable and the time of repair.

Since the precise inspection specified by the conventional “law” is accompanied by a power failure, the corona discharge of the insulator is stopped. Therefore, actual corona discharge cannot be measured. The present invention is meaningful for measurement in an applied state that creates a state in which corona discharge or the like is generated. For this reason, it is necessary to employ a Rogowski coil and a high-frequency detection CT as a detection coil.

In the figure, electrical device and cable: Corona discharge etc. generated in 2: Corona discharge etc. generated from 3 Current: 10 as shown by the arrow Electrical equipment mounting case (casing etc.): 1 ,
I. In the case of Class A grounding electrode: 4-1, discharge current such as corona discharge returns to the extra high / high voltage power source side; 5 using the earth or space as electromagnetic waves. This discharge current is detected by a high frequency detection CT coil: 6-1.
II. In the case of the C type and D type grounding electrode: 4-2, the discharge current passes through the ground or space and returns to the power source side through the B type grounding electrode, and the high frequency detection CT coil: 6-2 And detected respectively.
III. In the case of the B type grounding electrode: 4-3, the detected discharge current in which the sum of the discharge currents of the above-mentioned item 2 (C type + D type) grounding electrode is detected by the high frequency detection CT coil 6-3 is: 7 is subjected to waveform processing, converted into a DC voltage signal, data is accumulated by the logger 8 :, and the trend recording such as corona discharge can be observed by data processing of the trend recording by the PC: 9.

By setting a CT coil for detecting corona discharge or the like in the vicinity of each ground wire outlet of the electric device / cable, it is possible to identify the electric device / cable in which corona discharge or the like is generated.

Circuit diagram for detecting discharge current such as corona discharge

DESCRIPTION OF SYMBOLS 1 Electrical equipment equipment casing 2 Electrical equipment equipment and cable 3 Corona discharge generation part 4-1 Class A grounding electrode 4-2 Class C grounding electrode, Class D grounding electrode 4-3 Class B grounding electrode 5 Extra high, high voltage power supply 6-1 CT coil for class A grounding line high frequency detection 6-2 CT coil for class C and class D grounding line high frequency detection CT coil for type B grounding line high frequency detection 7 Discharge current detection / shaping circuit for corona discharge, etc. 8 Logger 9 Display device such as PC 10 Route of discharge current such as corona discharge

Claims (4)

It can continuously detect the long-term trend of increasing high-frequency current in a wide band generated by partial discharge, corona discharge, and creeping discharge (hereinafter referred to as corona discharge, etc.) generated by applying electricity to electrical equipment and cable insulation. Measurement that can measure the remaining life of the insulation (which directly leads to the remaining life of the electrical equipment) that can easily and continuously measure the bathtub characteristics of the deterioration of the insulation due to the adoption of the measurement circuit method at the installation location of electrical equipment and cables apparatus A specific frequency with a different frequency generated from partial discharge, corona discharge, and creeping discharge contained in corona discharge, etc., detected by a Rogowski coil or high-frequency detection CT, which detects a minute high-frequency discharge current generated by corona discharge, etc. The band is always detected through a filter, converted to DC voltage, digitized, recorded on a logger, etc. over a long period of time, and the record of the logger, etc. is periodically displayed on an image display device such as a PC and measured. A measuring device that estimates and grasps the remaining life by comparing with the deterioration bathtub curve from the increasing trend of voltage According to a discharge current having a specific frequency band generated from a corona discharge detected by the method shown in [Claim 2] and a reference frequency, a beat is taken and smoothed to detect a DC voltage signal; [Claim 2] Measuring device that can be stored in a logger, etc. using the same method to estimate and grasp the remaining life Since the magnitude of the corona discharge generated in the insulator is indicated by the discharge charge amount: Q (unit: pico-coulomb), the discharge charge amount Q = Σ discharge charge amount (ai), and the elementary discharge amount A high frequency current having a high frequency (fi) corresponding to (ai): Ii (ai, fi) generated by Ii (ai, fi) is detected by the detection method shown in [Claim 2], and the high frequency current (I) = ΣIi ( ai, fi) are collectively detected and processed in a waveform, and then converted into a DC voltage detection signal through an integration circuit, and the discharge charge amount Q = (Σai) ∝high frequency current (I) ∝continuous as a DC voltage detection signal. A measurement method for observing the discharge charge amount Q is adopted by adopting a method for measuring automatically.
Since a capacitor circuit is used for analysis of discharge phenomena such as corona discharge, the relationship between the measured high-frequency discharge current and the amount of discharge charge is: charge (Q) = current (I) × time (t), frequency The unit is (1 / time: t), and the discharge response time and the frequency are inversely proportional. Therefore, from the relational expression between the discharge charge amount: Q, the discharge current: I, and the frequency: f, the DC voltage By establishing the relational expression of the detection signal and the amount of discharge charge: Q, a discharge current sensor such as corona discharge that can be easily and continuously measured at the installation location of the electric equipment and cable is provided.
The measured DC voltage detection signal is stored in a logger or the like in the same manner as [Claim 2], and the remaining life is estimated and grasped from the trend record.

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