JPH05111147A - Deterioration monitor for zinc oxide type arrestor - Google Patents

Abstract

PURPOSE:To judge the deterioration accurately and simplify the constitution of an electric path more by employing time series data for each charge quantity signal having specified period and providing a deterioration judging part, which performs the judgment based on time series data and deterioration judgment criteria. CONSTITUTION:A current transformer 4 detects the current signal proportionate to the leak current flowing to the grounding conductor 3 of a zinc oxide type arrestor 2 and sends it to a deterioration judging part 30. An amplifier 31 amplifiers this current signal, and a rectifying circuit 32 rectifies it into a half wave, and then an integrator 33 temporally integrates it, and it performs a specified time of temporal integration and a specified time of pause and detects the charge quantity signals cycled on this. Three cycles of each charge quantity signal is observed plural times in a specified period, and it is stored in a memory 34 as temporal series data. The deterioration judgment criteria of a zinc oxide type arrestor is also stored in the memory 34, and CPU 35 performs the judgment of the deterioration based on the time series data and the deterioration judgment criteria at the end of a specified time or any time during it.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deterioration monitor for a zinc oxide type arrester applied to a power system.

[0002]

2. Description of the Related Art FIG. 6 is a circuit diagram showing a conventional deterioration monitoring device for a zinc oxide type arrester disclosed in Japanese Patent Laid-Open No. 129881/1990, and FIG. 7 shows a zinc oxide type arrester with a non-linear resistance and electrostatic discharge. It is the equivalent circuit diagram represented by the parallel circuit of capacity. Figure 6
7 and FIG. 7, 1 is a transmission line for one phase of a three-phase transmission line, 2 is a zinc oxide type arrester connected to the transmission line 1, 2a is an equivalent non-linear resistance specific to the zinc oxide type arrester 2, 2b Is an equivalent capacitance specific to the zinc oxide type arrester 2, 3 is a ground wire for grounding the zinc oxide type arrester 2, 4 is electromagnetically coupled to the ground line 3 to detect a leakage current, and a current signal proportional thereto , 5 is a capacitor-type transformer that divides the ground voltage of the transmission line 1 and detects a voltage signal proportional thereto, 10 is a deterioration determination unit that determines the deterioration of the zinc oxide surge arrester 2, and 11 is In addition to calculating the capacitance current flowing in the capacitance 2b by the voltage signal detected by the capacitor type transformer 5 and outputting the capacitance current signal, it also outputs the voltage signal at that time and the timing signal when the zero point of the ground voltage passes. Voltage calculator, 12
Is a current calculation unit that calculates a resistance current flowing through the non-linear resistance 2a based on the current signal from the current transformer 4, the capacitance current signal from the voltage calculation unit 11 and the timing signal, and outputs a resistance current signal. An A / D converter that converts the voltage signal from the arithmetic unit 11 and the resistance-divided current signal from the electric current arithmetic unit 12 from an analog amount to a digital amount, respectively, and 14 is a resistor corresponding to a predetermined ground voltage higher than the normal ground voltage. A memory for storing the divided current signal as a reference current signal, 15 is a CPU, which compares the resistance divided current signal with the reference current signal of the memory 14. If the resistance divided current signal is large, the zinc oxide type arrester 2 is deteriorated. It is determined that there is, and the resistance component current signal and voltage signal at that time are output to the interface 16. If the resistance component current signal is small, it is determined that there is no deterioration and no output is performed.
Reference numeral 21 is a printer that prints out the resistance current and the ground voltage by using the resistance current signal and the voltage signal.

Further, FIG. 8 is a waveform explanatory view showing respective waveforms of a resistance component current (dotted line), a capacitance component current (chain line) and a ground voltage (dashed line) in a normal state of the zinc oxide type arrester 2, and FIG. 9 is a zinc oxide. 4 is a characteristic curve diagram showing the relationship between the resistance current flowing through the non-linear resistance 2a of the surge arrester 2 and the voltage to ground, the solid line portion corresponding to the normal state of the zinc oxide arrester 2, and the broken line portion corresponding to its deteriorated state.

Next, the operation will be described. The insulator type zinc oxide surge arrester 2 has a structure in which a plurality of zinc oxide elements are stacked and housed inside an insulator tube, and lids are fixed to the flanges attached to both ends of the insulator tube and hermetically sealed. Therefore, the zinc oxide type arrester 2 can be represented equivalently by a parallel circuit of the nonlinear resistance 2a and the electrostatic capacitance 2b due to its structure (see FIG. 7), and the leakage current flowing through the ground wire 3 of the zinc oxide type arrester 2 is It is a combined current of the resistance component current flowing through the non-linear resistance 2a and the capacitance component current flowing through the electrostatic capacitance 2b. When the zinc oxide arrester 2 is in a normal state, the peak value of the resistance component current is usually smaller than that of the capacitance component current (see FIG. 8). By the way, if a commercial frequency ground voltage is applied to the zinc oxide surge arrester 2 for a long period of time, the zinc oxide element deteriorates and the resistance value of the non-linear resistance 2a changes, and the resistance component current increases (Fig. 9). Further, since the electrostatic capacitance 2b of the zinc oxide type arrester 2 is determined by its structure and arrangement, the capacity current does not change regardless of the deterioration of the zinc oxide element. Therefore, when the zinc oxide arrester 2 deteriorates, the leakage current flowing through the ground wire 3 has a waveform that is greatly distorted from a sine wave.

A voltage signal proportional to the ground voltage of the transmission line 1 is detected by the capacitor type transformer 5 and a current signal proportional to the leakage current flowing through the ground wire 3 of the zinc oxide type arrester 2 is detected by the current transformer 4. And sends them to the deterioration determination unit 10.
The voltage calculation unit 11 calculates a capacitance component current having a 90 degree phase advance based on the voltage signal, outputs the capacitance component current signal and the timing signal to the current calculation unit 12, and outputs the voltage signal as it is. The current calculation unit 12 calculates the resistance component current from the current signal, the capacitance component current signal, and the timing signal, and outputs the resistance component current signal. The voltage signal from the voltage calculation unit 11 and the resistance current signal from the current calculation unit 12 are converted into digital quantities by the A / D converter 13 and input to the CPU 15 together. C
In PU15, the resistance current signal and the reference current signal stored in the memory 14 are compared. If the resistance current signal is large, it is determined that the zinc oxide arrester 2 has deteriorated and the resistance current signal and voltage signal at that time are compared. Printer via interface 16
Output to 21 and print resistance current and ground voltage. If the resistance component current is small, it is determined that the zinc oxide arrester 2 has deteriorated. The reference current signal stored in the memory 14 may be a resistance current corresponding to √3 times the normal ground voltage of the transmission line 1.

[0006]

The conventional deterioration monitoring device for a zinc oxide type lightning arrester is constructed as described above, and the voltage calculating unit 11 calculates the current for the capacitance by the voltage signal detected by the capacitor type transformer 5, When the zinc oxide type lightning arrester 2 is in a normal state, the resistance component current is normally converted into the capacitance component current in addition to the resistance component current being calculated by the current calculation unit 12 based on the capacitance component current signal and the current signal detected by the current transformer 4. Since the peak value is smaller than that in comparison, the calculated resistance current is inaccurate, the deterioration of the zinc oxide arrester 2 cannot be accurately determined, and the configuration of the electric path is complicated.

The present invention has been made to solve the above problems, and can monitor the deterioration of a zinc oxide surge arrester, which can accurately determine the deterioration of the zinc oxide surge arrester, and which has a simpler electric circuit structure. The purpose is to obtain the device.

[0008]

A zinc oxide type arrester deterioration monitoring apparatus according to the present invention has one end of a zinc oxide type arrester connected to a power transmission line and the other end grounded, and the zinc oxide type lightning arrester is connected to the ground voltage of the transmission line. In detecting the deterioration of the zinc oxide type arrester by detecting a current signal proportional to the leakage current flowing through the lightning arrester, perform half-wave rectification or full-wave rectification of the current signal, and then perform time integration for a predetermined time and pause for a predetermined time. To detect the charge amount signal with this period as a cycle, observe each charge amount signal of a predetermined cycle multiple times over a predetermined period to make time series data, and use this time series data and deterioration of the zinc oxide arrester. A deterioration determination unit that determines based on a determination standard is provided.

[0009]

The deterioration determining unit according to the present invention performs time integration for a predetermined time and rest for a predetermined time on the current signal that has been half-wave rectified or full-wave rectified to detect a charge amount signal having this cycle as a predetermined period. Each charge amount signal of a cycle is observed a plurality of times over a predetermined cycle to form time series data, and the judgment is made based on this time series data and the deterioration judgment standard of the zinc oxide type arrester.

[0010]

EXAMPLES Example 1. FIG. 1 is a circuit diagram showing an embodiment of the present invention. In the figure, 1 to 4 and 21 are the same as those in a conventional deterioration monitoring device for a zinc oxide type arrester. 30 is a deterioration determination unit that determines the deterioration of the zinc oxide type arrester 2, 31 is an amplifier that amplifies the current signal detected by the current transformer 4, 32 is a half-wave of the current signal that is amplified by the amplifier 31 A rectifying circuit for rectifying, 33 is an integrator for time-integrating the half-wave of the half-wave rectified current signal, and 34 is a memory for storing time-series data of a charge amount signal obtained by time-integrating the half-wave of the current signal and a deterioration determination standard. ,
Reference numeral 35 is a CPU for judging deterioration based on time series data of the charge amount signal and deterioration judgment reference, and 41 is a display for displaying the result judged by the CPU 35.

FIG. 2 is an explanatory diagram of waveforms of the zinc oxide arrester 2 in a deteriorated state. FIG. 2A shows waveforms of a resistance component current (dotted line), a capacitance component current (chain line), and a ground voltage (broken line). The phase relationship is shown, (B) shows the waveform of the leakage current that combines the resistance current and the capacitance current, and (C) shows the waveform obtained by half-wave rectifying the leakage current. In FIG. 3, the current signal proportional to the leakage current is half-wave rectified, and the time integration of the predetermined time T ₁ and the predetermined time T _{2 are performed.}
4 is a bar graph showing time-series data obtained by observing charge amount signals of three cycles a plurality of times over a predetermined period.

Next, the operation will be described. The leakage current flowing through the ground wire 3 of the zinc oxide arrester 2 is a combined current of the resistance component current flowing through the non-linear resistance 2a and the capacitance component current flowing through the electrostatic capacitance 2b. If the zinc oxide arrester 2 is in a normal state,
Normally, the resistance component current has a smaller peak value than the capacitance component current, and the waveform of the leakage current is slightly distorted from the sine wave, but when the zinc oxide type arrester 2 deteriorates, the nonlinear resistance 2a
Resistance value changes, the peak value of the resistance current increases (see Fig. 2 (A)), and the sine wave is greatly distorted (Fig. 2).
(See (B)). A current signal proportional to the leakage current flowing through the ground wire 3 of the zinc oxide surge arrester 2 is detected by the current transformer 4 and sent to the deterioration determination unit 30. This current signal is amplified by the amplifier 31 and half-wave rectified by the rectifier circuit 32 (see FIG. 2 (C)), and the integrator 33 performs time integration to detect the charge amount signal (see FIG. 3). .. The charge amount signal is a combination of the resistance current signal and the capacitance current signal that are integrated over time. The time integration of the resistance current signal is the power consumed by the nonlinear resistance 2a of the zinc oxide arrester 2. What is proportional to the loss and which is obtained by time-integrating the current signal corresponding to the capacitance is always constant regardless of the deterioration of the zinc oxide arrester 2. The deterioration of the zinc oxide arrester 2 is caused by the power loss of the non-linear resistance 2a. Therefore, the deterioration of the zinc oxide type arrester 2 can be determined from the charge amount signal. The half-wave rectified current signal is time-integrated by the integrator 33,
This detects the amount of charge signal having a period by performing pause time integration and the predetermined time T ₂ of the predetermined time T ₁ (see FIG. 3),
Each charge amount signal of three cycles is observed a plurality of times in a predetermined period and stored in the memory 34 as time series data (see FIG. 4). The memory 34 also stores the criteria for deterioration of the zinc oxide type arrester 2, and the CP can be stored at the end of a predetermined period or at any time during that period.
At U35, the deterioration is judged based on the time series data and the deterioration judgment standard. The result of this judgment, the time series data, and the deterioration judgment standard are displayed on the display unit 41 and printed out by the printer.

In the above embodiment, the current signal is half-wave rectified by the rectifier circuit 32. However, full-wave rectification may be performed, and the half-wave rectified current signal is integrator 33 for a predetermined time T _1. performed and the time integration and the predetermined time T ₂ pause, which detects the amount of charge signal having a period, it is assumed to observe the amount of charge signals of three cycles is not limited to 3 cycles, It may be any cycle.

Example 2. FIG. 5 is a circuit diagram showing a deterioration determining unit according to another embodiment of the present invention, in which the current signal sent to the deterioration determining unit 50 is amplified by the amplifier 51 and digitalized by the A / D converter 52. After the conversion into the amount, the CPU 54 detects the charge amount signal and determines the deterioration. According to this embodiment, the configuration of the deterioration determination unit 50 becomes simpler. In each of the above embodiments, the zinc oxide type arrester 2 is an insulator type having a structure in which a plurality of zinc oxide elements are stacked inside the porcelain tube and the lids are fixed to the flanges attached to both ends of the porcelain tube for sealing. However, it goes without saying that it may be of a tank type having a structure in which a plurality of zinc oxide elements are laminated and fixed inside a metal container and filled with an insulating gas.

[0015]

As described above, according to the present invention, the charge amount signal having the period as the cycle is obtained by performing the half-wave rectification or the full-wave rectification of the current signal, performing the time integration of the predetermined time and the rest of the predetermined time. A deterioration determination unit that detects each of the charge amount signals of a predetermined cycle a plurality of times over a predetermined period to form time series data, and determines based on this time series data and the deterioration determination standard of the zinc oxide surge arrester. Since the above is provided, it is possible to accurately determine the deterioration of the zinc oxide type lightning arrester and to simplify the configuration of the electric circuit.

[Brief description of drawings]

FIG. 1 is an electric line diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram of waveforms in a deteriorated state of the zinc oxide arrester.

FIG. 3 is a waveform diagram showing a charge amount signal.

FIG. 4 is a bar graph showing time series data.

FIG. 5 is an electric line diagram showing a deterioration determining unit according to another embodiment of the present invention.

FIG. 6 is a circuit diagram showing a conventional deterioration monitoring device for a zinc oxide surge arrester.

FIG. 7 is an equivalent circuit diagram of a zinc oxide type arrester.

FIG. 8 is a waveform explanatory diagram of the zinc oxide arrester in a normal state.

FIG. 9 is a characteristic curve diagram showing the relationship between resistance component current and ground voltage.

[Explanation of symbols]

 1 Transmission Line 2 Zinc Oxide Lightning Arrester 3 Ground Wire 4 Current Transformer 21 Printer 30 Deterioration Judgment Section 32 Rectifier Circuit 33 Integrator 34 Memory 35 CPU 41 Display

Claims (1)

[Claims] 1. A zinc oxide arrester is connected to one end of a transmission line and the other end is grounded, and a current signal proportional to a leakage current flowing through the zinc oxide arrester is detected by the ground voltage of the transmission line. In determining the deterioration of a zinc oxide surge arrester, the current signal is half-wave rectified or full-wave rectified, and then a time integration of a predetermined time and a rest of a predetermined time are performed to detect a charge amount signal having this cycle as a cycle. Then, each charge amount signal of a predetermined cycle is observed a plurality of times over a predetermined period as time series data, and a deterioration determination unit for determining based on this time series data and the deterioration determination standard of the zinc oxide arrester is provided. A deterioration monitoring device for a zinc oxide type lightning arrester characterized by being provided.