KR200206967Y1 - A new diagnostic technique and equipment for lightning arrester by leakage current harmonic analysis on power service - Google Patents

Abstract

The present invention relates to a method and apparatus for diagnosing deterioration of an arrester which protects a power facility by discharging surge voltage and surge current such as overvoltage and lightning in a substation among power facilities that supply electric power. Determining the conclusion that deterioration of the arrester cannot be diagnosed by measuring only the total amount of leakage current, and confirming the arrester deterioration degree by analyzing the total amount of the arrester leakage current as well as 2, 3, and 5 harmonic components. It relates to a method and apparatus and a diagnostic service.

Description

{A new diagnostic technique and equipment for lightning arrester by leakage current harmonic analysis on power service}

The present invention is a lightning arrester monitoring diagnostic device (Fig. 2) to determine the arrester deterioration degree and deterioration state of the arrester life and deterioration degree of the arrester, the defect of the existing leakage current meter and counter circuit 1 The purpose of the present invention is to determine the deterioration state of the arrester based on FIG. 8 and to precisely perform a function corresponding to the monitoring diagnosis tendency of the power plant recently to ensure a basic insulation level occupied by the arrester.

In general, a leakage current meter 10 for measuring the leakage current 15 and a counter 13 for confirming the operation of the arrester are necessarily attached to the ground wire of the arrester. In recent years, power substations such as substations have been newly installed in existing substations to automatically diagnose electric power facilities and predict failures. At this time, if the lightning arrester, which is the lowest insulation point of the power equipment and the basic voltage of insulation voltage, is not able to operate normally due to failure or deterioration, it may cause the transformer winding and all other power equipment to burn out. In order to detect in advance to prevent the situation of a power outage and the like attached to the arrester and the counter 13 and the leakage ammeter (10) is attached.

At this time, the counter 13 and the ammeter 10 to be used have the following problems.

First, since the leakage current amount of the arrester is considerably small in the normal operating state, 200 μA-1 mA, it is impossible to display the correct current in the current ammeter 10.

Second, the currently installed ammeter 10 is an instrument measuring only the total amount of leakage current in an analog form and cannot determine the arrester deterioration characteristics obtained from the fracture test results (Figs. 8A and 8B).

Third, in the case of distribution lines, the leakage current of the arrester is not measured at all, which causes a problem in the manager of the arrester.

The concept of the present invention is a new arrester deterioration system which is intended to determine the deterioration state of the arrester by applying the arrester destruction test results accurately to the problems of the current transformer.

The present invention is to solve the above problems, and can accurately determine the deterioration state of the arrester based on the result of the arrester destruction test (Fig. 8) and the actual measurement waveform (Fig. 9 to Fig. 11) in the field using the system. Do.

First of all, the device of the present invention consists of four parts.

First, the current measuring circuit 31 for acquiring current information from the clamp-type current transformer 22 and processing the current information;

Second, since the amount of leakage current 15 changes as the voltage of the line bus 14 changes, the voltage measuring circuit 32 which acquires and processes the voltage of the line bus 14 so as to accurately normalize it.

Third, the deterioration determination system 33 which obtains information from the current measuring circuit 31 and the voltage measuring circuit 32 to process and judge the deterioration determination.

Fourth, it is composed of a display device 34 to inform the user of the measuring device of the present invention the correct state of the arrester (2).

1 is a leakage current measuring instrument of the current arrester.

Figure 2 is a current transformer diagnostic system according to the present invention.

3 is a current measurement circuit applied to the ground electrode

4 is a potential measurement circuit for measuring earth potential

5 is a deterioration determination system according to the present invention

6 is a display device according to the present invention

7A shows a normal arrester leakage current measurement waveform.

7b shows the frequency spectrum of a normal arrester leakage current.

Fig. 8A is a waveform of lightning arrestor leakage current immediately before breakdown.

Fig. 8B shows the arrester leakage current frequency spectrum immediately before destruction

9A is a leakage current measurement waveform in which deterioration was measured in the field with a measuring instrument of the present invention.

Figure 9b is the frequency spectrum of the leakage current measured waveform that started to deteriorate measured in the field with the measuring instrument of the present invention

Figure 10a Leakage current measurement waveform is in progress deterioration measured by the measuring device of the present invention

Fig. 10b Frequency spectrum of leakage current measured waveforms in progress of degradation measured in the field by the measuring device of the present invention

Fig. 11a Leakage current measurement waveform with significant deterioration measured in the field by measuring instrument of the present invention

Fig. 11B Frequency spectrum of leakage current measured waveform with significant deterioration measured in the field by measuring instrument of the present invention

<Description of Signs of Major Parts of Drawings>

1. Conventional leakage ammeter and counter attached to lightning arrester

2. Lightning arrester

3 Line side terminal for installing existing leakage current

4. Grounding terminal for installing existing leakage current

5. Linear Resistance to Limit Current

6. Zinc element varistor for operating the counter 12 during the operation of the arrester

Zinc lightning arrestor for passing lightning current during operation of 7, 8, 9 arresters

10. Analog ruler indicating leakage current

11. Zener element to protect the coil for operating the analog ruler (10)

12. Condenser for starting the counter to display the number of operation of the arrester

13. Counter relay indicating the number of operation of the arrester

14. Protected line busbar connected to the arrester (2)

15. Lightning arrester leakage current

21. Phase voltage input terminal for precise diagnosis

22. Clamped Current Transformer for Measuring Leakage Current

31. Current measuring circuit for measuring current information from current transformers

32. Voltage measuring circuit that processes voltage information by receiving phase voltage

33. Arrester deterioration determination system for determining the deterioration state of the arrester by processing the leakage current and the phase voltage proposed in the present invention

34. Display device for visually identifying the deterioration state of the arrester

41. Impedance matching circuit for processing current information without straining the current transformer

42. HPF (High Pass Filter) that processes current information

43. LPF (Low Pass Filter) for processing current information

44. Analog / Digital Converter Discretizes Current Information

51. Impedance matching circuit for processing voltage information supplying phase voltage

52. HPF (High Pass Filter) that processes voltage information

53. LPF (Low Pass Filter) that processes voltage information

54. Analog-to-digital converter for discretizing voltage information

61. Discretized Voltage Information

62. Frequency analyzer for analyzing discretized voltage and current information by frequency

63. Voltage compensation circuit to determine precise leakage current

64. Current information analyzed by frequency

65. Discrete Current Information

66. Phase Information Analyzed by Frequency

67. Degradation Decision Algorithm

71. Frequency display device for displaying leakage current and phase for each frequency

72. Display device for displaying leakage current and phase by frequency

73. Selector switch to select frequency and phase

74. Selection switch to distinguish between 3-phase batch measurement and phase measurement

75. 3-Phase Batch Measurement Status Indicator

76. Phase measurement status indicator

The existing type (FIG. 1) for measuring the current of the lightning arrestor leakage current (15) in consideration of the problem of lack of precision and lack of judgment of the measuring device (1) by periodically or periodically checking the existing measuring device (1). The purpose of the present invention system (Fig. 2) to determine the degree of deterioration by accurately analyzing the function and the arrester current (15) to correct the error.

In order to achieve this purpose

First, the current measuring circuit 31 passes through an impedance matching circuit 41 for accurately processing current information coming from the clamp type current transformer 22. In this circuit, the portion of the current transformer 22 that can minimize the load and the current measured in the actual field include many noise components due to the influence of the magnetic field in the atmosphere and the electric field. This noise component mainly includes a filter that removes the signal above 10 kHz. It also includes a circuit for removing the DC component included in the current information obtained from the current transformer 22. The current information from which the noise is removed passes only the frequency band necessary for determining the deterioration of the arrester while passing through the HPF 42 and the LPF 43 constituted by the operational amplifier. The current information passing through the HPF 42 and the LPF 43 is converted into a digital signal through the A / D conversion 44 and transferred to the deterioration determination system 33 which is digital processing hardware.

Second, in general, the line bus 14 voltage is not always a constant voltage due to the condition of the power system, and some voltage change may occur, and the voltage change acts to increase and decrease the leakage current 15 of the arrester. As such, when the leakage current 15 of the arrester increases or decreases due to the bus voltage 14, it may affect the analysis of the leakage current 15 by analyzing the leakage current 15, so as to compensate for the potential measurement circuit (FIGS. 4 and 32). Is applied. This potential measurement circuit (FIG. 4) passes through the impedance matching circuit 51 which minimizes the burden on the transformer supplying the bus voltage 14, and the HPF 52 and LPF 53 which pass only the necessary bands. The voltage information is transmitted to the deterioration determination system 33 which processes the digital signal while passing through the A / D conversion 54 for discretizing the received signal. In addition, the voltage information in the voltage measuring circuit 32 is used as important information for calculating the phase difference between voltage information and current information, which is one element of the deterioration determination of the arrester.

Third, the voltage information and the current information passed through the voltage measuring circuit 31 and the current measuring circuit 32 become discrete signals to reach the deterioration determination system. In this case, the voltage information and the current information are A / D converted at the same time. This makes it possible to measure the phase difference between the correct voltage and current without error. The deterioration determination system 33 shown in FIG. 5 is converted into frequency-specific information by passing through a frequency analyzer 62 using the pre-transformer method, which is a frequency analyzer method which generally uses the voltage information 61 and the current information 65. . The frequency-specific voltage information 61 and the current information 62 thus converted are accurate voltage and current information through the voltage compensation circuit 63 for magnitude compensation by the measured voltage. The voltage and current information thus processed are stored in the frequency-specific current information 64 and the frequency-dependent phase information 66 constituted by the hardware, and the degradation determination algorithm 67 is in a state capable of determining the deterioration state of the arrester. The deterioration determination algorithm determines the arrester deterioration state by using the following properties. The following properties are carried out on the basis of the arrester destruction characteristics and field measurement waveforms.

When the arrester starts to deteriorate, the phase between the leakage current 15 and the bus voltage 14 changes from the phase where the current is faster than the voltage to in phase.

As the arrester deteriorates, 120HZ, two harmonics of the commercial frequency (60Hz) of the leakage current, is generated.

As the arrester deteriorates, the 3rd and 5th harmonics of leakage current continuously increase.

As the arrester deteriorates, the leakage rate and crest factor of the leakage current increase.

As the arrester deteriorates, the effective value of the leakage current increases and then decreases or becomes constant.

Fourth, the arrester deterioration degree determined by the degradation diagnostic apparatus is in a state that can be transmitted from the user by the arrester deterioration display device 34 of FIG. The arrester deterioration determination display device is roughly divided into portions 74, 75 and 76 for determining the degree of deterioration and display portions 71, 72 and 73 for displaying accurate data. Here, a three-phase collective type for power distribution and a selector switch 74 for enabling phase inspection of the transformer are provided. In addition, it is characterized by the ability to see the necessary information by continuously pressing the selector switch 73 to view the data only necessary information.

The effect of the present invention is as follows.

First, the deterioration state of the existing arrester (2) can be measured in the live state,

Second, by compensating for the arrester leakage current 15 value by using the voltage information 61, the accurate leakage current can be measured even if the voltage value of the bus 14 changes,

Third, by implementing the algorithm proved through several arrester destruction tests and field demonstrations, it is possible to accurately determine the degree of deterioration of the arrester.

Fourthly, the deterioration state of the arrester is accurately determined by judging the leakage current 15 of the arrester based on accurate frequency information instead of determining the effective value.

Fifth, it is an advantage of the precision arrester deterioration determination system used to determine the arrester up to the phase difference between voltage information and current information.

Claims (3)

In the deterioration determination for the lightning arrester in operation, it uses the bus voltage and the leakage current during the live ship, and implements the algorithm based on the lightning arrester destruction characteristic, and based on the leakage current characteristic and the phase characteristic by frequency generated by the arrester deterioration. Method and apparatus for determining deterioration characteristics of arrester from leakage current 2. A method according to claim 1, wherein a method of compensating current with a voltage element and using magnitude characteristics and phase characteristics of 2, 3 and 5 harmonics of leakage current for deterioration determination of an arrester A service and a method for carrying out deterioration diagnosis of an arrester using the terms of claim 1 and 2.