JPH0650330B2 - Deterioration diagnosis method for zinc oxide type arrester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention comprises one or a plurality of series connected non-linear resistance elements containing zinc oxide as a main component in a container. The present invention relates to a deterioration diagnosing method for a zinc oxide type arrester, which diagnoses the presence or absence of deterioration of the non-linear resistance element by using a resistance component current having the same phase as the arrester terminal voltage passing through the arrester constituting each phase of the phase arrester.

[Conventional technology]

In a lightning arrester in which one or more non-linear resistance elements containing zinc oxide as a main component (hereinafter simply referred to as elements) are housed in series in a container, due to the characteristics of the elements, the The amount of current that can flow is extremely small, usually on the order of μA, and normal temperature rise of the element and deterioration of the element due to this temperature rise cannot occur at this level of current, so the discharge gap in series with the non-linear resistance element is It is usually omitted and is used in practice. Therefore, a small current always flows through the nonlinear resistance element.

However, the element may deteriorate due to repeated operation under abnormal abnormal voltage or thermal cycle due to weather conditions.If this deterioration progresses, it will not be able to withstand the constant phase voltage in the system. , The element will be damaged and it will hinder the system operation. Therefore, there is a demand for a monitoring method capable of continuously monitoring the resistance component current that can determine the initial state of deterioration during operation.

FIG. 3 shows the voltage-current characteristics of the device. In the figure, the solid line 25 shows the characteristic when the element is in a normal state, and the alternate long and short dash line 35 shows the characteristic when the deterioration has progressed. Here, the current on the horizontal axis indicates only a resistance current that does not include a capacitive current based on the electrostatic capacitance between the two end faces of the element normally formed in a disc shape. When the phase voltage of the system is Vn, the current flowing through the element under this voltage varies depending on the temperature of the element, but if the element is deteriorated, a large difference occurs in the current flowing even under the same temperature. For example, assuming that the temperature of the element is θ ₂ , the current I _R1 flowing when the element is normal changes greatly to F _R2 . Therefore, measure the resistance current that constantly flows,
The presence or absence of deterioration can be accurately determined by comparing with the current of the element in the normal state corresponding to the temperature at the time of measurement. In the figure, the magnitude relationship of the temperature θ is θ ₂ > θ ₁
Is.

By the way, when the current passing through the lightning arrester is measured by the current detector connected in series with the lightning arrester, the voltage applied to the lightning arrester contains an alternating current at the operating frequency, and therefore, a capacitive component current is included in addition to the resistance component current. . FIG. 4 shows a lightning arrester 2 whose upper and lower ends are connected to the line and the ground, respectively. This lightning arrester 2 includes an insulator and an element when the container that accommodates the element is an insulator, and indicates only the element when the container is a grounded metal. FIG. 5 shows an electrical equivalent circuit of the lightning arrester shown in FIG. The element is usually formed in the shape of a disc and has a relatively large capacitance C between its two end faces.
Therefore, the current passing through the lightning arrester is the vector sum of the resistance component current I _R that causes the temperature rise of the device and the capacitance component current I _c that passes through the capacitance, and to determine the deterioration of the device, Only the resistance current I _R needs to be extracted from this vector sum. In the figure, L indicates the inductance of the ground conductor of the lightning arrester. Note that when container arrester is insulators, in the capacity of current I _c is also included capacity of current and capacitance of the insulator.

FIG. 6 shows a conventional resistance current measuring method, and FIG. 7 shows voltage and current waveforms measured by the method shown in FIG. The lightning arrester 2 connected to the bus bar or the transmission line 1 is a current detector 4
And a voltage detector 3 is further connected to the bus or power transmission line and the other end is grounded. The outputs from the current detector 4 and the voltage detector 3 are input to the calculator 8 via the amplifiers 6 and 7, respectively, and the resistance current is calculated. The calculation of the resistance of current, as shown in FIG. 7, a differential waveform of the voltage V measured by the voltage detector 3 from the total current I _s, which is measured by the current detector 4 from the peak value of the Figure 5 It is performed by amplifying and subtracting so as to match the I _c peak value. The resistance component current I _R thus obtained is compared with the normal resistance component current at the element temperature measured in parallel with this measurement to determine the presence or absence of deterioration.

[Problems to be solved by the invention]

However, using this method, a three-phase surge arrester connected
When automatic monitoring is performed for the deterioration diagnosis of the phase arrester, as shown in FIG.
Are shared, the three-phase current detectors 41, 42, 4
3 requires the voltage detectors 31, 32, 33, and has a large number of switching contacts so that the current detection value and the voltage detection value of the same phase can be input to the amplifiers 6, 7, respectively. Requires vessel 5. Since the progress of deterioration of the element is on the order of time at the fastest, the method of making determination while sequentially switching each phase can sufficiently serve the purpose.

As described above, the diagnosis of deterioration by the conventional method requires a large number of current detectors and wirings as the number of power transmission lines increases, and the size of the switch becomes large to complicate the control for diagnosis. Since the grounding side conductors from the three-phase lightning arrester housed in the container are drawn out from the terminals provided on the container wall, there is a risk of impairing the airtightness and insulating properties of the container. A diagnostic method that has a simple structure and is reliable has been desired.

It is an object of the present invention to provide a simple diagnosis method in which the number of power transmission lines to which a lightning arrester is connected is remarkably increased along with an increase in current detectors and wiring, and the structure replaces the conventional method.

[Means for solving problems]

In order to achieve the above object, according to the present invention, one or a plurality of non-linear resistance elements whose main component is zinc oxide, which are connected in series, are housed in a container, and The current passing through each phase of the arrester is combined into a three-phase vector to eliminate the capacitive current contained in each phase current and obtain the combined waveform of only the resistance current.The three-phase arrester is used from this combined waveform. In the deterioration diagnosis method for diagnosing whether or not there is a lightning arrester in which the nonlinear resistance element inside has deteriorated,
The ground side conductors of each phase of the three-phase lightning arrester are collectively connected in a container accommodating the three-phase lightning arrester, and the collectively connected connection conductors are connected to the annular core through a sealed terminal provided on the container wall. The through-type current transformer that is provided is penetrated and grounded, and the through-current transformer is used to obtain the combined waveform of the resistance component current.

[Action]

First, the principle of the deterioration diagnosis method according to the present invention will be described.

As shown in Fig. 1, the measuring circuit for the three-phase vector synthesis of the current passing through each phase of the three-phase surge arrester is configured, and the capacity current contained in each phase current is erased and only the resistance current is removed. The composite waveform of is obtained as shown in FIG. A zero-phase current transformer, for example, is used as the current detector 44 in FIG.
Each of the ground side conductors 1, 22, 23 collectively penetrates the current transformer core to be grounded, and the secondary side output of the current transformer is input to the amplifier 6 for amplification to obtain the composite waveform. ing. In addition to the combined waveform 420, the surge arrester terminal voltage waveform of each phase is additionally shown in FIG.

As can be seen from the current waveform of FIG. 2, the waveform of this composite waveform shows that the voltage-current characteristic of the element, that is, the current sharply increases as the applied voltage increases, and sharply decreases as the applied voltage decreases. As shown in the figure, the waveform has a waveform including a large amount of the third harmonic, and the position of its peak value coincides with the peak value of the voltage waveform. Therefore, if the element of the arrester of any phase in the three-phase arrester has deteriorated, the peak value of the current of that phase is higher than the peak value of the current of the remaining phase that appears every 60 electrical degrees following this peak value. It is diagnosed that the device has become large and the element of that phase is deteriorated. However, since only the combined current waveform is measured by the measuring circuit of FIG. 1, it is not possible to identify the phase in which the element is deteriorated only from this waveform. However, in a three-phase lightning arrester in which three phases of lightning arrester are housed in a common container, replacement of a new one is performed for all phases even if the element deteriorates in any phase Therefore, in the case of such a three-phase arrester, the present invention provides an extremely simple deterioration diagnosis method as compared with the conventional one.

〔Example〕

FIG. 1 shows an embodiment of the deterioration diagnosis method of the present invention. Lightning arresters 21, 2 are provided for each phase 11, 12, 13 of the bus or transmission line.
Only 2, 23 are connected, and the grounding side conductors of the respective phases of the three-phase lightning arrester are collectively connected in a metal container that commonly accommodates the three-phase lightning arrester indicated by the broken line 80, and this is collectively connected. The connection conductor is grounded through a current detector on the ground side of a sealed terminal (not shown) provided on the container wall. A zero-phase current transformer is used for this current detector, and the secondary side output of the current transformer is input to the amplifier 6 and amplified.
This zero-phase current transformer can accurately measure the small current of a specific phase on the primary side.
In addition to the characteristics of outputting to the secondary side, the iron core is saturated at the time of a large current, and an excessive voltage is not output to the secondary side, which is a characteristic suitable for the deterioration diagnosis of the arrester.

FIG. 2 shows the current waveform obtained from the output side of the amplifier 6 by the circuit configuration of FIG. 1 and the three-phase voltage waveform that produces this current waveform in an overlapping manner. Where 111,11
Reference numerals 213, 422, and 42 denote ground voltages of the respective phases that flow through the arresters of the respective phases of the bus and the transmission line.
Reference numeral 3 denotes a peak value that appears every 60 electrical degrees in a combined current waveform 420 obtained by vector-combining the currents flowing through the phase arresters. In addition, the waveform of this combined current has a characteristic that the voltage-current characteristics of the element, that is, the current sharply increases when the applied voltage becomes high, and sharply decreases when the applied voltage becomes small. A waveform containing many harmonics is taken, and the position of its peak value coincides with the position of the peak value of the voltage waveform. Therefore, if the element of the arrester of any one phase of the three-phase arrester has deteriorated, the current peak value of that phase follows the peak value and the electrical angle 6
It becomes larger than the current peak value of the remaining phase that appears every 0 °, and it is diagnosed that the element of that phase is deteriorated. In the deterioration diagnosing method of the present invention, the grounding side conductors of each phase of the three-phase lightning arrester are collectively connected in the container accommodating the three-phase lightning arrestor, and the collectively connected connection conductors are provided on the container wall. Since the measurement is performed via the sealed terminal, the voltage waveform of each phase is not measured, so it is not possible to specify in which phase the deterioration has occurred. If the phase arrester is housed in a common metal container, even if any of the phases is deteriorated, all three phases will be replaced with new ones and the update will be completed promptly. Such a voltage detector is omitted to simplify the circuit configuration for diagnosis.

〔The invention's effect〕

As described above, according to the present invention, one or more serially connected nonlinear resistance elements containing zinc oxide as a main component are housed in a container, and the three-phase arrester By synthesizing the currents passing through each phase of the three-phase vector, the capacity current contained in each phase current is erased to obtain the resistance-current-only composite waveform, and from this composite waveform, the three-phase surge arrester In the deterioration diagnosis method for diagnosing whether or not there is a lightning arrester in which the non-linear resistance element is deteriorated, the ground side conductors of each phase of the three-phase lightning arrester are collectively connected in the container housing the three-phase lightning arrester. , The collectively connected connection conductors are grounded by penetrating a through-type current transformer having an annular iron core through a sealed terminal provided on the container wall, and combining the resistance currents by the through-type current transformer. Since the waveform is calculated, the target of deterioration diagnosis Even if the number of surge arresters is large, the number of current detectors and wiring required for deterioration diagnosis is significantly smaller than before, and the number of sealed terminals leading out the ground side conductor from the arrester to the outside of the metal container is small. As a result, the airtightness and insulation of the container can be improved, and the deterioration diagnosis of the three-phase lightning arrester that does not require the identification of the deterioration phase can be performed with a simple structure and at an extremely low cost.

[Brief description of drawings]

FIG. 1 is a configuration diagram for diagnosing deterioration of a lightning arrester element according to an embodiment of the present invention, and FIG. 2 is a combined current waveform of a three-phase arrester obtained by the configuration of FIG. 1 and a bus or transmission line that causes this waveform. Waveform diagram showing each relative ground voltage waveform of the electric wire superimposed on this combined current waveform, Fig. 3 is a diagram showing the difference between the normal characteristics of the arrester element and the characteristics when deteriorated, and Fig. 4 is the external circuit of the arrester Fig. 5 is a single line diagram showing the connection state with the lightning arrester, Fig. 5 is an equivalent circuit diagram of the lightning arrester showing the current component in the current passing through the lightning arrester, and Fig. 6 is for extracting only the resistance current from the current passing through the lightning arrester. An example of a conventional measurement circuit diagram configured for one phase of the arrester, FIG. 7 is a current waveform diagram showing the waveform of the total current passing through the arrester and the waveform of the current component in the total current, and FIG. 8 is Extract only the resistance current from the current passing through the arrester It is an example of a conventional measuring circuit diagram of a three-phase arrester fit. 2,21,22,23: Lightning arrester, 3,31,32,3
3: Voltage detector, 4, 41, 42, 43, 44: Current detector, 80: Metal container, 420: Three-phase vector composite current waveform.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Nobuyuki Takao, No. 1 Tanabe Shinden, Kawasaki-ku, Kawasaki City, Kanagawa Prefecture Fuji Electric Co., Ltd. (72) No. 1, Sana Tanabe, Kawasaki-ku, Kawasaki City, Kanagawa No. 1 in Fuji Electric Co., Ltd. (72) Inventor Yoshihiro Tanabe 1-1, Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Fuji Electric Co., Ltd. (56) Reference JP-A-54-34043 (JP, A)

Claims (1)

[Claims] 1. One or a plurality of units connected in series,
A non-linear resistance element containing zinc oxide as a main component is housed in a container, and a current contained in each phase of the three-phase arrester is combined by three-phase vector synthesis to obtain a capacitance contained in each phase current. In the deterioration diagnosis method for deciding whether or not there is a lightning arrester in which the non-linear resistance element in the three-phase lightning arrester has deteriorated, the composite waveform of only the resistance component current is obtained by erasing the component current, and The grounding side conductors of each phase of the phase arrester are collectively connected in the container that houses the three-phase arrester, and the connection conductors that are collectively connected are penetrated with an annular core through the sealed terminal provided on the container wall. A method for diagnosing deterioration of a zinc oxide surge arrester, characterized in that a through-type current transformer is grounded, and a synthetic waveform of the resistance component current is obtained by the through-current transformer.