JP3321479B2 - Fault location system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fault locating system used as a preventive maintenance system applied to confirm and monitor the reliability of each storage device in a gas insulated switchgear in which power devices are stored compactly. It is.

[0002]

2. Description of the Related Art In recent years, the amount of power supply in urban areas has tended to increase. In addition, land prices soaring make it more and more difficult to secure land for substation facilities. Under these circumstances, a gas-insulated switchgear excellent in environmental resistance and compactness is an indispensable device for enhancing substation facilities.

[0003] The gas insulated switchgear, with an insulating gas such as superior SF ₆ gas insulation and arc-extinguishing properties, disconnectors, housed and arranged such the substation equipment sealed grounded metal container breaker Device. Here, an example of a typical gas insulated switchgear will be specifically described with reference to an arrangement diagram shown in FIG.

[0004] In FIG. 3, reference numeral 1 denotes a pressure-resistant metal container having a ground potential, which is generally called a grounded metal container. In the grounded metal container 1, a lightning arrester 2, a transformer 3, a grounding switch 4, a disconnector 5, a current transformer 6, a circuit breaker 7, and a bus 8 are housed and arranged as power application units. Further, an insulating gas 9 such as SF ₆ is sealed in the grounded metal container 1, and the grounded metal container 1 and the power receiving section are electrically insulated by the insulating gas 9.

On the other hand, in the grounded metal container 1, insulating spacers 10a to 10d for supporting the busbars 8 are provided at appropriate intervals.
The mechanical strength and the dielectric strength of the bus bar 8 are maintained by 10 to 10d. In addition, each of the insulating spacers 10a to 10d
The space in the grounded metal container 1 is arranged so as to be air-tightly divided from the necessity of separation and arrangement in maintenance.
That is, the space in the grounded metal container 1 is
A plurality of gas sections are divided by 0a to 10d, and an insulating gas 9 is sealed in each gas section. In addition, 1 in the figure
Reference numeral 1 denotes a gas cylinder. Each gas compartment in the grounded metal container 1 is filled with gas from the gas cylinder 11 via a gas cubicle 12 and a valve 13. Among them, the gas cubicle 12 also has a function of detecting the pressure of each gas section.

Further, in FIG. 3, the main circuit is connected to a transformer 19 via a bushing 14 via a disconnector 5 and a circuit breaker 7. Although FIG. 3 shows a one-line power receiving main circuit, power is supplied from a power receiving main circuit (not shown) on the right side of the power receiving main circuit to the transformer 19 via the disconnector 5. In some cases.

In the figure, reference numeral 15 denotes a switchboard, and switches (switch disconnectors 5, breakers 7,
It has a function of giving an energizing signal to each operating device 17 of the earthing switch 4) and controlling switching of main circuits and switching operation of switches. Further, in the figure, reference numeral 18 denotes a compressor facility serving as a drive source for switches. A predetermined pressure (for example, generally 15 kg / cm ² ) obtained by the compressor equipment 18 is supplied to each operating device 1 via the operating cubicle 16.
7 to operate switches.

The gas insulated switchgear having the above configuration has the following advantages. That is, due to the excellent characteristics of the insulating gas 9, the size of the storage device can be reduced,
Compactness of the entire device can be realized. That is,
The occupied volume per KV · A becomes small, and the effective use of the installation site becomes possible. At the same time, 2
Stacking of three to three levels is possible, and block stacking is possible, so that a large area configuration with a small area is possible. .

Further, since the grounded metal container 1 is grounded, there is no fear of electric shock even when approaching during power application. Furthermore, since the power application unit is housed in the grounded metal container 1, there is no direct exposure to salt damage, wind and rain. Therefore, there is no fear of deterioration due to external factors, and the environment resistance is high. Moreover, since various switches are arc-treated in SF ₆ gas having a high arc-extinguishing ability, the breaking capacity per main contact can be greatly improved.

However, the gas insulated switchgear shown in FIG. 3 has the above advantages, but also has the following disadvantages. That is, as a result of downsizing the entire gas insulated switchgear, the size of the rotating operation or the reassembly operation during maintenance and inspection of the storage device is limited to a small size. Therefore, it takes a long time for the maintenance and inspection work of the storage device, and the work efficiency is significantly reduced.

In addition, since the insulating gas 9 sealed in the grounded metal container 1 is expensive, the production technology for preventing gas leakage to the outside becomes high-grade, and kv /
Since the diameter is large and the decrease in gas pressure reacts very sensitively to the insulation margin, a complete emergency repair system for gas leakage is required. Furthermore, in the replacement work due to the consumption of the main contacts of various switchgears, it takes a lot of time to collect and refill the insulating gas, so the downtime of the gas insulated switchgear becomes longer, which hinders the stable supply of power. There is also a drawback that causes.

As described above, the gas insulated switchgear has not only advantages but also several disadvantages. However, the performance advantages of gas insulated switchgear are more than enough to compensate for the shortcomings, so the recent spread of gas insulated switchgear has been remarkable, the number of installation locations has increased, and mass production systems have been adopted. I have. As a result, the gas insulated switchgear is required to have higher reliability, and the maintenance and maintenance of the device and the preparation of an emergency repair system and the variation in quality have become a problem that cannot be ignored.

As measures against the above-mentioned problems in the gas insulated switchgear, there is an urgent need to establish a preventive maintenance system capable of confirming the reliability of the normal operation state of operation and early monitoring when an abnormality occurs. ing. The introduction of this preventive maintenance system is expected to prevent the accident of the gas insulated switchgear and to stably supply electric power, while minimizing the economic loss caused by the accident.

As an example of such a preventive maintenance system, a fault point locating system has been conventionally proposed. The fault point locating system is a system for locating a fault point using a gas pressure sensor. That is, when an accident occurs in the gas compartment of the gas insulated switchgear, the gas pressure fluctuates due to the internal arc energy. On the contrary,
By disposing a gas pressure sensor in the gas compartment of the gas insulated switchgear, a gas pressure fluctuation in the gas compartment is detected by the gas pressure sensor and a gas pressure signal is output. Also, by connecting the detector to the gas pressure sensor and connecting the receiver to the detector, the gas pressure signal from the gas pressure sensor is sent to the detector, processed here and output to the receiver as a detection signal. I do.

According to such a fault location system,
The point of failure in a sealed grounded metal container can be accurately and quickly located without resorting to visual inspection. As a result, it is possible to expedite accident response and contribute to early recovery. Moreover, it is possible to efficiently apply the substation at the time of the accident. Therefore, the range of the accident can be minimized.

FIG. 4 shows the configuration of a gas pressure sensor used in the above-described fault location system.
As shown in FIG. 4, the gas pressure sensor is
Is configured within. That is, first, in this case 21
A gas pipe 22 filled with gas is drawn out from the inside, and the tip (not shown) is connected to a grounded metal container of the gas insulated switchgear. A liquid chamber 24 is provided at a base end inside the case 21 of the gas pipe 22 via an elastic partition film 23, and the gas in the gas pipe 22 and the liquid chamber are separated by the partition film 23. 24 and a liquid such as oil.

On the opposite side of the partition film 23 in the liquid chamber 24, a diaphragm 25 made of stainless steel or the like is provided.
A piezoresistive element 26 that converts distortion of the diaphragm 25 into a resistance change amount is attached to the outer surface of the liquid chamber 24 of the diaphragm 25. Further, a resistance element 27 is connected to the piezo resistance element 26, and a bridge circuit is configured by the piezo resistance element 26 and the resistance element 27.

An electronic circuit 28 for amplifying the signal and an output signal line 30 are sequentially connected to the bridge circuit. The output signal line 30 is drawn out of the case 21 and connected to a detector (not shown). In the figure, reference numeral 29 denotes a power supply circuit for supplying power to the electronic circuit 28, and reference numeral 31 denotes a power supply line.

In the gas pressure sensor of FIG. 4 configured as described above, when the pressure of the insulating gas in the grounded metal container of the gas insulated switchgear changes and the gas pressure in the gas pipe 22 changes, the pressure change Is transmitted to the piezoresistive element 26 via the partition film 23, the liquid in the liquid chamber 24, and the diaphragm 25. The piezoresistive element 26 converts this pressure change into a resistance change amount, and the electronic circuit 28 amplifies the resistance change amount into an electric signal, which is transmitted to the detector side. In general, the resolution Pc of the gas pressure sensor in a relatively short time is
Is set to about 0.001 kg / cm ² .

With the gas pressure sensor having the above-described configuration, an accident point in a gas compartment can be detected as follows. That is, first, a quasi-stationary gas pressure increase value due to an arc generated in a grounded metal container at the time of an accident is examined as in CIGRE WG and the like.
It can be almost evaluated by the following equation (1).

ΔP = (C · I · t) / V (1) where ΔP _f : pressure rise value (kg / cm ² ) C: coefficient (0.2 to 0.35) I: arc current (KA) t: arc duration time (ms) V: container volume (l)

The arc current I is almost determined by the position on the power system of the substation where the gas insulated switchgear is installed. Further, the arc continuation time t is substantially determined by the operation time of the protection relay and the current interruption time of the circuit breaker. Therefore, once the volume V of each gas compartment is determined,
The gas pressure rise value ΔP _f at the time of an accident in each gas compartment can be obtained. For example, in the case of a single-line ground fault in an ineffective grounding system, I = 0.1 KA, t = 134 ms, V = 10
When 0 to 2100 l is set, the gas pressure rise value ΔP _f is calculated from the above equation (1) as follows: ΔP _f = 0.04 to 0.02 kg
/ Cm ² .

FIG. 5 shows a measurement example of gas pressure fluctuation when a ground fault occurs in a grounded metal container of a gas insulated switchgear. As shown in FIG. 5, when an accident occurs, the gas pressure has a vibration waveform. In substations or switchyards where gas-insulated switchgears are installed, noise from power transmission lines, noise due to surge voltage generated during operation of equipment, noise due to ground potential fluctuation when ground fault occurs (that is, ground fault surge) And so on.
The signal output by the gas pressure sensor is greatly affected by these noises.

Therefore, when a gas pressure sensor is applied, a high-frequency component is removed from the vibration waveform as shown in FIG. 5 to detect a gas pressure fluctuation, and a preset gas pressure rise value expected at the time of an accident. Processing for comparison with ΔP _f is required. As a method of removing the influence of noise from the pressure signal in this way, there is a method of sampling pressure data at a constant period Δt, calculating an average value of the pressure data a plurality of times, and using the average as a pressure signal. Conventionally, removal of high-frequency components and removal of external noise as described above
This is performed by a processing device connected to the receiver. Such a fault point locating system is disclosed in, for example, Japanese Utility Model Laid-Open No. 3-39313 and Japanese Patent Laid-Open No. 5-126896.
(Japanese Patent Application No. 3-287798) .

[0024]

However, the conventional fault locating system as described above has the following drawbacks. That is, the A / D converter ( A
Sampling processing via a analog / digital converter ) and averaging processing multiple times are required.
Data processing becomes complicated. In addition, multiplexers and A /
The use of the D converter complicates the circuit configuration and increases the cost. Further, there is a problem that detection sensitivity to a predetermined pressure fluctuation cannot be obtained due to a sampling error for performing A / D conversion or noise generated by the A / D conversion circuit itself.

The present invention has been proposed in order to solve the above-mentioned drawbacks, and its object is to remove noise sufficiently, to have a simple circuit configuration, and to provide a high-performance failure. To provide a point location system.

[0026]

In order to achieve the above object, a fault locating system according to the present invention comprises a plurality of gas insulated switchgear having a high voltage conductor housed in a grounded metal container filled with an insulating gas. Divided into gas compartments.
A gas pressure sensor that measures a gas pressure in a corresponding gas compartment and outputs a gas pressure signal is provided, and the gas pressure sensor processes the gas pressure signal from the gas pressure sensor and outputs a detection signal. A fault locating system in which a detector is connected and a receiver for processing a detection signal from the detector is connected to the detector has the following features.

That is, the detector of the fault locating system of the present invention comprises a signal converter for converting a gas pressure signal from the gas pressure sensor into an appropriate voltage signal, and a voltage / voltage converter for converting the voltage signal from the signal converter into a voltage / voltage signal. A voltage / frequency converter for frequency-converting and outputting a detection signal is provided. Further, the receiver of the fault locating system of the present invention measures a pulse of a detection signal from the detector, a counter circuit that outputs a count value,
A data processing unit for processing a count value from the counter circuit is provided.

The fault locating system according to the present invention comprises:
The normal pressure measurement range of the gas pressure sensor is P, the minimum detected value of the pressure fluctuation required for fault location is ΔP, the frequency range of the voltage / frequency converter corresponding to the pressure measurement range P of the gas pressure sensor is ΔF, and the counter is When the maximum count number of the circuit is N _max and the measurement time of the receiver is T, the relationship of (P / ΔP) ≦ ΔF · T ≦ N _max is established.

Generally, the voltage / frequency converter is configured to output an optical signal as a detection signal, and the detector and the receiver are connected by an optical fiber. In this case, the receiver further includes an optical / electrical conversion unit that converts the optical signal into an electric signal, and the counter circuit measures a pulse of the electric signal obtained by the optical / electrical conversion unit and outputs a count value. It is composed of

The fault locating system of the present invention preferably further comprises a higher-level processing system for averaging the output from the receiver. In addition, the signal converter of the fault locating system of the present invention generally includes a filter circuit that removes a high-frequency component from the gas pressure signal from the gas pressure sensor with a cutoff frequency.

[0031]

The operation of the present invention having the above configuration is as follows. That is, in this embodiment, first, the signal converter receives the gas pressure signal from the gas pressure sensor and converts it into a voltage signal. In this case, generally, a filter circuit removes high-frequency components in the gas pressure signal by a cutoff frequency, and extracts only a quasi-stationary or steady gas pressure signal. However, simply using the filter circuit as described above may not completely remove noise from the gas pressure signal, and may overlap noise from a DC power supply or the like.

On the other hand, in the present invention, the voltage signal is converted from voltage to frequency by the voltage / frequency converter of the detector, a detection signal is output, and the detection signal is processed by the receiver. That is, generally, an optical signal is output as a detection signal from the voltage / frequency converter, and this optical signal is
The signal is converted into an electric signal by an optical / electrical conversion unit of the receiver and sent to a counter circuit. With this counter circuit, the pressure value can be measured by counting the pulses at every fixed measurement time T.

In this case, in the present invention, (P / Δ
P) ≦ ΔF · T ≦ _Nmax . In this conditional expression, the resolution ΔP and the measurement time T of the system are determined from the viewpoint of the function of the system, and the maximum count number _Nmax of the counter circuit is determined by hardware. Therefore, by selecting the frequency range ΔF that satisfies this conditional expression, the noise can be removed as efficiently as possible within the limited measurement time T.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a fault locating system according to the present invention will be specifically described below with reference to FIGS.

(1) Configuration of Embodiment As shown in FIG. 1, the fault locating system of this embodiment is
It has a gas pressure sensor 41, a detector 47, and a receiver 54. Among them, the configuration and operation of the gas pressure sensor 41 are the same as those of the conventional gas pressure sensor shown in FIG. In the present embodiment, the detector 47 and the receiver 54 are housed in a field relay board.

The detector 47 of this embodiment has an I / V converter (current / voltage converter) 4 as an internal circuit.
2, a low-pass filter 43, and a V / F converter (voltage / frequency converter) 44 are sequentially connected and provided. Further, the I / V converter 42, the low-pass filter 43, and the V / F converter 44 include a DC power supply 45.
Is connected. An optical fiber 46 is connected to the V / F converter 44. This optical fiber 46 insulates a portion for transmitting the output signal from the V / F converter 44 to the receiver 54 side.

The I / V converter 42 is a circuit for converting a gas pressure signal from the gas pressure sensor 41 (that is, an electric signal from the electronic circuit 28 as shown in FIG. 4) into a voltage signal. The low-pass filter 43 is a filter circuit that removes high-frequency components from the gas pressure signal based on the cutoff frequency and extracts only a quasi-stationary or steady gas pressure signal. The cutoff frequency of the low-pass filter 43 is about several Hz. Further, the V / F converter 44 is a conversion unit that performs voltage / frequency conversion on the gas pressure signal extracted by the low-pass filter 43 and outputs an optical signal.

Next, the inside of the receiver 54 of this embodiment is
/ E converter (optical / electrical converter) 53, counter circuit 4
8, CPU (data processing unit) 49, RAM 51, ROM
52, and an interface (IF) 50. Among them, the O / E converter 53 is a circuit for converting the transmitted optical signal into a voltage signal, and the counter circuit 48 measures the pulse of the voltage signal obtained by the O / E converter 53 and counts the pulse. It is a circuit that outputs a value. Also, C
The PU 49 is a circuit that performs various types of data processing including processing of the count value from the counter circuit 48. Further, R
The AM 51 is a storage unit for storing data.
A storage unit 2 stores a program. On the other hand, the interface (IF) 50 outputs the obtained data to a higher-level processing system (not shown).

In this embodiment, P corresponds to the normal pressure measurement range of the gas pressure sensor 41, ΔP corresponds to the minimum detection value of the pressure fluctuation required for fault location, and P corresponds to the pressure measurement range P of the gas pressure sensor 41. When the frequency range of the V / F converter 44 is ΔF, the maximum count of the counter circuit 48 is N _max , and the measurement time of the receiver 54 is T, the following equation (2) is established. Have been.

(P / ΔP) ≦ ΔF · T ≦ N _max Equation (2)

(2) Operation of the Embodiment The operation of the embodiment having the above configuration will be described. First, in general, in order for a failure point location system to accurately and quickly locate a failure point with high accuracy, it is necessary to determine a gas pressure fluctuation at the time of occurrence of an accident with high accuracy. Therefore, the following two requirements are required when determining the gas pressure fluctuation. One is to determine the gas pressure fluctuation at every ΔT (usually, on the order of seconds).
One is to determine the gas pressure fluctuation on the order of mV. The system is required to have a resolution on the order of mV because the output of the gas pressure sensor is converted to about 1 to 5 V. In order to realize the determination of the gas pressure fluctuation on the order of mV, it is necessary to remove noise from the gas pressure signal output by the gas pressure sensor 41.

On the other hand, in the present embodiment, noise can be removed by the low-pass filter 43 of the detector 47. For example, as shown by a waveform A in FIG. 2, noises of various frequencies overlap with the gas pressure signal from the gas pressure sensor 41. In the present embodiment, the gas pressure signal including such noise is included. The detector 4
By performing the processing at 7, noise can be removed and a noise-free waveform as shown in waveform B can be obtained. That is, in the detector 47 of the present embodiment, first, the I / V converter 42 receives the gas pressure signal (the electric signal from the electronic circuit 28) from the gas pressure sensor 41 and converts it into a voltage signal. Subsequently, the low-pass filter 43 removes high-frequency components in the gas pressure signal at a cutoff frequency of about several Hz, and can extract only a quasi-stationary or steady gas pressure signal as shown by a waveform B in FIG. .

However, simply using the low-pass filter 43 as described above may not completely remove the noise from the gas pressure signal. In addition, noise is generated in the DC power supply 45, and this noise overlaps with the gas pressure signal. In some cases. Therefore, the low-pass filter 43
It is necessary to further remove noise from the gas pressure signal processed by the method.

In this case, in this embodiment, the frequency range ΔF of the V / F converter 44 is selected so as to satisfy the above equation (2), and the gas from the low-pass filter 43 is selected by the V / F converter 44. By converting the pressure signal into an optical signal, sending the optical signal to the receiver 54, and counting the pulses at every predetermined measurement time T by the counter circuit 48, in other words, by counting the frequency per unit time, An accurate pressure value without noise can be measured.

That is, first, in a steady state, V /
The optical signal from the F converter 44 is converted into an electric signal via the O / E converter 53 and sent to the counter circuit 48.
Here, assuming that the frequency (number of pulses) per unit time corresponding to the pressure value in the steady state is f ₀ and the noise component as described above is Δf, the average value f _ave of the frequency at a fixed measurement time T (ie, , The average value of the pressure values) is obtained by the following equation (3).

(Equation 3) Here, assuming that the measurement time T is T = N · ΔT, the following equation (4) is obtained from the above equation (3).

(Equation 4) From this equation (4), it can be seen that the noise component can be reduced by increasing the value of N.

However, the value of N in the above equation (4) is related to the measurement time T during which the receiver 54 detects the pressure rise after the occurrence of the fault arc, and the capacity (number of bits) of the counter circuit 48. Subject to restrictions. Further, the measurement time T of the receiver 54 is limited in terms of the function of detecting a failure and outputting the orientation result to the system side. Then, within the measurement time T thus limited, the V / F converter 44
Is selected so as to satisfy the condition of the above equation (2), the noise can be removed as efficiently as possible. This will be described below.

That is, here, the normal pressure measurement range of the gas pressure sensor 41 is P, and the minimum detection value of the pressure fluctuation required for fault location (the resolution of the system including the detector 49 and the receiver 54) is ΔP. The frequency range of the V / F converter 44 corresponding to the pressure measurement range P of the gas pressure sensor 41 is ΔF, and the maximum count number of the counter circuit 48 is _Nmax . The range of the count number measured for each measurement time T is Δ
Expressed as FT. That is, corresponding to the pressure measurement range P
Therefore, the count number changes within a range of ΔFT.
You. Therefore, the minimum measurement unit of the pressure value is ｛P / Δ
F · T｝. Since the pressure value corresponding to one count in the measurement time T becomes the resolution of the system, and the pressure value corresponding to this one count becomes {P / (ΔF · T)}, the following equation (5) holds. become.

ΔP ≧ P / (ΔF · T) Expression (5) Also, the number of pulses is counted for each measurement time T.
Therefore, the maximum count number of the counter circuit 48 is set to _Nmax .
And the counted value is over unless it is less than _Nmax.
-Flow occurs, and accurate counts cannot be obtained. Mosquito
Since the range of the number of counts is .DELTA.FT, the maximum count of pulses within this range must be equal to or less than _Nmax , so the following equation (6) holds.

ΔF · T ≦ N _max Equation (6) Accordingly, the above equation (2) is obtained from these equations (5) and (6).

In the above equation (2), the system resolution ΔP and the measurement time T are determined from the viewpoint of the function of the system, and the maximum count number N _max of the counter circuit 48 is determined by hardware. Δ that satisfies 2)
F will be selected. That is, by selecting the frequency range ΔF of the V / F converter 44 that satisfies the expression (2), the noise can be removed as efficiently as possible within the limited measurement time T.

(3) Effects of Embodiment As described above, according to the present embodiment, the V / F converter 44 is used as a part of the detector 47, and the light from the V / F converter 44 is used. The signal is sent to the receiver 54, and the counter circuit 48 is configured to count the pulses at every predetermined measurement time T. In particular, the frequency range ΔF of the V / F converter 44 is appropriately selected as described above. By
A high-performance fault locating system having a simple circuit configuration and high performance can be configured.

Further, in this embodiment, since the detector 47 and the receiver 54 are connected by the optical fiber 46, there is an advantage that the influence of the surge generated when a failure occurs can be eliminated. That is, the internal circuits of the gas pressure sensor 41 and the detector 47 can be configured to ensure sufficient insulation strength to the ground, but since the receiver 54 has the built-in CPU 49, It is more difficult to ensure sufficient withstand voltage performance and noise resistance than the 47 side. Therefore, as in the present embodiment, the detector 47 and the receiver 54 are electrically separated and insulated by the optical fiber 46, thereby ensuring sufficient reliability against a surge or the like generated when a failure occurs. be able to.

(4) Other Embodiments The present invention is not limited to the above-described embodiment. For example, the averaging process may be performed by a higher-level processing system not shown in FIG. It is also possible to configure. That is, in FIG. 1, the output of the counter circuit 48 of the receiver 54 is
0, it is transmitted to a higher-level processing system (not shown). In this higher-level processing system, when the output of the counter circuit 48 is averaged, variations in the detected data can be removed, so that the accuracy of the fault location can be improved.

As described above, when the averaging process is performed in the higher-level processing system, it is necessary to appropriately select the measurement time in the receiving unit 54. That is, the fault point locating time _Tmax including the upper processing system is given as the system specification. This fault location time T
_In practice, _max is determined from the speed of response to a failure or the like. In this case, the time T _ave required for the averaging process in the upper processing system is given by the following equation (7).

T _ave = m · T ≦ T _max Equation (7) where m is an integer.

Therefore, as described above, when the averaging process is performed in the upper processing system, the above equation (2) is used.
It is necessary to appropriately select the measurement time T and the frequency range ΔF of the V / F converter 44 so as to satisfy Expression (7). On the other hand, when the averaging process is not performed in the higher-level processing system, the measurement time T in the above equation (2) becomes equal to the fault point locating time _Tmax .

On the other hand, in the above embodiment, the detector 47
Although the optical fiber 46 is used to connect between the optical fiber 46 and the receiver 54, a photocoupler can be used instead of the optical fiber 46 because the surge level is low in a device having a low voltage class. Further, instead of outputting an optical signal as a detection signal from the V / F converter 44, an electric signal may be output from the V / F converter 44 as a detection signal. Further, the gas pressure sensor 4
The specific configurations of 1, the detector 47, and the receiver 54 can be appropriately changed.

[0054]

As described above, according to the fault locating system of the present invention, a voltage / frequency converter is used as a part of a detector, and an optical signal from the voltage / frequency converter is used as a receiver. And a certain measurement time T by the counter circuit.
Each pulse is counted, and in particular,
By properly selecting the frequency range ΔF of the voltage / frequency conversion unit, noise can be removed as efficiently as possible within a limited measurement time T, so that the circuit configuration is simpler than in the past. And a high-performance failure point locating system can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of a fault point location system according to the present invention.

FIG. 2 is a signal waveform diagram showing an example of signal processing in the embodiment shown in FIG.

FIG. 3 is a layout diagram showing an example of a general gas insulated switchgear.

FIG. 4 is a sectional view showing a conventional gas pressure sensor.

FIG. 5 is a signal waveform diagram illustrating a measurement example of gas pressure fluctuation when a ground fault arc occurs in the gas insulated switchgear.

[Explanation of symbols]

 41 Gas pressure sensor 42 I / V converter 43 Low pass filter 44 V / F converter 45 DC power supply 46 Optical fiber 47 Detector 48 Counter circuit 49 CPU 50 Interface 51 RAM 52 ROM 53 O / E converter 54 Receiver

Continuation of the front page (72) Inventor Masayuki Akasaki 2-1 Ukishima-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Inside the Hamakawasaki Plant, Toshiba Corporation (58) Fields investigated (Int. Cl. ⁷ , DB name) G01R 31/08

Claims (4)

(57) [Claims] A gas-insulated switchgear having a high-voltage conductor housed in a grounded metal container filled with an insulating gas is divided into a plurality of gas compartments, and each gas compartment has a gas pressure in a corresponding gas compartment. A gas pressure sensor that measures and outputs a gas pressure signal is provided, and a detector that processes a gas pressure signal from the gas pressure sensor and outputs a detection signal is connected to the gas pressure sensor. In a fault locating system to which a receiver that processes a detection signal from the detector is connected, the detector includes a signal converter that converts a gas pressure signal from the gas pressure sensor into an appropriate voltage signal. A voltage / frequency converter for converting a voltage signal from the signal converter into a voltage / frequency to output a detection signal, wherein the receiver measures a pulse of the detection signal from the detector, and counts a count value. And a data processing unit for processing the count value from the counter circuit, wherein P is a normal pressure measurement range of the gas pressure sensor, ΔP is a minimum detection value of pressure fluctuation required for fault point location, When the frequency range of the voltage / frequency conversion unit corresponding to the pressure measurement range P of the gas pressure sensor is ΔF, the maximum count number of the counter circuit is N _max , and the measurement time of the receiver is T, (P / A fault point locating system characterized in that a relationship of ΔP) ≦ ΔF · T ≦ N _max is established. 2. The voltage / frequency conversion section is configured to output an optical signal as a detection signal, the detector and the receiver are connected by an optical fiber, and the receiver converts the optical signal into an electric signal. Further comprising an optical / electrical conversion unit for
2. The fault point locating system according to claim 1, wherein the counter circuit is configured to measure a pulse of an electric signal obtained by an optical / electrical conversion unit and output a count value. 3. The fault locating system according to claim 1, further comprising a higher-order processing system connected to said receiver and for averaging an output from said receiver. 4. The fault locating system according to claim 1, wherein said signal converter includes a filter circuit for removing a high frequency component from a gas pressure signal from said gas pressure sensor by a cutoff frequency. .