JP3266003B2 - Ground fault detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground fault detecting device for detecting a zero-phase voltage generated at the time of a ground fault in a three-phase AC distribution line.

[0002]

2. Description of the Related Art A conventional ground fault detecting apparatus is shown in FIGS.
3 will be described.

As a method for detecting a zero-sequence voltage generated at the time of a ground fault occurring in a three-phase AC distribution line, as shown in FIG. One ends of C1, C2 and C3 are connected, the other ends are connected in common, connected to one end of a zero-phase detection capacitor C0, the other end of the zero-phase detection capacitor C0 is connected to the ground,
Further, a zero-phase voltage detector (hereinafter referred to as ZP) configured to connect a step-down insulating transformer 27 in parallel with the zero-phase detection capacitor C0.
D) is common.

Further, as described in Japanese Patent Application Laid-Open No. Hei 4-27775, in FIG. 13, a high-voltage capacitor Cp25 and a low-voltage capacitor C
There is a ground fault detecting device having a configuration in which s26 is connected in series and a step-down insulating transformer 28 is connected in parallel with Cs26. The ground fault detecting device of this configuration is a high-voltage capacitor Cp25.
Is connected to an arbitrary phase of the three-phase high-voltage distribution line 3, for example, the S-phase, and one end of the low-voltage capacitor Cs26 is connected to the ground,
The zero-phase voltage is obtained from the difference between the measured values by measuring the S-phase voltage to ground connected to the ground fault detecting device.

The voltage measurement output value V2 by the ground fault detecting device is
V2 = Vs × Cp / (Cp + Cs)

When the zero-phase voltage is generated, V2g is given by: V2g = Vsg ×
Cp / (Cp + Cs). Voltage Vsg to ground at the time of accident
Is Vsg = Vs−Vo, and Vsg = Vs−Vo, the zero-phase voltage Vo is −Vo = Vsg−Vs = (Cp + Cs) / Cp
× (V2g−V2), and by measuring the above V2 and V2g via the step-down insulating transformer 28, the signal processing for calculating Vo is executed by the waveform processing circuit 29 to detect the zero-phase voltage. ing.

Further, voltage measuring means constituted by an optical voltage sensor is installed in each phase of a three-phase AC distribution line, and the measured value of the voltage measuring means is converted to an equivalent signal proportional to the voltage between each phase to ground. There is also a method of detecting the zero-phase voltage by performing a three-phase vector operation on the measured value.

[0008]

However, the conventional ZPD system and the zero-phase voltage detection system described in Japanese Patent Application Laid-Open No. 4-27775 have the following problems.

(1) In order to measure the voltage between each phase and the ground, a measuring section must be directly connected to the charging section of the high-voltage distribution line, and it is necessary to stop the power during the operation.

(2) In the case of installation in a high-voltage live state, remove the covering of the distribution line or remove the clamp cover of the connection part such as a switch or a transformer installed beforehand, and connect directly to the charging part. Requires very dangerous work and complicates the installation work.

(3) In terms of reliability, it is necessary to provide a sufficient insulation distance in order to increase the withstand voltage characteristics of the device, and the device becomes large.

(4) In the method of use, since one end is directly connected to a high-voltage charging unit, it is generally used in a waterproof housing such as a high-voltage power receiving facility. In the event that a short circuit occurs due to poor insulation of the high-voltage capacitor of the apparatus, a high voltage is directly applied to the low-voltage capacitor, which may cause an accident in the distribution line due to equipment failure and an accident spread to the measuring device. Conversely, even if an accident occurs on the low voltage side, the accident may spread to the high voltage distribution line because it is electrically connected.

When a zero-phase voltage is detected by a three-phase vector operation method using a voltage measuring means constituted by an optical voltage sensor, it is necessary to keep the characteristics of the measuring device of each phase in equilibrium. Management becomes particularly difficult. In addition, the potential difference signal measured by the voltage measuring means composed of the optical voltage sensor is not a potential difference signal proportional to the voltage between the ground and the potential difference signal due to the capacity coefficient formed by each phase distribution line. Even if a vector operation is executed, the operation value does not become zero, and it is necessary to perform signal processing of the operation value to detect a zero-phase voltage. In the case of an optical voltage sensor, which is expensive, when an optical voltage sensor for each phase is prepared, the ground fault detecting device becomes particularly expensive.

Further, when detecting a ground fault in a three-phase AC distribution line and limiting the fault section, it is necessary to install a large number of directional ground fault detectors on the distribution line. A ground fault detection device constituting the detection device is also required.

In this case, since the ground fault detecting device is directly connected to the high voltage charging section, it is necessary to guarantee the reliability of the device itself for a long time. Further, in order to satisfy the withstand voltage characteristic of the device itself, the device is required. In addition, the installation work becomes complicated and the installation work becomes complicated due to the safety of the installation work, which leads to an increase in the total cost for the user. There are also problems such as impairing the aesthetics when the pillars are mounted.

An object of the present invention is to solve the above-mentioned problem, and an object of the present invention is to provide a ground fault detecting device for detecting a zero-sequence voltage generated at the time of a ground fault.

[0017]

In order to achieve this object, a ground fault detecting device according to claim 1 comprises a potential difference measuring means for calculating a potential difference by measuring an electric field strength of a three-phase AC distribution line; A change amount detecting means for comparing and calculating a difference between a potential difference in a current cycle from the potential difference measuring means and a potential difference in a normal state at least one cycle before; and a zero detecting means for detecting a zero-phase voltage based on output data from the change amount detecting means. Phase voltage detecting means.

The ground fault detecting device according to a second aspect of the present invention provides a correction calculating means for correcting a change in the potential difference calculated by the change detecting means, and a correction element input means for inputting a correction parameter to the correction calculating means. And

The ground fault detecting device according to a third aspect of the present invention is capable of communication capable of transmitting and receiving the correction element input means and the correction calculation means.

[0020]

According to a fourth aspect of the present invention, in the ground fault detecting apparatus, an optical voltage sensor is used as the potential difference measuring means, and a signal from the optical voltage sensor is transmitted through an optical fiber cable.

According to a fifth aspect of the present invention, in the ground fault detecting device, the correction element input means includes a data input section for inputting a correction parameter, and a data conversion section for converting data input from the data input section into predetermined data. And a data communication unit capable of transmitting and receiving the data converted by the data conversion unit.

Further, the ground fault detecting device according to claim 6 is a potential difference measuring means for calculating a potential difference by measuring the electric field strength of the three-phase AC distribution line, and at least one potential difference from the current cycle from the potential difference measuring means. A change amount detecting means for comparing and calculating a difference from a potential difference at a healthy state before the cycle; a zero-phase voltage detecting means for detecting a zero-sequence voltage based on output data from the change amount detecting means; Zero-phase current detection means for detecting a phase current; a ground fault which determines a ground fault direction based on a zero-phase voltage detection signal from the zero-phase voltage detection means and a zero-phase current signal from the zero-phase current detection means. Direction determining means.

[0024]

According to the first aspect of the present invention, since an electric field strength of a three-phase AC distribution line is measured, an accident due to equipment failure of the ground fault detecting device of the present invention may occur. There is no risk of accidents spreading to the low-voltage section and distribution lines.
Further, the zero-phase voltage can be detected in a non-contact manner with the high voltage charging unit.

According to a second aspect of the present invention, in the first aspect of the invention, the amount of change in the calculated potential difference is corrected.
A more accurate zero-sequence voltage can be detected.

According to a third aspect of the present invention, a communication capable of transmitting and receiving the correction element input means and the correction operation means can be performed. The input of the correction value can be performed without removing the ground fault detecting device and again. The correction value can be changed without working on the pillar.

[0027]

According to a fourth aspect of the present invention, an optical voltage sensor is used as a potential difference measuring means, and a signal from the optical voltage sensor is transmitted through an optical fiber cable. Good.

According to a fifth aspect of the present invention, the correction element input means includes a data input section for correction parameters, a data conversion section, and a data communication section capable of transmitting and receiving data, and capable of transmitting and receiving the correction value. The correction value can be changed without removing the ground fault detecting device and without performing the work on the pillar again, and the correction value setting of a plurality of ground fault detecting devices can be performed by one correction element input means. It becomes possible.

According to a sixth aspect of the present invention, the potential difference is calculated by measuring the electric field strength of the three-phase AC distribution line, and the difference between the potential difference in the current cycle and the potential difference in the normal state at least one cycle before is calculated. By detecting the zero-sequence voltage and determining the direction of the ground fault accident, even if an accident occurs due to equipment failure of the ground fault detecting device of the present invention, the fault is transmitted to the low-voltage part and the distribution line. The zero-phase voltage can be detected without contact with the high voltage charging unit. Furthermore, the direction of the ground fault that can be used for permanent use and emergency use can be determined.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. (Embodiment 1) FIG. 1 is an overall configuration diagram of a ground fault detecting device according to Embodiment 1 of the present invention, which is composed of a potential difference measuring means 4 and a signal processing circuit means 7, and each configuration will be described below. I do.

The potential difference measuring means 4 is an electrode 1 and an electrode 2 for efficiently measuring the electric field strength of an electric field formed around any one phase of the three-phase AC distribution line 3 (the electrode 1 and the electrode 2 Electrode 1 and electrode 2)
A voltage sensor 5 for inputting a potential difference between the electrodes and converting the voltage into a light modulation signal proportional to the potential difference; electrodes 1 and 2; The first measuring unit 6 is configured to have a predetermined positional relationship, and the optical fiber cable 13 is a signal transmission medium between the optical voltage sensor 5 and the input / output converter 8. .

On the other hand, the signal processing circuit means 7 inputs and outputs the optical modulation signal measured by the potential difference measuring means 4 and converts it into an electric signal proportional to the optical modulation signal. Of the potential difference signal, which is at least one cycle before, and a change amount detection unit 9 for detecting an amount of change in the potential difference signal, and a three-phase AC distribution system in which the potential difference measuring means 4 is installed. Electric wire 3
An input unit 10 for inputting a correction parameter value according to the mounting condition of the column and the arrangement position of the potential difference measuring means 4, a correction operation unit 11 for determining and storing a correction operation value based on the correction parameter value input from the input unit 10. , A zero-phase voltage detector 12 that detects a zero-phase voltage by inputting the results of the change amount detector 9 and the correction calculator 11 and performing signal processing.

The potential difference measuring method of the potential difference measuring means 4 and the transmission medium of the measurement signal are not limited to the photoelectric sensor 5 and the optical fiber cable 13, but the potential difference measuring method using an electric field strength meter, and the transmission means are infrared communication or radio wave. Communication means such as this may be used.

The operation of the ground fault detecting device according to the present embodiment having the above configuration will be described with reference to FIGS.

FIG. 2 is a diagram showing the relationship between the potential difference measuring means 4 and the three-phase AC distribution line 3. Hereinafter, the means for measuring the potential difference by the potential difference measuring means 4 will be described with reference to FIGS.

R, S, T are three-phase AC distribution lines 3, Qr, Q
s and Qt are the electric charges Q of each phase distribution line of the three-phase AC distribution line 3, and Cr1, Cr2, Cs1, Cs2, Ct1 and Ct2 are capacitance coefficients formed by the positional relationship between each phase distribution line and the electrodes 1 and 2. It shows.

Here, the electric field intensity E1 and the electric field intensity E2 of the electrode 1 and the electrode 2 are respectively E1 = Qr / Cr1 + Qs / Cs1 + Qt / Ct1 (V / m) E2 = Qr / Cr2 + Qs / Cs2 + Qt / Ct2 (V / m) Is shown. Therefore, the potential difference E generated between the electrode 1 and the electrode 2 is E = E1-E2 = Qr × (1 / Cr1-1 / Cr2) + Qs
× (1 / Cs1-1 / Cs2) + Qt × (1 / Ct1-1 / C
t2) (V).

When (1 / Cr1-1 / Cr2) = Cre (1 / Cs1-1 / Cs2) = Cse (1 / Ct1-1 / Ct2) = Cte, the potential difference E = Cre × Qr + Cse × Qs + Cte × Qt (V). As is well known, Cre, Cse, and Cte are determined by the positional relationship between the three-phase distribution line and the electrode and the electrode length.

The potential difference formed as described above is converted into an optical modulation signal proportional to the potential difference by the optical voltage sensor 5 and measured by the signal processing circuit means 7.

As described above, the electrode 1 and the electrode 2 which are not in contact with any one phase of the three-phase AC distribution line 3 are used as the potential difference measuring means 4.
And a light voltage sensor 5 for measurement, and a non-metallic optical fiber cable 13 as a transmission medium of the measurement signal.
Therefore, a high-voltage part and a low-voltage part can be insulated and separated from each other, so that a device that is excellent in insulation reliability and is non-inductive to noise can be provided.

FIG. 3 shows an input / output converter 8 for converting a light modulation signal proportional to the potential difference signal E measured by the potential difference measuring means 4 into an electric signal, and a potential difference signal converted into an electric signal by the input / output converter 8. FIG. 4 is a diagram showing the configuration of a change amount detection unit 9 for detecting a change amount ΔV of a potential difference signal by calculating a difference between the potential difference signal Eo in a healthy state at least one cycle before E and detecting a ground fault accident. This shows the function up to detection of the amount of change ΔV in the potential difference signal accompanying the generation of the zero-sequence voltage.

The potential difference signal E measured by the potential difference measuring means 4 is converted by the input / output converter 8 into an electric signal proportional to the potential difference signal E, and output to the change amount detector 9. The change amount detection unit 9 performs a vector operation on the potential difference signal Eo at least one cycle earlier from the latest potential difference signal En of the potential difference signal converted by the input / output conversion unit 8, thereby causing a ground fault accident in the three-phase AC distribution line. The configuration is such that the amount of change ΔV of the potential difference signal accompanying the generation of the zero-phase voltage is detected. A more detailed description will be given based on FIG.

The input / output conversion unit 8 includes the optical fiber cable 1
3 as a signal transmission medium, a light emitting unit 8A for supplying a constant amount of light to the optical voltage sensor 5, a light receiving unit 8B for receiving an optical modulation signal modulated by the optical voltage sensor 5, and an optical signal received by the light receiving unit 8B. It comprises an I / V converter 8C for converting the signal into a proportional electric signal, and an amplifier 8D for amplifying the signal of the I / V converter 8C to an appropriate signal level. The change amount detection unit 9 which receives the potential difference conversion signal E output from the amplifying unit 8D and detects the amount of change in the potential difference is stored in a storage unit 9A which stores the input conversion signal E for a period of time in units of one cycle.
Vector operation of the latest input signal of the potential difference signal E and the potential difference signal E stored by the storage unit 9A;
A computing unit 9B that outputs a memory data update command to A,
It comprises a variation output section 9C that outputs the result of the calculation section 9B.

The change amount detecting section 9 will be described with reference to FIGS. When the potential difference signal output from the input / output conversion unit 8 is stored in the storage unit 9A, the potential difference signal of the next cycle is input to the storage unit 9A and also to the calculation unit 9B. In the calculation unit 9B.

(1) “Potential difference signal (A) in next cycle−stored potential difference signal (B)” = potential difference change amount (ΔV) (2) Determination process of potential difference change amount ΔV ≧ constant value (Sh).
And (3) when the potential difference change amount ΔV is equal to or less than a certain value, the storage unit 9
A storage unit 9A control for outputting a memory update command Rs to A. I do.

When the memory update command Rs is input from the arithmetic unit 9B, the storage unit 9A deletes the memory data stored therein and records the newly input potential difference signal.

According to FIG. 4, the potential difference signal is subjected to a vector operation with the stored potential difference signal to measure a change amount ΔV. In this case, since the change amount ΔV is equal to or smaller than the fixed value, when the calculation unit 9B outputs the memory update command Rs to the storage unit 9A, the storage unit 9A updates the memory data to a potential difference signal. In the same manner, the potential difference signal, the memoized potential difference signal, and a vector operation are performed to measure the change amount ΔV. As shown in FIG. 4, when the change amount ΔV between the potential difference signal and the memory data after the vector calculation detects a constant value (Sh) or more, the memory update command Rs is not output and the memory data is fixed by the potential difference signal. Measure the quantity state.

According to the present embodiment, when the three-phase AC distribution line is in a healthy state, the control of updating the memory waveform is performed in one cycle unit, but after the memory control of the initial potential difference signal, the memory waveform is updated. Does not perform M cycle (M ≧ 2) update or memory update control. Alternatively, a method may be used in which a preset potential difference signal is used as a memory signal and memory control is not controlled.

Next, referring to FIG. 5, the state of the poles of the three-phase AC distribution line 3 on which the potential difference measuring means 4 is installed (for example, the arrangement of the distribution lines, the ground height, the distance between lines, the number of lines) and the potential difference measuring means An input unit 10 for inputting a correction parameter value using the arrangement position of 4 as a correction parameter, and a correction operation unit 1 for determining a correction value based on the correction parameter value input from the input unit 10
1 will be described.

FIG. 5 shows the mounting condition of the three-phase AC distribution line and the capacity coefficient formed by each phase distribution line and the ground. Cr, Cs, and Ct are capacity coefficients formed between each phase distribution line and the ground. Crs, Cst, and Ctr are capacity coefficients formed between the phase distribution lines, and Qr, Qs, and Qt are three-phase AC distribution lines 3.
Is the charge amount Q of each phase distribution line. Where each charge Q
Qr = Vr × Cr + Vs × Crs + Vt × Ctr Qs = Vr × Crs + Vs × Cs + Vt × Cst Qt = Vr × Ctr + Vs × Cst + Vt × Ct Here, Vr, Vs, and Vt indicate respective relative ground voltages of the three-phase AC distribution line 3.

Next, the relative ground-to-ground voltages (Vrg, Vs) due to the zero-phase voltage Vo generated by the ground fault of the three-phase AC distribution line 3
g, Vtg) is expressed as Vrg = Vr-VoVsg = Vs-Vo Vtg = Vt-Vo, and the charge Qg of each phase distribution line at this time is Qrg = Vrg * Cr + Vsg * Crs + Vtg * Ctr Qsg = Vrg * Crs + Vsg × Cs + Vtg × Cst Qtg = Vrg × Ctr + Vsg × Cst + Vtg × Ct

When the potential difference E of the three-phase AC distribution line at the time of sound and at the time of a ground fault is expressed, the potential difference at the time of sound Ea = Cre × Qr + Cse × Qs + Cte × Qt (V) The potential difference at the time of a ground fault Eg = Cre × Qrg + Cse × Qsg + Cte × It is represented by Qtg (V).

The potential difference Ea and Eg signals are measured by the potential difference measuring means 4 when the three-phase AC distribution line is sound and when there is a ground fault.
The potential difference change signal ΔV obtained by the configuration of the input / output converter 8 and the change detector 9 is ΔV = Eg−Ea = Cre × (Qrg−Qr) + Cse × (Qsg−Qs) + Cte × (Qtg−Qt) If the mounting state of the three-phase AC distribution line 3 and the positional relationship between the phase distribution lines and the electrodes are constant, this is determined by the amount of change in the amount of charge of each phase distribution line.

QRg−Qr = − (Vo × Cr + Vo × Crs + Vo × Ctr) = − Vo × (Cr + Crs + Ctr) = − Vo × C1 Qsg−Qs = − (Vo × Crs + Vo × Cs + Vo × Cst) = − Vo × (Crs + Cs + Cst) = −Vo × C2 Qtg−Qt = − (Vo × Ctr + Vo × Cst + Vo × Ct) = − Vo × (Ctr + Cst + Ct) = − Vo × C3 From the equation, the potential difference variation ΔV is ΔV = −Vo × C1 × Cre−Vo × C2. × Cse−Vo × C3 × Cte = −Vo × (C1 × Cre + C2 × Cse + C3 × Cte) = − Vo × H (H = C1 × Cre + C2 × Cse + C3 × Cte) The fact that the potential difference change amount ΔV is expressed as above means that if the change amount signal ΔV detected by the change amount detection unit 9 is divided by the correction operation value H, the zero-phase voltage Vo
Can be detected (Vo = −ΔV /
H). The correction calculation value of the present apparatus indicates the correction coefficient H determined by the mounting condition of the three-phase AC distribution line and the arrangement position of the potential difference measuring means.

The input section 10 and the correction operation section 11 are input means for inputting correction parameter values indicating the mounting condition of the three-phase AC distribution line 3 on which the potential difference measuring means 4 is disposed and the arrangement position of the potential difference measuring means 4. And a means configured to calculate a correction operation value H based on the correction parameter value.

The zero-phase voltage detector 12 receives the change amount signal ΔV detected by the change amount detector 9 and the correction operation value H calculated by the correction operation unit 11, and performs a division process (ΔV ÷
H), the zero-phase voltage Vo is detected.

Next, a first measurement which incorporates the electrodes 1 and 2 and the optical voltage sensor 5 and is configured so that the positional relationship of the electrodes with respect to the three-phase AC distribution line 3 becomes a preset positional relationship. The unit 6 and the potential difference measuring means 4 having a configuration in which the arrangement position of the potential difference measuring means 4 can be adjusted will be described.

FIG. 6 incorporates the electrode 1 and the electrode 2 and the optical voltage sensor 5, and is configured so that the positional relationship of the electrodes with respect to the three-phase AC distribution line 3 becomes a preset positional relationship.
FIG. 3 is a diagram illustrating a configuration of a first measurement unit 6;
A is the upper unit of the first measuring unit 6, and 6B is the first unit.
The lower unit 6C of the measuring unit 6 of FIG. 1 shows a clamp unit for clamping a distribution line formed when the upper and lower units are combined.

In the clamp section 6C, S which is an arbitrary phase of the three-phase AC distribution line 3 is always set regardless of the diameter of the distribution line.
The spacer 6D corresponding to the wire diameter is inserted so that the phase 3A is at the center of the clamp 6C, and is fixed and fixed so as to be at the center of the clamp 6C. Then, as shown in FIG.
The electrode 2 is configured in the lower unit 6B in advance so as to be located at r1 and r2 from the center of the clamp portion 6C, so that the three-phase AC distribution line 3 has a structure for securing a relative position to any one phase. I have.

FIG. 7 shows a configuration and an external view of the potential difference measuring means 4 which constitutes the second measuring unit 6E at one end of the arm 4A while being insulated from the arm 4A. Except for omitting the structures of the clamp unit 6C and the spacer 6D, the basic configuration and structure including the electrodes 1 and 2 and the optical voltage sensor 5 are the same as those of the first measurement unit unit 6 shown in FIG. Further, the second measuring unit 6E
A removable positioning ruler 4 made of an insulator 24;
B is provided so that the relative position to the distribution line can be determined. The other end of the arm 4A is fixed to the utility pole 23.

In both the embodiments shown in FIGS. 6 and 7, the measurement of the potential difference between the electrodes 1 and 2 is based on the optical voltage sensor 5 and the transmission medium of the measurement signal is based on the optical fiber cable 13. .

From the above, it is possible to install the potential difference measuring means 4 on a pole without using a bucket truck or the like which is normally required, and it is possible to simplify the installation work and reduce the installation work cost. Become. By providing the removable positioning ruler 4B, the relative position with respect to any one phase can be determined only by giving the wire diameter of the distribution line, and since it becomes an indicator for installation at the time of installation work, further installation work can be performed. It can be facilitated. After installation, by removing the ruler, a configuration in which it is completely disconnected from the distribution line becomes possible.

When the distribution line has multiple lines, the capacity coefficient formed by each distribution line may be calculated to calculate a correction operation value according to the state of the multi-line. , The correction operation value H required to detect the zero-phase voltage can be calculated.

Further, the zero-phase voltage can be detected with high accuracy by the above-described one-potential difference measuring means, and the zero-phase voltage can be detected by the one-potential difference measuring means. Conventionally (a zero-phase voltage detection apparatus to which a three-phase addition method is applied) to provide a phase voltage detection apparatus and detect a zero-phase voltage from a measurement signal of a potential difference measuring means having one configuration
Can eliminate the need for control for keeping the characteristics of each phase measurement device in equilibrium, and can facilitate the work in terms of manufacturing and management, thereby making it possible to reduce the cost of the device.

(Embodiment 2) The present embodiment 2 is a zero-phase voltage detecting device in which the input section of Embodiment 1 is constituted by a communication means 14 capable of transmitting and receiving, comprising a transmitting section 14A and a receiving section 14B. FIG. 8 shows the configuration.

In this configuration, the correction parameter value indicating the mounting state of the three-phase AC distribution line 3 on which the potential difference measuring means 4 is installed is converted into a correction element input device 15 configured as a device different from the ground fault detection device. , And obtains respective correction parameter values from the correction element input device 15.

FIG. 9 shows communication means 1 according to the second embodiment.
4 is a ground fault detection device configured to directly input the output of the zero-phase voltage detection unit to the zero-phase voltage detection unit, wherein the correction calculation unit 11 for calculating the correction calculation value H is configured in the correction element input device 15, and the correction element input device 15 Is a ground fault detecting device configured to calculate the correction calculation value H from the correction element input device 15 and obtain the correction calculation value H from the correction element input device 15. In the two embodiments, the other configurations and respective functions are the same as those in the first embodiment. In the case of the second embodiment shown in FIG. 9, a function of storing the correction operation value H is added to the zero-phase voltage detection unit 12.

FIG. 10 shows the configuration of the correction element input device 15. The correction element input device 15 includes an input unit 16 for inputting a correction parameter value indicating a mounting state of the three-phase AC distribution line 3 on which the potential difference measuring unit 4 is installed, and a correction parameter value input by the input unit 16 for a predetermined value. And a communication unit 18 capable of transmitting and receiving the data relating to the correction operation value converted by the data conversion unit 17 to the ground fault detection device. When a function of calculating the correction calculation value H is added to the correction element input device 15, the same function as that of the correction calculation unit 11 may be added to the data conversion unit 17.

According to the second embodiment, it is possible to input the correction parameter value even after the three-phase AC distribution line 3 is installed, and even if the correction parameter value is erroneously input, the installed ground fault is detected. Correction parameter values can be re-input without removing the device and without re-performing the work on the pole, thereby facilitating the work.

Further, since the correction parameter value can be input by communication, it is not necessary to configure an input terminal unit necessary for inputting the correction parameter value in the ground fault detecting device, and the ground fault detecting device can be reduced in size and size. It can be made lightweight.

A correction operation unit 1 for calculating a correction operation value H
It is also possible to improve the accuracy of the correction operation value H by making the device 1 a dedicated device, and it is also possible to easily add a circuit unit and a software program configuration for improving the accuracy of the correction operation value H.

Considering further the economic effect, the use of the ground fault detecting device installed in the three-phase AC distribution line 3 and recognizing the direction of use requires the ground fault detecting device corresponding to the use.
The input terminal unit (and the correction operation unit 1) is connected to each ground fault detection device.
Rather than configuring the method 1), a dedicated device may be used as the correction element input device 15 so that the correction element setting of the ground fault detection device can be performed by one correction element input device 15.

In the second embodiment, the communication means 1
8, a transmission unit 18A and a reception unit 18B are provided. This is because when the ground fault detection device receives the transmission data transmitted by the correction element input device 15, the ground fault detection device responds to the received data. Then, the received data is transmitted as a response to the correction element input device 15 in such a manner. When the correction element input device 15 is provided with a display unit 19 for displaying the result of the response transmission, as a means for confirming whether the ground fault detecting device has correctly received the transmission data from the correction element input device 15. Alternatively, it may be configured as a means for reconfirming whether or not an erroneous input has been made in the input of the correction parameter value.

(Embodiment 3) FIG. 11 shows Embodiment 3 of the present invention.
1 is a configuration diagram of a ground fault detecting device for recognizing a direction using a ground fault detecting device of the present embodiment, where R, S, and T are each phase of the three-phase AC distribution line 3, and 16 is a ground fault of the third embodiment. A zero-phase voltage detector, which is a short-circuit detector, and a zero-phase current detector 20, which detects each phase current of the three-phase AC distribution line 3 by a core and a photocurrent sensor (not shown). 20A, and an operation unit 20B for detecting a zero-phase current by performing three-phase addition (vector operation) of each phase current detected by each phase current detection unit 20A. Reference numeral 21 denotes a ground fault direction determining unit which receives outputs of the zero-phase voltage detecting unit 12 and the zero-phase current detecting unit 20 to determine a ground fault direction, and 22 denotes a ground fault detected by the ground fault direction determining unit 21. This is an output unit that outputs a direction determination result.

According to this configuration, if a ground fault occurs in the three-phase AC distribution line 3, the three-phase AC distribution line 3 becomes unbalanced. A zero-phase current is detected at the output of the operation unit 20B that performs phase addition.
Also in the zero-phase voltage detection unit 12, as described above, a change occurs in the charge amount of each phase distribution line, so that a potential difference change amount is generated and the zero-phase voltage is detected. As is known, since the zero-phase voltage and the zero-phase current have a specific phase relationship according to the direction of the ground-fault accident, the ground-fault and the ground-fault are determined from the detection level and the phase difference between the zero-phase current and the zero-phase voltage. The direction of the accident can be detected.

According to the third embodiment, since optical measurement is used, a highly insulated and non-inductive type device can be realized and high reliability is achieved.
Further, since the present apparatus can be installed without a power failure during the installation work and can be easily attached to a distribution line, it is possible to provide a ground fault detecting apparatus that recognizes a direction in which the apparatus can be used for permanent use and emergency use.

[0078]

According to the present invention, the following excellent effects can be obtained.

(1) Since the potential difference is calculated by measuring the electric field strength of the three-phase AC distribution line, since it is not in contact with the high-voltage charging section, installation work is facilitated and excellent safety is achieved. Can be.

(2) Since the amount of change in the potential difference is corrected, a more accurate zero-phase voltage can be detected.

(3) Since the communication capable of transmitting and receiving between the correction element input means and the correction calculation means can be performed, the input terminal unit can be omitted from the ground fault detecting device, and the ground fault detecting device can be made small and light, so that excellent economy can be achieved. Simplicity and workability.

[0082]

(5) Since the optical voltage sensor is used as the potential difference measuring means and the signal from the optical voltage sensor is transmitted through the optical fiber cable, a highly insulated and non-inductive ground fault detecting device can be realized, and the noise resistance can be improved. Improvement can be achieved.

(6) The correction element input means includes: a data input section for correction parameters; a data conversion section for converting the input data into predetermined data; and a data communication section capable of transmitting and receiving the converted data. Because it has
There is no need to provide a data input section for correction parameter values in the ground fault detection device, and correction values for a plurality of ground fault detection devices can be set by one correction element input unit. The economic effect can be improved.

(7) The potential difference is calculated by measuring the electric field strength of the three-phase AC distribution line, and the zero-phase voltage is calculated by comparing the difference between the potential difference in the current cycle and the potential difference in the normal state at least one cycle before. And the direction of the ground fault accident is also determined, so that an accurate zero-sequence voltage can be obtained,
It is possible to determine the direction of a ground fault that can be used for permanent and emergency use.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a zero-sequence voltage detection device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a potential difference measuring unit and a three-phase AC distribution line according to the first embodiment.

FIG. 3 is a configuration diagram of an input / output conversion unit and a change amount detection unit according to the first embodiment.

FIG. 4 is a functional conceptual diagram of a change amount detection unit according to the first embodiment.

FIG. 5 is a state diagram showing a capacitance formed by the three-phase AC distribution line according to the first embodiment.

FIG. 6 is a configuration diagram showing a first measurement unit unit according to the first embodiment.

FIG. 7 is a configuration and external view showing a potential difference measuring unit according to the first embodiment.

FIG. 8 is an overall configuration diagram of a ground fault detecting device according to the second embodiment.

FIG. 9 is an overall configuration diagram of a second ground fault detecting device according to the second embodiment.

FIG. 10 is an overall configuration diagram of a correction element input device according to the second embodiment.

FIG. 11 is an overall configuration diagram of a ground fault detection device that recognizes a direction using the ground fault detection device according to the third embodiment.

FIG. 12 is a first configuration diagram showing a conventional ground fault detection device.

FIG. 13 is a second configuration diagram showing a conventional ground fault detection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 electrode 1 2 electrode 2 3 Three-phase alternating current distribution line 3A S phase which is an arbitrary phase of three-phase alternating current distribution line 4 Potential difference measuring means 4A Arm 4B Ruler 5 Optical voltage sensor 6 First measuring unit 6A Upper unit 6B Lower unit 6C Clamp unit 6D Spacer 6E Second measurement unit unit 7 Signal processing circuit unit 8 Input / output conversion unit 8A Light emission unit 8B Light reception unit 8C I / V conversion unit 8D amplification unit 9 Change amount detection unit 9A Storage unit 9B calculation Unit (vector operation) 9C change amount output unit 10 input unit 11 correction operation unit 12 zero-phase voltage detection unit 13 optical fiber cable 14 communication means 14A transmission unit 14B reception unit 15 correction element input device 16 input unit 17 data conversion unit 18 communication Means 18A Transmission section 18B Receiving section 19 Display section 20 Zero-phase current detection section 20A Each phase current detection section 20B Operation section 21 Ground Accident direction determination section 22 output section 23 utility pole 24 insulator 25 for step-down high-voltage capacitor Cp 26 low capacitor Cs 27, 28 insulation transformer 29 waveform processing circuit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01R 29/16 G01R 31/02 G01R 31/08-31/11

Claims (6)

(57) [Claims] 1. A potential difference measuring means for calculating a potential difference by measuring an electric field strength of a three-phase AC distribution line, and a difference between a potential difference in a current cycle from the potential difference measuring means and a potential difference in a healthy state at least one cycle before. And a ground fault detection device comprising: a zero-phase voltage detection unit that detects a zero-phase voltage based on output data from the variation detection unit. 2. The ground according to claim 1, further comprising: a correction operation unit that corrects a change amount of the potential difference calculated by the change amount detection unit; and a correction element input unit that inputs a correction parameter to the correction operation unit. Tangle detection device. 3. The ground fault detecting device according to claim 2, wherein the correction element input means and the correction calculation means are capable of transmitting and receiving communication. 4. The ground fault detecting device according to claim 1, wherein an optical voltage sensor is used as the potential difference measuring means, and a signal from the optical voltage sensor is transmitted through an optical fiber cable. 5. A correction element input unit, comprising: a data input unit for inputting a correction parameter; a data conversion unit for converting data input from the data input unit into predetermined data;
The ground fault detecting device according to claim 3, further comprising a data communication unit capable of transmitting and receiving the data converted by the data conversion unit. 6. A potential difference measuring means for calculating a potential difference by measuring an electric field strength of a three-phase AC distribution line, and a difference between a potential difference in a current cycle from the potential difference measuring means and a potential difference in a healthy state at least one cycle before. , A zero-phase voltage detecting means for detecting a zero-phase voltage based on output data from the variation detecting means, and a zero-phase current detecting means for detecting a zero-phase current of the three-phase AC distribution line. And a ground fault detection means for determining a ground fault direction based on a zero-phase voltage detection signal from the zero-phase voltage detection means and a zero-phase current signal from the zero-phase current detection means. .