JP3189294B2 - Distribution line fault section determination system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention measures a distribution line current at a terminal station provided for each section on a distribution line, detects short-circuit, disconnection and ground fault information to determine a failure section of the distribution line. The present invention relates to a system for determining a fault section of a distribution line that can perform the operation.

[0002]

2. Description of the Related Art A distribution line is a line installed between a substation and a customer, and a large number of distribution lines are supplied from one substation. Each distribution line is provided with a section switch at regular intervals in addition to a circuit breaker. If an accident such as a short circuit, disconnection, or ground fault occurs in the middle of a distribution line, the circuit breaker will be opened and the corresponding switchgear will be opened accordingly to protect the distribution line.In this case, the cause of the failure will be investigated. It is important to detect where the fault section is located in order to supply power other than the fault section.

Therefore, in the related art, the terminal station (may be provided at the same place as the divided switch or at another place at regular intervals of the distribution line. It does not have to be). This terminal station has three current sensors for measuring each phase current Ia, Ib, Ic and three voltage sensors for measuring each phase voltage Va, Vb, Vc. I0, positive-phase current I1 and negative-phase current I2 are calculated, zero-phase voltage V0 is calculated from the three voltage sensors, and short-circuit, disconnection, and ground fault information is collected in the terminal station based on these currents and voltages. The failure is transmitted to the master station, and the master station regards the section located between the terminal station that detected the failure and the terminal station that does not detect the failure as a failure section (see Japanese Patent Application Laid-Open No. 2-266823).

[0004]

The above-mentioned terminal station requires three voltage sensors. These voltage sensors are directly attached to a distribution line which is usually laid, and optically apply the voltage to the ground. The measurement type is used.
However, because it measures high voltages (eg, 6.6 kV),
There is a disadvantage that it is greatly affected by the insulation resistance to the ground. For example, if the insulation resistance with respect to the ground fluctuates due to weather, contamination of the voltage sensor surface, or the like, the phase angle of the measured voltage deviates from the phase angle of the actual voltage, or an error occurs in the magnitude of the measured voltage itself.

Therefore, if the voltage sensor is constituted by the transformer PT and is incorporated in the terminal station, the above disadvantage does not occur, but it is necessary to provide as many as three expensive transformers PT to detect the zero-phase voltage V0. There's a problem. Since a large number of terminal stations are arranged on each distribution line, and considering the large number of distribution lines, it is preferable to simplify the configuration of the terminal station as much as possible. It is better to have as few as possible.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned technical problems and to provide a distribution line fault section determining system capable of determining a fault section of a distribution line without installing a voltage sensor as compared with the related art. It is to be.

[0007]

According to the first aspect of the present invention, there is provided a distribution line fault section determining system for achieving the above object.
A terminal station is arranged in each section of the distribution line divided into a plurality of sections, a master station for receiving data from the terminal station is arranged, and in each terminal station, each phase current Ia, Ib, A current sensor for detecting Ic, short-circuit determination means for determining a short-circuit in the distribution line by comparing each of the phase currents Ia, Ib, Ic with a threshold value, and a positive-phase current I1 based on the detection current of the current sensor. Calculating means for calculating the magnitude of each of the phase currents Ia, Ib, and Ic with a threshold value, and calculating the magnitude of the positive-phase current I1 and the magnitude of the negative-phase current I2.
The second comparing means for comparing the ratio I2 / I1 of the magnitude of I.2 with the threshold value, and the first comparing means for each phase current Ia, Ib, I
If any one of c is smaller than the threshold value and the second comparing means determines that the ratio I2 / I1 has exceeded the threshold value, the terminal station is determined to be on the load side from the disconnection point. As a result of comparison by the third comparing means, the third comparing means for comparing the change ΔI1 of the positive-phase current I1 and the change ΔI2 of the negative-phase current I2 with a threshold value, respectively. If the change ΔI1 in the phase current I1 and the change ΔI2 in the negative phase current I2 both exceed the threshold value, the terminal station is on the power supply side from the ground fault point, and the change ΔI1 in the positive phase current I1 or Change ΔI2 of phase current I2
If the measured point does not exceed the threshold value, the measurement point is determined to be on the load side of the ground fault point, and the data of the determination results of the short-circuit determination means, the disconnection determination means, and the ground fault determination means are transmitted. Transmission means to perform, the master station, based on the determination result included in the data received from each terminal station,
A terminal provided with a failure section determining means for distinguishing terminal stations having different determination results and determining a section existing between terminal stations adjacent to each other as a failure section of a distribution line in the group of terminal stations thus distinguished. It is.

According to a second aspect of the present invention, there is provided a distribution line fault section determining system, wherein a short-circuit determining means, first, second, and third comparing means, a disconnection determining means, and a ground fault determining means are provided on a master station side. Things.

[0009]

According to the first and second aspects of the present invention,
When a short-circuit fault occurs in a distribution line, if any of the phase currents becomes larger than a threshold value, it is determined that a short-circuit has occurred, and a terminal station group that detects a short-circuit point and a terminal station group that does not detect a short-circuit point , And a section located between adjacent ones of the distinguished terminal stations can be determined as a faulty section of the distribution line.

When a disconnection fault occurs in a distribution line, each phase current Ia, Ib,
At least one of the magnitudes of Ic decreases (in theory, 0
And the magnitude of the negative-sequence current I2 is
By using the fact that the ratio increases in comparison with the size of the terminal station (theoretically, the ratio becomes 1), a terminal station group that detects a disconnection point is distinguished from a terminal station group that does not detect a disconnection point. A section located between adjacent ones of the terminal stations thus set can be determined as a failure section of the distribution line.

Further, when a ground fault occurs in the distribution line, the fact that both the positive-phase current I1 and the negative-phase current I2 may increase depending on the positional relationship between the ground fault and the terminal station is utilized. A terminal station group that detects a ground fault point in the direction in which the transmitting end exists and a terminal station group that detects a ground fault point in the direction opposite to the direction in which the transmitting end exists is distinguished. A section located between adjacent stations can be determined as a ground fault section of the distribution line.

The principle of the ground fault section determination will be described in detail. FIG. 2 is a conceptual diagram of a distribution line.
It is assumed that power supplies b and Ec exist. Terminal stations installed adjacent to each other are denoted as T1 and T2. Terminal station T
It is assumed that a ground fault has occurred between T1 and T2, and the ground fault resistance is Rg. C1 and C2 are the earth capacities of the distribution lines on the power supply side and the load side of the ground fault point, respectively.

In a normal state without a ground fault, the zero-phase current I
0 is 0 and the negative-phase current I2 is 0, but the positive-phase current I1 is I1 = jωC2Ea. When a ground fault occurs, the zero-phase voltage V0 at the ground fault point
Is expressed as follows: V0 = -Ea / (1 + 3jωCRg) Here, C = C1 + C2. The zero-phase current I0, the positive-phase current I1, and the negative-phase current I2 detected by the terminal station T1 are as follows: I0 = C1 Ig / 3C I1 = j.omega.C2Ea + Ig / 3 (1) I2 = Ig / 3 ( 2), and what is detected by the terminal station T2 is: I0 = -C2 Ig / 3C I1 = jωC2Ea (3) I2 = 0 (4) Here, Ig = 3jωCEa / (1 + 3jωCRg).

From the above equations (1) and (3), the terminal station T1 detects the positive-phase current I1 added by Ig / 3 from the terminal station T2, and from the above equations (2) and (4), The terminal station T1 is the terminal station T
It can be seen from FIG. 2 that the negative-phase current I2 added by Ig / 3 is detected. Therefore, the positive-phase current I1 and the negative-phase current I2 detected by the terminal stations T1 and T2 are constantly monitored.
When the increment appears, it is possible to distinguish between a terminal station group that detects a ground fault point in the direction where the transmitting end exists and a terminal station group that detects a ground fault point in the direction opposite to the direction where the transmitting end exists. ,
A section located between adjacent ones of these distinguished terminal stations can be determined as a ground fault section of the distribution line.

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 3 is a distribution system diagram. The distribution substation 1 is provided with a transformer 11 having a Δ-Δ connection.
1 is reduced to 6.6 kV by the circuit breakers 3a, 3
are supplied to the distribution lines 4a, 4b,. The distribution lines 4a, 4b, ... have Y-Y connection transformers 5a1, 5a2, ... for distributing power to consumers.
, 5b1, 5b2,... Are connected, and each transformer 5a1, 5a
Terminal stations 7a1, 7a2, ..., 7b1, 7b near 2, ...
2, ... are provided.

Each of the terminal stations 7a1, 7a2,... Has the same configuration, and has a zero based on the phase current Ia, Ib, Ic information extracted from CT1, CT2, CT3 for detecting the current of each phase. Calculate the phase current I0, the positive-phase current I1, and the negative-phase current I2,
An arithmetic processing unit 71 that determines whether there is a ground fault, short circuit, or disconnection, and a transmission unit 72 that transmits data of the determination result obtained by the arithmetic processing unit 71 to the master station 9 (see FIG. 7).

As shown in FIG. 4, the arithmetic processing unit 71
Adder circuit for adding values of phase current, b-phase current and c-phase current
716, a sample and hold circuit 711 for sampling the value of the a-phase current Ia, a sample and hold circuit 712 for sampling the value of the b-phase current Ib, a sample and hold circuit 713 for sampling the value of the c-phase current Ic, A sample and hold circuit 71 for sampling the value of the current I0
4, a multiplexer 720 for sending out the sampled and held values in chronological order, a conversion circuit 730 for A / D converting the data output from the multiplexer 720, and a digital operation for the A / D converted data. The phase currents Ia, Ib, Ic, the zero-phase current I0, the positive-phase current I1
And the magnitude of the negative-phase current I2, and the ratio I of the magnitude of the negative-phase current I2 to the magnitude of the positive-phase current I1
The calculation circuit 740 for calculating 2 / I1 and the data of the magnitude of the positive-phase current I1 and the data of the magnitude of the negative-phase current I2 in the past several cycles are totaled, and each past m (m is, for example, 5 Average) <I1><I
2>, the calculated data of the calculating circuit 740, and the average value <I1> of the number of positive-phase currents I1 stored in the memory 770 and the current average value <I1> of 10 cycles before.
I1>, the difference .DELTA.I between the average <I2> 10 to 10 cycles before and the current average <I2> of the negative phase current I2.
Judgment circuit for judging ground fault, short circuit and disconnection based on 2
750. The average of the past m cycles is taken as a measure against noise. The difference between the average value <I1> several to ten cycles ago and the current average value <I1> is calculated after the failure. This is because the current flows for 10 cycles because the circuit breaker does not work.

Further, the arithmetic processing unit 71 includes a fundamental wave pulse generating circuit 760 for generating a fundamental wave pulse for each period of the power supply current through the PLL 717, and a predetermined frequency dividing ratio (for example, 1 / A frequency divider 761 that divides the frequency by a factor of 12 and a finer frequency division ratio (for example, 1/4) obtained by dividing the frequency division ratio of the frequency divider 761 by the number of sample and hold circuits.
8), and a switching controller 763 for supplying a switching control signal to the sample and hold circuits 711 to 714 based on the output pulse of the frequency divider 762. Calculation processing is performed using the output pulse of the frequency divider 761 as a synchronization signal.

The calculation circuit 740 calculates the magnitude and phase angle of the current by using a conventionally known method. For example,
The magnitude can be obtained by obtaining a Fourier sine component and a Fourier cosine component over one period, and taking a root mean square of both components. Also, the phase angle can be obtained by taking tan ^-1 of the ratio between the Fourier sine component and the Fourier cosine component.

FIG. 1 is a flowchart showing the procedure of the ground fault, short circuit and disconnection determination performed by the determination circuit 750. According to FIG. 1, the determination circuit 750 performs a short-circuit determination (step (1)) based on various current data supplied from the calculation circuit 740.
Send to 2. As shown in FIG. 5, the short-circuit determination in step (1) determines whether any of the phase currents Ia, Ib, Ic Ia, Ib, Ic has exceeded a reference current (eg, 1.2 times the rated current). Is determined. In FIG. 5, the reference current is 480 A
(Rated current is 400 A).

If it is determined that there is no short circuit, disconnection determination (step (2)) is performed, and if it is determined that a disconnection has occurred, a code representing the disconnection is transmitted. As shown in FIG. 6, the disconnection determination in step (2) determines that any one of the phase currents Ia, Ib, and Ic exceeds 1% of the rated current and that the magnitudes of the positive-phase current I1 and the negative-phase current I2. Judgment is made when the ratio I2 / I1 exceeds 0.6 times. In FIG. 6, “1% of the rated current” is indicated by 4A. The figure of 0.6 times is empirically determined.

If it is determined that there is no disconnection, ground fault determination (steps (3) and (4)) is performed. In step (3), the zero-phase current I0 is compared with the threshold value Ix. If the zero-phase current I0 exceeds the threshold value Ix, it is considered that a ground fault has occurred.
In (4), it is determined whether the change ΔI1 in the magnitude of the positive-phase current I1 and the change ΔI2 in the magnitude of the negative-phase current I2 exceed the threshold values Iy and Iz, respectively. The thresholds Iy and Iz are determined in consideration of the field test results, using Ig / 3 in the above equations (1) and (2) as a guide.

If YES in step (4), it is assumed that there is a ground fault point on the load side of the terminal station, and a code representing "load-side ground fault" is transmitted. In step (4), N
If it is O, it is considered that there is a ground fault point on the power supply side with respect to the terminal station, and a code representing "power supply ground fault" is transmitted. In this embodiment, the change ΔI1 in the magnitude of the positive-phase current I1 and the change ΔI2 in the magnitude of the negative-phase current I2 are compared with threshold values. This is because the relationship between the phase angle of the positive-phase current I1 or the negative-phase current I2 and the phase angle of Ig / 3 differs depending on the condition of the ground fault, and cannot be determined unconditionally. Some change appears in the magnitudes of the phase current I1 and the negative phase current I2, and the ground fault direction can be determined by comparing the magnitude changes.

The ground fault determination in steps (3) and (4) means determination of one-line ground fault. In the case of two-wire ground fault and three-wire ground fault, the short-circuit determination in step (1) is performed. Therefore, no two-line ground fault or three-line ground fault is determined in steps (3) and (4). When a short circuit or disconnection occurs, the result of YES appears in step (4). However, since the determination in steps (1) and (2) is prioritized, the determination of disconnection or short circuit does not occur.

If it is determined that there is no ground fault, a code indicating no failure is transmitted in step (9). The transmitting section 72 transmits the code received from the determination circuit 750 to the master station 9 through a medium such as wireless, optical, or infrared (step (10)). The master station 9 includes a receiving section 91 and a failure section determining section 92 as shown in FIG. Failure section determination unit 9 of master station 9
2 is based on the code received from the transmission unit 72 of each terminal,
It is determined in which section a ground fault, short circuit or disconnection has occurred. The method of the determination is as follows.

As shown in FIG. 8, the terminal station 7 extends along the distribution line.
Assume that a1,..., 7a6 are arranged. When a one-line ground fault occurs between the terminal station 7a3 and the terminal station 7a4 (see FIG. 8A), the terminal stations 7a1, 7a1
The information sent from 7a2 and 7a3 is information representing "load-side ground fault". However, the information sent from the terminal stations 7a4, 7a5, 7a6 on the load side from the ground fault point is information representing "power-supply ground fault". Therefore, the master station 9 knows that a ground fault has occurred between the terminal stations 7a3 and 7a4 having different information contents.

Next, when a short-circuit fault occurs between the terminal station 7a3 and the terminal station 7a4 (see FIG. 8B), the short-circuit fault is transmitted from the terminal stations 7a1, 7a2, 7a3 located on the power transmission side from the fault point. The incoming information is "short circuit" information, whereas the information sent from the terminal stations 7a4, 7a5, 7a6 located on the load side from the failure point is either "disconnection" information (in the case of a two-wire short circuit) or "failure". None "(in the case of a three-wire short circuit). Therefore, it is clear that a short-circuit fault has occurred between the terminal station 7a3 and the terminal station 7a4.

Next, when a disconnection fault occurs between the terminal station 7a3 and the terminal station 7a4 (see FIG. 8C), the terminal station 7a1, 7a2, 7a3 which is located on the power transmission side from the fault point transmits the fault. The information coming from the terminal stations 7a4, 7a5, 7a6 located on the load side from the point of failure is the information on "disconnection", while the information coming from the terminal station 7a4, 7a5, 7a6. Therefore, the master station 9
It can be seen that a disconnection failure has occurred between the terminal station 7a3 and the terminal station 7a4.

Although the present invention has been described based on the embodiments, the present invention is not limited to the above embodiments. For example, the fundamental wave pulse generation circuit 760 generates a pulse in synchronization with the power supply current, but may use a synchronization completely independently of the power supply. Various other changes can be made without changing the gist of the present invention.

[0030]

As described above, according to the invention of the system for determining a faulty section of a distribution line according to the first aspect, each terminal station determines the phase currents Ia, Ib, Ic and the positive-phase current I1 and the negative-phase current I2. By detecting and determining a short circuit, disconnection or ground fault, and transmitting the determination data to the master station, the master station determines a faulty section of the distribution line based on the data sent from each terminal station. Can be determined. In this case, there is no need to measure the voltage at the terminal station.
Compared to measuring the line voltage, the configuration of the terminal station is simplified, the cost can be reduced, and this is particularly advantageous when a large number of terminal stations are arranged. Further, according to the invention of the distribution line fault section determination system according to the second aspect, the master station can determine a short circuit, a disconnection or a ground fault and determine a fault section of the distribution line. Also in this case, the terminal station does not need to measure the voltage in particular, so that the configuration of the terminal station becomes simpler and the cost can be reduced as compared with the conventional measurement of the three-wire voltage. This is particularly advantageous when a large number of terminal stations are arranged.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating a procedure of a ground fault, short circuit, and disconnection determination performed by a determination circuit.

FIG. 2 is a circuit diagram of a distribution line in which a ground fault has occurred for explaining the principle of the present invention.

FIG. 3 is a power distribution system diagram in which terminal stations are arranged.

FIG. 4 is a block diagram showing an internal configuration of an arithmetic processing unit provided in a terminal station.

FIG. 5 is a logic circuit diagram for performing short circuit determination.

FIG. 6 is a logic circuit diagram for performing disconnection determination.

FIG. 7 is a block diagram showing a main part configuration of a master station.

FIG. 8 is a terminal station layout diagram for explaining a method of determining a faulty section of a distribution line.

[Explanation of symbols]

 4a, 4b Distribution line 7a1, 7a2, 7b1, 7b1 Terminal station 72 Transmitter 740 Calculation circuit 750 Judgment circuit 9 Parent station 92 Failure section determiner CT1, CT2, CT3 Current sensor T1, T2 Terminal station

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-266823 (JP, A) JP-A-61-109418 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02H 7/26

Claims (2)

(57) [Claims] 1. A distribution line failure section determining system for determining a failure section when a failure occurs in a distribution line, wherein a terminal station is arranged in each section of the distribution line divided into a plurality of sections. The station includes a current sensor for detecting each phase current Ia, Ib, Ic of the distribution line, and a short-circuit determining means for determining a short-circuit of the distribution line by comparing each of the phase currents Ia, Ib, Ic with a threshold value. Calculating means for calculating the positive-phase current I1 and the negative-phase current I2 based on the detection current of the current sensor;
first comparing means for comparing the magnitudes of b and Ic with a threshold value; and second comparing means for comparing the ratio I2 / I1 of the magnitude of the positive-phase current I1 and the magnitude of the negative-phase current I2 with the threshold value. And the first comparing means determines that one of the phase currents Ia, Ib, Ic is smaller than the threshold value, and the second comparing means determines that the ratio I2 / I1 exceeds the threshold value. When the terminal station is disconnected, the terminal station determines that the terminal station is on the load side from the disconnection point, and a change ΔI1 of the positive-phase current I1.
And a third comparing means for comparing the change .DELTA.I2 of the negative-phase current I2 with the threshold value, respectively. As a result of the comparison by the third comparing means, the change .DELTA.I1 of the positive-phase current I1 and the change of the negative-phase current I2 If both the components ΔI2 exceed the threshold value, the terminal station is on the power supply side from the ground fault point, and the positive-phase current I
When the change ΔI1 of 1 or the change ΔI2 of the negative-sequence current I2 does not exceed the threshold value, ground fault determining means for determining that the measurement point is on the load side of the ground fault point, short-circuit determining means,
Transmission means for transmitting data of the determination result of the disconnection determination means and ground fault determination means is provided, and further, a master station for receiving data from the terminal station is arranged, in this master station,
Based on the determination result included in the data received from each terminal station, a group of terminal stations having different determination results is distinguished, and a section of the distinguished terminal station group existing between mutually adjacent terminal stations is distributed. A fault section determining means for determining a fault section of the distribution line. 2. A distribution line failure section determining system for determining a failure section when a failure occurs in a distribution line, wherein a terminal station is arranged in each section of the distribution line divided into a plurality of sections. The station has a current sensor for detecting each phase current Ia, Ib, Ic of the distribution line, a calculating means for calculating the positive-phase current I1 and the negative-phase current I2 based on the detected current of the current sensor, and a calculating means for calculating. And the phase current I
transmission means for transmitting the data of a, Ib, and Ic are provided;
Further, a master station for receiving data from the terminal station is arranged, and the master station has a short circuit for determining a short circuit of the distribution line by comparing each of the phase currents Ia, Ib, Ic with a threshold value. Determining means, first comparing means for comparing the magnitude of each phase current Ia, Ib, Ic included in the data received from each terminal station with a threshold value, respectively; Second comparing means for comparing the ratio I2 / I1 of the magnitude of the phase current I2 with the threshold value, and the magnitude of one of the phase currents Ia, Ib, Ic is smaller than the threshold value by the first comparing means. Disconnection determination means for determining that the measurement point is on the load side of the disconnection point when the ratio I2 / I1 exceeds the threshold value by the second comparison means;
1 and the change ΔI2 of the negative-sequence current I2 are compared with threshold values, respectively. The result of the comparison by the third comparison means is that the change Δi of the positive-phase current I1
When both the change ΔI2 of I1 and the negative current I2 exceed the threshold value, the terminal station is on the power supply side from the ground fault point, and the change ΔI1 of the positive current I1 or the change of the negative current I2. Ground fault determining means for determining that the measurement point is on the load side of the ground fault point when ΔI2 does not exceed the threshold value;
Based on the judgment results of the short-circuit judging means, the disconnection judging means and the ground fault judging means, different terminal station groups having different judgment results are distinguished, and a section existing between terminal stations adjacent to each other among the distinguished terminal station groups. And a failure section determining means for determining a failure section of the distribution line as a failure section of the distribution line.