JP2009118678A - Power line earth fault protection system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power line earth fault protection system capable of avoiding malfunction even if a residual current is large. <P>SOLUTION: A power line earth fault protection system 10 includes a calculation part 12 consisting of an accident type discriminating processing in which zero phase voltage V<SB>0</SB>and first to fourth zero phase currents I<SB>01</SB>-I<SB>04</SB>input from an input processing part 11 are stored in a memory 13 at specified time intervals, and it is discriminated whether an earth fault accident is a bus line earth fault accident, a single circuit simple earth fault accident, or a different point different phase earth fault accident, based on a zero phase voltage change amount ΔV<SB>0</SB>and first to fourth zero phase current change amounts ΔI<SB>01</SB>-ΔI<SB>04</SB>acquired from the zero phase voltage and the first to fourth zero phase currents I<SB>01</SB>-I<SB>04</SB>before and in earth fault accident read from the memory 13, and a shielded breaker decision processing for deciding breakers to be shielded and their order among first to fourth breakers 5<SB>1</SB>-5<SB>4</SB>based on the first to fourth zero phase current amounts ΔI<SB>01</SB>-ΔI<SB>04</SB>. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a distribution line ground fault protection system, and particularly suitable for protecting a plurality of distribution lines from a ground fault by controlling a plurality of circuit breakers respectively installed on a plurality of distribution lines branched from a bus. To a distribution line ground fault protection system.

  Conventionally, when a 6kV busbar breaker is installed at a distribution substation and used in parallel with other busbars, the distribution lines (lines) branched from the busbars are sequentially cut off in a predetermined order. The function of the electric wire ground fault sequence interruption was locked.

  As a technique for solving this problem, it is conceivable to employ a technique in a ground fault direction relay disclosed in Patent Document 1 below. This ground fault direction relay calculates the effective value and phase of the zero-phase voltage and zero-phase current in the branch circuit, and overwrites and stores the calculated value in the process of writing the latest voltage based on the calculated effective value and phase of the zero-phase voltage. Voltage vector difference between the vector and the voltage vector based on the effective value and phase of the zero-phase voltage stored overwritten, the latest current vector based on the calculated effective value and phase of the zero-phase current, and the effective zero-phase current stored overwritten The current vector difference with the current vector based on the value and the phase is calculated, and when the effective value of the current vector difference exceeds a predetermined value, the branch circuit is grounded based on the phase of the current vector difference with respect to the phase of the voltage vector difference. By determining whether or not there is a ground fault, it is possible to reliably determine the ground fault circuit without being affected by the leakage current that flows in the absence of a ground fault. So that it is possible.

In addition, in the following Patent Document 2, the applicant of the present invention had a high possibility of blocking other than the accident line and the accident removal time was also slow because the conventional order blocking function method determined the blocking order in advance. In order to solve the problem, the current of the line connected to the bus of the high resistance grounding system is detected, and when the accident continues, the line with high possibility of the accident is preferentially selected and cut off. We have proposed a protective relay device that shortens the duration and narrows the power outage range to facilitate system recovery.
JP 2004-201356 A JP 2004-297967 A

  However, in the ground fault direction relay disclosed in Patent Document 1, the branch circuit uses the voltage vector difference and the current vector difference based on the effective values of the zero-phase voltage and zero-phase current of the branch circuit and the amount of phase change. May be effective for circuits with small residual current, but for circuits with large residual current, zero-phase current may flow from the sound line when there is a ground fault. However, since the zero-phase current may not change much, it is necessary to increase the detection sensitivity. For this reason, there is a problem that malfunction may occur if the detection sensitivity is excessively increased in a line having a large residual current.

  An object of the present invention is to provide a distribution line ground fault protection system capable of preventing malfunction even when a residual current is large.

The distribution line ground fault protection system of the present invention controls a plurality of circuit breakers (5 _{1 to} 5 ₄ ) respectively installed on a plurality of distribution lines (2 ₁ to 2 ₄ ) branched from the bus (1). A distribution line ground fault protection system (10) for protecting the plurality of distribution lines from a ground fault, which is a zero-phase voltage (7) input from a grounded instrument transformer (7) installed on the bus. V ₀ ) before and after the ground fault accident (ΔV ₀ ) and a plurality of zero-phase currents respectively input from a plurality of zero-phase current transformers (6 _{1 to} 6 ₄ ) installed on the plurality of distribution lines. Based on the amount of change (ΔI _{01 to} ΔI ₀₄ ) before and after the ground fault in (I _{01 to} I ₀₄ ), the ground fault is the result of the bus ground fault, one-line simple ground fault, and different-point ground fault Accident type determination processing means (12) for performing an accident type determination process for determining which is an accident type determination processing unit A circuit breaker determination process for determining a circuit breaker to be interrupted among the plurality of circuit breakers and an order thereof is performed based on a change amount of the plurality of zero-phase currents before and after the ground fault according to a determination result in the stage. And a circuit breaker determination processing means (12) to be interrupted.
Here, the accident type determination processing means and the interruption target circuit breaker determination processing means are configured such that the accident type determination processing and the interruption target circuit breaker determination processing are performed on the condition that the zero phase voltage is equal to or higher than a zero phase voltage set value. May be performed.
The distribution line in which the phase of the change amount of the zero-phase current before and after the ground fault accident is delayed by about 90 ° with respect to the change amount of the zero phase voltage before and after the ground fault accident is a healthy line The interruption type circuit breaker determination processing means, the phase of the sum total of the amount of change before and after the ground fault of the zero-phase current flowing through the distribution line other than the distribution line that is a healthy line When the current is about 90 °, the circuit breaker to be interrupted is sequentially disconnected from the circuit breaker installed on the distribution line through which the zero-phase current having a large change amount before and after the ground fault accident flows. A determination process may be performed.
When the phases of the change amounts of the plurality of zero phase currents before and after the ground fault accident are all within a range of −90 ° ± α with respect to the change amounts of the zero phase voltage before and after the ground fault accident, the accident type determination The processing means determines that it is a ground fault in the bus, and the circuit breaker determination processing means is a circuit breaker installed on a distribution line through which a zero-phase current having a large amount of change before and after the ground fault flows. You may determine so that it may interrupt | block in order.
The phase of the change amount of the zero phase current before and after the ground fault of the plurality of zero phase currents before and after the ground fault is 90 ° with respect to the change amount of the zero phase voltage before and after the ground fault. When within the range of ± α, the accident type determination processing means determines that there is a ground fault in the distribution line in which the one zero-phase current has flowed among the plurality of distribution lines, and the interruption target interruption The circuit breaker determination processing means may determine to block only the circuit breaker installed on the distribution line through which the one zero-phase current flows among the plurality of circuit breakers.
The sum of the amount of change of two or more zero-phase currents before and after the ground fault of the plurality of zero-phase currents before and after the ground fault accident with respect to the amount of change of the zero phase voltage before and after the ground fault When the phase is in the range of 90 ° ± α, the accident type determination processing means determines that a ground fault has occurred in the distribution line in which the two or more zero-phase currents flowed among the plurality of distribution lines. Then, the circuit breaker determination processing means for breaking the circuit breaks in order from the circuit breaker installed on the distribution line through which the zero-phase current having a large change amount before and after the ground fault accident flows among the two or more zero-phase currents. You may decide to go.
When a fine ground fault in which the zero-phase voltage is smaller than the zero-phase voltage settling value occurs in the plurality of distribution lines, the accident type determination processing means is configured to cause the zero-phase voltage ground in the plurality of distribution lines. This is a micro ground fault in a distribution line in which two or more zero-phase currents that are not in the range of −90 ° ± α of the sum of the amount of change before and after the ground fault accident with respect to the amount of change before and after the fault accident. From the circuit breaker installed on the distribution line through which the zero-phase current having a large amount of change before and after the ground fault among the two or more zero-phase currents flows. You may determine so that it may interrupt | block in order.
Also, distribution line ground fault protection system of the present invention, controls the bus (1) a plurality of distribution lines branched from ₍₂₁ to ₂₄₎ to respectively installed a plurality of circuit breakers (5 ₁ to 5 ₄₎ And a distribution line ground fault protection system (10) for protecting the plurality of distribution lines from a ground fault, and an analog input from a grounded instrument transformer (7) installed on the bus. A plurality of analog zero-phase currents (I _{01 to} I ₀₄ ) respectively input from a zero-phase voltage (V ₀ ) and a plurality of zero-phase current transformers (6 _{1 to} 6 ₄ ) respectively installed on the plurality of distribution lines. ) At a predetermined sampling period and analog / digital conversion, and then extracting only a predetermined frequency component, thereby converting the analog zero-phase voltage and the plurality of analog zero-phase currents into a digital zero-phase voltage and a plurality of analog zero-phase voltages. For digital zero-phase current An input processing unit (11) for switching, and the digital zero-phase voltage and the plurality of digital zero-phase currents input from the input processing unit are stored in a memory (13) at predetermined time intervals, and the memory The amount of change (ΔV ₀ ) of the zero-phase voltage before and after the ground-fault accident and the ground-fault accidents of the plurality of zero-phase currents obtained from the zero-phase voltage and the plurality of zero-phase currents before and after the ground fault An accident type determination process for determining whether the ground fault is a bus ground fault, one-line simple ground fault, or different-point ground fault accident based on the amount of change (ΔI _{01 to} ΔI ₀₄ ) before and after, , determine the breakers and the order to block the plurality of zero-phase current multiple breakers installed respectively ground fault based on the amount of change before and after the plurality of distribution lines (5 ₁ to 5 ₄₎ Perform the target circuit breaker decision process Characterized by comprising a calculation unit (12).
Here, according to the breaker instruction signal that is input from the calculation unit and that interrupts the breaker and the order of the breaker, the breaker instructed by the breaker instruction signal among the plurality of breakers one or more generates a trip signal (T ₁ through T _4), trip signal generating unit for one or more trip signal thus generated is output in the order designated by the blocking instruction signal (14), said trip A trip signal output unit (15) that outputs the one or more trip signals input from the signal generation unit to the circuit breakers instructed by the interruption instruction signal in the order of input may be further provided.
And further comprising a settling unit (16) for setting a zero-phase voltage settling value, wherein the calculation unit sets the accident type determination process and the condition on the condition that the zero-phase voltage is not less than the zero-phase voltage settling value. A circuit breaker determination process may be performed.

The distribution line ground fault protection system of the present invention has the following effects.
(1) Based on the amount of change in the zero-phase voltage before and after the ground fault and the amount of change in the multiple zero-phase currents before and after the ground fault, the ground fault is a bus ground fault, one-line simple ground fault, and different points. Accident type determination processing is performed to determine which of the different-phase ground faults, and a plurality of interruptions are performed based on the amount of change of the zero-phase currents before and after the ground fault accident according to the determination result in the accident type determination processing. By performing the circuit breaker determination process for determining the circuit breaker to be interrupted and the order of the circuit breakers, it is possible to prevent malfunction even if the residual current is large.
(2) The ground fault direction relay device and the ground fault overvoltage relay device can be obtained by performing the accident type determination process and the breaker circuit breaker determination process on condition that the zero phase voltage is equal to or higher than the zero phase voltage settling value. Can be integrated.
(3) In the case of a bus ground fault, by sequentially shutting off from the circuit breaker installed on the distribution line through which the zero phase current with a large amount of change before and after the ground fault accident flows among the multiple zero phase currents, Even if the bus is used in parallel with other buses, the ground fault sequence can be reliably cut off.

  Based on the amount of change of the zero-phase voltage before and after the ground-fault accident and the amount of change of the plurality of zero-phase currents before and after the ground-fault accident, the ground-fault accident is a bus-ground fault, one-line simple ground fault, and Determine which of the different-phase out-of-phase ground-fault accidents, and break out of the multiple circuit breakers based on the amount of change of the zero-phase current before and after the ground-fault accident according to the determination result in the accident type determination process This was achieved by determining the circuit breakers to perform and their order.

Embodiments of the distribution line ground fault protection system of the present invention will be described below with reference to the drawings.
As shown in FIG. 1, a distribution line ground fault protection system 10 according to an embodiment of the present invention includes a zero-phase voltage V ₀ input from a grounded instrument transformer (GPT) 7 installed on the bus 1, First input from _{first to fourth} zero-phase current transformers (ZCT) 6 _{1 to} 6 ₄ respectively installed in _first to _fourth distribution lines 2 ₁ to 2 ₄ branched from the bus 1. _1st to _4th circuit breakers (CB) 5 _{1 to} 5 respectively installed in the _1st to _4th distribution lines 2 ₁ to 2 _{4 based} on _1st to _4th zero phase currents I _{01 to} I _{04 4} is controlled.

  As shown in FIG. 2, the distribution line ground fault protection system 10 includes an input processing unit 11, a calculation unit 12, a memory 13, a trip signal generation unit 14, a trip signal output unit 15, a settling unit 16, A setting command input / output unit 17 and a transmission control unit 18 are provided.

The input processing unit 11 samples the zero-phase voltage V ₀ and the first to fourth zero-phase currents I _{01 to} I ₀₄ at a predetermined sampling period, performs analog / digital conversion, and then performs a predetermined frequency component (for example, a commercial frequency). By extracting only the 60 Hz component), the analog zero-phase voltage V ₀ and the analog first to fourth zero-phase currents I _{01 to} I ₀₄ are converted into the digital zero-phase voltage V ₀ and the first to fourth digital zero-phase voltages. To zero-phase currents I _{01 to} I ₀₄ .

The arithmetic unit 12 stores the digital zero-phase voltage V ₀ and the digital first to fourth zero-phase currents I _{01 to} I ₀₄ input from the input processing unit 11 in the memory 13 at predetermined time intervals. At this time, the calculation unit 12 also calculates the digital zero-phase voltage V ₀ (residual zero-phase voltage) and the digital first to fourth zero-phase currents I _{01 to} I ₀₄ (residual zero-phase current) before the ground fault. Store.
The arithmetic unit 12 is zero-phase voltage obtained from a ground fault time and ground fault before the zero-phase voltage V ₀ and the first to fourth zero-phase currents I ₀₁ ~I ₀₄ read from the memory 13 V ₀ Change (vector difference) ΔV ₀ (hereinafter referred to as “zero phase voltage change amount ΔV ₀ ”) before and after the ground fault accident and ground fault accident before and after the first to fourth zero phase currents I _{01 to} I ₀₄ On the basis of the change amount (vector difference) ΔI _{01 to} ΔI ₀₄ (hereinafter referred to as “first to fourth zero-phase current change amounts ΔI _{01 to} ΔI ₀₄ ”). First to fourth based on an accident type determination process for determining whether a line simple ground fault or a different-point different-phase ground fault and the first to fourth zero-phase current variations ΔI _{01 to} ΔI ₀₄ breaker for interrupting of the circuit breaker 5 ₁ to 5 ₄ and performing the blocking target breaker determination process for determining the order.

At this time, the arithmetic unit 12 is based on the condition that the zero-phase voltage V ₀ is equal to or higher than the zero-phase voltage set value input from the settling unit 16 (that is, on the premise of the operation of the ground fault overvoltage relay device). The function of the ground fault overvoltage relay device is provided.) The accident type determination processing is performed based on the following concept.
As shown in FIG. 3 (a) as an example, the phase of the total sum (vector sum) ΔI _0i1 + ΔI _0i2 of the amount of change of the zero-phase current flowing through the distribution line (ground fault line) where the ground fault has occurred before and after the ground fault Advances about 90 ° with respect to the zero-phase voltage variation ΔV ₀ . Further, as shown in FIG. 3B, for example, the phase of the change amounts ΔI _{001 to} ΔI ₀₀₄ before and after the ground fault of the zero phase current flowing through the distribution line (sound line) where no ground fault has occurred is zero phase. It is delayed by about 90 ° with respect to the voltage change amount ΔV ₀ .
Therefore, the distribution line in which the phase of the change amount before and after the ground fault accident is delayed by about 90 ° with respect to the zero-phase voltage change amount ΔV ₀ is regarded as a healthy line.
On the other hand, if the phase of the sum of the amount of change of the zero-phase current flowing through the distribution line other than the distribution line that is a healthy line is about 90 °, the amount of change before and after the ground fault The circuit breaker is cut off in order from the circuit breaker installed on the distribution line through which the zero-phase current has flowed (that is, the amplitude of the change amount before and after the ground fault is large).
The change amount before and after the ground fault (zero phase current change amount) is used to remove the influence of the residual zero phase current.

Therefore, in the electric power system shown in FIG. 1, the arithmetic unit 12 performs the following operation on the condition that the zero-phase voltage V ₀ is equal to or higher than the zero-phase voltage set value input from the settling unit 16 as follows. Judgment processing and breaking target circuit breaker determination processing are performed.

(1) Bus ground fault As shown in FIG. 4 (a), the first to fourth zero-phase current changes ΔI _{01 to} ΔI ₀₄ (zero-phase currents of all lines) with respect to the zero-phase voltage change ΔV ₀ . ) Are all within a range of −90 ° ± α (for example, α = 10 °), the calculation unit 12 determines that a ground fault has occurred on the bus 1 (bus ground fault).
The calculation unit 12 also includes the first to fourth zero-phase currents I _{01 to} I ₀₄ at the time of the ground fault and the first to fourth zero-phase currents I _{01 to} I ₀₄ (the residual zero phase before the ground fault). Current) is read from the memory 13, and the vector difference between the former and the latter is obtained to obtain the first to fourth zero-phase current change amounts ΔI _{01 to} ΔI ₀₄ , and the obtained zero-phase current change amounts are in descending order. A cutoff instruction signal for instructing to shut off the _{first to} fourth breakers 5 _{1 to} 5 ₄ is generated.

(2) One-line simple ground fault A phase of one zero-phase current change amount among the first to fourth zero-phase current change amounts ΔI _{01 to} ΔI ₀₄ with respect to the zero-phase voltage change amount ΔV ₀ is −90. If not within the range of ±± α, the calculation unit 12 causes the ground fault in the distribution line in which the zero-phase current flows among the _first to _fourth distribution lines 2 ₁ to 2 ₄ (single line simple ground). together determined to be fault accident), it generates a blocking instruction signal instructing to block only the installed circuit breaker to the first to the distribution line of the fourth breaker 5 ₁ to 5 _4.
For example, as shown in FIG. 4B, when the phase of the first zero-phase current change amount ΔI ₀₁ is within the range of 90 ° ± α with respect to the zero-phase voltage change amount ΔV ₀ , 12 determines that it is a ground fault in the first distribution line 2 _1, and generates an interruption instruction signal instructing to interrupt only the first circuit breaker 5 ₁ .

(3) Different-point / out-of-phase ground fault A total of two or more zero-phase current variations among the first to fourth zero-phase current variations ΔI _{01 to} ΔI ₀₄ with respect to the zero-phase voltage variation ΔV ₀ When the phase is in the range of 90 ° ± α, the calculation unit 12 causes a ground fault in the distribution line in which these zero-phase currents flow among the _first to _fourth distribution lines 2 ₁ to 2 ₄ ( It is determined that it is a different point ground fault accident).
For example, as shown in FIG. 4C, the phase of the sum ΔI ₀₁ + ΔI ₀₂ of the first and second zero-phase current changes ΔI ₀₁ and ΔI ₀₂ with respect to the zero-phase voltage change ΔV ₀ is 90 ° ±. When it is within the range of α, the calculation unit 12 determines that a ground fault has occurred in the first and second distribution lines 2 ₁ and 2 ₂ .
In addition, the calculation unit 12 has a zero-phase current change amount which is large among two or more zero-phase currents whose phase of the zero-phase current change amount is not within −90 ° ± α with respect to the zero-phase voltage change amount ΔV ₀ . A breaking instruction signal is generated to instruct to break in order from a breaker installed on the distribution line through which the phase current flows.
For example, in the example shown in FIG. 4C, when the second zero-phase current change amount ΔI ₀₂ is larger than the first zero-phase current change amount ΔI ₀₁ , the second circuit breaker 5 _2. And the interruption | blocking instruction | indication signal which instruct | indicates to interrupt | block in order of the _1st circuit breaker 51 is produced | generated.

The trip signal generation unit 14 sets one or more circuit breakers instructed by the interruption instruction signal among the _{first to fourth} circuit breakers 5 _{1 to} 5 ₄ according to the interruption instruction signal input from the arithmetic unit 12. One or more trip signals (one or more of the first to fourth trip signals T _{1 to} T ₄ ) for generating the cutoff are generated, and the generated one or more trip signals are instructed by the cutoff instruction signal. Are output in the order they are specified.
The trip signal output unit 15 receives one or more trip signals input from the trip signal generation unit 14 by one or more of the first to fourth circuit breakers 5 _{1 to} 5 ₄ instructed by the interruption instruction signal. Output to each circuit breaker.

  The settling unit 16 receives the zero-phase voltage set value and the first to fourth zero-phase currents in response to a set command signal sent from the central monitoring device or the like via the transmission control unit 18 and the set command input / output unit 17. Set the settling value.

The settling command input / output unit 17 receives a settling command signal and a test command signal from a central monitoring device or the like from the transmission control unit 18, a settling command signal input from the settling unit 16, settling recording data, test recording data, and the like. Is transmitted to the central monitoring device or the like via the transmission control unit 18.
The transmission control unit 18 wirelessly transmits and receives various signals to and from the central monitoring device.

Next, the operation of the distribution line ground fault protection system 10 will be described with reference to the flowchart shown in FIG.
The input processing unit 11 of the distribution line ground fault protection system 10 includes an analog zero-phase voltage V ₀ input from the grounded-type instrument transformer 7 and first to fourth zero-phase current transformers 6 _{1 to} 6 _4. The analog first to fourth zero-phase currents I _{01 to} I ₀₄ that are respectively input are sampled at a predetermined sampling period, and after analog / digital conversion, only a predetermined frequency component is extracted, thereby obtaining a digital zero. first to phase voltages V ₀ and digital to generate a fourth zero-phase current I ₀₁ ~I _04, generated first through the digital zero-phase voltage V ₀ and the digital-fourth zero-phase current I ₀₁ ~I ₀₄ is output to the calculation unit 12 (step S11).

The calculation unit 12 stores the zero-phase voltage V ₀ and the first to fourth zero-phase currents I _{01 to} I ₀₄ input from the input processing unit 11 in the memory 13 at predetermined time intervals.
In addition, the arithmetic unit 12 checks whether or not a ground fault has occurred based on the zero-phase voltage V ₀ and the first to fourth zero-phase currents I _{01 to} I ₀₄ (step S12).

As a result, if it is determined that a ground fault has occurred, the computing unit 12 checks whether the zero-phase sequence voltage V ₀ is the zero-phase voltage set value or more, the zero-phase voltage V ₀ is the zero-phase The accident type determination process described above is performed when the voltage is equal to or greater than the voltage set value (step S13).

When the calculation unit 12 determines that the ground fault is a bus ground fault, the calculation unit 12 performs the above-described circuit breaker determination process, and the first to fourth zero-phase current change amounts ΔI _{01 to} ΔI ₀₄ are in descending order. the first to fourth breaker 5 ₁ to 5 ₄ to generate a blocking instruction signal instructing to block, and outputs the generated power off instructing signal to the trip signal generator 14 (step S14).
For example, when the first zero-phase current change amount ΔI ₀₁ is large in the order of the fourth zero-phase current change amount ΔI ₀₄ , the trip signal generation unit 14 performs the first to fourth circuit breakers according to the cut-off instruction signal. After generating the _{first to} fourth trip signals T _{1 to} T ₄ for cutting off 5 _{1 to} 5 ₄ , respectively, the generated first to fourth trip signals T _{1 to} T ₄ are used as the first trip signal T. output from the ₁ to the trip signal output section 15 in the fourth order of the trip signal T _4.
The trip signal output unit 15 outputs the first to fourth trip signals T _{1 to} T ₄ to the first to fourth circuit breakers 5 _{1 to} 5 ₄ in the order sent from the trip signal generation unit 14, respectively. (Step S17).

When the arithmetic unit 12 determines that the ground fault is a one-line simple ground fault occurring in any one of the first to _fourth distribution lines 2 ₁ to 2 ₄ , the circuit breaker to be interrupted as described above. A determination process is performed to generate a cut-off instruction signal instructing to cut off only the breaker installed in the distribution line in which the ground fault has occurred among the _{first to} fourth breakers 5 _{1 to} 5 ₄ . The generated cutoff instruction signal is output to the trip signal generator 14 (step S15).
For example, when the third earth fault in distribution line 2 ₃ is determined to have occurred, the trip signal generator 14, in accordance with power off instructing signal, a third trip to cut off the third circuit breakers 5 ₃ After generating only the signal T ₃ , the generated third trip signal T ₃ is output to the trip signal output unit 15.
Trip signal output unit 15 outputs the third trip signal T ₃ in the third circuit breakers 5 ₃ (step S17).

Furthermore, if the arithmetic unit 12 determines that the ground fault is a different-point, out-of-phase ground fault that has occurred in two or more of the _first to _fourth distribution lines 2 ₁ to 24, the above-described circuit breaker to be interrupted is determined. The circuit breakers installed in the two or more distribution lines where the ground fault has occurred among the _{first to} fourth circuit breakers 5 _{1 to} 5 ₄ are processed, and the zero phase current having a large amount of change in the zero phase current A shutoff instruction signal is generated to instruct to shut off in order from the one installed on the distribution line through which the current flows, and the generated shutoff instruction signal is output to the trip signal generation unit 14 (step S16).
For example, it is determined that a different-point / out-of-phase ground fault has occurred in the second and fourth distribution lines 2 ₂ and 2 ₄ , and the fourth zero-phase current variation ΔI ₀₄ is the second zero-phase current variation. When it is larger than ΔI ₀₂ , the trip signal generation unit 14 second and fourth trip signals T ₂ for shutting off the second and fourth circuit breakers 5 ₂ and 5 ₄ , respectively, according to the shut-off instruction signal. , T ₄ are generated, and the generated second and fourth trip signals T ₂ , T ₄ are output to the trip signal output unit 15 in the order of the fourth trip signal T ₄ and the second trip signal T _2. .
Trip signal output unit 15 outputs the fourth trip signal T ₄ after outputted to the fourth circuit breaker 5 _4, the second trip signal T ₂ to the second circuit breaker 5 ₂ (step S17).

Incidentally, the zero-phase voltage V ₀ is less finely ground than the zero-phase voltage set point is in the event of the first to fourth distribution line 2 ₁ to 2 _4, the arithmetic unit 12 is different point hetero-phase ground fault Perform the same accident type determination process and breaker target breaker determination process as at the same time so that the circuit breakers are shut off in order from the breaker installed on the distribution line through which the zero-phase current flow is large. Good.

It is a figure for demonstrating the electric power grid | system in which the distribution line ground fault protection system 10 by one Example of this invention is used. It is a block diagram which shows the structure of the distribution line ground fault protection system 10 shown in FIG. It is a figure for demonstrating the concept used as the basis of the accident classification determination process in the calculating part 12 shown in FIG. It is a figure for demonstrating the accident classification determination process and the interruption | blocking object circuit breaker determination process in the calculating part 12 shown in FIG. It is a flowchart for demonstrating operation | movement of the distribution line ground fault protection system 10 shown in FIG.

Explanation of symbols

1 Busbar 2 _{1 to} 2 ₄ First to _Fourth Distribution Lines 3 Transformer 4 Transformer Secondary Circuit Breaker 5 _{1 to} 5 ₄ First to Fourth Circuit Breaker 6 _{1 to} 6 ₄ First to Fourth Zero Phase transformer 7 Grounding-type instrument transformer 10 Distribution line ground fault protection system 11 Input processing unit 12 Calculation unit 13 Memory 14 Trip signal generation unit 15 Trip signal output unit 16 Setting unit 17 Setting command input / output unit 18 Transmission control unit V ₀ Zero-phase voltage ΔV ₀ Zero-phase voltage change amount ΔI ₀ Zero-phase current change amount I _{01 to} I ₀₄ First to fourth zero-phase current ΔI _{01 to} ΔI ₀₄ First to fourth zero-phase current change amount ΔI _{0i1, ΔI 0i2, ΔI 001 ~ΔI} 004 amount of change earth fault before and after the zero-phase current T ₁ through T ₄ first to fourth trip signal S11~S17 step

Claims (10)

Protect the multiple distribution lines from ground faults by controlling the multiple circuit breakers (5 _{1 to} 5 ₄ ) installed on the multiple distribution lines (2 ₁ to 2 ₄ ) branched from the bus (1). Distribution line ground fault protection system (10) for
The amount of change (ΔV ₀ ) before and after the ground fault of the zero-phase voltage (V ₀ ) input from the grounded-type instrument transformer (7) installed on the bus and a plurality of installed respectively on the plurality of distribution lines Based on the amount of change (ΔI _{01 to} ΔI ₀₄ ) before and after the ground fault of a plurality of zero phase currents (I _{01 to} I ₀₄ ) respectively input from the zero phase current transformers (6 _{1 to} 6 ₄ ) of An accident type determination processing means (12) for performing an accident type determination process for determining whether the ground fault is a bus ground fault, a single-line simple ground fault, or a different-point different-phase ground fault;
According to the determination result in the accident type determination processing means, the circuit breaker to be disconnected among the plurality of circuit breakers based on the amount of change of the plurality of zero-phase currents before and after the ground fault and the interruption target interruption for determining the order thereof Circuit breaker determination processing means (12) for performing circuit determination processing,
A distribution line ground fault protection system, comprising:   The accident type determination processing means and the breaker breaker determination processing means perform the accident type determination process and the breaker breaker determination process on condition that the zero phase voltage is equal to or higher than a zero phase voltage set value. The distribution line ground fault protection system according to claim 1, wherein: The distribution line in which the phase of the change amount of the zero-phase current before and after the ground fault accident is delayed by about 90 ° with respect to the change amount of the zero phase voltage before and after the ground fault accident is a healthy line The accident type determination process,
When the circuit breaker determination processing means to be interrupted is a phase of the sum total of the amount of change before and after the ground fault accident of the zero-phase current flowing through the distribution line other than the distribution line that is a healthy line, The circuit breaker determination process to be interrupted is performed so that the circuit breaker is sequentially disconnected from the circuit breaker installed in the distribution line through which the zero phase current having a large change amount before and after the ground fault accident flows
The distribution line ground fault protection system according to claim 1 or 2, characterized by the above.   When the phases of the change amounts of the plurality of zero phase currents before and after the ground fault accident are all within a range of −90 ° ± α with respect to the change amounts of the zero phase voltage before and after the ground fault accident, the accident type determination The processing means determines that it is a ground fault in the bus, and the circuit breaker determination processing means is a circuit breaker installed on a distribution line through which a zero-phase current having a large amount of change before and after the ground fault flows. 4. The distribution line ground fault protection system according to claim 3, wherein the system is determined so as to cut off in order.   The phase of the change amount of the zero phase current before and after the ground fault of the plurality of zero phase currents before and after the ground fault is 90 ° with respect to the change amount of the zero phase voltage before and after the ground fault. When within the range of ± α, the accident type determination processing means determines that there is a ground fault in the distribution line in which the one zero-phase current has flowed among the plurality of distribution lines, and the interruption target interruption The circuit breaker determination processing means determines to block only the circuit breaker installed in the distribution line through which the one zero-phase current flows among the plurality of circuit breakers. Distribution line ground fault protection system.   The sum of the amount of change of two or more zero-phase currents before and after the ground fault of the plurality of zero-phase currents before and after the ground fault accident with respect to the amount of change of the zero phase voltage before and after the ground fault When the phase is in the range of 90 ° ± α, the accident type determination processing means determines that a ground fault has occurred in the distribution line in which the two or more zero-phase currents flowed among the plurality of distribution lines. Then, the circuit breaker determination processing means for breaking the circuit breaks in order from the circuit breaker installed on the distribution line through which the zero-phase current having a large change amount before and after the ground fault accident flows among the two or more zero-phase currents. 6. The distribution line ground fault protection system according to claim 3, wherein the distribution line ground fault protection system is determined so as to follow.   When a fine ground fault in which the zero-phase voltage is smaller than the zero-phase voltage settling value occurs in the plurality of distribution lines, the accident type determination processing means is configured to cause the zero-phase voltage ground in the plurality of distribution lines. This is a micro ground fault in a distribution line in which two or more zero-phase currents that are not in the range of −90 ° ± α of the sum of the amount of change before and after the ground fault accident with respect to the amount of change before and after the fault accident. From the circuit breaker installed on the distribution line through which the zero-phase current having a large amount of change before and after the ground fault among the two or more zero-phase currents flows. It determines so that it may interrupt | block in order, The distribution line ground fault protection system in any one of the Claims 1 thru | or 6 characterized by the above-mentioned. Protect the multiple distribution lines from ground faults by controlling the multiple circuit breakers (5 _{1 to} 5 ₄ ) installed on the multiple distribution lines (2 ₁ to 2 ₄ ) branched from the bus (1). Distribution line ground fault protection system (10) for
An analog zero-phase voltage (V ₀ ) input from the grounded-type instrument transformer (7) installed on the bus and a plurality of zero-phase current transformers (6 ₁ to 6) respectively installed on the plurality of distribution lines. 6 ₄ ), a plurality of analog zero-phase currents (I _{01 to} I ₀₄ ) respectively input from the analog signal are sampled at a predetermined sampling period and subjected to analog / digital conversion, and then only a predetermined frequency component is extracted. An input processing unit (11) for converting the zero-phase voltage and the plurality of analog zero-phase currents into a digital zero-phase voltage and a plurality of digital zero-phase currents;
The digital zero-phase voltage and the plurality of digital zero-phase currents input from the input processing unit are stored in a memory (13) at predetermined time intervals, and at the time of a ground fault and a ground fault read from the memory. The amount of change (ΔV ₀ ) before and after the ground fault accident of the zero phase voltage obtained from the zero phase voltage and the plurality of zero phase currents before the accident and the amount of change (ΔI _{01 to} ΔI ₀₄ ) before and after the ground fault of the plurality of zero phase currents. ) To determine whether the ground fault is a bus ground fault, one-line simple ground fault or different-point out-of-phase ground fault, and ground faults of the plurality of zero-phase currents. based on the amount of change before and after the accident operation performing breakers and the blocking target breaker determination process for determining the order in which blocking of the plurality the plurality of circuit breakers installed respectively on the distribution line (5 ₁ to 5 ₄₎ Part (12);
A distribution line ground fault protection system, comprising: One or more for interrupting each of the plurality of circuit breakers indicated by the circuit breaker instruction signal according to the circuit breaker to be interrupted and the circuit breaker instruction signal input from the arithmetic unit A trip signal generator (14) that generates a trip signal (T _{1 to} T ₄ ) and outputs the generated one or more trip signals in the order instructed by the shut-off instruction signal;
A trip signal output unit (15) for outputting the one or more trip signals input from the trip signal generation unit to the circuit breakers instructed by the interrupt instruction signal in the order of input;
The distribution line ground fault protection system according to claim 8, further comprising: A settling unit (16) for setting a zero-phase voltage settling value;
10. The distribution according to claim 9, wherein the calculation unit performs the accident type determination process and the breaking target circuit breaker determination process on condition that the zero phase voltage is equal to or higher than the zero phase voltage set value. Electric wire ground fault protection system.