JP2011155723A - Power transmission line protection relay system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power transmission line protection relay system which accurately performs distance measurement by a distance relay in spite of frequent arrangement of a branch power source in parallel/parallel-off directions. <P>SOLUTION: In the power transmission line protection relay system, a power source end distance relay 20 installed at the power source end of the power transmission line includes a distance measuring means which calculates a correction coefficient A=Ic/Ia based on a power source end fault current Ia and a branch end fault current Ic transmitted from a branch end PCM current differential relay 11c through a power source end PCM current differential relay 11a by using the transmission function of the PCM current differential relay, and which performs distance measurement based on the power source end fault current Ia and a power source end bus line fault voltage Va by using the calculated correction coefficient A. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a power transmission line protection relay system, and is particularly suitable for reducing a distance measurement error due to a shunt effect of a rear-end protection distance relay using a transmission function of a PCM current differential relay for main protection. The present invention relates to a transmission line protection relay system.

  Conventionally, in order to protect a power system from a transmission line accident, a transmission line protection relay system including a PCM current differential relay (PCM) having a transmission function as a main protection and a distance relay (DZ) as a back-up protection is provided. It has been adopted.

  For example, for a transmission line to which no power source is connected as shown in FIG. 4A, the power source instrument current transformer 2a, the power source circuit breaker 3a, and the power source PCM current are provided on the power source side (power source 1a side). A differential relay 11a and a power supply end distance relay 12a are installed, and a load end measuring device current transformer 2b, a load end circuit breaker 3b, a load end PCM current differential relay 11b and a load are installed on the load end side (the side opposite to the power supply 1a). The transmission line protection relay system is configured by installing the end distance relay 12b and connecting the power supply end PCM current differential relay 11a and the load end PCM current differential relay 11b via a communication line.

  In this transmission line protection relay system, when an accident (transmission line accident) occurs in the transmission line, the power supply end PCM current differential relay 11a is connected to the power supply end accident current Ia detected by the power supply end current transformer 2a. This power line fault is detected based on the load end fault current Ib detected by the load end current transformer 2b transmitted from the load end PCM current differential relay 11b via the communication line, and the power end is cut off. The device 3a is instantaneously shut off (opened).

At this time, if the power supply end breaker 3a is not instantaneously interrupted due to a failure of the power supply end PCM current differential relay 11a and / or the load end PCM current differential relay 11b, the power supply end distance relay 12a Accident point from power supply end based on power supply end fault current Ia detected by instrument current transformer 2a and power supply end bus fault voltage Va detected by instrument transformer (not shown) installed at power supply end bus Is measured, and based on the result, the power supply circuit breaker 3a is shut off at a predetermined operation time limit.
As shown in FIG. 5 (a), the distance measurement by the power supply end distance relay 12a is performed based on the power supply end fault current Ia and the power supply end bus fault voltage Va. % Impedance) Z (= Va / Ia).

  For the transmission line connected to the branch power source 1c as shown in FIG. 4B, the branch end instrument current transformer 2c, the branch end breaker 3c, and the branch end PCM current differential are also provided on the branch end side. The relay 11c and the branch end distance relay 12c are installed, and the power source PCM current differential relay 11a, the load end PCM current differential relay 11b, and the branch end PCM current differential relay 11c are connected by a communication line, thereby Constructs a wire protection relay system.

  The distance measurement by the power supply end distance relay 12a in this power transmission line protection relay system is also performed based on the power supply end fault current Ia and the power supply end bus fault voltage Va. Although Ia) is obtained, a shunt effect that causes an error in distance measurement due to the influence of the branch end fault current Ic from the branch power supply 1c becomes a problem.

That is, when the transmission line fault occurs in the load end near the transmission line (two-stage protection range of the power supply end distance relay 12a) is adapted to the impedance up to the branch point and the first impedance Z ₁ from the power source end of the transmission line when the impedance from the branch point of the transmission line to the fault point and the second impedance Z _2, if the branch end fault current Ic = 0 as shown in FIG. 5 (b) (i.e., the branch power 1c is opened In this case, since the fault current Is flowing from the branch point of the transmission line to the fault point is Is = Ia, the impedance Z _A0 from the power supply end of the transmission line to the branch point measured by the power supply end distance relay 12a is (1− 1) It is represented by the formula.
Z _A0 = Va / Ia
= (Ia · Z ₁ + Is · Z ₂ ) / Ia
= (Ia · Z ₁ + Ia · Z ₂ ) / Ia
= Z ₁ + Z ₂ (1-1)
On the other hand, as shown in FIG. 5C, when the branch end fault current Ic ≠ 0 (that is, when the branch power supply 1c is connected), the fault current Is = flowing from the branch point of the transmission line to the fault point Since it becomes Ia + Ic, the impedance Z _A from the power supply end of the transmission line to the branch point measured by the power supply end distance relay 12a is expressed by equation (1-2).
Z _A = Va / Ia
= (Ia · Z ₁ + Is · Z ₂ ) / Ia
= {Ia · Z ₁ + (Ia + Ic) · Z ₂ } / Ia
= (Z ₁ + Z ₂ ) + (Ic / Ia) · Z ₂ (1-2)
Therefore, when the branch end fault current Ic ≠ 0, the impedance Z _A measured by the power supply end distance relay 12a is “(Ic / Ia) · Z ₂ as expressed by the expression (1-3)”. Only an error will occur.
Z _A −Z _{A 0} = {(Z ₁ + Z ₂ ) + (Ic / Ia) · Z ₂ } − (Z ₁ + Z ₂ )
= (Ic / Ia) · Z ₂ (1-3)

Therefore, when the branch power supply 1c is connected to the power transmission line, the power supply end distance relay 12a is set in consideration of the shunt effect.
Specifically, since the setting of the one-stage protection range of the power supply end distance relay 12a does not allow overreach, the back power supply when examining the shunt effect is performed with the self-end current maximum and the branch end current minimum, Since the under-reach is not allowed in the setting of the two-stage protection range and the three-stage protection range, the back power supply when considering the shunt effect is set as the self-terminal current minimum and the branch end current maximum.

  In Patent Document 1 below, in a power transmission line protection relay device equipped with a protection method using a communication line and a directional distance protection method, a circuit for passing the directional distance first stage operation condition to another line protection relay device; A circuit that receives the first-stage operating condition of the other terminal direction distance from the other line protection relay device, and outputs a cutoff command on condition that the first-stage operating condition of the other terminal direction distance is input By providing a circuit for switching the output time, even if the main protection relay device is faulty or out of service, the rear protection DZ relay device can quickly shut off the 20% range of the near end of the counterpart, and the main protection PCM relay device A transmission line protection relay device is disclosed that realizes an operation time equivalent to the above and maintains high-speed operation and reliability of protection.

JP 2008-220051 A

However, when the branch power source 1c is a pumped storage power plant (provided with a plurality of generators), the branch power source 1c is frequently paralleled / disconnected. In practice, it is difficult to implement the setting change of the distance, and it is difficult to deal with errors in distance measurement. Therefore, depending on the situation of the power system, there is a problem that the power supply end distance relay 12a operates even in an accident other than the protection range.
Further, when the shunt effect changes due to the change of the power system configuration, there is a problem that the worker must go to the electric station each time to change the input of the set value of the power supply end distance relay 12a.

  In addition, the power transmission line protection relay device disclosed in the above-mentioned Patent Document 1 switches the operation timer of the rear protection DZ relay in the event of a failure of the main protection relay device, so that the near end of the other party is switched by the rear protection DZ relay device. The 20% range is also designed to achieve high-speed shut-off, and cannot cope with frequent parallel / disconnection of branch power supplies.

  An object of the present invention is to provide a power transmission line protection relay system capable of accurately measuring a distance in a distance relay even when a branch power supply is frequently paralleled or disconnected.

The power transmission line protection relay system of the present invention includes a power terminal PCM current differential relay (11a) and a power terminal distance relay (20) installed at a power terminal of a power transmission line to which a branch power source (1c) is connected, A power line protection relay system comprising a branch end PCM current differential relay (11c) and a branch end distance relay (12c) installed at a branch end of a power transmission line, wherein the power source distance relay is a power terminal Using the transmission function of the fault current (Ia) and the PCM current differential relay, the branch end fault current (Ic) transmitted from the branch end PCM current differential relay through the power source PCM current differential relay; And a distance measuring means for measuring a distance based on the power supply end fault current and the power supply end bus fault voltage (Va) using the calculated correction coefficient. Do
Here, the distance measuring means may calculate the correction coefficient by dividing the branch end fault current by the power source end fault current.
The distance measuring means substitutes the correction coefficient into the following equation to obtain the second impedance (Z ₂ ) from the branch point of the transmission line to the accident point, and then determines the obtained second impedance and the transmission power. The first impedance (Z ₁ ) from the power supply end of the electric wire to the branch point may be added to obtain the impedance from the power supply end of the transmission line to the accident point, and the distance may be measured based on the obtained impedance. .
Z ₂ = (Z _A −Z ₁ ) / (1 + A)
Z ₁ : First impedance
Z ₂ : Second impedance
Z _A : Impedance obtained based on power supply end fault current and power supply end bus fault voltage
A: Correction coefficient The power transmission line protection relay system according to the present invention includes a power terminal PCM current differential relay (11a) and a power terminal distance relay installed at the power terminal of the power transmission line to which the branch power supply (1c) is connected. (30) and a branch end PCM current differential relay (40) and a branch end distance relay (12c) installed at the branch end of the power transmission line, wherein the branch power source Is composed of a plurality of generators (1c ₁ , 1c ₂ ), and the power source distance relay is connected from the branch end PCM current differential relay to the power source end using the transmission function of the PCM current differential relay. A correction coefficient (A) is calculated based on the generator on / off information (Sc) transmitted via the PCM current differential relay, and the power supply end fault current and the power supply end bus fault are calculated using the calculated correction coefficient. Based on voltage (Va) And a distance measuring means for measuring the distance.

The power transmission line protection relay system of the present invention has the following effects.
(1) Based on the power supply end fault current and the branch end fault current transmitted from the branch end PCM current differential relay through the power supply end PCM current differential relay using the transmission function of the PCM current differential relay. By using the calculated correction factor to measure the distance based on the power supply end fault current and the power supply end bus fault voltage, the power supply end distance relay can accurately measure the distance even when the branch power supply is frequently paralleled or disconnected. Can be done.
(2) Using the transmission function of the PCM current differential relay, the correction coefficient calculated based on the generator on / off information transmitted from the branch end PCM current differential relay via the power source PCM current differential relay Using distance measurement based on power supply end fault current and power supply end bus fault voltage, distance measurement is performed more accurately at power supply end distance relays even when branch power supplies are paralleled and disconnected frequently be able to.
(3) Since the error of the power supply end distance measurement due to the influence of the branch power supply can be minimized, the malfunction and malfunction of the power supply end distance relay can be prevented, thereby improving the protection reliability and the supply reliability. it can.
(4) Since the branch end fault current or the generator on / off information is transmitted using the transmission function of the PCM current differential relay for main protection, it is not necessary to add a new transmission means.

It is a figure for demonstrating the power transmission line protection relay system by 1st Example of this invention, (a) is a figure which shows the structure of a power transmission line protection relay system, (b) is (a). It is a block diagram which shows the structure of the shown power supply end distance relay. It is a figure for demonstrating the distance measurement error by the shunt effect in the conventional power supply end distance relay 12a, (a) is a figure for demonstrating the distance measurement in case the branch power supply 1c is open | released, (b ) Is a diagram for explaining the distance measurement when the branch power supply 1c is connected. It is a figure for demonstrating the power transmission line protection relay system by 2nd Example of this invention, (a) is a figure which shows the structure of a power transmission line protection relay system, (b) is a figure to (a). It is a block diagram which shows the structure of the shown power supply end distance relay. It is a figure for demonstrating the structure of the conventional power transmission line protection relay system, (a) is a figure which shows the structure in the power transmission line to which the branch power supply 1c is not connected, (b) is the branch power supply 1c connected It is a figure which shows the structure in the transmitted power line. It is a figure for demonstrating the distance measurement by the power supply end distance relay 12a in the conventional power transmission line protection relay system, (a) is a figure for demonstrating the distance measurement in case the branch power supply 1c is not connected. (B) is a figure for demonstrating the distance measurement in case of branch fault current Ic = 0, (c) is a figure for demonstrating the distance measurement in case of branch fault current Ic ≠ 0.

  For the above purpose, the power supply end distance relay is transmitted from the branch end PCM current differential relay through the power supply end PCM current differential relay using the transmission function of the power supply end fault current and the PCM current differential relay. The correction coefficient is calculated based on the branch end fault current, and the distance is measured based on the power source end fault current and the power end bus fault voltage using the calculated correction coefficient.

Embodiments of a power transmission line protection relay system according to the present invention will be described below with reference to the drawings.
First, a power transmission line protection relay system according to a first embodiment of the present invention will be described with reference to FIG. 1 and FIG.
In the power line protection relay system according to the present embodiment, the power supply end distance relay 20 shown in FIG. 1A includes a power supply end fault current Ia input from the power supply end current transformer 2a and a PCM current differential relay. The correction coefficient A is calculated based on the branch end fault current Ic input from the branch end PCM current differential relay 11c through the power source PCM current differential relay 11a using the transmission function, and the calculated correction coefficient A Is different from the conventional transmission line protection relay system shown in FIG. 4B in that distance measurement is performed based on the power supply end fault current Ia and the power supply end bus fault voltage Va.

  Therefore, as shown in FIG. 1B, the power supply end distance relay 20 includes a correction coefficient calculation unit 21 that calculates a correction coefficient A based on the power supply end fault current Ia and the branch end fault current Ic, and a correction coefficient calculation. Based on the distance measurement performed by the distance measurement unit 22, the distance measurement unit 22 that measures the distance based on the power supply end fault current Ia and the power supply end bus fault voltage Va using the correction coefficient A calculated by the unit 21. And a trip signal generator 23 for generating a power supply trip signal TRa for cutting off (opening) the power supply circuit breaker 3a after a predetermined operation time when a power transmission line accident is detected.

Next, details of calculation of the correction coefficient A in the correction coefficient calculation unit 21 and distance measurement in the distance measurement unit 22 will be described.
As shown in the above equation (1-3), when the branch power supply 1c is connected (that is, when Ic ≠ 0), the power supply end distance relay 20 causes the power supply end fault current Ia and the power supply end bus fault. The impedance Z _A obtained based on the voltage Va includes an error of (Ic / Ia) · Z ₂ .
Therefore, from the above equation (1-2), the second impedance Z ₂ from the branch point of the transmission line to the accident point is expressed by equation (2-1).
Z ₂ = (Z _A −Z ₁ ) / {1+ (Ic / Ia)}
= (Z _A -Z ₁ ) / (1 + A) (2-1)
The correction coefficient A (= Ic / Ia) is calculated by the correction coefficient calculation unit 21 by dividing the branch end fault current Ic by the power supply end fault current Ia, and the distance measurement unit 22 calculates the power supply end fault current Ia and the power supply end bus fault voltage. Impedance Z _A (= Va / Ia) from the power supply end of the transmission line to the accident point measured based on Va, the first impedance Z ₁ from the power supply end of the known transmission line to the branch point, and the correction coefficient calculation unit 21 The second impedance Z ₂ from the branch point of the transmission line to the accident point is obtained by substituting the correction coefficient A calculated by the equation (2-1) into the above equation (2-1).
The distance measuring unit 22 adds the first impedance Z ₁ from the power supply end of the transmission line to the branch point and the second impedance Z ₂ from the calculated branch point of the transmission line to the accident point, thereby The impedance (= Z ₁ + Z ₂ ) from the power supply end to the accident point is obtained, and the distance is measured based on the obtained impedance.
Thereby, even if the branch power supply 1c is connected to the power transmission line, the power supply end distance relay 20 can set the distance measurement error to “0”.

For example, when setting the power supply distance relay 20 in the two-stage protection range with the back power supply set to the local current minimum and the branch current maximum, as shown in FIGS. 2 (a) and 2 (b), Impedance of power source 1a = 0.140, impedance of branch power source 1c = 0.484, first impedance Z ₁ from power line end of transmission line to branch point Z = 0.154, distance from branch point of transmission line to accident point When the second impedance Z ₂ = 0.374 and the third impedance Z ₃ = 0.051 from the branch power source 1c to the branch point of the branch transmission line, the power source end distance relay 20 when the branch fault current Ic = 0. Impedance Z _A0 when viewed from
Z _A0 = Z ₁ + Z ₂ = 0.154 + 0.374 = 0.528
(See FIG. 2A).
On the other hand, when the branch fault current Ic ≠ 0, the impedance Z _A when viewed from the power source distance relay 20 is
Ia = (0.484 + 0.051) / {(0.140 + 0.154) + (0.484 + 0.051)} × Is
= 0.645 x Is
Ic = (0.140 + 0.154) / {(0.140 + 0.154) + (0.484 + 0.051)} × Is
= 0.355 x Is
Than,
Ic / Ia = (0.355 × Is) / (0.645 × Is)
= 0355 / 0.645
= 0.550
So that
Z _A = 0.154 + 0.374 × {1+ (Ic / Ia)}
= 0.154 + 0.374 × (1 + 0.550)
= 0.734
It becomes.
As a result, in conventional distance measurement,
Z _A −Z _A0 = (0.734−0.528) /0.528×100=39.0 (%)
However, in the power supply end distance relay 20, the error can be set to “0”.

Next, a transmission line protection relay system according to a second embodiment of the present invention will be described with reference to FIGS.
The transmission line protection relay system according to the present embodiment transmits the PCM current differential relay after the power source distance relay 30 shown in FIG. 3A is input from the branch power source 1c to the branch end PCM current differential relay 40. Branch power on / off information Sc (first and second generators 1c constituting the branch power source 1c) input from the branch end PCM current differential relay 40 through the power source PCM current differential relay 11a using the function. Information indicating the on / off state of the first and second generator breakers installed between ₁ and 1c ₂ and the branch end bus (ie, in operation when the branch power source 1c is a pumped storage power plant) The correction coefficient A is calculated based on the number of generators)), and the distance is measured based on the power supply end fault current Ia and the power supply end bus fault voltage Va using the calculated correction coefficient A. Transmission line according to one embodiment Different from the MamoruTsugi power system.

Therefore, the branch end PCM current differential relay 40 includes means for transmitting the branch power on / off information Sc input from the branch power source 1c to the power source PCM current differential relay 11a using a built-in transmission function. This is different from the conventional branch end PCM current differential relay 11c.
Further, as shown in FIG. 3B, the power supply end distance relay 30 is calculated by the correction coefficient calculation unit 31 that calculates the correction coefficient A based on the generator on / off information Sc, and the correction coefficient calculation unit 31. A distance measurement unit 32 that performs distance measurement based on the power supply end fault current Ia and the power supply end bus fault voltage Va using the correction coefficient A, and a power supply end cutoff when a transmission line fault is detected based on the distance measurement in the distance measurement unit 32 A trip signal generator 33 for generating a power supply trip signal TRa for shutting off the device 3a.

  Even in the transmission line protection relay system according to the present embodiment, it is possible to reduce the error of the distance measurement in the power supply end distance relay 30, but the correction coefficient A is determined by determining the branch end accident current Ic based on the generator on / off information Sc. Since (= Ic / Ia) is calculated, the accuracy of distance measurement is lower than that of the power supply end distance relay 20 according to the first embodiment.

For example, when setting the two-stage protection range of the power supply end distance relay 30 with the back power supply set to the maximum self-end current and the maximum branch end current, the impedance of the power supply 1a = 0.096, the impedance of the branch power supply 1c = 0.484, impedance Z ₁ = 0.154 from the power supply end of the transmission line to the branch point, impedance Z ₂ = 0.374 from the branch point of the transmission line to the accident point, branch point from the branch power supply 1c of the branch transmission line Impedance Z ₃ = 0.051, the impedance Z _A when viewed from the power supply end distance relay 30 is
Ia = (0.484 + 0.051) / {(0.096 + 0.154) + (0.484 + 0.051)} × Is
= 0.681 x Is
Ic = (0.096 + 0.154) / {(0.096 + 0.154) + (0.484 + 0.051)} × Is
= 0.319 x Is
Than,
Ic / Ia = (0.319 × Is) / (0.681 × Is)
= 0319 / 0.681
= 0.468
So that
Z _A = 0.154 + 0.374 × {1+ (Ic / Ia)}
= 0.154 + 0.374 × (1 + 0.468)
= 0.703
It becomes.
As a result, the improvement in distance measurement is
(0.734-0.703) /0.703×100=4.4 (%)
It becomes.

1a power supply 1c branch power supply 1c ₁ , 1c ₂ first and second generators 2a, 2b, 2c power supply end, load end and branch end instrument current transformer 3a, 3b, 3c power supply end, load end and branch end cutoff 11a, 11b, 11c Power supply end, load end and branch end PCM current differential relays 12a, 12b, 12c Power supply end, load end and branch end distance relays 20, 30 Power end distance relays 21, 31 Correction coefficient calculation unit 22, 32 Distance measurement unit 23, 33 Trip signal generation unit 40 Branch end PCM current differential relay A Correction factor Ia, Ib, Ic Power supply end, load end and branch end fault current Is Accident current Va Power supply end bus fault voltage Z, Z ₁ ~Z _3, Z _A0, Z _A impedance TRa supply terminal trip signal Sc generator on-off information

Claims (4)

A power source PCM current differential relay (11a) and a power source distance relay (20) installed at the power source end of the transmission line to which the branch power source (1c) is connected, and a branch end installed at the branch end of the power transmission line A power line protection relay system comprising a PCM current differential relay (11c) and a branch end distance relay (12c),
The power terminal distance relay is transmitted from the branch terminal PCM current differential relay through the power terminal PCM current differential relay using a transmission function of a power terminal fault current (Ia) and a PCM current differential relay. A correction coefficient (A) is calculated based on the coming branch end fault current (Ic), and distance measurement is performed based on the power supply end fault current and the power supply end bus fault voltage (Va) using the calculated correction coefficient. A distance measuring means;
A transmission line protection relay system characterized by that.   2. The transmission line protection relay system according to claim 1, wherein the distance measuring means calculates the correction coefficient by dividing the branch end fault current by the power source end fault current. The distance measuring means substitutes the correction coefficient into the following equation to obtain the second impedance (Z ₂ ) from the branch point of the transmission line to the accident point, and then determines the obtained second impedance and the transmission power. Adding the first impedance (Z ₁ ) from the power source end of the electric wire to the branch point to obtain the impedance from the power source end of the transmission line to the accident point, and performing distance measurement based on the obtained impedance;
Z ₂ = (Z _A −Z ₁ ) / (1 + A)
Z ₁ : First impedance
Z ₂ : Second impedance
Z _A : Impedance obtained based on power supply end fault current and power supply end bus fault voltage
The transmission line protection relay system according to claim 2, wherein A: a correction coefficient. Power supply end PCM current differential relay (11a) and power supply end distance relay (30) installed at the power supply end of the transmission line to which the branch power supply (1c) is connected, and the branch end installed at the branch end of the transmission line A power line protection relay system comprising a PCM current differential relay (40) and a branch end distance relay (12c),
The branch power source is composed of a plurality of generators (1c ₁ , 1c ₂ ),
The power source end distance relay is transmitted from the branch end PCM current differential relay through the power end PCM current differential relay using the transmission function of the PCM current differential relay. ) Based on the power supply end fault current and the power supply end bus fault voltage (Va) using the calculated correction coefficient.
A transmission line protection relay system characterized by that.

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