JP3011968B2 - Distance relay for feeder circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention [Industrial Application Field] The present invention relates to a distance relay for a feeder circuit, and more particularly to detecting an accident such as a short circuit or a ground fault based on the impedance of an AC feeder circuit. The present invention relates to a distance relay for an electric circuit.

[Prior art] Conventionally, a feeder circuit distance relay (hereinafter simply referred to as a distance relay) calculates an impedance from the voltage and current of an AC feeder circuit, and when the impedance enters a fault impedance region. It operates as if a short circuit or ground fault has occurred in the AC feeding circuit. This fault impedance area is settled on a parallelogram area a in the impedance plane (R-X coordinates) in FIG.
The normal electric vehicle load impedance is in the range b where the power factor is 0.7 to 0.8, and approaches the coordinate origin as the load current increases. The setting of the fault impedance region is set so as not to include the electric vehicle load impedance in a normal state. Therefore, the load current and the fault current can be selected depending on whether or not the load impedance is in the fault impedance region.

In addition, the conventional distance relay is configured to inhibit the operation when the content ratio of the second harmonic current included in the load current to the fundamental current is 12% or more. That is, malfunction is prevented by the second harmonic current. Also, when a large current flows in the feeding circuit, a failure detection operation is performed regardless of the value of the load impedance,
Conversely, when the load current is equal to or less than the predetermined load current, the error rate becomes large, so that the operation is suppressed.

[Problems to be Solved by the Invention] However, when such a distance relay is used, it may operate as a failure of an electric circuit, even though it is not a failure, and cause a power failure. That is, as shown in FIG. 7, when the following train 52 enters this section (when passing through the section 53) while the train 51 is running in the feeding section of the substation 50, the train Excitation current flows through the 52 main transformers. That is, when the motor passes through the section 53 with the secondary side of the main transformer opened with the notch for speed adjustment cut off, a large inrush current flows. Since the exciting inrush current has a phase delay of 90 degrees from the voltage, the impedance region at this time falls within the region c in FIG.
Therefore, the combined impedance viewed from the substation 50 enters the area d and enters the fault impedance area, which is the operation area of the distance relay 54. This is called overload due to load competition. Conventionally, in response to such a phenomenon, the operation is stopped by the content of the second harmonic current (the content in the inrush current is large).
This alone cannot cope with the recent increase in vehicle load. That is, the above-mentioned phenomenon frequently appears due to an increase in the vehicle load, and the content of the second harmonic current with respect to the entire load current decreases, so that the unnecessary operation of the distance relay 54 cannot be suppressed.

The feeder circuit distance relay of the present invention solves the above problems,
It is an object of the present invention to reduce unnecessary operation due to load competition or the like and improve the reliability of electricity supply.

Configuration of the Invention [Means for Solving the Problems] A distance relay for a feeder circuit of the present invention calculates an impedance from a voltage and a current of an AC feeder circuit as illustrated in FIG. When the detected impedance enters a predetermined fault impedance region, the feeder circuit distance relay performs fault detection assuming that a fault current has flowed in the AC feeder circuit. Harmonic content calculating means for calculating the content of the third harmonic current or the fifth harmonic current; and setting the fault impedance region to be narrow when the calculated content is equal to or higher than the first reference value. Side, and when the calculated content rate is equal to or less than the second reference value, the setting of the fault impedance area is changed to a wide side, and the calculated content rate is changed to the first reference value. If between the second reference value, characterized in that a region changing means for performing on the basis of setting of the fault impedance region change in the fundamental wave current.

In the present invention, when the calculated content rate is between a first reference value and a second reference value, the area changing means compares the change in the fundamental wave current with a predetermined value. If the variation of the fundamental wave current is equal to or smaller than the predetermined value, the setting of the fault impedance region may be changed to a narrower side.

When the calculated content rate is between the first reference value and the second reference value, the area change unit compares the change in the fundamental wave current with a predetermined value, If the variation of the fundamental wave current is equal to or less than the predetermined value, the setting of the fault impedance area is changed to a narrower side. And the reference time, and if the duration is less than the reference time, set the fault impedance area to the middle between the narrow side and the wide side, and if the duration is equal to or longer than the reference time, set the fault impedance area You may comprise so that a setting may be set to a narrow side.

[Function] The feeder circuit distance relay according to the present invention having the above-described configuration,
When the content of the third or fifth harmonic current with respect to the fundamental current of the AC feeding circuit calculated by the harmonic content calculation means is equal to or greater than the first reference value, the area changing means sets the fault impedance area to Set to the narrow side. Usually, the electric vehicle load current contains a large amount of the third and fifth harmonic currents, but hardly any fault current due to a short circuit or the like. For this reason, when a large amount of the above-mentioned harmonic currents are included, the load impedance is hard to enter the fault impedance region by reducing the fault impedance region, thereby reducing unnecessary fault detection operations. Conversely, when the content rate is equal to or less than the second reference value, the area changing unit sets the fault impedance area to a wider side. At the time of a fault, the content of the above harmonic current is low, so the fault impedance area is set wider than when the content is high, the load impedance surely enters the fault impedance area, and the fault detection operation can be performed accurately. Done. Further, when the content ratio is between the first reference value and the second reference value, taking into account that the variation of the fundamental wave current at the time of failure becomes large, the region changing means performs the fault impedance region Is set based on the change in the fundamental wave current.

Embodiment In order to further clarify the configuration and operation of the present invention described above, a preferred embodiment of a feeder circuit distance relay of the present invention will be described below.

FIG. 2 is a schematic configuration diagram of a distance relay used in an AC AT feeding substation as one embodiment.

The distance relay 10 includes an input converter 11, a filter unit 12, and a calculation unit.
13, a setting unit 14, a display unit 15, an output unit 16, and a system bus 17 are provided.

The input converter 11 includes a current transformer CT1 for detecting a current of the feeder line F, a current transformer CT2 for detecting a current of the trolley line T,
Connect a transformer PT for detecting the voltage between the trolley wire T and the rail R, input a signal corresponding to the voltage and load current of the AC feeding circuit, convert the signal to a predetermined level, Output. The load current is obtained by combining currents flowing through the feeder line F and the trolley line T.

The filter unit 12 converts the load current into a fundamental current, a second harmonic current, a third harmonic current (or a fifth harmonic current).
Are individually extracted, and their values are converted into digital quantities via an A / D converter (not shown). Also, the output voltage from the instrument transformer PT is A / D converted.

In the following description, various processes are performed based on the third harmonic current.
It may be a harmonic current.

The operation unit 13 is composed of a digital computer having a well-known CPU, RAM, ROM, and the like configured as an arithmetic and logic operation circuit, performs a feeding circuit failure detection process described later, and determines a failure of the AC feeding circuit. .

The setting unit 14 is a keyboard provided for the operator to set the fault impedance area in advance into a plurality of patterns.

The display unit 15 is a CRT for confirming the set value during the set operation of the fault impedance area. Also, the state and the like when the AC feeding circuit malfunctions are displayed.

The output unit 16 is an interface that outputs an abnormal signal to the feeder circuit breaker S or the like when the arithmetic unit 13 detects a failure in the AC feeder circuit.

The filter unit 12, the arithmetic unit 13, the settling unit 14, the display unit 15, and the output unit 16 are mutually connected by a system bus 17, and exchange various signals.

Next, a fault impedance region set in the distance relay 10 of the present embodiment will be described. FIG. 3 shows an impedance plane (R-X coordinates). The fault impedance area as a protection area of the AC feeding circuit is set in the following four patterns.

That is, a region A set by the resistor R3 and the reactance X3 and a region B set by the resistor R2 and the reactance X2
(Including the region A), a region C (including the region B) settled by the resistance R1 and the reactance X1, and a region D (hereinafter referred to as an L-shaped characteristic) wider than the region C (hereinafter referred to as an L-shaped characteristic). (Including region C). Resistance R1, R2,
The values of R3 and reactances X1, X2, X3 are set in advance by the operator operating the settling unit. Further, the region D of the L-shaped characteristic is constant irrespective of the operation of the settling unit, and the region for the resistance is widened. This is an area for detecting a high-resistance ground fault at the start of feeding, as described later.

Next, the four types of fault impedance areas A, B,
A process for detecting a failure in the AC feeder circuit using C and D will be described with reference to FIG.

FIG. 4 shows a feeder circuit failure detection routine repeatedly executed by the arithmetic unit 13. First, the load current I0, the fundamental wave current I1, the second harmonic current I2, the third harmonic current I3, the voltage V Is read (S100). Next, it is determined whether the load current l0 is smaller than a predetermined maximum reference current Imax (S110),
If “NO”, that is, if I0 ≧ Imax, it is determined that a large current has flowed and a failure signal is output (S120), and the present routine is terminated once. At this time, a failure signal is output to the feeder circuit breaker S and the like, and the AC feeder circuit is cut off.

On the other hand, if it is determined in step 110 that I0 <Imax, the impedance Z is determined based on the fundamental wave current I1 and the voltage V.
(Z = V / I1) is calculated (S130).

Subsequently, a fault impedance area setting process is performed (S140). This processing is executed according to the flowchart showing the fault impedance area setting subroutine of FIG. Note that the initial values of the flags F1 and F2 used in this process are set to 0.

First, it is determined whether the voltage V is equal to or lower than a predetermined reference voltage V0 (S141). This determination is to determine the start of feeding or automatic re-injection. If it is determined that V ≦ V0, it is the start of feeding or automatic re-injection.
It is determined whether the value of the flag F1 is 0 (S142). The flag F1 indicates that V ≦ V0, and when the value is 0, the value 1 is set to the flag F1 (S143). Then, a timer T1 (not shown) is started (S144).

After the processing in step 144 or in step 142, the flag F1
If it is determined that = 1, it is determined whether or not the value of the timer T1 (hereinafter, this value is referred to as T1) is less than a predetermined reference period ta (S145). Sets the fault impedance area to the area D in FIG. 3, that is, the L-shaped characteristic (S146), temporarily ends the subroutine, and proceeds to step 170 in FIG. In step 145, T1 ≧
If it is determined to be ta, the process proceeds to step 149 described below. That is, when V ≦ V0, the fault impedance region is set to the L-shaped characteristic until the predetermined reference time ta elapses. This L-shaped characteristic is used to protect up to an adjacent AT (auto-transformer, not shown) point of the feeding circuit when the feeding is started in a state where an accident factor such as a ground fault has not been removed. It is settled in. That is, it is a fault impedance region for detecting a high-resistance ground fault at the start of feeding.

If it is determined in step 141 that V> V0,
The flag F1 is reset to 0 (S147), and the timer T1 is reset (S148).

After the process of step 148 or when it is determined in step 145 that T1 ≧ ta, the content G3 of the third harmonic current I3 with respect to the fundamental current I1 (G3 = I3 / I1) is calculated (S14).
9). Subsequently, it is determined whether or not the content rate G3 is equal to or less than 5% (second reference value) (S150). If G3 ≦ 5%, the fault impedance region is settled from (X1, R1) in FIG. Area C
(S151), the subroutine is temporarily terminated, and the fourth
The process moves to step 170 in the figure.

If it is determined in step 150 that the content rate G3 exceeds 5%, the content rate G3 is further increased to 10% (first reference value).
It is determined whether or not this is the case (S152), and “NO”, that is, 5% <G3
In the case of <10%, the change (absolute value) of the fundamental current I11
I1 is calculated (S153). Subsequently, the change ΔI1 is equal to the predetermined value A.
Is determined (S154), and if △ I1> A,
Further, it is determined whether or not the value of the flag F2 is 0. This flag F2
Indicates that there is a situation where △ I1> A, that is, a situation where the change in the fundamental current I1 is large. If the value is 0, the value 1 is set to the flag F2 (S156). Then, a timer T2 (not shown) is started (S157).

After the processing in step 157 or in step 155, the flag F2
If it is determined that = 1, it is determined whether or not the value of the timer T2 (hereinafter, this value is referred to as T2) is less than a predetermined reference time tb (S158). If it is determined that T2 <tb,
The fault impedance region is set to a region B settled from (X2, R2) in FIG. 3 (S159). Conversely, if it is determined that T2 ≧ tb, the fault impedance region is changed to (X3, R3) in FIG. R
The region A is set in the region A set from (3) (S160), and this subroutine is temporarily terminated.

If the content rate G3 is equal to or greater than 10% in step 152 or if the variation ΔI1 of the fundamental current I1 is equal to or less than the predetermined value A in step 154, the flag F2 is reset to 0 (S16).
1), the timer T2 is reset (S162). Then, the fault impedance area is set to the area A (160),
This subroutine is temporarily ended, and step 170 in FIG.
Move to the processing of.

In other words, when the content rate G3 is 5% or less, the area C
If it is 10% or more, it is set to the area A. Further, when the content rate G3 is more than 5% and less than 10%, if the variation ΔI1 of the fundamental wave current I1 is large, it is set in the region B only for a predetermined time tb, and after the predetermined time tb or the variation ΔI1 Is smaller, the region A is set.

When the above-described fault impedance area setting processing is completed, the processing shifts to the processing of step 170 in FIG. step 1
At 70, the impedance Z calculated at step 130 is calculated.
Is within the fault impedance region set as described above. "NO", that is, when it is determined that the impedance Z is out of the fault impedance region,
This routine is once terminated assuming that no failure has occurred in the AC feeding circuit. If the determination in step 170 is “YES”, the content rate G2 of the second harmonic current I2 with respect to the fundamental current I1 (G2 = I2 / I1) is further calculated (S180), and the content rate G2 is set to 12
% Is determined (S190). If it is determined that G2 ≧ 12%, this routine is terminated without causing a failure as an effect of the inrush current flowing through the main transformer of the vehicle.

If it is determined in step 190 that G2 <12%,
Further, it is determined whether the load current I0 is larger than a predetermined minimum reference current Imin (S200). If it is determined that I0 ≦ Imin, the detection error rate increases because the load current I0 is too small, and thus this routine is temporarily terminated without causing the AC feeder circuit to fail. Conversely, if it is determined that I0> Imin, it is determined that an accident such as a short circuit or ground fault has occurred in the AC feeding circuit, a failure signal is output (S120), and this routine is temporarily terminated. Therefore, a failure signal is output to the feeder circuit breaker S and the like, and the AC feeder circuit is cut off. In other words, the processing of steps 190 and 200 is based on the content of the second harmonic current I2 even if the impedance Z is within the fault impedance region.
If G2 is high or if the load current I0 is too small, it does not indicate that the AC feeding circuit has failed.

As described above, the distance relay of the present embodiment sets the fault impedance region to the narrow side when the content G3 is high, based on the content G3 of the third harmonic current I3, and sets the content G3 If is low, change to the wide side. Normally, the content G3 of the third harmonic current I3 with respect to the fundamental current I1 is high irrespective of an increase in the vehicle load, and the content G3 at the time of failure such as ground fault or short circuit is low. Thus, when the content rate G3 is high, by narrowing the fault impedance area, the impedance Z is less likely to enter the fault impedance area, and unnecessary fault detection operation is prevented.
Is smaller, the fault impedance region is widened, so that the impedance Z easily enters the fault impedance region so that the fault detection operation is performed reliably.

Further, since the variation ΔI1 of the fundamental wave current I1 at the time of failure increases, when the variation ΔI1 is large,
Set the fault impedance area to the wide side for a predetermined time (5%
<G3 <10%).

Therefore, the erroneous detection operation due to load competition and the like (determined as failure even though it is not an AC feeding circuit failure) seen in the conventional distance relay is prevented, the failure detection accuracy is improved, and the reliability of electricity supply is improved. Sex is improved. In addition, the use of an arithmetic unit composed of a microcomputer makes it possible to provide a high processing capability and a protection function for a plurality of lines.
In addition, the size can be reduced.

Although the embodiments of the present invention have been described above, the present invention is not limited to such embodiments at all. For example,
A configuration in which the number of patterns in the faulty impedance region is changed may be adopted, and it goes without saying that the present invention can be implemented in various modes without departing from the gist of the present invention.

Effects of the Invention As described in detail above, according to the feeder circuit distance relay of the present invention, the setting of the fault impedance region is performed based on the content of the third or fifth harmonic current with respect to the fundamental current. When the rate is high, the load impedance is changed to the narrow side, so that the load impedance hardly enters the fault impedance region, and unnecessary fault detection operations are reduced. That is, the third and fifth harmonic currents are included in the load current at the normal time irrespective of the increase in the vehicle load, but are not substantially included at the time of failure due to a short circuit or the like. By changing the fault impedance region, the erroneous fault detection operation can be reduced. As a result, the reliability of the power supply is improved.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a basic configuration of the present invention, FIG. 2 is a schematic configuration diagram of a distance relay for a feeder circuit, FIG. 3 is a graph showing a fault impedance plane, and FIG. FIG. 5 is a flowchart showing a detection routine, FIG. 5 is a flowchart showing a fault impedance area setting subroutine, and FIGS. 6 and 7 are diagrams for explaining the prior art.
FIG. 6 is a graph showing a fault impedance plane, and FIG. 7 is an explanatory diagram showing a position of a train during unnecessary operation. 10,54 ... Distance relay for feeder circuit 12 ... Filter unit, 13 ... Calculation unit 14 ... Settling unit A, B, C, D, a ... Fault impedance area

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Nobuyuki Kobayashi 5-1-63 Sakabegaoka, Yokkaichi-shi, Mie (56) References JP-A-3-183318 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) H02H 3/32-3/52 B60M 3/00 G01R 27/16-27/18

Claims (3)

(57) [Claims] An impedance is calculated from a voltage and a current of an AC feeding circuit, and when the calculated impedance enters a predetermined fault impedance region, it is determined that a fault current flows in the AC feeding circuit. In a feeder circuit distance relay for performing failure detection, a harmonic content calculating means for calculating a content rate of a third harmonic current or a fifth harmonic current with respect to a fundamental current of the AC feeder circuit; If the content rate is equal to or higher than the first reference value,
Change the setting of the fault impedance area to the narrow side,
When the calculated content rate is equal to or less than the second reference value,
Change the setting of the fault impedance area to a wider side,
When the calculated content rate is between the first reference value and the second reference value, a region changing means for setting the fault impedance region based on a change in the fundamental wave current. A distance relay for a feeder circuit, characterized in that: 2. The method according to claim 1, wherein when the calculated content rate is between a first reference value and a second reference value, the area change means compares the change in the fundamental wave current with a predetermined value. 2. The feeder circuit distance relay according to claim 1, wherein the setting of the fault impedance region is changed to a narrower side if the variation of the fundamental wave current is equal to or less than the predetermined value. 3. The region changing means compares a change in the fundamental wave current with a predetermined value when the calculated content rate is between a first reference value and a second reference value. If the variation of the fundamental wave current is equal to or less than the predetermined value, the setting of the fault impedance area is changed to a narrower side, and if the variation of the fundamental current exceeds a predetermined value, the fault impedance region is exceeded. If the duration is less than the reference time, the setting of the fault impedance area is set between the narrow side and the wide side, and if the duration is longer than the reference time, the fault is set. 2. The feeder circuit distance relay according to claim 1, wherein the setting of the impedance region is set to a narrow side.