JPH11178199A - Distance relay - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a countermeasure to unnecessary operation of a distance relay other than faulty phase. SOLUTION: A distance relay for detecting a fault in the protective section of a transmission line comprises a first means 1 for calculating the resistance component R and the reactance component X as the impedance up to a fault point from the voltage and current at the installing position of the relay, and a second means 2 for selecting two variables a, b as numerical values identical to or different from those before the fault upon occurrence of a fault. At the time of failure, (a) and (b) in the following expression of ellipse are varied from set values Rs , Xs . When (b) is fixed and (a) is decreased in the expression of ellipse, operating region is increased on the resistance component R side and it is decreased when (a) is increased. The variable (b) acts similar to the reactance component X. Consequently, the characteristics can be varied to eliminate unnecessary operation by varying the variables a, b upon occurrence of a fault. (R-Rs /2)<2> /a<2> +(X-Xs /2))<2> /b<2> <=(Rs /2a)<2> +(Xs /2b)<2> where, Rs and Xs represent set values of the distance relay.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance relay for protecting a transmission line of a power system.

[0002]

2. Description of the Related Art The principle of detecting a fault in a distance relay is to calculate the impedance up to the fault point of a transmission line, and if the calculated impedance is equal to or less than the impedance required for the operation of the distance relay, output an operation. If it is larger, the operation output is not performed. The calculation of the impedance up to the fault point of the transmission line is obtained by dividing the voltage introduced into the distance relay by the current.

The operation of the distance relay is determined for each phase in order to detect a fault in the transmission line. The calculation method for calculating the impedance of the distance relay is not the main object of the present invention and will not be described here. For example, "Protective Relay Engineering" P-1 published by the Institute of Electrical Engineers of Japan.
21 to 122 describe the principle.

The characteristics of the distance relays that are mainly applied are shown in FIG.
It consists of a Mo type distance relay having a circular characteristic as shown in FIG. 29 and a reactance relay having a linear characteristic. In addition,
Z _s , X _s1 , and X _s2 denote the set _values of the mo distance relay and the reactance relay, respectively, ZM denotes the impedance using the memory voltage, and Z and X denote the impedance and reactance measured by the relay. The functional block diagram up to the operation determination in this case is as shown in FIG.

(Z _s −Z) * ZM ≧ 0 X ≦ X _s1 X ≦ X _s2

[0005]

As described above, it is necessary that the distance relay does not output the operation when the impedance is calculated out of the operation responsibility range. However, when a distance relay of a healthy phase (or a phase including a healthy phase, hereinafter referred to as a healthy phase) should be originally inoperative, there is a possibility that an impedance is erroneously calculated within an operation duty range and an operation is output.

[0006] This phenomenon is considered as an advanced phase overreach.
2 and so on. As an example, at the time of the BC phase two-wire short-circuit accident, the short-circuit distance relay calculates the impedance as follows.

[0007]

## EQU2 ## Impedance seen by AB phase virtual distance relay Z _AB = 2 · (Z _B1 + Z _L1 ) · ε ^{(-j60 °)} Impedance seen by BC phase virtual distance relay Z _BC = (Z _B1 + Z _L1 ) CA phase virtual Impedance seen by the distance relay Z _CA = 2 · (Z _B1 + Z _L1 ) · ε ^{(+ j60 °)}

[0008] Here, the virtual distance relay is a distance relay installed after the impedance at the back.
_B1 indicates the impedance behind the distance relay, and Z _L1 indicates the impedance from the distance relay to the fault point. FIG. 31 shows the impedance at this time in an R-X plan view. That is, the fault phase (BC phase) distance relay accurately calculates the impedance (P-F) up to the fault point, but the distance relays of the other phases are twice as large in size and ± 6 in phase.
The impedance (PN, PM) shifted by 0 ° is calculated.

In addition, when the operating range of the distance relay is wide, the location of the fault point and the existence range of the impedance seen by the relay are as shown in FIG. 31. As the fault point approaches the relay installation point, the sound phase relay is easily operated. It turns out that it becomes a tendency. For this reason, the leading phase (AB phase) distance relay may output an erroneous operation. In particular, the operation of the relay including the sound phase is not preferable because the second stage element and the second stage elements are timed interruptions, while the first stage element is momentary interruptions.

As a means for solving this problem, for example, as described in the Electric Cooperative Research “Reserve Protection Relay System” on page 41, a countermeasure circuit to which an overcurrent relay is added as shown in FIG. 32 is provided. The operation range is limited to such an extent that the operation range characteristics of the mo-type distance relay do not operate.

[0011] Regarding the above-mentioned fear of malfunction due to overreach, there is a possibility that a ground fault distance relay on a healthy line side may malfunction due to overreach when an accident occurs in one of two parallel transmission lines. It is pointed out in the collaborative research “Reserve protection relay method” on page 39. As a countermeasure, the compensation method of the zero-phase current is controlled to forcibly make the distance measurement value underreach while preventing the relay characteristics, thereby preventing unnecessary operation.

The present invention has been made to solve the above problems, and has as its object to provide a distance relay that does not require measures against unnecessary operation of the distance relay other than in the accident phase.

[0013]

A distance relay according to a first aspect of the present invention is a distance relay for detecting an accident in a protection section of a transmission line by introducing a voltage and a current at a relay installation point to a fault relay point. A first means for calculating a resistance R and a reactance X as an impedance of the first and second means for selecting two variables a and b as the same or different values before the accident at the time of an accident, and a set value R _The operation is determined from _s and Xs according to the following equation or an equation equivalent thereto.

(R−R _s / 2) ² / a ² + (X−X _s / 2) ² / b ² ≦ (R _s / 2a) ² + (X _s / 2b) ² where R _s , X _s represents the resistance of the respective distance relay, the setting value of the reactance.

The first means is an impedance calculation necessary for determining the operation of the distance relay, and the second means changes a and b of the formula [3] expressed by a so-called elliptic formula at the time of an accident. [Equation 3] is an elliptic equation. Therefore, if b is fixed and a is reduced, the operating range on the resistance R side increases, and conversely, if a is increased, the operating range on the resistance R side decreases. . Regarding the variable b, the same operation is performed on the reactance X side. For this reason, by varying the variables a and b at the time of an accident, it is possible to change the characteristics so that unnecessary operations are not performed.

A distance relay according to a second aspect of the present invention is a distance relay for detecting an accident in a protection section of a transmission line, in which a voltage and a current at a relay installation point are introduced, and a resistance R as an impedance to the accident point is provided. And a first means for calculating a reactance component X, a second means for calculating a reference voltage (hereinafter, referred to as a reference voltage), and variable in accordance with a phase difference φ between a voltage directly used for operation determination. Third means for calculating the variables a and b, and the configuration is such that the operation is determined by Expression 3 or an expression equivalent thereto.

The first means is the same as that of claim 1, but the third means is based on the phase difference φ from the reference voltage, which is the second means, that the voltage phase changes at various accidents before and after the accident. By changing a and b in the equation of the ellipse of [Equation 3], it is possible to change the relay operation range and change to a characteristic that does not perform unnecessary operation.

A distance relay according to a third aspect of the present invention is the distance relay according to the first aspect, wherein the operation is determined by the following equation or an equation equivalent thereto instead of the equation (3).

Equation 4] _{(R-a '· R s} / 2) / a 2 + (X-b' · X s / 2) / b 2 ≦ (a '· R s / 2a) 2 + (b' · X _s / 2b) ² where R _s and X _s are set values for the resistance and reactance of the distance relay, respectively.

The variables a and b in the first and second terms on the left side of the equation (4) operate in the same manner as in claim 1, and a 'related to R _s / 2 in the parentheses in the first term on the left side is a resistance. The function of varying the operating range on the R side and b ′ related to X _s / 2 in the second parenthesis on the left side
Acts to change the operation range of the reactance. For this reason, the operation range can be controlled at the same time for the reactance X and the resistance R side, and the operation range can be changed to an unnecessary operation range.

A distance relay according to a fourth aspect of the present invention, in the distance relay according to the second aspect, operates according to the equation shown in the above equation (4) instead of the above equation (3) or an equation equivalent thereto. It was configured to determine.

A distance relay according to a fifth aspect of the present invention is a distance relay for detecting an accident in a protection section of a transmission line, in which a voltage and a current at a relay installation point are introduced, and a resistance R as an impedance up to the accident point. And a first means for calculating a reactance component X. According to the value of the reactance component X by the first means, the variable a or b in the equation (3)
Alternatively, the variable a, a ', b, b' in the equation (4) is made variable.

As the fault point approaches the relay installation point, the relay of the sound phase or the phase including the healthy phase easily enters the operating range, so that the variables a, a depending on the reactance X value.
By controlling b, it is possible to control to an operation range where unnecessary operation is not performed.

A distance relay according to a sixth aspect of the present invention is a distance relay for detecting an accident in a protection section of a transmission line of a power system. The distance relay introduces a voltage and a current at a relay installation point, and an impedance up to the accident point. And the first means for calculating the resistance component R and the reactance component X. When the operation is determined by the above [Equation 3] or [Equation 4], the variables a and b or the variables a, a ', A plurality of distance relays in which b and b 'are set to constants are configured. For example, if the first-stage element has a vertically long characteristic in which the operating range of the R-axis is reduced by the resistance, and the second-stage and higher elements have a horizontally long elliptical characteristic,
The first stage can have characteristics that make it difficult to perform unnecessary operations.

A distance relay according to a seventh aspect of the present invention is a distance relay for detecting an accident in a protection section of a transmission line, in which a voltage and a current at a relay installation point are introduced, and a resistance R as an impedance to the accident point. And first means for calculating a reactance component X, and fourth means for detecting a ratio of the own-line zero-phase current I ₀₁ and the adjacent line zero-phase current I ₀₂ at the time of a ground fault at a predetermined value or more, From the fifth means for detecting that the phase difference between I ₀₁ and I ₀₂ is within a predetermined range, when both the fourth means and the fifth means or the fourth means is established, 4] The variable a, a ', b, b' in the equation is made variable.

The fourth and fifth means operate to determine whether or not the line on which the relay is installed is an accident line.
When the line is healthy, the variables a, a ', b, and b' can be varied to prevent unnecessary operation due to overreach of the ground fault distance relay.

The distance relay according to claim 8 of the present invention is characterized in that, in claims 1 to 7, after the distance relay is determined to be in operation, for the set values R _s , X _s , R _s ′ <R _s ,
Switch to operation determination by the following formula in X _s' <X _s the relationship.

Equation 5] _{(R-a '· R s} ' / 2) / a 2 + (X-b '· X s' / 2) / b 2 ≦ (a '· R s' / 2a) 2 + (b '· X _s ' / 2b) ² where R _s and X _s are set values for the resistance and reactance of the distance relay, respectively.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) (Claim 1)
FIG. 1 is a functional block diagram showing a first embodiment of the present invention. In FIG. 1, an impedance calculator 1
Is the same as in the prior art. Here, the resistance R and the reactance X are calculated.

Reference numeral 2 denotes an operation determination formula calculation unit, which uses the variables a and b from the R and X and the set values R _s and X _s to obtain the above [Equation 3].
The operation is determined by the equation, and the distance relay operation output is performed when the condition is satisfied. Here, R _s and X _s indicate the set values of the distance relay, respectively.

[Equation 3] is a so-called elliptic equation.
Central Considering in -X plane is _{(R s / 2, X s} / 2),
The R axis and the X axis indicate the lengths of 2a and 2b, respectively. 3
Is an accident detection unit, which detects an accident based on the degree of undervoltage caused by the undervoltage relay. In other words, the voltage value | V | when is smaller than the settling V _k, are with the accident. Reference numeral 4 denotes a variable variable unit which changes an operation range by changing variables a and b of a distance relay corresponding to the output phase when an accident is detected, thereby preventing a malfunction of a healthy phase.

In FIG. 1, when an undervoltage relay is output, the variables a and b of the distance relay corresponding to the output phase are assumed to be the same as the values before the accident (for example, a = b = 1), and the other phases are set. For the variables a and b of the distance relays, smaller values are used than before the accident.

For example, this value is a = 1/2, b = 1, etc., assuming that the sound phase relay does not operate with the impedance seen by the healthy phase relay when the bc phase two-wire short circuit occurs. As a result, the operating characteristics of the fault-phase relay (bc phase) are the circular characteristics indicated by the broken line in FIG. 2, and the operating characteristics of the healthy-phase relay (ab phase, ca phase) are such that the long axis of the reactance component side is invariable. Since the short axis on the resistance component side is halved, the solid line has an elliptical characteristic as shown in FIG. 2 and unnecessary operation of the healthy phase relay can be prevented.

As a result, since the sound phase can be determined from the operation of the other relay elements, the operation range can be reduced. On the other hand, the accident phase maintains the same characteristics as before the accident. The above description is for the case where the characteristics before the accident have an operating range. However, the variables before the accident are assumed to be a = b = 1, and the variables of the accident phase are assumed to be a = 1/2 and b = 1 at the time of the accident. If this is the case, the characteristics change will be the reverse of the above, and the same effect will be obtained.

As described above, the operation range of the accident phase can be sufficiently ensured, and the operation range of the sound phase can be reduced or made to have no operation range to such an extent that unnecessary operation is not performed. Therefore, unnecessary operation due to overreach can be prevented.

(Second Embodiment) (corresponding to claim 2) FIG. 3 is a functional block diagram showing a second embodiment of the present invention. 3, the same functional portions as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. A description will be given focusing on portions different from FIG. Reference numeral 5 denotes a reference voltage calculation unit which sets a voltage having a quadrature phase relationship with the determination phase. FIG. 3 shows a functional block diagram of the short-circuit distance relay.
Phase, bc phase, and ca phase relays have c-phase voltage,
The a-phase voltage and the b-phase voltage are reference voltages.

Reference numerals 6 and 7 denote phase difference calculators, and 6 obtains a phase difference φ ₁ from the line voltage before the accident, and 7 obtains a phase difference φ ₂ between the reference voltage and the line voltage at the time of the accident. The variable variable section 4-1 changes the phase difference | φ |
Find variables a and b. The reference voltage calculation unit 5, the phase difference calculation units 6 and 7, and the variable variable unit 4-1 use the following equation V _base ,
φ ₁ , φ ₂ , | φ |, a, b are calculated.

(Equation 6)

In general, the voltage tendency at the time of various accidents is as shown in FIG. 4. Therefore, the phase difference between the reference voltage and the line voltage becomes as shown in Table 1 before and after the accident. That is,
Although there is not much phase difference in the accident phase, a phase change accompanies the healthy phase.

[0036]

[Table 1]

For this reason, in the variable variable section 4-1 in FIG. 3, the variables a and b are selected such that one is fixed and the other is proportional to the phase difference | φ |, or both are proportional to the phase difference | φ | .
For example, assuming that kb = 0, b is fixed at 1 and a = 1− | φ | /
Assuming 180, in the event of an accident, the accident-phase relays are a = 1 and b =
1, which is a circular characteristic, and a healthy phase relay has a <1, b =
It becomes 1 and becomes an elliptic characteristic. Therefore, unnecessary operation due to overreach of the healthy phase relay can be prevented.

The above is the case of the short-circuit distance relay. In the case of the ground-fault distance relay, the reference voltage is a line voltage in a quadrature phase, and the phase difference between the two is as shown in Table 2. In addition,
Although not shown in FIG. 3, if there is no input sufficient for calculating the phase of the reference voltage or the line voltage, the phase difference is not obtained. At this time, if the reference voltage is small, it can be determined that the judgment phase is sound. Therefore, the variables a and b are reduced to narrow the operation range, and if the line voltage is small, the judgment phase becomes the accident phase. Since it can be determined, the variables a and b are unchanged. The description is omitted below.

FIG. 5 shows a modification of the first embodiment (FIG. 1).
A description will be given focusing on portions different from the embodiment shown in FIG. The phase difference cos φ between the reference voltage and the voltage is obtained, for example, by dividing the result of the scalar product as shown in the phase difference calculation unit 7-1 by the amplitude of the reference voltage and the voltage.

The difference from FIG. 1 is that the reference voltage calculator 5
And a phase difference calculating unit 7-1 and a variable varying unit 4-2. The reference voltage calculation unit 5, the phase difference calculation unit 7-1, and the variable variable unit 4-2 calculate the following expressions V _base , cos φ, a, and b, respectively.

(Equation 7)

As for variables a and b, one is fixed and the other is | cos ⁿ
φ | (n ≧ 0), or both | cos ⁿ φ |
If the proportionality constants ka and kb are set so as to be proportional to (n ≧ 0), when the phase difference between the reference voltage and the voltage is in-phase, that is, unchanged, the variables a and b remain unchanged from those before the accident, and the phase difference increases. As shown in FIG. 2, the variables a and b become smaller, the operating range of the healthy phase is narrowed, and unnecessary operation is prevented by overreach.

For example, n = 1, b = 1, proportional constant ka =
Assuming that the short-circuit distance relay of the healthy phase and the fault phase when the bc phase is 2φS is 1, the fault phase is a = | cos 0 ° | = 1 and the healthy phase is a = | cos 60 when the phase change is the largest.
° | = 0.5, which is the same characteristic as FIG.

FIG. 6 is another modified example of FIG. 1, and a description will be given focusing on portions different from FIG. The parts different from FIG. 5 are the phase difference calculation unit 7-2 and the variable variable unit 4-3 in FIG. In the phase difference calculation unit 7-2, the following equation sin φ is used.
Calculates the following expressions a and b, respectively.

(Equation 8)

One of the variables a and b is fixed and the other is | 1-si
n ⁿ φ | (n ≧ 0), or both are | 1-si
n ⁿ φ | (n ≧ 0). Here, the proportional coefficients ka, kb, and φ indicate the phase difference φ between the reference voltage and the voltage. As in FIG. 5, when the phase difference between the reference voltage and the voltage is in-phase, that is, unchanged, | 1-sin ⁿ φ | can be obtained by reducing the variables a and b as the phase difference is widened without changing the variable before the accident. As described above, the operation range of the healthy phase is narrowed, and unnecessary operation is prevented by overreach.

For example, n = 1, b = 1, proportional constant ka =
Assuming that the short-circuit distance between the healthy phase and the fault phase when the bc phase is 2φS is 1, the fault phase is a = | 1-sin 0 ° | = 1 and the healthy phase is a = | 1-
sin 60 ° | = 0.134, and the characteristics can be narrower than those in FIG.

FIG. 7 shows another modification of FIG. 5. The difference from FIG. 5 is a phase difference calculation section 7-3 and a variable variable section 4-4.
The preceding phase difference calculation unit 7-3 and the variable variable unit 4-4 use the following equation tan
φ, a, and b are calculated respectively.

(Equation 9)

One of the variables a and b is fixed and the other is proportional to | 1-K · tan ⁿ φ | (n ≧ 0), where K is a constant, or both are | 1-K · tan ⁿ φ | (n ≧ 0). Here, the proportional coefficients ka, kb, and φ indicate the phase difference φ between the reference voltage and the voltage.

For example, n = 1, b = 1, proportional constant ka =
Assuming that the short-circuit distance relay of the healthy phase and the fault phase when the bc phase is 2 φS is 1/2, the fault phase is a = | 1-tan 0 ° / 2 | = 1 and the healthy phase Is a
= | 1-tan 60 ° / 2 | = 0.134, and FIG.
The same operation range as that described above can be obtained with narrowed characteristics. Therefore, the same effect as in FIG. 5 can be obtained.

FIG. 8 shows still another modification of FIG.
The difference from the above is a phase difference calculation section 7-4 and a variable variable section 4-5. The preceding phase difference calculating section 7-4 and variable variable section 4-5 calculate the following expressions φ, a, and b, respectively.

[Equation 10]

The variables a and b and the phase difference φ between the reference voltage and the voltage are set in a one-to-one correspondence, and the variables a and b according to the phase difference φ are selected. For example, when the phase difference φ is 0 °, the variable a is set to 1 so that the values of the variables a and b decrease as the phase difference φ increases. The effect of the present embodiment is similar to that of FIG.

FIG. 9 is a functional block diagram showing a third embodiment of the present invention. 9, the same functional portions as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. The difference from FIG. 1 is an operation determination formula calculation unit and a variable variable unit. The operation determination equation in the present embodiment is as shown in the above [Equation 5].

Also, the variable variable section sets the variables to a ← 1, a ′ ← 1, b ← when it is not established, depending on the judgment of the undervoltage relay.
1, b '← 1, and when satisfied, the variables are a ← 2/3, a ′ ←
2/3, b ← 2/3, b ′ ← 2/3. This embodiment is the same as claim 1 (FIG. 1) except that the operation determination formula is changed, the numerical value given to the variable is changed, and the number of variables is changed.

That is, in the equation (5), the variables a, a ',
b, b ′, and the variables a and b of the first and second terms on the left-hand side of the equation (5) are as in the embodiment of FIG. 1, and R _s / The a 'corresponding to 2 and the b' corresponding to X _s / 2 in the second term parenthesis on the left side act to change the center of the ellipse. For this reason, the reactance component X and the resistor component R, both of which have a and b as variables, can simultaneously control the operation range, control the center position of the characteristic, and change to an operation range in which unnecessary operation is not performed.

For this reason, for example, in order to prevent malfunction of the sound phase short distance relay when the bc phase two-wire short circuit occurs, the variable a = a ′ = b = b ′ = 1 before the accident and the variable a Assuming that = a '= b = b' = 2/3, the operating range of each phase before and after the accident changes as shown in FIG. 10, and the malfunction of the healthy phase relay can be prevented.

FIG. 11 is a functional block diagram showing a fourth embodiment of the present invention. 11, the same parts as those in FIG. 3 are denoted by the same reference numerals, and the description will be omitted. The feature of the present embodiment is that the operation determination expression of the operation determination unit 2-1 is as shown in [Equation 4]. Other configurations are the same as those in FIG.
The operation and effect are the same as those in FIG.

FIG. 12 is a modification of FIG. 5, and the same reference numerals are given to the same functional portions as in FIG. 5, and the description will be omitted. In this modified example, the equation shown in [Equation 5] is used as the operation determination equation, and there are four variables (a, a ', b, b'). They are only provided in correspondence with each other, and are basically the same as FIG. 5 except for the operation determination formula.

FIG. 13 is a modification of FIG. 6, and the same reference numerals are given to the same functional parts as in FIG. 6, and the description will be omitted. In this modified example, the operation determination expression shown in Expression 5 is used, and four variables (a, a ',
b, b '), so that only variable variable sections 4-7 are provided in correspondence with the above numbers, and are basically the same as FIG. 6 except for the operation determination formula.

FIG. 14 is a modification of FIG. 7, and the same reference numerals are given to the same functional parts as in FIG. 7, and the description will be omitted. In this modified example, the operation determination expression shown in Expression 5 is used, and four variables (a, a ',
b, b '), so that only variable variable sections 4-8 are provided corresponding to the above-mentioned number, and are basically the same as FIG.

FIG. 15 is a modification of FIG. 8, and the same reference numerals are given to the same functional portions as in FIG. 8, and the description will be omitted. In this modified example, the operation determination expression shown in Expression 5 is used, and four variables (a, a ',
b, b '), the variable variable sections 4-9 are provided only in correspondence with the number, and are basically the same as FIG. 8 except for the operation determination formula.

FIG. 16 is a modification of FIG. 5, and the same parts as those of FIG. In this example, the positive-phase voltage is used as the reference voltage. 5-1 is a reference voltage calculator. Fig.
The calculation is performed in 5-1 of 16; an example of which is described in the following literature, and is omitted here.

The positive-phase voltage is a positive-phase voltage of the symmetrical coordinate method as described in PSR-96-5, P47 of the Institute of Electrical Engineers of Japan, and has the advantage of little phase change before and after the accident. is there. For this reason, when calculating the phase difference between the reference voltage and the line voltage, in FIG. 3, the phase correction before and after the accident is performed such that the phase difference φ is obtained from the difference between the phase φ ₁ before the accident and the phase φ ₂ after the accident. However, it can be unnecessary with a positive-sequence voltage. [Table 2] and [Table 3] show the phase difference between the normal phase voltage and the voltage at the time of various general accidents.

[0062]

[Table 2]

[0063]

[Table 3]

Also in this case, since the phase difference of the accident phase hardly changes and the phase difference of the healthy phase changes, the embodiments of the invention corresponding to FIGS. 3 to 8 and FIGS. The functions and effects described in the form or the modified example are provided. In Table 3, at the time of the bc accident, the phase difference of the a-phase relay is 0 °, and there is no characteristic change.
It is obvious that the phase a is a sound phase and the impedance is out of the operation of the relay.

FIG. 17 is a modification of FIG. 16, and the same parts as those of FIG. In this modification, the positive-phase voltage is, for example, the voltage two cycles before the occurrence of the accident, which is 5-2 in FIG. 17. By using the voltage before the accident at the time of the accident, there is no phase change before and after the accident as in FIG. It becomes the reference voltage.

FIGS. 3, 4 to 8 and FIGS.
Regarding the embodiment and the modified example of the present invention corresponding to No. 15, the operation and effect can be described by replacing the reference voltage with the pre-accident voltage, and thus the details are omitted. Further, before the accident, the two cycles before the occurrence of the accident are not limited.

FIG. 18 is a functional block diagram showing a fifth embodiment of the present invention. In FIG. 18, reference numeral 1 denotes a portion for introducing a voltage and a current at a relay installation point, and calculating a resistance R and a reactance X as impedances up to the fault point. The variable variable unit 4-10 in FIG. 18 is configured to make the variables a and b in the equation (3) variable in proportion to the calculated reactance X.

As the fault point approaches the relay installation point, the impedance seen by the healthy phase becomes more likely to enter the distance relay operation area as shown in FIG. 31. By changing the variable in proportion to the reactance X, As the fault point approaches the relay installation point, the reactance X decreases, and thus the variables also decrease, so that the operating range can be reduced.
Thereby, the overreach operation of the healthy phase can be prevented. In the present embodiment, the relationship is proportional. However, the present invention is not limited to this, and the variables a, b, a ', and b' are replaced with the expression [5] instead of the expression [3]. You may make it variable.

FIG. 19 is a functional block diagram showing a sixth embodiment of the present invention. In FIG. 19, reference numeral 1 denotes a portion for introducing a voltage and a current at a relay installation point, and calculating a resistance R and a reactance X as impedances up to the fault point. In addition, 8-1 in FIG. 19 is a part for determining the operation of the first-stage element according to the [Equation 3], and sets the variables a and b to constants.
a> b. Similarly, from 8-2 to 8-
In FIG. 3, a distance relay is configured by combining elements of the second and higher stages in a relationship of a <b.

As shown in FIG. 20, since the first-stage element satisfies a> b, the operation characteristic becomes a vertically long elliptical characteristic.
Since the elements of the second stage and above have a horizontally long characteristic, a margin for unnecessary operation of the first stage element of the sound phase relay due to overreach is secured, and the protection operation of the second and higher elements which is time-blocked is conversely performed. The duty of protection of the distance relay will be improved by expanding the area. Although not shown in the drawings, the elements of the second and higher stages may have a vertically long elliptical characteristic in order to prevent unnecessary operation due to a constant load current.

FIG. 21 is a functional block diagram showing a seventh embodiment of the present invention. In FIG. 21, reference numeral 1 denotes a portion for introducing a voltage and a current at a relay installation point, and calculating a resistance R and a reactance X as an impedance up to the fault point.

The zero-phase current component calculating section 9 shown in FIG. 21 includes a portion for detecting the ratio of the zero-phase current I ₀₁ of the own line and the zero-phase current I ₀₂ of the adjacent line to a predetermined value or more, and the positions of I ₀₁ and I ₀₂ . This is a part for detecting that the phase difference is within a predetermined range (± α). These detection results are configured as an AND as shown in 10, and when both are satisfied, the variable variable unit 4-11 [Equation 5] Variable a,
a ', b, b' are configured to be variable.

In the ground fault distance relay, the overreach of the healthy line side relay due to the adjacent line zero-phase current compensation at the time of operation of two parallel lines of the transmission line is described in detail in the above literature.
Briefly, it is as follows. The principle of impedance calculation (ranging) up to the fault point of a ground fault distance relay is
It can be expressed by the following equation. Here, Z is the calculated impedance, V _a and I _a are the voltage and current of each phase, I ₀₁ and I ₀₂ are the zero-phase current of the own line and the adjacent line, and K and K ′ are constants.

[Equation 11]

In the relay on the healthy line side with two parallel lines, I ₀₂
Is equivalent to the fault current, and Z is measured to be smaller than Z which should be measured as a ground fault distance relay. For example, assuming that the distance to the opposite end is 1 in two parallel lines as shown in FIG. 22 and a ground fault occurs at a point 0.25 from the own end of the adjacent line, the following relationship is obtained when there is no power flow. is there.

I ₀₁ : I ₀₂ = 0.25: 1.75 ∴I ₀₂ = 7 · I ₀₁

Since I _a = 3 · I ₀₁ , the impedance Z calculated by the sound circuit-side relay is given by the following equation.

(Equation 13)

When there is no adjacent line compensation, the following equation is obtained, and 1 / 3.8 of the original impedance of 1.75 is obtained.
Will be measured to 0.46.

[Equation 14]

In order to prevent the overreach of the relay on the healthy line side by this, it is judged at 23 in FIG.
When the condition is satisfied by the AND circuit 10, it can be regarded as a healthy line side, so that the variables are, for example, a = 0.46 / 2, a '<0.
If 46/2, b <0.46 / 2, b '<0.46 / 2, the operating range can be reduced as shown in FIG. 23, and the above-mentioned unnecessary operation can be prevented. Although not shown in the figure,
A similar effect can be obtained by changing a variable when the ratio between the zero-phase current of the own line and the zero-phase current of the adjacent line is equal to or greater than a predetermined value.

FIG. 24 is a functional block diagram showing an eighth embodiment of the present invention. In FIG. 24, the dashed line portion is an embodiment of the distance relay according to claims 1 to 7 of the present invention, so details are omitted, but after the operation of the fault-phase relay is determined, the operation is determined by the formula [4]. To maintain the operation determination.

Here, the operation and effect of the equation (4) will be described. At the time of the near-end accident, the voltage of the accident phase may become 0. At this time, the calculated impedance R, X is a positive / negative value near 0 in the operation determination formula by the formula [3] or [5]. As a result, an unstable determination result that repeats the operation and the return is obtained.

After it is once determined that the operation is performed according to [Equation 4],
Assuming that R _s ′ and X _s ′ are R _s ′ <R _s and X _s ′ <X _s , the characteristic of moving the center position of the elliptic characteristic backward as described in the third embodiment is as follows. It can be changed to the rear offset characteristic shown in FIG. Thereby, a stable relay operation output can be obtained continuously even at the time of the near-end accident.

FIG. 26 is a functional block diagram showing a modification of the present invention. 26 are the same as those in the modified examples of the second to eighth aspects of the present invention and the modified examples of the fourth to FIG. 17 aspects of the present invention. Is configured to display the phase difference φ between the reference voltage and the voltage obtained in the above.

When the variable is controlled by the phase difference as described above, a reference voltage and a line-to-line or phase voltage are applied during a performance test, and the phase difference differs for each of the three phases of the relay. For this reason, in order to grasp what phase difference the relay of each phase has due to the input condition, it is necessary to obtain the phase difference by calculation from the display value of the measuring instrument.

For example, in the case of the test input configuration of the short-circuit distance relay shown in FIG.
To calculate the phase difference between the b-phase and ca-phase relays, complicated calculations must be performed. To make calculations easier,
As shown in FIG. 27 (b), a phase measuring device is inserted between each phase voltage, but the number of test equipment is increased. Therefore, in order to increase the efficiency of the test or reduce the number of test equipment, the phase difference calculated inside the relay is displayed to minimize the required test equipment. Can be easily grasped.

FIG. 28 is a functional block diagram showing a modification of the present invention. The broken line portion in the functional block diagram of FIG. 28 is the same as that of the embodiments and modified examples of claims 1 to 26 of the present invention, and details are omitted. The variables a and b in the equation (3) and the variables a and b in the equation (5)
a ', b, b' are configured to be displayed. In the distance relay according to the present invention, when an accident is encountered in an actual system, it is difficult to grasp the state of operation of the relay when the accident is encountered in order to change the characteristics.

Therefore, by displaying the variables used for the operation determination, it is possible to easily determine what state the relay characteristics are in. In addition to the easiness of the response analysis, the variable values are also determined in advance during the test. By determining whether a variable corresponding to a test input that can be predicted is displayed, maintenance of the relay is also facilitated. That is, when there is no display value of a variable measured in advance at the time of test input, for example, a shift in gain or phase of the input unit can be predicted, so that the input unit that is likely to change over time is also checked.

[0086]

As described above, according to the present invention, the operation judgment formula of the distance relay based on the formula of the ellipse is adopted, and the variables corresponding to the major axis and the minor axis of the ellipse are changed before and after the accident. This can prevent unnecessary operation due to overreach of a healthy phase or a healthy line-side relay at the time of an accident.

[Brief description of the drawings]

FIG. 1 is a functional block diagram of a distance relay according to a first embodiment of the present invention.

FIG. 2 is a characteristic diagram of a changed distance relay according to the present invention.

FIG. 3 is a functional block diagram of a distance relay according to a second embodiment of the present invention.

FIG. 4 is a diagram showing voltage trends at various accidents.

FIG. 5 is a functional block diagram of a distance relay according to a modified example of the present invention.

FIG. 6 is a functional block diagram of a distance relay according to another modification of the present invention.

FIG. 7 is a functional block diagram of a distance relay according to still another modification of the present invention.

FIG. 8 is a functional block diagram of a distance relay according to still another modification of the present invention.

FIG. 9 is a functional block diagram of a distance relay according to a third embodiment of the present invention.

FIG. 10 is a characteristic diagram of a distance relay after a change according to the third embodiment of the present invention.

FIG. 11 is a functional block diagram of a distance relay according to a fourth embodiment of the present invention.

FIG. 12 is a functional block diagram of a distance relay according to a modified example of FIG. 5 of the present invention.

FIG. 13 is a functional block diagram of a distance relay according to a modified example of FIG. 5 of the present invention.

FIG. 14 is a functional block diagram of a distance relay according to a modified example of FIG. 5 of the present invention.

FIG. 15 is a functional block diagram of a distance relay according to a modification of FIG. 5 of the present invention.

FIG. 16 is a functional block diagram of a distance relay according to a modified example of FIG. 5 of the present invention.

FIG. 17 is a functional block diagram of a distance relay according to a modified example of FIG. 5 of the present invention.

FIG. 18 is a functional block diagram of a distance relay according to a fifth embodiment of the present invention.

FIG. 19 is a functional block diagram of a distance relay according to a sixth embodiment of the present invention.

FIG. 20 is a characteristic diagram of a distance relay according to a sixth embodiment of the present invention.

FIG. 21 is a functional block diagram of a distance relay according to a seventh embodiment of the present invention.

FIG. 22 is a view showing an accident condition of a parallel two-circuit transmission line.

FIG. 23 is a characteristic change diagram of the distance relay according to the seventh embodiment of the present invention.

FIG. 24 is a functional block diagram of a distance relay according to another modification of the present invention.

25 is a characteristic change diagram of the distance relay according to the embodiment of FIG. 24 of the present invention.

FIG. 26 is a functional block diagram of a distance relay according to another modification of the present invention.

FIG. 27 illustrates a test configuration.

FIG. 28 is a functional block diagram of a distance relay according to another modification of the present invention.

FIG. 29 is a characteristic diagram of a conventional distance relay.

FIG. 30 is a functional block diagram of a conventional distance relay.

FIG. 31 is a diagram showing the impedance and the relay characteristic seen by the relay at the time of bc phase 2φS.

FIG. 32 is a diagram showing countermeasures for advanced phase overreach.

[Explanation of symbols]

1 Impedance calculation unit 2,2-1,2-2 Operation judgment formula calculation unit 3 Accident detection calculation unit 4,4-1 to 4-11 Variable variable unit 5,5-1,5-2 Reference voltage calculation unit 6, 7, 7-1 to 7-4 Phase difference calculators 8-1, 8-2, 8-3 First stage element, second stage element, third stage
Stage element 9 Zero-phase current component calculation unit

Claims (8)

[Claims] In a distance relay for detecting an accident in a protection section of a transmission line, a voltage and a current at a relay installation point are introduced, and a resistance R and a reactance X are calculated as impedances to the accident point. Means and a second means for selecting two variables a and b at the time of the accident as the same or different values as before the accident, and from the set values R _s and X _s by the following equation or an equation equivalent thereto: A distance relay configured to perform an operation determination. (R−R _s / 2) ² / a ² + (X−X _s / 2) ² / b ² ≦ (R _s / 2a) ² + (X _s / 2b) ² where R _s , X _s represents the resistance of the respective distance relay, the setting value of the reactance. 2. A distance relay for detecting an accident in a protection section of a transmission line, wherein a voltage and a current at a relay installation point are introduced, and a resistance R and a reactance X are calculated as impedances to the accident point. Means, a second means for calculating a reference voltage (hereinafter, referred to as a reference voltage), and a third means for calculating variables a and b that are varied according to a phase difference φ between the voltage and a voltage directly used for operation determination. And a means for judging the operation by the formula [1] or a formula equivalent thereto. 3. A distance relay for detecting an accident in a protection section of a transmission line, wherein a voltage and a current at a relay installation point are introduced, and a resistance R and a reactance X are calculated as impedances up to the accident point. Means and a second means for selecting two variables a, b and a ', b' in the event of an accident as the same or different values as before the accident, and
_s, the distance relay to the the X _s, characterized by being configured to perform the operations determined by the following formula or an equivalent expression. [Number 2] _{(R-a '· R s} / 2) / a 2 + (X-b' · X s / 2) / b 2 ≦ (a '· R s / 2a) 2 + (b' · X _s / 2b) ² where R _s and X _s are set values for the resistance and reactance of the distance relay, respectively. 4. A distance relay for detecting an accident in a protection section of a transmission line, wherein a voltage and a current at a relay installation point are introduced, and a resistance component R and a reactance component X are calculated as impedance to the accident point. Means, a second means for calculating a reference voltage (hereinafter, referred to as a reference voltage), and variables a, b and a ', b' which vary according to a phase difference [phi] between a voltage directly used for operation determination. And a third means for calculating the distance, and wherein the operation is determined by the equation [2] or an equation equivalent thereto. 5. A distance relay for detecting an accident in a protection section of a transmission line, wherein a voltage and a current at a relay installation point are introduced, and a resistance component R and a reactance component X are calculated as impedance to the accident point. Means, and according to the value of the reactance component X by the first means, the variables a and b of the equation (1) or the variables a, b, a 'and (2) of the equation (2)
4. The distance relay according to claim 1, wherein b 'is variable. 6. A distance relay for detecting an accident in a protection section of a transmission line, wherein a voltage and a current at a relay installation point are introduced, and a resistance component R and a reactance component X are calculated as impedances to the accident point. A plurality of distance relays in which the variables a and b or the variables a, b, a 'and b' are set to constants when performing the operation determination by the expression [1] or [2]. A distance relay characterized by comprising: 7. A distance relay for detecting an accident in a protection section of a transmission line, wherein a voltage and a current at a relay installation point are introduced, and a resistance component R and a reactance component X are calculated as impedance to the accident point. Means for detecting the ratio of the zero-phase current I _{01 of} the own line to the zero-phase current I ₀₂ of the adjacent line is equal to or more than a predetermined value, and the phase difference between I ₀₁ and I ₀₂ is within a predetermined range. The variable a, b, a ', b' of the equation (2) is varied when both the fourth means and the fifth means or the fourth means are established from the fifth means for detecting the existence. A distance relay characterized in that it is configured as described above. 8. After the distance relay is determined to be in operation, the operation is switched to the operation determination by the following equation with respect to the set values R _s and X _{s in a} relationship of R _s ′ <R _s and X _s ′ <X _s. The distance relay according to claim 1, wherein the distance relay comprises: Equation 3] _{(R-a '· R s} ' / 2) / a 2 + (X-b '· X s' / 2) / b 2 ≦ (a '· R s' / 2a) 2 + (b '· X _s ' / 2b) ² where R _s and X _s are set values for the resistance and reactance of the distance relay, respectively.