JPS6011532B2 - 2-wire fault distance relay device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to an improvement in a two-wire fault distance relay system for detecting and protecting against two-wire short circuit faults.

Although this invention can be applied to systems with and without branch ends, the invention will be described for systems without branch ends. Conventionally, as a distance relay device that responds to a two-wire failure in a normal power transmission line as shown in FIG. 1 without a branch end in the middle, a device that satisfies the following operating formula has been proposed.

IV2-ZS121>IV. -ZSI. 1...
{11IV2-2212l>IV. 1
...[21 This was proposed based on the following idea.

Figure 2a is an equivalent circuit diagram when a two-wire short circuit fault occurs in the system shown in Figure 1, where the positive-sequence and negative-sequence voltages at the relay installation point RY are V, , V2, and the positive-sequence and negative-sequence currents are 1,,12
, the positive-sequence and negative-sequence impedances from the relay installation point RY to the fault point F are Z, F, Z illusion, and the positive-sequence and negative-sequence voltages at the fault point F' are V, F, V, then V, - Z, F1,
=V,F """[31V2-I2; M2F .....[4] Both formulas hold true, and VIF2V2F,..Ni-12
"""[5I has the relationship.

Note that in the above {3}, (2) equations (hereinafter also referred to as the same device), the polarity of the positive-phase and negative-phase currents is positive in the direction of flowing from the power supply side to the line side. Therefore, instead of Z small Z2F (generally Z, F: Z2F = ZF) in the formula 31 and '41, the impedance within the protection area, ie, the settling impedance Zs
By introducing (v,-poorS,.) and (v2-Z3;2)
Derive the fault at the settling point, that is, Zs=Z, F=
If Z2F, (V, - Zsl,) = (V2 - Zs12
) ...{6}V, = (V2 - Zs12)
It becomes... The relationship between each vector in this case can be expressed as
Shown in Figure b. Here 1. :-12 and Z, F=Z2p
Therefore, Z, F1, and Z2F12 have equal absolute values and opposite polarities. Therefore, the internal fallen camphor, that is, IZS->-Z
, FI is (V, -ZS1,)<V conversion (V2-Shi2)>V cape (VI-Zjl)<(V2-ZS12) skin"■V
．． <(V2 primary s12) ...{9}.

Also, if there is an external failure, that is, IZsl - IZ, FI, then (V, - Zsl,) > V, F (V2 - Zs12) < V2p, so (V - ZSII) > (V2 - ZS12) ...
00VI>(V2-Z312)...
Becomes blood.

Therefore, by comparing (V, Si,) and (V2-ZS12) or V, and (V2-Zs12), it is possible to detect whether a two-wire fault has occurred internally or externally. However, as is well known, depending on the nature of the fault, the phase relationship between the normal phase component and the negative phase component may differ by 120 degrees from each other, so it becomes necessary to compare the magnitudes of their absolute values. Based on this idea, a distance relay system that responds to formulas [1] and (2) was eventually proposed. However, the relay equipment layer applied to the above formulas '1' and '21 does not take into account the fault resistance, that is, the arc resistance Rf. Arc resistance Rf
When considering this, the equivalent circuit becomes as shown in FIG. In Figure 3, the voltage drop due to arc resistance Rf is Vf
Then, the positive sequence voltage V at the fault point F, F is the negative sequence voltage V
Since it is equal to the sum of the target and Vf, V2F + Vf = V, F, that is, V - VIF - Vf - VI - ZIF11 - Vf
D V2-Z2F12. ．．・．． ...The relationship is (12).

Therefore, the above equations {1} and {2) cannot be expected to operate accurately when arc resistance is taken into account. This is the fourth
This will be explained using figures. FIG. 4A is a vector diagram showing each vector in FIG. 3 and the -Zs12 vector when Zs=Z, F=Z2F, that is, a fault accompanied by arc resistance Rf occurs on the settling point. In the case of a failure on the settling point, if there is no arc resistance Rf, from the above equation '6}, V2 - Kosho i20Z
．． F1. =V・v21 (Z cross 2F) 12=V,…”
It should be (13) (.:11-12).

However, if there is a voltage drop Vf due to arc resistance Rf.
V2- (Z.F cross 2F) 120 Vf:V. ...(14)
), and considering Zs=Z, F=Z2F,
(V2-2Si2)<(V.-ZSL)(V2-phantom s1
2)<V, (because .:1,=-12 is unchanged), and as is clear from the above equation '2} and (11), it is determined that there is an external failure.

Needless to say, this error is caused by the voltage drop Vf due to the arc resistance Rf. Therefore, in order to eliminate this error, it is sufficient to avoid the influence of the voltage drop Vf due to the lack of arc resistance f. Voltage drop V due to this arc resistance
Since f is in phase with -12, in order to avoid the influence of Vf, all the voltages in the above equation (14) should be made into only the component perpendicular to -ra', that is, the reactance component voltage. That is (14)
In the equation, the phase difference angle between V and 1 is defined as Q, (V2 - friend s1
When the phase difference angle between 2) and (-12) is 6, IV2-2
212lsin6>IV,lsinQ…. ...(15)
If the operating formula is obtained, an accurate distance relay layer that is no longer affected by the arc resistance Rf can be obtained.

In Figure 4 A, IV2-Zs12lsin6=IV,ls
inQ, which becomes the limit point of inoperability. The opening in FIG. 4 is a vector diagram in the case where the relay is activated when a two-wire short circuit fault occurs at a location closer to the relay installation rule than the setting point.

Since IZsl>IZ, Fl, IZ2FI, comparing the components perpendicular to Riko, IV2-22121Sin8>I
V. It operates as ISinQ. FIG. 4C is a vector diagram in the case where a two-wire short circuit fault occurs at a location far from the settling point and the device becomes inoperable.

In this case, -ZSI<IZ, Fl, IZ2pl, so comparing the components perpendicular to -12, we get IV2-2212
lsin6<IV, lsinQ and becomes inoperable.

Instead of formula (15), IV2-Zs et al. ISin8>IV. 1ZS121Sin
y. The same effect can be obtained by using the operation formula (16).

However, the angle formed by 81'ma v2-2Si2 and -12, the relay layer according to the operation formula of [1', Therefore, a special filter is required to obtain a symmetrical component from each phase voltage and current obtained from the CT and PT of the grid, and the disadvantage is that the input circuit is more complicated than a normal distance relay. It is.

As an example, FIG. 5 shows a block diagram of a relay circuit whose operation formula is expressed by equation (16).

In other words, the right side of equation (16) is composed of a positive-sequence voltage filter {11 that derives the positive-sequence voltage V, from each phase voltage V^, VB, and Vc, and a positive-sequence voltage filter {11} that derives the positive-sequence voltage V, from each phase current 1^, IB, and lc. A calculation circuit 51 that calculates the suppressing force reactance voltage -v, -ZS;, -siny, which is a composite quantity of these outputs, is necessary for the positive sequence current filter '21 which derives the current 1, -siny.
to obtain (v, -ZSi,) and (v, -ZSi,)
Find the sine quantity of 1,=-121 of Si,), that is, its reactance voltage -v,''ZSi,-siny.In this), y is the phase difference angle of (v,-Si,) and -12. On the other hand, regarding the left side of equation (16), the negative phase voltage filter 3 which derives the negative phase voltage V2 from each phase voltage V^, V8, Vc and the negative sequence current from each phase current 1, , 12, H A negative-sequence current filter 4 is required to derive the operating force reactance voltage IV2-Zs12l, which is a composite quantity of these outputs.
It is synthesized by the arithmetic circuit 6 that calculates sin8, and (V2-Z
s12) and the sine amount of (V2-Zs12) for (-Z), that is, its reactance voltage IV2
- Find Zs12lsin8. In this), 3 is (v2-Z
This is the phase difference angle of Si2) and Kuichi12). Furthermore, 7 is a determination circuit which compares the magnitude of the outputs of the arithmetic circuits 5 and 6, and takes out the output only when the output of the arithmetic circuit 6, that is, the operating force exceeds it, and uses it as a relay output. However, as mentioned above (
Equation 16) requires four symmetrical filters of V, , V2, 1, and 12, making the input circuit complicated. Further, if the input voltage of each phase contains a harmonic component, and for example, only the voltage between AB and phase becomes a triangular wave, the above-mentioned filter is greatly affected. However, here, sample equations for the positive-sequence voltage and the negative-sequence canal pressure film configuration are given by equations (17) and (18). pair, =
Ma Misaki 10 BCeJi skin” (17). . . ・i
z3 (18)3V2=VBc ten V^Be-
−... y=group (Sino-kin38 Tomu in58...)...
...(19) Here, Y is the peak value of the triangular wave.

Considering up to the second term, triangular wave = fundamental wave x 3rd harmonic --- (20) For example, in the case of a ratio-phase two-wire short circuit fault, A
When the B phase line voltage ^B becomes a triangular wave, 3 is obtained from equation (17).
The error of V, is (-ki in38), and from equation (18), the error of 3 V2 is (-ki in38) ej type 3 = tenki in
38 (a 60 degree lead of the fundamental wave corresponds to a 180 degree lead of the third harmonic), so if this error is taken into consideration, the positive sequence voltage V. is V, = fundamental wave - 3rd harmonic, negative phase voltage V2
V2=fundamental wave 10th harmonic, and its approximate waveform is shown in FIG. 6C and D.

Note that FIG. 6A shows the fundamental waveform, and B shows the third harmonic waveform. In such a case, correct response cannot be expected even if the reactance voltage is determined as in equations (15) and (16).
FIG. 6A is a fundamental waveform, B is a third harmonic waveform, and C and D are waveform diagrams of a positive phase voltage V and a negative phase voltage V2. For example (15
) Determining the right-hand side IV,lsinQ of the equation means determining the instantaneous value when the alternating current electrical quantity V, reaches a predetermined phase. When the phase difference angle between V, and - is Q, the seventh
Obtain it by sampling as shown in the figure.

If t-12I-12ISin (mountain t-Q) of VI-IVIISin, a sampling pulse is generated when 1L is 0, that is, t-Q=0, and V is set at the timing of this PS. , then V,
Since ■t=Q, the instantaneous value of is IV,lsinQ.

When determining IV,lsin by sampling in this manner, it is assumed that the waveform of V, is not distorted, and if the waveform of V, is distorted as shown in FIG. 6, the error becomes large.

For example, if the phase difference angles Q, 8, y, and 6 are all 90 degrees, as is clear from the waveform in FIG.
The value of V,lsinQ increases by the above error, and the formula (
16) The values of -V, -ZSi, -siny on the right side are also increased by the above error.

On the other hand, the value of the left side of equation (15) IV2-2 to 12l sin6 is reduced by the above error, and the left side of equation (16),
The value of i21sinG is also reduced by the above error. In other words, the value on the left side decreases and the value on the right side increases, which acts in the direction of non-operation, resulting in underreach. As explained above, '11
The relay layer based on the operating formula of the , ■ formula is weak in arc resistance and requires a symmetrical filter, and the circuit is complicated, and (15)
, (16) is strong against arc resistance, but the four symmetric filters V, , V2, 1, and 12
, 2, 3, and 4 are required, and correct reach cannot be obtained due to the influence of voltage distortion.

Although this invention is weak against arc resistance, it eliminates the need for the above-mentioned positive-sequence voltage filter and negative-sequence voltage filter when introducing voltage input, and the two-wire fault distance can avoid the effects of voltage distortion without complicating the input circuit. The purpose is to provide a relay system layer.

That is, each phase voltage V^. Introducing the line voltages of VB and Vc, lkVBcl, lkVc^l, lkV^, respectively
8l (where k is a constant) and 12 filters that derive the negative phase current 12 from each phase current i^, IB, IC, and then pass through a circuit designed to obtain 8l (k is a constant) and 12 filters that derive the negative phase current 12 from each phase current i^, IB, IC. ), the l-2212
The configuration is such that a determination output is obtained when l is larger than any one of lkVBcl, lkVc^l, and lkV^BI. Now, when there is a relationship like Shikinori, '4', '5} V
, - V2 = - ZF12 ... (21) Considering the setting impedance Zs, the internal fault, i.e., IZsl
> IZ, pl, then (V, -V2) × 2212, but for the reason mentioned above, by comparing the magnitudes of the absolute values on both sides, IV, -V2l × IZs12l
...(22) can be made.

Here, FIG. 8 is a block diagram of an embodiment of this invention, and FIG.
The figure shows a phase characteristic diagram of a general electric appliance according to the present invention whose operation formula is as shown below. Now considering the BC phase two wire short circuit failure, VBc = VB - Vc = (a2 - a) (V, - V2)...
...(23) v. -v2=a mushroom sheep...(24) Poi=
Substituting the Senpune equation (24) into the equation (22), 1 Makoto 1 < 1 - 3121... (25) Since the left side is the absolute value, if k = 1 3 1 = art, then lk
VBCI<1-22121 (26).

In addition, for C phase and AB phase two-wire short circuit failures,
A phase line voltage V.

^, From AB phase line voltage V^8, lkVC^1 < 1-2
121...--(27)'kV^8l<l-2212l...(28) may be applied.

Since the above equations (26), (27), and (28) use line voltage, the input circuit can be simplified by eliminating the need for positive-sequence voltage filters, negative-sequence voltage filters, and positive-sequence current filters. , the effect of the voltage distortion mentioned above also affects the absolute value l of the line voltage
kV8Gl, lkVc^l, lkV^BI and l-Zs
Since the AC voltage is used, it is sufficient to perform full-wave rectification of the alternating current electrical quantity, so even if there is waveform distortion, the error is small.

Thus, in FIG. 8, the right-hand sides of equations (26), (27), and (28) include the negative-sequence current filter 9 that derives the negative-sequence current 12, and the left-hand sides of the There is a circuit 8 which introduces voltages and obtains an input proportional to these.

Next, the output of the aforementioned circuit 8 is the three suppression cars kVBc! ，
lkVc^l, lkV^BI operation circuits 10a, 10b,
10c, the output of the negative phase current filter circuit 9 is applied to the operation circuit 11, respectively, and the output l-2212l and the output lkVBCl, l
kVc^l and lkV^BI are determined by respective judgment circuits 12.
A, 12b, and 12c are compared, and the output is taken out only when the output of the arithmetic circuit 11, that is, the operating force is superior, and the OR circuit 13
There are three judgment circuits 12a that can provide a reactive output through the
, 12b, 12. If even one of the outputs of c is output, the relay output can be obtained.

Therefore, compared to the conventional example shown in FIG. 5, the filter circuit requires only the negative-sequence current filter 9, and since the negative-sequence current 12 is used, it is less susceptible to the influence of power flow.
{21, (15), (16) are the same as each relay whose operation type is used. As described above, according to the distance relay system layer for two dependent relays of the present invention, the voltage drop due to arc resistance cannot be avoided, and the arc resistance is equivalent to that of the secondary relay based on formulas [1', '2}. In terms of performance, since the filter circuit is used only as a negative phase current filter and the line voltage is introduced for the rest, the circuit configuration is simple and the influence of voltage distortion can be avoided.

[Brief explanation of the drawing]

Figure 1 is a system diagram showing a normal two-terminal system, Figure 2a is an equivalent circuit diagram when a two-wire short circuit fault occurs in the system in Figure 1,
Figure 2b is a vector diagram in this case, Figure 3 is an equivalent circuit diagram when a two-wire short circuit with arc resistance occurs in the system in Figure 1, and Figure 4 is a vector diagram in this case. , Fig. 5 is a block diagram of a conventional relay circuit, Fig. 6 is an output waveform diagram of a positive-sequence voltage filter and a negative-sequence voltage filter when affected by a triangular wave in a conventional device, and Fig. 7 is an output waveform diagram of a conventional device affected by a triangular wave. FIG. 8 is a block diagram of a relay circuit according to an embodiment of the present invention, and FIG. 9 is a phase characteristic diagram according to the present invention. In the figure, 8 is a circuit that obtains an input proportional to the line voltage, 9 is a negative phase voltage filter, and 10a, 10b, and 10c are suppressing forces l, respectively.
An arithmetic circuit that calculates kV8cl, lkVc^l, and lkV^BI; 11 is an arithmetic circuit that computes operating force l-2 and 12l; 12a, 12b, and 12c are determination circuits; and 13 is an OR circuit. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 8 Figure 9 Figure 6 Figure 7

Claims (1)

[Claims] 1. Introducing the line voltages of each phase voltage ■_A, ■_B, ■_C of the protected system, respectively |k■_B_C|, |k■
A circuit that derives ＿C_A|, |k■_A_B| (where k is a constant), a negative-sequence current filter that introduces each phase current ■_A, ■_B, and ■_C and derives the negative-sequence current I_2 of the protected system. , an arithmetic circuit that obtains |-2■_S■_2| from the output of this negative-phase current filter and the setting impedance ■_S, and |-2■_S■_2| is |k■_B_C|,
A two-wire failure distance relay device comprising a determination circuit that outputs a determination output when it is larger than either |k■_C_A| or |k■_A_B|.