JPH065255B2 - Fault location method for power transmission system - Google Patents

Description

Detailed Description of the Invention A. TECHNICAL FIELD The present invention relates to a fault location system for a power transmission system.

B. SUMMARY OF THE INVENTION According to the present invention, when locating a fault point of a power transmission system according to a locating principle formula, non-stretching is performed by locating a faulty phase from a line constant and current, voltage, and zero-phase current detection value for each phase and each phase. This is intended to reduce the localization error due to the difference in the failure phases of the power transmission system that becomes the system.

C. BACKGROUND ART The applicant of the present application has already proposed a method for locating a fault point in a power transmission system, which is a method of locating a fault point by calculation using a voltage, a current, and a known line constant measured at an electric station at one end of a transmission line. (For example, Japanese Patent Application No. Sho 59-143056,
Japanese Patent Application No. 59-143057).

An apparatus configuration based on the above method is as shown in FIG. Each phase voltage Va, Vb, Vc at each end and each phase current I
a, Ib, Ic are detected by the transformer PT and the current transformer CT,
These detection signals are taken into the first circuit D ₁ of the orientation device D as sampling data of a constant cycle, and the zero-phase voltage Vo is also obtained by the _second circuit D ₂ using these data, and the third circuit D ₃
Self-impedance Za per unit length from mutual impedance Zm, obtain the data of the self-address Mick drawers Ys, circuit D _2, a phase from the fourth circuit D _4, for example, following orientation principle expression from the data D ₃ Find the fault point distance x at the time of ground fault (ignore the admittance Ys of the line).

Real [A] / Imag [B] -Imag [A] / Real [B] = 0 However, A = V _a -{(Zs-Zm) ・ Ia + Zm / 3Io} x B = 3Io D. Problems to be Solved by the Invention In the conventional fault point locating method, there is no problem in the power transmission system or the balanced line (suspended system), but in the general unbalanced line (non-suspended system). Self-impedance Zaa, Zbb, Zcc and mutual impedance Zab, Zbc, Zca of each phase.
There is a problem that there is a location error in the orientation from Zaa ＝ Zbb ＝ Zcc ＝ Zs Zab ＝ Zbc ＝ Zca ＝ Zm, which is different from that of the conventional method. It was This error occurrence takes time to find the failure point when observing the failure point.

E. Means and Actions for Solving Problems The present invention has been made in view of the above problems, and the phase currents Ia, Ib, Ic and the phase voltages Va, V at the self ends a, b, c of the transmission line are provided.
b, Vc, zero-phase current Io, self-impedance Zaa, Zbb, Zcc for each phase per unit length of the transmission line, and mutual impedances Zab, Zbc, Zca from the following expressions Real [A] / Imag [B]- Imag [A] ・ Real [B] = 0 However, when the transmission line has a three-phase short circuit, a three-phase ground fault, a two-phase short circuit, and a two-phase ground fault, A = (V _B -V _C )-{ (Zba-Zca) Ia + (Zbb-Zcb) Ib + (Zbc-Zcc) Ic} x B = Ib-Ic When the transmission line has one-phase ground fault, for phase a, A = V _a- {Zaa ・ Ia + Zab ・The distance x from the self-end to the fault point is calculated according to Ib + Zac · Ic} x B = 3Io.

By using this orientation method, the orientation constants that minimize the occurrence of orientation errors due to the difference in the line constants and fault states for each phase due to the non-suspended system are obtained.

F. Embodiment An embodiment of the present invention will be described in detail with reference to FIGS.

In FIG. 1, the third circuit D ₃ is a line constant Raa, Xaa, Rbb, Xbb, Rcc, Xc for each phase per unit length of the transmission line.
Generates data of c, Rab, Xab, Rbc, Rbc, Rca, and Xca. Here, Raa, Rbb, Rcc: resistance of each phase Xaa, Xbb, Xcc: reactance of each phase Rab, Rbc, Rca: resistance of interphase Xab, Xbc, Xca: reactance of interphase.

The circuit D 4 in FIG. ₄ is the phase currents Ia, I from the _second circuit D _2.
b, Ic, phase voltages Va, Vb, Vc, zero-phase current 3Io, and self-impedance Zaa, Zbb, Zcc and mutual impedance Zab, Zbc, Z of each phase obtained from the line constant from the third circuit D _3.
Calculation of the following formula by ca Real [A] ・ Imag [B] -Imag [A] ・ Real [B] = 0 ......... (1) where A = (V _B -V _C )-{(Zba-Zca ) Ia + (Zbb-Zcb) Ib + (Zbc-Zcc) Ic} x ………… (2) B = Ib−Ic ………… (3) Two-phase short circuit (above formula is bc phase short circuit), two-phase simultaneous Distance to fault point for ground fault, 3-phase short circuit, 3-phase ground fault x
Ask for.

In addition, the fourth circuit D ₄ uses the following equation for A and B of the above equation (1) for the one-phase ground fault A = V _a- {Zaa · Ia + Zab · Ib + Zac · Ic}. x ……… (4) B ＝ 3Io ……… (5) Find the distance x to the failure point (the above equation is for a-phase ground fault).

With such orientation, the line constant is changed according to the fault phase, the influence of other phases is included to reduce the fluctuation of the orientation error due to the difference of the fault phase, and the orientation value x is an unbalanced line (non-suspended system). ) Is also obtained as a value with a small orientation error.

In the embodiment, the zero-phase current 3Io can be detected from the residual circuit or the tertiary circuit of the transformer PT and the calculation by the second circuit D ₂ can be omitted.

The reason why the orientation error is reduced by the above equations (1) to (5) will be described in detail below.

As shown in Fig. 2, with respect to the single-phase three-phase unbalanced line connected to the three-phase balanced power supply through the back impedance, with the other end being the non-power supply end, the ground capacitance and load of the line were ignored. At each end, each phase voltage Va, Vb, Vc, current Ia, I
b, Ic and distance x to the accident point, phase voltage Vfa, Vf of each accident point
The basic circuit equation holds between b and Vfc.

However Here, the accident point impedance Zf in FIG. 2 is a pure resistance that does not change with time, and has the form shown in FIG. 3 depending on the accident type. Based on the relational expressions and assumptions that are established for each accident type, the respective arithmetic logical expressions are as follows.

(3.1) In case of three-phase ground fault (1) Relational expression established at the accident point (2) Assumption It is assumed that the two-phase accident point resistances are equal. For example, Rfb ＝ Rfc ＝ Rf ……… (14) (3) Theoretical formulas (11) to (14) show that Vb-Vc ＝ {(Zba-Zca) ・ Ia + (Zbb-Zcb) ・ Ib + ( Zbc-Zcc) ・ Ic} x + Rf ・ (Ib-Ic)… (15) (3.2) In case of three-phase short circuit (1) Relational expression established at the accident point (2) Assumption It is assumed that the two-phase accident point resistances are equal. For example, Rfb = Rfc = Rf ……… (17) (3) Theoretical formulas (12), (13), (16), and (17) show that Vb-Vc ＝ {(Zba-Zca) ・ Ia + ( Zbb-Zcb) ・ Ib + (Zbc-Zcc) ・ Ic} x + Rf ・ (Ib-Ic) …… (18) (3.3) In case of two-phase short circuit (bc phase) (1) Relationship established at the accident point formula (2) Assumption It is assumed that the two-phase accident point resistances are equal. For example, Rfb = Rfc = Rf ……… (20) (3) Theoretical formulas (11), (12), (19), and (20) show that Vb-Vc ＝ {(Zba-Zca) ・ Ia + ( Zbb-Zcb) ・ Ib + (Zbc-Zcc) ・ Ic} x + Rf (Ib-Ic) ...... (21) In the formula (11), the terms (Zba-Zca) ・ Ia are unnecessary,
Leave it for the load current to be introduced later.

(3.4) In case of 2-phase short circuit (bc phase) (1) Relational expression established at the accident point (2) No assumptions.

(3) Theoretical formulas (11), (12), and (20) show that Vb-Vc = {(Zba-Zcc) ・ Ia + (Zbb-Zcb) ・ Ib + (Zbc-Zcc) ・ Ic} x + Rf・ (Ib-Ic) …… (23) However, consider that Rf ＝ Rfb ＝ Rfc.

In the equation (23), the term of (Zba-Zca) · Ia is unnecessary, but it is retained because a load current will be introduced later.

(3.5) In the case of 1-phase short circuit (a phase) (1) Relational expression that holds at the accident point Rfa = Rf 3Io ……… (24) Here, 3Io = Ia, but since the load current is introduced later, Expressed in 3 Io.

(2) No assumptions.

(3) Computational theory From equations (11) and (12), Va = {Zaa ・ Ia + Zab ・ Ib + Zac ・ Ic} x + Rf ・ 3Io …… (25) In equation (25), Zab ・ Ib The + Zac / Ic term is unnecessary, but it is retained because it introduces the load current later.

From the above, the theoretical calculation formulas for each accident type can be summarized as follows.

(A) For 3-phase ground fault, 3-phase short circuit, 2-phase ground fault, and 2-phase short circuit, when using b and c phase data, Vb-Vc = {(Zba-Zca) ・ Ia + (Zbb-Zcb)・ Ib + (Zbc-Zcc) ・ Ic} x + Rf ・ (Ib-Ic) …… (26) (B) About 1-phase ground fault, Va = {Zaa ・ Ia + Zab ・Ib + Zac ・ Ic} x + Rf ・ 3Io (27) From the above equations (26) and (27), the orientation principle equation ignores the fault point resistance Rf, and the above equations (1) to (3) or (1) ), (4), and (5), and the error can be reduced by the orientation from these expressions even in the non-suspended system.

The table below shows the conventional method for the simulated line (22KV) and the above (1)
~ The experimental result of the orientation error by (3) is shown, and it was confirmed that the orientation error becomes small.

G. EFFECTS OF THE INVENTION As described above, according to the present invention, the line constant for each phase and each phase is used to obtain the orientation value from the orientation principle formula according to each phase voltage, current, zero-phase current and line constant of the power transmission system. Since it is decided to locate each fault phase, it is possible to reduce the orientation error due to the difference of the fault phases and to apply it to the non-suspended system for accurate orientation. Further, along with this, there is an effect such as facilitating the fault point search work by orientation.

[Brief description of drawings]

FIG. 1 is a block diagram of the orientation device, and FIGS. 2 and 3 are basic circuit diagrams of a power transmission system for explaining the principle of the method of the present invention (second
FIG. 3 is an equivalent circuit diagram (FIG. 3) of the fault point impedance Zf for each fault type. D ... Orientation device, PT ... Instrument transformer, CT ... Current transformer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshihisa Funabashi 2-1-1-17 Osaki, Shinagawa-ku, Tokyo Stock company inside the company Meidensha (72) Inventor Tetsuya Mizutori 2-1-1-17 Osaki, Shinagawa-ku, Tokyo Stock association In Shameidensha (56) Reference JP-A-60-164264 (JP, A) JP-A-61-222644 (JP, A)

Claims (1)

[Claims] 1. A phase current Ia of each end a, b, c of a transmission line,
Ib, Ic and phase voltages Va, Vb, Vc and zero-phase current Io
And the distance x from the self-end to the fault point according to the self-impedance per unit length and the mutual impedance of the transmission line
In order to obtain, the self-impedance of each phase of the transmission line Zaa, Zbb,
Zcc and mutual impedance between each phase Zab, Zb
c, Zca from the following formula Real [A] ・ Imag [B] -Imag [A] ・ Real [B] = 0 However, the transmission line has a three-phase short circuit, a three-phase ground fault, a two-phase short circuit and a two-phase ground fault. Then, for bc phase, A = (V _B -V _C )-{(Zba-Zca) Ia + (Zbb-Zcb) Ib + (Zbc-Zcc) Ic} x B = Ib-Ic Then, the fault location of the transmission system is characterized in that the distance x from the self-end to the fault point is obtained according to A = V _a- {Zaa ・ Ia + Zab ・ Ib + Zac ・ Ic} x B = 3Io for the a phase. method.