JPH0713651B2 - Fault location method for parallel two-line transmission line - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to a fault point locating method for locating a fault point of a one-line ground fault of a parallel two-line transmission line in which neutral points at both ends of the transmission line are grounded directly or via a resistance or a reactor.

[Prior art]

As a fault location method (hereinafter referred to as Io method) using a zero-phase current Io in a parallel two-circuit power transmission line
The thing described in the 59-211869 gazette is known. This Io method will be briefly described. Considering a simplified zero-phase equivalent circuit of parallel two lines 1L and 2L as shown in FIG.
Since the zero-phase currents _1L Io and _2L Io flowing in the lines 1L and 2L are distributed by the zero-phase impedance seen from the fault point F, the distance α from one end where the fault point locator FL is installed to the fault point F is Can be found at. α ・_1L Io ＝ (2-α) ・_2L Io …… (1) In addition, in FIG. 4, NGR represents a neutral point ground resistance. Since the equation (2) neglects the influence of the ground capacitance of the transmission line, that is, the capacitance to ground, the influence of the capacitance to ground cannot be ignored and an error occurs when the total length of the transmission line becomes long. Therefore, in order to correct the error due to the ground capacitance with respect to the equation (2), paying attention to the fact that the zero-phase current flowing through the ground capacitance is advanced by 90 ° with respect to the zero-phase voltage. By taking the effective component (COS component) of each zero-phase current value in equation (2), the effect of the ground capacitance can be corrected. The arithmetic expression in this case is represented as the following expression. In equation (3), _1L θ and _2L θ are the phase difference between each zero-phase voltage and each zero-phase current. This equation (3) is the principle equation of the Io method.

[Problems to be Solved by the Invention]

However, although the expression (3) can be located only by the data of its own end, there is a restriction that the other end is non-power supply / non-grounding as is clear from the equivalent circuit of FIG. It is an object of the present invention to provide a fault point locating method capable of locating a fault point even if one end of a parallel two-line power transmission line is not a non-power source / non-ground.

[Means for solving problems]

Orientation is performed using the effective component of the zero-phase current of both lines that can be measured at the self-end, the neutral point ground resistance value and the zero-phase impedance value that are known fixed values of the system.

[Action]

By using the neutral point ground resistance value and the zero-phase impedance, which are fixed values of the system known in advance, it is possible to perform the orientation only with the data that can be measured at the own end regardless of the grounding condition of the other end.

Examples of the invention

In the present invention, when performing the orientation calculation, instead of directly obtaining the electrical quantity of the other end to perform the orientation, the neutral point ground resistance value and the system constant that are fixed values of the system are used to obtain the electrical quantity of the other end. By indicating, the orientation is performed only by the electric quantity of the own end, and the orientation method will be described below. FIG. 3 shows a configuration diagram of the both-ends grounding system and shows a state in which a one-line ground fault accident occurs at a failure point F in the middle of the line 1L. Zero-phase current _1L I for parallel 2 lines 1L, 2L respectively
^{_{o A, 2L Io A, 1L}} Io B, 2L Io B flows, and A end, each neutral grounding resistor NGR ^A to B end, the neutral point current through the NGR ^B I _N ^A, I _N ^B
Flows. In the figure, R _F shows the resistance at the fault point. Here, considering that the circuit of FIG. 3 is a superposition of two circuits of which one end is not grounded centering on the A end and the B end, the circuit of FIG. 3 is as shown in FIG. 2 (a), (b). Can be divided. FIG. 2 (a) shows the case where the end B is not grounded, and FIG. 2 (b) shows the case where the end A is not grounded. Since the circuits of FIGS. 2 (a) and 2 (b) have the same configuration as that of FIG. 3, if the zero-phase currents flowing in the parallel two lines 1L and 2L are i _1S , i _2S , i _1R and i _2R respectively, a failure occurs. The position of the point F can be obtained as follows in the same manner as the equation (2). In the case of circuit (a) For the circuit of (b) By the way, the following relationship is established between the circuit of FIG. 3 and the circuit of FIG. ^{_{1L Io A = i 1S + i}} 2R ...... (6) 2L Io A = i 2S -i 2R ...... (7) I N A = i 1S + i 2S ...... (8) I N B = i 1R + i _2R …… (9) The following formula is obtained from the formulas (6) and (7). _1L Io ^A + _2L Io ^A = i _1S + i _2S (10) By substituting equation (10) into equation (4), the following equation is obtained. From equation (7), i _2S = _2L Io ^A + i _2R , so i _2S is given by (11)
By substituting into the formula, the following formula is obtained. Further, by substituting the equation (9) into the equation (5), the following equation is obtained. By eliminating i _2R from Eqs. (12) and (13), the following equation is obtained. α ・ ( _1L Io ^A + _2L Io ^A ) ＝ _2.2L Io ^A + (1-α) ・_IN ^B ……
(14) In this equation (15), in order to obtain the neutral point current I _N ^B which is the inflow current at the other end (B end), as shown in FIG. 1, the resistance values of the neutral point ground resistances NGR ^A and NGR ^B , R _N ^A , R _N ^B , zero-phase self-impedance Zo, zero-phase mutual impedance Z
Assuming that m is the same, the potentials at the fault points F seen from both ends are equal, and the following equation is established. R _N ^A・ I _N ^A + α (Zo ・_1L Io ^A + Zm ・_2L Io ^A ) = R _N ^B・ I _N ^B ＋ (1-α) {Zo ( _2L Io ^A + I _N ^B ) + Zm ( _-2L I
o ^A )} (16) The following equation holds when this equation (16) is summarized for I _N ^B. {R _N ^A + (1-α) Zo} I _N ^B = (R _N ^A + αZo) I _N ^A- (Zo-Zm) _2L I0 ^A ...... (17) Here, from the above formula (15) , Is obtained, the following equation is obtained by substituting equation (18) into equation (17). The following equation is obtained by solving this equation (19) for α. α {(R _N ^A + R _N ^B ) I _N ^A + (Zo + Zm) _2L Io ^A } = R _N ^A・ I _N ^A +2 ・ R _N ^B・_2L Io ^A + (Zo + Zm) _2L Io ^A = R _N ^A・ I _N ^A + {R _N ^B ( _1L Io ^A + _2L Io ^A ) -R _N ^B・_1L Io ^A + R _N ^B・_2L Io ^A } + (Zo + Zm) _2L Io ^A ＝ (R _N ^A + R _N ^B ) I _N ^A -R _N ( _1L Io ^A - _2L Io ^A ) + (Zo + Zm) _2L Io ^A ...... (20) Here, from I _N ^A = _1L Io ^A + _2L Io ^A , I _N ^A- ( _1L Io ^A _-2L Io ^A ) = _2.2L Io ^A. However, N _R = R _N ^A / R _N ^B , N _Z = (Zo + Zm) / R _N ^B. Equation (21) is the resistance value of the neutral point ground resistance N _R = R _N ^A / R _N ^B and the system constant N
_Z = (Zo + Zm) / R _N ^B, and zero-phase current and neutral point current that can be measured at the A terminal (This neutral point current flows through both lines without direct measurement. It can be obtained from the sum of)), so that the fault point position can be located only by measuring the zero-phase current flowing in both lines at the self-end. Equation (21) is for the case where a failure occurs on the line 1L side, but when a failure occurs on the line 2L side, the failure point position can be similarly determined by the following equation. Also, in order to correct the effect of the ground capacitance,
Similar to equation (3), the effective component (COS
Minutes). Therefore, the fault location calculation formula that corrects the influence of the ground capacitance is (21), (2
From equation (2), it can be calculated as follows. In equations (23) and (24), θ _N ^A , _1L θ ^A , _2L θ ^A ,
Represents the phase difference between the neutral point current and the neutral point voltage, and each zero-phase current and each zero-phase voltage.

【The invention's effect】

According to the present invention, since the neutral point earthing resistance value and the system constant, which are fixed values of the system, are used to represent the electricity amount of the other end, the electricity amount of only the own end does not depend on the earthing condition of the system. It is possible to perform highly accurate one-line ground fault localization. Further, according to the present invention, in order to obtain an effective component of the neutral point current and the zero phase current from the phase difference between the neutral point current and the neutral point voltage and the phase difference between the zero phase current and the zero phase voltage, The point voltage and zero-phase voltage are used as the phase reference. Therefore, even when the phase voltage input is very small as in the case of a one-line ground fault, the fault point can be located with high accuracy without being affected by the error of the input circuit.

[Brief description of drawings]

1, 2 and 3 are system circuit diagrams for explaining a fault point locating method according to the present invention, and FIG. 4 is a system circuit diagram for explaining a conventional fault point locating method. . F …… Failure point, 1L, 2L …… Line, _1L Io ^A , _1L Io ^B , _2L Io ^A , _2L I
o ^B: Zero-phase current, I _N ^A , I _N ^B: Neutral point current, NGR: Neutral point ground resistance, R _F: Fault point resistance.

Claims (1)

[Claims] 1. A fault point locating method for locating a fault point of a one-line ground fault of a parallel two-line transmission line in which a neutral point of both ends is grounded, and a zero-phase current flowing in a line in which a fault occurs at its own terminal A. _1L I _O
^A and fault zero-phase current _2L I _O ^A flowing through the line no measured respectively, the neutral point current of the own end ^{_{I N A = 1L I O A}} + 2L I O A and the zero-phase current and a neutral Effective point current _1L I _O ^A COS _1L θ ^A , _{2L
^{I O A COS 2L θ A,}} I N A COS 1L θ N A and, the neutral point grounding resistance value in its own end and the other end R _N ^A, and R _N ^B, zero-phase self-impedance Z
_{Using O} and the mutual impedance between zero-phase lines Z _m , the distance α from the self-end to the failure point is A fault location method for parallel two-circuit transmission lines, characterized by