JPH0713652B2 - Fault location method for parallel two-line transmission line - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

In the present invention, the neutral point of at least one end of the transmission line is directly
Alternatively, the present invention relates to a fault point locating method capable of locating a fault point of a one-line ground fault of a parallel two-line transmission line even when grounded via a resistor 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. As shown in FIG. 4, when a simplified zero-phase equivalent circuit of parallel two lines 1L and 2L is considered, zero-phase currents _1L Io and _2L Io flowing in lines 1L and 2L fail. Since it is distributed by the zero-phase impedance viewed from the point F, the distance α from one end where the failure point locating device FL is installed to the failure point F can be obtained by the following equation. 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. An object of the present invention is to provide a fault point locating method capable of locating a fault point in a parallel two-line transmission line even if one end is not a non-power source / non-ground.

[Means for solving problems]

Terminal devices are installed at both ends, zero-phase current and zero-phase voltage flowing in both lines are measured, and each zero-phase current and zero-phase voltage are collected in one place for synchronization.

[Action]

For each synchronized zero-phase current, double the effective component of the zero-phase current value flowing through the line without failure measured at its own end and the effective zero-phase current value flowing through both lines measured at the other end. The distance from the self-end to the failure point is calculated based on the value obtained by dividing the sum of the minutes and the sum of the effective fractions of the zero-phase current values flowing in both lines measured at both ends.

Examples of the invention

FIG. 3 shows a configuration diagram of a parallel two-line transmission line to which the present invention is applied. In the figure, A1 and B1 indicate terminals installed at the A end and B end, respectively, and each terminal A1 and B1 has zero phase current _1L I flowing in parallel 2 lines 1L and 2L at the A end and B end, respectively.
^{_{o A, 2L Io A, 1L}} Io B, is configured to measure a _2L Io ^B and zero-phase voltage. The zero-phase currents and zero-phase voltages measured at the terminals A1 and B1 are sent to the processing device C, and the zero-phase currents and zero-phase voltages are synchronized in the processing device C, and then the calculation of the fault location is performed. Done. The method described in Japanese Patent Application No. 61-93069 can be used to synchronize the zero-phase current and the zero-phase voltage. Next, the calculation of the fault location in the processing device C will be described. FIG. 2 shows a configuration diagram of the both-ends grounding system and shows a state where 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 the circuit of FIG. 2 as 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. 2 is as shown in FIG. 1 (a), (b). Can be divided into
FIG. 1 (a) shows the case where the end B is not grounded, and FIG. 1 (b) shows the case where the end A is not grounded.
Since the circuit of (b) has the same configuration as that of FIG. 4, assuming that the zero-phase currents flowing in the parallel two lines 1L, 2L are i _1S , i _2S , i _1R , i _2R , the position of the fault point F is (2 It can be calculated as follows in the same manner as the equation). In the case of circuit (a) For the circuit of (b) By the way, the following relationship is established between the circuit of FIG. 1 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 this 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, the following equation is obtained by substituting the equation (9) into the equation (5). 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) Here, assuming that each zero-phase current at the B end is _1L Io ^B , _2L Io ^B , I _N ^B
= _1L Io ^B + _2L IO ^B holds, so by substituting this I _N ^B into Eq. (15), the following equation is obtained. This equation (16) is expressed only by the zero-phase currents _1L Io ^A , _2L Io ^A , _1L Io ^B , _2L Io ^B flowing in each line 1L, 2L at the A end and B end, so that A end, B By measuring these zero-phase currents at the ends and synchronizing them and substituting them into Eq. (16), the fault point position can be obtained. Equation (16) 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 calculated by the following equation. Also, in order to correct the effect of the ground capacitance,
Similar to equation (3), the effective component (COS
Minutes). In this case, since the zero-phase voltage at the A terminal, the zero-phase voltage at the B terminal, and the zero-phase voltage at the fault point are considered to be approximately in phase, whichever zero-phase voltage at the A terminal or the B terminal is used as a reference. You can Therefore, the formula for calculating the fault location, which corrects the influence of the capacitance to ground, can be obtained from Eq. (16) as follows. In the equation (18), _1L θ ^A , _2L θ ^A , _1L θ ^B , and _2L θ ^B represent the phase difference between each zero-phase voltage and each zero-phase current at the A and B ends, respectively. Of course, in the case of a failure on the line 2L side, the effect of the ground capacitance can be similarly corrected.

【The invention's effect】

According to the present invention, since the zero-phase current and zero-phase voltage measured at both ends of the parallel two-line transmission line system are used for the orientation, the high-precision 1
Line faults can be located.

[Brief description of drawings]

1 and 2 are system circuit diagrams for explaining a fault location method according to the present invention, FIG. 3 is a configuration diagram of a parallel two-line transmission line to which the present invention is applied, and FIG. 4 is a conventional fault. The system circuit diagram for demonstrating a point orientation method is shown. A1, B1 ... Terminal, C ... Processor, F ... Failure point, 1L, 2L
…… Line, NGR, NGR ^A , NGR ^B …… Neutral ground resistance, _1L Io ^A ,
_1L Io ^B , _2L Io ^A , _2L Io ^B …… Zero-phase current, I _N ^A , I _N ^B …… Neutral point current, 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 power transmission line, wherein a zero-phase current and a zero-phase voltage flowing in both lines at both ends are detected and located in one place. After collecting and synchronizing each zero-phase current and zero-phase voltage, double the effective value of the zero-phase current flowing through the line without failure measured at its own end and flowing through both lines measured at the other end. The sum of each zero-phase current value and the effective component,
A fault point locating method for a parallel two-line transmission line, characterized in that the distance from the self end to the fault point is obtained based on a value divided by the sum of the effective components of the zero-phase currents flowing in both lines measured at both ends. .