JPH0235379A - Locating method of ground fault point - Google Patents

Abstract

PURPOSE:To locate a fault point in a non-synchronous manner by utilizing that the amounts of zero-phase voltages at the fault point are equal when viewed from the opposite ends of a section of a transmission line which is an object of location, and by regarding as the fault point a point whereat the amounts are equal and whereat the sum of distances from the opposite ends becomes the full length of a line in the section being the object of location. CONSTITUTION:The opposite ends of a section which is an object of location are taken as reference points of points of computation, and the respective amounts VOA and VOB of zero- phase voltages at the two points A and B of computation are compared with each other. The point of computation whereat the value of said amount is smaller is shifted by a unit length in the direction of the opposite end. The amount of zero-phase voltage at the new point of computation is set to be the sum of the amount of zero-phase voltage at the old point of computation and the product of zero-phase impedance and zero-phase current for the unit length. In addition, a charging current is calculated from the amount of zero-phase voltage and zero-phase earthing capacity at the new point, and the amount of zero-phase current is thereby corrected. This process is repeated until the sum of distances from the opposite ends of a transmission line being the object of location to the two points of computation becomes the full line length of the transmission line, and when the sum of the distances becomes the full line length of the transmission line, the relevant point of computation is regarded as a fault point.

Description

[Detailed Description of the Invention] [Industrial Application Field] In order to ensure the reliability of power supply, the present invention provides ground fault fault points that occur in the power transmission 11, measured at both terminals of the power transmission line. The present invention relates to a method for locating a fault point using zero-sequence current and zero-sequence voltage to speed up fault recovery.

[Conventional technology]

There are several methods for locating ground faults by capturing the voltage and current amounts at both ends of a power transmission line, but among them, one method that requires fewer input points is the "fault point locating method" (Japanese Unexamined Patent Application Publication No. 1983-1992). 168976). This method is a method of locating using zero-sequence voltage and zero-sequence current at both ends of the power transmission line. Consider the power transmission system shown in Figure 3. If a fault occurs within the target section of the transmission line, the zero-sequence current and zero-sequence voltage that appear at both ends of the transmission line will be captured using devices IA and IB, and this will be A/D converted. Transmit to the actual device or to the other import device. The solid device or acquisition device uses the collected zero-sequence voltage and zero-sequence current 11t- at both ends of the power transmission line to locate the fault point using the following equations (1) and (2).

...... (1) x -... (2) ZO ('OA+'OB) (Zo = zero-sequence impedance per unit length) This method calculates the zero-sequence voltage (vector ) This is a method in which the solution is a point where voF is the same whether viewed from the A end or the B end.

[This is what the invention is trying to solve! Title]

However, since Equations (1) and (21) are vector calculations, simultaneity is required to capture the zero-sequence voltage and zero-sequence current at both ends of the transmission line.Therefore, a method that does not require simultaneity of capture As such, there is a method using the following equation (3).This method becomes a vector-scalar comparison equation by taking the absolute values of both sides of the equation, and there is no need to look at the phase component that requires synchronization of acquisition. There is an advantage to this.

(3) In equation (3), V and I are the phase voltage amount and phase current amount of the phase where the ground fault occurred, and VF is the phase voltage amount at the fault point. However, this method requires the acquisition of the phase voltage amount and phase current amount for each phase, and has the disadvantage of being large-scale. Furthermore, since such amounts of voltage and current are used, when there is a slight ground fault or the current is large compared to the fault current, there is a problem that the detection of the fault current is insufficient and the accuracy of the location result deteriorates.

Therefore, the present invention captures only the zero-sequence voltage amount and zero-sequence current amount at both ends of the power transmission S, is not affected by power flow, fault point resistance, and charging current, and furthermore, by focusing only on the scalar amount of vector calculation, data The purpose of this invention is to provide a method for locating ground fault points that does not require synchronization of capture.

[Means to solve the problem]

Incorporate the zero-sequence voltage and zero-sequence current at both ends of the transmission line that is the target of location, and from these and the known quantities zero-sequence impedance, zero relative ground capacity il, and the transmission line's track length, calculate the following (a): Calculate the location of the ground fault point by following the steps from ~(d).

(b) Both ends of the orientation target section are used as the base points of the calculation point.

(b) Compare each zero-sequence voltage amount at the two calculation points.

(c) Move the calculation point with the smaller value toward the other end by the unit amount. The zero-sequence voltage amount at the new calculation point is the sum of the zero-sequence voltage amount at the old calculation point, the product of the zero-sequence impedance per unit length, and the zero-sequence current. In addition, the charging current is calculated from the zero-sequence voltage and zero-relative ground capacity at the new point,
Correct the zero-sequence current amount.

(d) Until the sum of the distances from both ends of the transmission line that is the target of orientation to the two calculation points becomes the track length of the transmission line (
0) and (c) are repeated, and when the sum of the distances reaches the length of the transmission line, the calculated point is determined as the failure point.

[Effect]

By using the fact that the zero-sequence voltage at the fault point seen from both ends of the transmission line is equal, the zero-sequence impedance, zero-to-ground capacity, and section of the transmission line can be determined based on the zero-sequence voltage at both ends of the section. The zero-sequence voltage at each point within the section is calculated from the zero-sequence current at both ends, and the point where the magnitude is equal and the sum of the distances from both ends is the track length of the section to be located is regarded as the fault point. It is possible to accurately locate the failure point using the formula.

[Implementation row]

FIG. 1 is a flowchart showing an embodiment of the present invention, and FIG. 2 is an explanatory diagram for explaining an overview of a fault location system to which the present invention is applied and a location calculation method according to the present invention.

In order to carry out the present invention, as shown in FIG. 2(a), a terminal device IA is used which takes in two quantities, zero-sequence voltage and zero-sequence current, at both ends of the target section of one power transmission line.

Requires IB or other device to detect this 2ft. The captured data 211 at both ends are transmitted to the solid device 2 or terminal devices IA and IB shown in FIG. 2(A), and are subjected to orientation calculations within the device. Strict synchronization at both ends is not necessarily required as long as the timing of 2:1 capture at both ends is within the time when the ground fault continues. The calculations within the device are as described above, but this can be expressed in the following equation.

VOA-xZO'0Al=l■OB (L-X)Zo
'on=1vOF (4) Each symbol in formula (4) shall be as shown in FIG. this(
Equation 4) is a basic equation, and if we add to it the zero-sequence current flowing into the zero-relative earth volume 11co shown in Figure 2 (a), we get nX (unit length) from the A end and mX (unit length) from the PB end. ) at zero-sequence voltage v. A(n), voB(m) are 'oA(n)-?
. A(n-1) Z. (n-1)roA(n-1)...
... (5) roA(n)=i. A(n 1) J ωCo(n)
VOA('')... (6) ?oB(m)-?.n(m-x)-i, (L-m+l
)ioB(m-1)... (7) It is expressed as follows. In addition, ...... (9). Also, L - (Length of the track in the specified section) ÷ (Unit length)
, and j represents an imaginary number symbol. Furthermore, ZO(
”) r Co(n) is nX (unit length) from A11l
Indicates the zero-sequence impedance and zero-to-earth capacitance at the point, and assumes the values given in advance. Then, the point where the ground fault occurs is a point that satisfies VoA(n) l-I VoB(m) . . . Ql and m + n = L . . . aυ. For this purpose, for example, processing as shown in FIG. 1 is performed.

That is, in step ■, the variables m and ni are each set to 0'', and the initial value V.A(0)1'0A(0) shown in equation (9) is set.
l vOB(0) and I. B(0)t-find (■
reference). Then VoA(n) and V. Compare with B(m) (see ■), the smaller value in parentheses (VoA(n
)>VoB(m), then m, VoA(n)<v. B(
If m), increase n) (see ■, ■), and for the increased value, use formulas (5), (6) or (71, (8))
Calculate the expression (see ■, ■) and return to step ■. In addition, during this time, it is necessary to make a complete judgment as to whether or not equation (11) holds.■
(Refer to (2)), if it holds, it is determined that the points from A point to nX (unit length) 9B point to QmX (unit length) are the failure points (refer to [Phase]). The above method is conceptually shown in Figure 2 (b).
The result will be as shown below.

Above, we explained the case where there is only one power transmission line, but this
The case of two parallel lines will be explained below.

In other words, for a single power transmission line as shown in Figure 2 (a), it can be located using equations (5) to αυ, but
Regarding a power transmission line with two parallel circuits, a similar calculation can be performed by taking in the zero-sequence voltage amount at both ends and the zero-sequence current amount at both ends of each of the first and second circuits.

In other words, equation (5) is: Ma. A1(n)-standing. A1(n-1)z. 1. c.
n 1) IoAl(n 1)”rn(” 1) ■O
A 2 (n-1)... It is transformed into 2. Note that the subscript 1.2 attached to VoA, Zo, and ■oAVC means the amount of 1 and 2 lines, respectively. Moreover, - is mutual impedance between lines. Similarly to equation (5), equation (7) also has "C'oBum"
−＜'. B1 (rn 1) Z. 1 (L-m+l
)IOB1(m-1)-Zm(m1)IOB2
(''1), and equation (6) is '0A1('')='0A1(''-1) tωcal(
n) and 0AI('')-JaICm('')Δstanding. It is transformed as A(n) a<. Here, ΔVo A(n) is nX (difference in zero-sequence voltage between lines at a point of unit length,
That is, for equation (14), (l is equal.Similarly, for equation (8), it becomes as follows.

-j arcm(L-m)ΔVOB(m)・・・・・・
・α6) Note that ΔVoA, Δ■oB and Crrl are each Vo
A.

If it is smaller than the voB and Co terms, (l(a), a
Such a ring ft of Cm in the e-formula can be ignored. Furthermore, the above describes the processing for the first line side when there are two parallel lines, and therefore equations α2 to α0 are performed for the second line side in parallel with the first line side. Further, for the 1st line side, the calculations of the equations (1■, (1υ) are also performed.

〔Effect of the invention〕

According to the present invention, location calculations can be performed without requiring synchronization of voltage and current intake at both ends of the location section, so a synchronization signal transmitting/receiving circuit is not required. Another advantage is that calculations are not affected by fault point resistance, power flow, and charging current.

In addition, due to the calculation format, impedance and ground capacitance fluctuations at each point of the transmission line can also be set for each unit length.

[Brief explanation of the drawing]

Fig. 1 is a flowchart showing an embodiment of the present invention, Fig. 2 is an explanatory diagram for explaining an overview of a fault point locating system to which the present invention is applied and a locating method according to the present invention, and Fig. 3 is an explanatory diagram for explaining a conventional fault location calculation method. It is an explanatory diagram for explaining an example of a failure point locating system and an example of zero-sequence voltage distribution. Code explanation IA, IB...Intake device ff (terminal device), 2.
...Solid device, voA, voB...Zero-sequence voltage, VOA (n). Vo n (rn)...Zero-sequence voltage per unit length, 'OA IIoB-...Zero-sequence current, 1:0
A(n) l 'OB (ffl) - Zero-sequence current per unit length, Zo...Zero-sequence impedance, C
o...Zero relative earth capacity.

Claims (1)

[Claims] The zero-sequence voltage and zero-sequence current at both ends of the power transmission line to be located are taken in, and from these and the known quantities zero-sequence impedance, zero-to-earth capacity, and line span length of the power transmission line. , below (a)
A ground fault fault point location method that calculates the position of the ground fault fault point using the steps of ~(d). (b) Both ends of the orientation target section are used as the base points of the calculation point. (b) Compare each zero-sequence voltage amount at the two calculation points. (c) Move the calculation point with the smaller value toward the other end by the unit length. The zero-sequence voltage amount at the new calculation point is the sum of the zero-sequence voltage amount at the old calculation point, the product of the zero-sequence impedance per unit length, and the zero-sequence current. In addition, the charging current is calculated from the zero-sequence voltage and zero-relative ground capacity at the new point,
Correct the zero-sequence current amount. (d) Until the sum of the distances from both ends of the transmission line that is the target of orientation to the two calculation points becomes the track length of the transmission line (
Repeat b) and c), and when the sum of the distances reaches the length of the transmission line, the calculated point is determined to be the failure point.