JPH10253691A - Method for locating failure point - Google Patents

Abstract

PROBLEM TO BE SOLVED: To locate a failure point without discriminating failure kinds, failure phases and lines and without a need of a positive-phase impedance. SOLUTION: Data on a phase current and data on a voltage are fetched from respective terminal nodes at a parallel two-line transmission system having a plurality of branch points. An own-end-side node-point voltage six-phase vector V, an inflow-current six-phase vector Iin from an own-end-side node and an inflow-current six-phase vector Iin ' from a partner-end-side node are computed. By using their computed results and stored data on an impedance sixth-order forward matrix Z per unit length of a failure section, a distance (x) up to a failure point from an own-end-side node point is computed by x=Im[V.(Iin +Iin ')*]/Im[ZIin .(Iin +Iin ')*], where * represents a conjugate complex number. The (x) is added to a distance up to the own-end-side node point from an own end, and a locating value is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fault point locating method for locating a fault point in a parallel two-line multi-terminal power transmission system by impedance calculation.

[0002]

2. Description of the Related Art With the spread of PCM current differential relays and data transmission, terminal data other than the own terminal can be used for locating, and the locating accuracy is more accurate than locating using only the own terminal data. Also improved.

In the case of a three-terminal system as shown in FIG.
The distance X from to the failure point F can be obtained by the equation (1) or the equation (2).

[0004]

(Equation 4)

[0005]

(Equation 5)

[0006]

However, the above (1)
When a fault point or a reference point is obtained by the equation or the equation (2), there are the following problems.

(1) Prior to location, it is necessary to determine the type of fault (ground fault, short circuit), fault phase, and faulty line.

[0008] (2) In the fault fault localization, the self and mutual impedances are used, while in the short fault fault localization, the positive phase impedance is used. Therefore, the impedance must be converted and both impedances must be held. No.

(3) In short-circuit fault locating, the effect of line imbalance cannot be considered.

(4) If there is an unbalanced branching power source or load, correction must be made.

The present invention has been made in view of the above-mentioned conventional problems, and has as its object to determine the type of fault, the fault phase, the fault line, and to eliminate the need for positive-phase impedance. It is an object of the present invention to provide a method for locating a failure point.

[0012]

According to the present invention, a fault point of a parallel two-line power transmission system having a plurality of branch points is taken into a fault point locating device by taking phase current and phase voltage data transmitted from each terminal node. In the fault locating method of locating by the impedance calculation, the fetched data is used to determine the voltage six-phase vector V at the self-end node point, the current six-phase vector I _in flowing from the self-end node, and the other end. Calculates the inflow current six-phase vector I _in ′ from the node, and calculates the distance from the self-end node point to the fault point using the calculation result and the stored data of the impedance sixth-order square matrix Z per unit length of the fault section. x is

[0013]

(Equation 6)

And calculating the calculated result x in addition to the distance from the self-end to the self-end side node point as an orientation value.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG.
This will be described with reference to FIG. FIG. 1 shows a power transmission system having n terminals. The line connecting the own terminal 1 and the partner terminal n is called a main line, and the other is called a branch line.

A fault in the branch line (an even-numbered section) in FIG. 1 can be treated as a fault in the main line by renewing a terminal connected to the fault section as a partner terminal.

As shown in FIG. 2, attention is paid to the section of the fault F. Here, the inflow current vector I _in from the own end node, the inflow current vector I _in ′ from the other end node, and the fault current _If are six-phase vectors. For example, the inflow current vector I _in represents the currents of the lines 1L and 2L as I _1L , I _2L ,
Phase current I _a ~I _c line 1L, when a phase current of the line 2L and I _a '~I _c', can be expressed as follows.

[0018]

(Equation 7)

Similarly, the voltage vector V at the self-end side node point
The fault point voltage vector _Vf is also a six-phase vector. For example, the voltage vector V represents the voltages of the lines 1L and 2L as V _1L ,
V _2L, the phase voltage V _a ~V _c line 1L, when the phase voltage of line 2L and V _a '~V _c', can be expressed as follows.

[0020]

(Equation 8)

Further, the inflow current vectors I _in and I _in ′ can be calculated using the current I _{i of} each terminal as shown in Table 1.

[0022]

[Table 1]

I _in + I _in 'is the fault location (main line / branch line)
Note that this is the sum of all terminal currents regardless of

Z is an impedance matrix (sixth order square matrix) per unit length of the fault section, and the imbalance between phases and between lines is also taken into consideration as in the following equation.

[0025]

(Equation 9)

[0026] The voltage V _f under the failure point, the current I _f can be expressed by the following equation.

[0027]

[Number 10] Taking the inner product of the complex conjugate of _{V f = V-xZI in I} f = I in + I in 'V f and I _f, the following equation is obtained.

[0028]

[Equation 11]

Here, the fault point is generalized and considered as shown in FIG.

[0030] impedance as seen from the point of failure (the sixth-order square matrix) and put the Z _f,

[0031]

(Equation 12)

[0032]

(Equation 13)

At nodes N and N ',

[0034]

[Equation 14]

Note that

[0036]

(Equation 15)

Therefore, V _f · I _f * is a real number. Then, the imaginary of V _f · V _f * is,

[0038]

(Equation 16)

Therefore, the phase current and phase voltage data transmitted from each terminal node are taken into the fault point locating device,
V, Z and I _in , I _in ′ are obtained, and the distance x from the self-end node point to the fault point is obtained by calculating equation (3), and the pre-stored self-end to self-end node point is obtained. By adding the distance L to the distance, the distance X from the self end to the failure point can be located.

[0040]

[Equation 17]

As is clear from the simulation of the fault point (FIG. 3), this equation can be applied to the orientation regardless of the ground fault or the short-circuit fault.

Further, since the fault point resistance is erased in the derivation process, it can be said that the equation (3) is an equation considering the fault point resistance.

Power supply (or load) to the partner terminal or branch terminal
In the case where there is an influence, since the three-phase current values flowing into 1L and 2L are obtained from them, they are included _in I _in and I _in '.

If the branch terminal is an unbalanced branch terminal, I
_In , I _in ′, the terminal current element of the bridge without branch may be set to 0.

[0045]

(Equation 18)

[0046]

[Equation 19]

[0047]

Since the present invention is configured as described above, the following effects can be obtained.

(1) Failure type (ground fault, short circuit), failure phase,
Location can be performed without determining the faulty line.

(2) Since the orientation can be performed using only the self and mutual impedances and not using the positive phase impedance, there is no need to perform the impedance conversion procedure and save the positive phase impedance.

(3) The short-circuit fault can be located in consideration of the unbalance of the line.

(4) There is no need to compensate for an unbalanced branch power supply (load).

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a section distance, a current, and the like of a power transmission system according to an embodiment.

FIG. 2 is an explanatory diagram of current, voltage, and the like in a failure occurrence section.

FIG. 3 is a simulation circuit diagram generalizing a fault point.

FIG. 4 is an explanatory diagram of a three-terminal system according to a conventional example.

[Description of Signs] 1L, 2L: circuit number 1 to n: terminal number T: terminal number corresponding to the fault section k: fault section l _i : section length of section _i L: self-terminal node of the fault section from terminal 1 flowing current vector I _in from the distance I _a ~I _c ... phase current I _in ... local end node from the distance X ... local end to the point to point of failure from the distance x ... local end node to fault point '... flowing current vector V ... voltage vector V _a ~V _c ... phase voltage V _f ... fault point voltage vector Z ... section impedance matrix per length unit of the fault phase voltage or local end node point of the local end from the other end node side Z _f : Common component of impedance viewed from the fault point Z _G : Ground fault component of impedance viewed from the fault point Z _s : Short-circuit component of impedance viewed from the fault point

Claims (3)

[Claims] 1. A fault point locating method for fetching a fault point of a parallel two-line power transmission system having a plurality of branch points into a fault point locating device by taking phase current and phase voltage data transmitted from each terminal node and performing impedance calculation. Using the acquired data, a voltage six-phase vector V at the self-end node point, a six-phase vector I _in flowing from the self-end node, and a six-phase vector flowing from the other end node I _in ′ is calculated, and the distance x from the self-end node point to the fault point is expressed by the following equation using the calculation result and the storage data of the sixth order square matrix Z per unit length of the fault section. And calculating the calculated result x in addition to the distance from the self-end to the self-end side node point as an orientation value. 2. The current of an unbalanced branch terminal i for calculating the six-phase vector components I _in , I _in ′ according to claim 1, wherein the branch terminal of the first line is unbalanced. The six-phase vector component I _i is expressed by the following equation: A fault point locating method characterized by calculating by using 3. The unbalanced branch terminal i for calculating the inflow current six-phase vector component currents I _in and I _in ′ according to claim 1, wherein the branch terminal of the second line is unbalanced. The current six-phase vector component I _i is expressed by the following equation: A fault point locating method characterized by calculating by using