JPH0583874B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a fault point locating device for locating the distance to a fault point in a power transmission line consisting of three terminals.

[Technical background of the invention and its problems]

If a failure occurs in a system with electric stations A, B, and C as shown in Figure 2, knowing the distance from electric stations A, B, and C to the point of failure is important for subsequent repair of the defective point. It is necessary and essential for work etc.

For this reason, conventional fault point locating methods for power transmission lines include surge reception methods, pulse radar methods, and impedance measurement methods. The first two require expensive communication equipment or signal coupling equipment to power lines.

On the other hand, the latter impedance measurement method is
This method uses the voltage and current obtained from voltage transformers and current transformers to locate, and does not require new equipment to obtain input quantities. For this reason, impedance measurement methods have recently attracted particular attention, such as the
−29471 “Accident Point Discrimination Method” etc. have been proposed.

Now, to simplify the explanation, assuming a three-phase short circuit at point _F1 , the equivalent circuit shown in FIG. 3 is established. In the following explanation, all electric quantities are vector quantities.

In the equivalent circuit of FIG. 3, if E _A = E _B = E _C , the current flowing through the circuit is only the fault component and is a positive sequence current. Also, there may be a fault point resistance due to an arc or the like at the fault point, but for the sake of simplicity, this will be omitted as a complete short circuit.

Here, the fault current flows into the fault point from each end.
I _A , I _B , and I _C will flow. Also, the impedance from electrical station A to fault point F ₁ is Z _A1 , the impedance from fault point F ₁ to branch point J is Z _A2 , and the impedance from electrical stations B and C to branch point J is Z _B1 ,
Let Z _C1 . Now, if we express the relationship between voltage and current at electric station A using the formula, it becomes V _A = V _A1 · I _A ...(1). Calculating the impedance Z _A from this, Z _A = V _A / I _A = Z _A1 · I _A / I _A ... (2) By dividing this formula (2) by the impedance Z _a per unit length, it is possible to reach the failure point. It is possible to calculate the distance X _a of , and the location method is based on the conventional impedance measurement method including the invention of Japanese Patent Publication No. 58-29471.

Determining the impedances Z _B and Z _C seen from electric stations B and C, V _B = Z _B1 I _B + Z _A2 (I _B + I _C ) ...(3) Z _B = V _B / I _B = Z _B1 + Z _A2 ( 1+I _C /I _B ) ...(4) V _C =Z _C1・I _C +Z _A2 (I _C +I _B ) ...(5) Z _C =V _C /I _C =Z _C1 +Z _A2 (1+I _B /I _C ...(6), and the distances X _b and X _c are measured by dividing by the impedance or impedance per unit length, but there is an error term compared to the impedance Z _A or the distance X _a .

Also, considering that the failure point is points F ₂ and F ₃ in Figure 2, the point is
At F ₂ , the impedances Z _A and Z _C and at point F ₃ , the impedances Z _A and Z _B have error terms, so only one terminal can accurately locate the fault point among the three terminals. It's going to happen.

[Purpose of the invention]

In view of the above, the present invention stores the location values of a device for locating fault points using commercial frequency voltage and current in one or multiple locations at an electrical station, and
The purpose of the present invention is to provide a fault point locating device that can be assembled at electrical station A or electrical stations B and C in the figure to perform final fault location and accurately determine the distance to the fault point.

[Summary of the invention]

The present invention is based on the following principle. now,
At electric station A, the standard value X _a of its own end, electric station B,
Assuming that the orientation values X _b and X _c of C are obtained, since the distance from each electrical station to the branch point is known, the electrical station that is located within the branch point can be accurately determined without including error terms. This results in orientation.

That is, equation (2) is used at electric station A, and at electric stations B and C.
By using the equation in which the subscript A in equation (2) is replaced by B and C, the orientation value (distance) of each electrical station can be calculated as the orientation value X _a of electrical station A, the orientation value X _b of electrical station B, and the electrical Let the location value of station C be X _c , and the distance from each electric station to the branch point is
If l _a , l _b , l _c , then X _a < l _a , X _b > l _b , X _c > l _c ...(7) X _a > l _a , X _b < l _b , X _c > l _c ……(8) X _a > l _a , X _b > l _b , X _c < l _c …(9). If any of equations (7), (8), and (9) hold true, the location value of the electrical station located within the branch point will be the final location result. . Furthermore, for accidents near or beyond the branch point, if equations (7), (8), and (9) are used alone to judge accidents, each of them may result in values containing errors.
In other words, if none of equations (7), (8), and (9) hold true, for example, if one terminal is suspended, the orientation values of the remaining two terminals are located beyond the branch point, or an accident occurs near the opposite end. In this case, it is impossible to identify whether an accident in one's own section is an accident on an adjacent line.

Therefore, the orientation value became the orientation beyond the branch point.
The orientation value of the remaining terminal is calculated using the orientation value of the terminal. In other words, assuming a _three -phase accident at point F in Figure 2, and assuming the orientation values of ends A and B to be X _a and X _B , X _a = V _A /Z _a・I _A ...(10) X _b =V _B /Z _b・I _B ...(11). Z _a and Z _b indicate impedance per unit length. Also, the branch point voltage is from V _J = V _A −I _A Z _a・l _a
V _A = V _J + I _A Z _a・l _a , V _B = V _J + I _B Z _b・l _b Equation (10), (11)
_From the formula _, X _a = V _J + I _A Z _a・l _a /Z _a・I _A = V _J / _{Z a}・I _A + _{l a} ……(12 _{) b}・I _B =V _J /Z _b・I _B +l _b ...(13) Also, V _J = (I _A + I _B )・Z _C (l _c −X _a ) ...(14) and l All you need to do is find out _c −X _c .

X _a −l _a =V _J /Z _a・I _A ...(22) X _b −l _b =V _J /Z _b・I _B ...(23) l _c −X _c =V _J /(I _A +I _B )・Z _C ... (24) If Z _a = Z _b = Z _c = Z, then by combining and transforming equations (22) and (23), (X _a −l _a )×(X _a −l _a )/(X _a −l _a )+(X _b −l _b )=V _J
/Z・I _A ×V _J /Z・I _A /V _J /Z・I _A +V _J /Z・I _B =1/
I _A・I _B・V _J /Z/(1/I _A +1/I _B )=V _J /(I _A +I _B )
・Z=l _c −X _c ……(15) Since the distance l _c from the branch point is known as shown in equation (15), the distance from the C end to the failure point l _c − (l _c −X _c ) It becomes possible to find.

Note that if the value of equation (15) is negative, it means that the accident occurred behind the C end, and it is possible to provide an out-of-section determination function.

In addition, in the case of accident F ₁ , electric stations B and C or accident F ₂
In this case, it is possible to calculate using the orientation values of electric stations A and C.

Therefore, in a fault point locating device for a three-terminal system,
Even if the orientation values of all three terminals cannot be obtained, that is, in a case where one terminal is suspended, the orientation values of the remaining two terminals can be obtained.

However, even if the orientation values of the two terminals are located beyond the branch point, the failure point cannot be determined by this alone, but since the distance or impedance from each end to the junction point can be determined, which two terminal orientation values should be used? The point of failure can be identified by calculating whether the

[Embodiments of the invention]

Next, FIG. 1 shows the hardware of an embodiment of the failure point locating device according to the present invention.

In Figure 1, 1 is the target power transmission line, 2 is a transformer, 3 is a current transformer, 4 and 5 are input conversion circuits, and 6
is an analog-digital conversion circuit (hereinafter referred to as AD conversion circuit) 7 is an arithmetic circuit, 8 is an output 7 of the arithmetic circuit 7
It is a receiving device that receives measured values 8a and 8b from the terminal a and the other two terminals, and inputs the outputs 8c, 8d, 8e to the arithmetic circuit 9, and calculates the above-mentioned equations (7), (8), and (9). )formula,
This is an arithmetic circuit that performs calculations such as equations (22), (23), and (15). Further, 10 is a display device that displays the distance based on the calculation result of the calculation circuit 9. The input conversion circuit 4 converts the output of the transformer 2 to an appropriate level, and generates an output through a pre-filter for removing high frequency components. These are commonly used methods and no internal configuration diagrams are shown. The input converter 5 is substantially similar and converts the secondary current of the current transformer 3 to an appropriate voltage level and produces an output via a prefilter. The AD conversion circuit 6 samples the input at regular intervals, performs AD conversion, and applies a digital output to the arithmetic circuit 7.

The arithmetic circuit 7 includes the invention disclosed in Japanese Patent Publication No. 58-29471, and its output 7a is applied to the receiving device 8. Similarly, the orientation values 8a and 8b are applied from the other two ends to the receiving device 8 via the transmission line, etc., and the arithmetic device 9 performs the above-mentioned calculation, and displays the result only when it is determined to be a faulty location. It is output to the device 10 and displayed. Here, as the location value data to be transmitted to the other end, even if it is the location value X data, (1-X)
Of course, the data may also be used.

In the above description of the embodiment, the case where only one terminal is installed is shown, but the other terminals can also be used to perform orientation calculations at each end by configuring the receiving device 8 in FIG. 1 to have a transmitting function. Alternatively, it is also possible to transmit from each terminal to a completely unrelated reception point, learn the orientation value there, and calculate the distance.

Although the present invention requires a transmission device to transmit information from one end to the other end, various kinds of transmission devices are currently being applied for remote measurement or system control/protection, and the same device can be used in the present invention. Easy to apply.

〔Effect of the invention〕

From the above, it is not necessary to gather voltage and current information at each end at one end for location, and if the location values for each end are obtained, it is possible to determine the location value up to the failure point, which was not previously proposed. It is possible to provide a simpler failure point locating device than the conventional method.

In addition, using only the positioning values of the failure point locating device at each end of a three-terminal system will contain errors for accidents beyond the branching point, so it is not possible to accurately locate the distance to the failure point using the positioning values at each end. Become.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of a fault point locating device showing an embodiment of the present invention, Fig. 2 is an explanatory diagram of a power transmission line system with three terminals and one circuit, and Fig. 3 is an explanation of a positive phase branch circuit in a three-phase short circuit fault. It is a diagram. 1...Power line, 2...Transformer, 3...Current transformer,
4, 5...Input conversion circuit, 6...A/D conversion circuit, 7, 9...Arithmetic circuit, 10...Display circuit.

Claims (1)

[Claims] 1. In a fault point locating device for locating a fault point in a three-terminal power transmission line, each terminal measures the voltage and current of its own terminal, and the voltage and current of the own terminal are set in advance. Using the first means of calculating the distance from the line constant of the transmission line to the fault point, and the orientation of each terminal calculated by this first method, a comparison means that compares the distances to the branch point and outputs the position value of any one of the three terminals when the position value of the terminal is within the distance to the branch point; If the orientation value of any one of the terminals is not within the distance to the branch point, or if one terminal is at rest, the orientation value of the two terminals that calculated the orientation value beyond the junction point is used for the remaining terminals. A failure point locating device characterized by comprising a calculation means for calculating and outputting a locating value of one terminal.