JPH0660926B2 - Fault location method for multi-terminal transmission system - Google Patents

Description

Detailed Description of the Invention

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a fault point locating method in a power transmission system including multiple terminals, and particularly to a system in which one end of the applicable system is disconnected or the load end is not grounded, and a terminal device is provided at a terminal other than this one end. Installed at one place to collect the amount of electricity measured by each terminal device, calculate the impedance up to the failure point using the phase voltage and phase current value at the time of failure, and for systems without terminal device installed The present invention relates to a fault point locating method capable of locating a distance to a fault point.

[Prior art and its problems]

When a failure occurs in the power transmission system, knowing the distance or position from the terminal to the failure point is necessary and indispensable for subsequent repair work of the failure point. Therefore, a device that can measure the position of the failure point has been developed, but up to now, (a) the propagation time of the traveling wave generated with the occurrence of the failure is measured. (B) A traveling wave is artificially applied as the failure occurs, and the time until the reflected wave is received is measured. (C) The impedance is calculated using the voltage value and current value when a failure occurs, and the failure point is located. Etc. However, the methods (a) and (b) require special equipment, and in a high-resistance grounding system or arc-extinguishing reactor system, the traveling wave generated on the line is distorted due to various factors, and therefore appropriate measurement is required. There is a drawback that it is difficult to do. On the other hand, in the method of (c), when the system is branched because the electric quantity of only one terminal is used for the localization, if there is a failure ahead of the branch point, the main line failure or the branch line failure does not occur. There is a drawback that it is impossible to orient because it cannot be distinguished.

[Object of the Invention]

The present invention is a fault point locating method capable of locating a fault point in a multi-terminal transmission system in which one end of the system is disconnected or ungrounded at the load end, including a branch system at the disconnected or load end. The purpose is to provide.

[Points of the Invention]

The main point of the present invention is to measure the voltage and current amount of terminals other than the disconnection or load end and collect them in one place, and to determine the failure point or load by a predetermined orientation calculation formula based on the collected voltage and current amount. Determine which section or branch point is distinguished by the terminal other than the end and the branch point, and if it is not the branch point, calculate the distance to the fault point by the orientation calculation formula according to the determined section. If it is a branch point, the voltage and current amount at this branch point are calculated, and the distance to the fault point of the branch system at the disconnection or load end is calculated by the orientation calculation formula from one end based on the calculated voltage and current amount. That's what I asked for.

Examples of the invention

In the following, a one-line power transmission system will be described as an example. First, a description will be given of determination of which section or branch point the fault point exists between each terminal provided with the terminal device and the branch point. FIG. 1 is a transmission line diagram of one line and three terminals for explaining the present invention. In FIG. 1, terminal devices A1 and B1 for measuring the voltage and current of the system are provided at the terminals A and B, and the data measured by the terminal devices A1 and B1 are collected in one place to calculate the fault point. Is performed. In FIG. 1, the C end (the ungrounded load end) is connected to the branch point P, and the A end to the B end.
The distance to the end is L _AB , the branch point P from the A end, the branch point P from the B end, and the branch point P from the C end are called sections AP, BP, CP, and the distance of each section is L _AP , L _BP , L _CP . Here, let us consider the fault location between the two terminals A and B without considering the C end. The self-impedance per unit length of each phase is _calculated as Z _aa , Z _bb , Z _cc , between ab phases, between bc phases, and ca.
The mutual impedance per unit length between the phases is Z _ab ,
_Letting Z _bc and Z _ca and the currents flowing in each phase be I _a , I _b and I _c , the voltage drop per unit length of each phase is expressed by the following equations. Here, assuming a phase 1 line ground fault accident, the failure point resistance is R _F
Then, the equivalent circuit at that time is as shown in FIG. However, the fault point F is set to the distance of αL _AB from the A end, and 0 <
a <1. The voltage V _a ^F at the fault point ^F is V _a ^F = R _F (I _a ^A + I _a ^B ) due to the fault point resistance R _F , so if the A end is the measurement point, then V _a ^A −αL _AB (Z _aa I _a ^A + Z _ab I _b ^A + Z _ca I _c ^A ) ＝ R _F (I _a ^A + I _a ^B ) …… (2) Letting the B end be the measurement point, V _a ^B- (1-α ) L _AB (Z _aa I _b ^B + Z _ab I _b ^B + Z _ca I _c ^B ) = R _F (I _a ^A + I _a ^B ) ... (3) Since the failure point resistance R _F cannot be measured (2), the distance from the A terminal to the failure point F when the C end is not considered when the distance is obtained by deleting R _F using the equation (3) (α
If we find L _AB ) ′, Becomes However, equation (4) is a fault location formula for phase a. If a phase 1 line ground fault occurs in section AP, first
Orient according to equation (4). This orientation result (αL _AB ) ′ is a value that does not consider the voltage and current values at the C end. This (4)
The relationship between the equation and the accurate orientation value by the orientation calculation equation of the three terminals when the voltage and current values at the C terminal can be collected will be described below. FIG. 3 is a circuit diagram in the case where an a-phase 1-line ground fault occurs in the section AP. In the figure, only the self-impedance and mutual impedance of the transmission line are shown for the a-phase fault location formula. Has been done. According to FIG. 3, the voltage at the C end,
Considering the relational expression considering the current value, the potential at the fault point is V _a
^{When F} is set, the potential of the fault point F seen from the A end is shown on the left side of the equation (2), but the potential of the fault point F seen from the B end is the inflow of current from the C end to the fault point F. Therefore, it is expressed by the following equation. V _a ^F = V _a ^B- (1-α) L _AB (Z _aa I _a ^B + Z _ab I _b ^B + Z _ca I _c ^B ) − {(1-
α) L _AB -L _BP } (Z _aa I _a ^C + Z _ab I _b ^C + Z _ca I _c ^C ) …… (5) The distance from the A end to the fault point F from Eqs. (2) and (5) When we find α L _AB , However, A = Z _aa I _a ^A + Z _ab I _b ^A + Z _ca I _c ^A B = Z _aa I _a ^B + Z _ab I _b ^B + Z _ca I _c ^B C = Z _aa I _a ^C + Z _ab I _b ^C + Z _ca I _c ^C. If equation (6) is expressed using equation (4), Becomes Since the fault occurrence section is between _APs , L _AP ≧ αL _AB
Than, Holds, so Becomes In the second term on the right side of Eq. (9), Z and I are vector values, so the term C / (A + B) represents the magnitude and the sign is {(1-α) L _AB -L _BP }. Will be decided. (1-α) L _AB -L _BP = L _AB -L _BP -αL _AB = L _AP -αL _AB ≥0 ...
... (10), so Becomes As a result, (α L _AB ) ′ ≦ L _AP is established, and the orientation value according to the equation (4) does not exceed the P point when viewed from the A end. Also, the equal sign indicates the case where the failure occurs at the branch point P. That is,
If the orientation is performed using the orientation formula of the two terminals A and B without considering the C end, the orientation value within the section AP can be obtained for the fault between the APs. Similarly, for faults between BPs as well, if orientations between ABs are performed, orientation values within the section BP can be obtained. The fault at the branch point P is the case of {(1-α) L _AB -L _BP } = 0 in the equation (8). In this case, the voltage and the current value at the C end become irrelevant, and the orientation formula between AB is determined. The correct orientation can be done with. This is the same for the faults between CPs. From the orientation formula between ABs, all faults between CPs are determined to be faults at the branch point P. As described above, 2 of A and B without considering the voltage and current value of the C end
By performing the orientation formula between the terminals, the intervals AP, BP,
CP can be determined. When the determination of the section in which the failure has occurred is completed in this way, then the failure point in each section is located. The orientation when the a-phase 1-line ground fault occurs in the section AP will be described with reference to the explanatory diagram shown in FIG. When the fault is a one-line ground fault (a phase), the fault current flowing into the fault point is the sum of zero-phase currents, so the current I _a ^F flowing from the branch point P to the fault point ^F is the fault current I _a. ^{As F} , Becomes Than this, Becomes Since the current values of the b and c phases of the sound phase do not change at the A end and the branch point P, I _b ^F = I _b ^A and I _c ^P = I _c ^A. Branch point P
Considering the voltage drop from the B end to the branch point P, the fault phase voltage V _a ^F at V _a ^P = V _a ^B -L _BP (Z _aa I _a ^B + Z _ab I _b ^B + Z _ca I _c ^B ) ... (14) From the above, the voltage and current at the branch point P can be obtained. Therefore, if A and P are considered as two terminals and the orientation calculation equation similar to the equation (4) is obtained, it becomes as follows. Since there are no unknowns in equation (15), orientation calculation can be performed. Similarly, the one-line ground fault of the other phase can be located. In the case of 2-wire short-circuit, ground fault, and 3-phase short-circuit, the fault current is generally much larger than that of the 1-line ground fault, so the shunt current to the C end is small, and therefore there is no large error. The value used can be used as the orientation calculation result. As described above, in the case of a one-line ground fault, the expression (15) can be used as the distance from the A end in the section AP to the failure point F in the case of other failures. Similarly, when an a-phase 1-line ground fault occurs during the section BP, the branch point P will be considered based on the explanatory diagram shown in FIG.
Therefore, the current I _a ^P ′ flowing at the fault point F is I _a ^P ′ = 3 (I _o ^A + I _o ^B ) −I _a ^B (16), as in the equation (13). In addition, since the current values of the b and c phases of the sound phase do not change at the B end and the branch point P, I _b ^P ′ = I _b ^B and I _c ^P ′ = I _c ^B.
Considering the voltage drop from the A end to the branch point P, the fault phase voltage V _a ^P ′ at the branch point P is V _a ^P ′ = V _a ^A -L _AP (Z _aa I _a ^A + Z _ca I _c ^A ) …… (17) The orientation calculation formula for obtaining the distance β L _BP from the branch point P to the fault point F is as follows, considering the same as the formula (15). Therefore, the distance from the end A to the failure point F is L _AP + βL _BP
Can be obtained by In the case of 2-wire short-circuit, ground fault, and 3-phase short-circuit, it can be calculated by equation (4). In this way, fault location between AB can be performed. Although the distance from the A end to the failure point F is obtained in the above description, the distance from the B end to the failure point F can be similarly obtained. Next, the fault location of the branch destination when the fault of the branch P is determined by the section determination will be described. In this case, each phase voltage at the branch point P can be obtained by considering the amount of voltage drop from the A terminal or the B terminal to the branch point P. Also,
The current value of each phase flowing into the branch destination is the sum of the A-terminal and B-terminal currents. The branch point voltages V _a ^P ″, V _b ^P ″, V _c ^P ″, and the branch point currents I _a ^P ″, I _b ^P ″, and I _c ^P ″ of each phase are expressed by the following equations. Since the voltage and current value of each phase at the branch point P can be obtained as described above, it is possible to perform the orientation based on the data of only the P end with the branch point P as one end. The orientation calculation formula will be described below. Orientation in the case where an a-phase 1-line ground fault has occurred in the section CP will be described with reference to the explanatory diagram shown in FIG. For a phase 1 line ground fault, than that obtained by the sum of the fault current is zero-phase current, as described above, the fault current I ^F ", when the fault point resistance and 3Rg, fault point F from the branch point P Considering the voltage drop up to, the following equations hold respectively: V _a ^P ″ −αL _CP (Z _aa I _a ^P ″ + Z _ab I _b ^P ″ + Z _ca I _c ^P ″) −3RgI
^F ″ = 0 (25) I ^F ″ = I _o ^A + I _o ^B (26) From equation (25), Becomes Eliminating the fault point resistance Rg, which is assumed to be pure resistance by taking the imaginary part lm of equation (27), the right side of equation (27) becomes Therefore, the following equation is established. However, I ^{F *} is a conjugate complex of I ^F ″. Lm [V _a ^P ″ · I ^{F *} ] = αL _cp · lm [Z _aa I _a ^P ″ + Z _ab I _b ^P ″ + Z _ca I _c ^P ″ ) ・^{IF *} ]
(28) Therefore, the following orientation calculation formula is obtained from the formulas (26) and (28). Since the unknowns are not included in Eq. (29), the orientation can be performed without being affected by the fault point resistance. Next, the case of a two-wire short circuit fault will be described. In this case, assuming that the fault point resistance R _F << load, it is assumed that no current flows from the fault point F to the C terminal. Where b, c
If the two-phase short circuit of 1 is considered and solved using the symmetric coordinate method, the equivalent circuit diagram becomes as shown in FIG. Therefore, the following formula is established when viewed from the A end. Also, from the above assumption, Normally, it can be set as Z ₁ ≈Z ₂ , so the following formula is established from the formula (30). V ₁ ^A -V ₂ ^A -L _AP Z ₁ (I ₁ ^A -I ₂ ^A ) ＝ (αL _cp Z ₁ + R _F ) {(I ₁ ^A -I ₂ ^A ) + (I ₁ ^B -I ₂ ^B )} …… (32) From this, Becomes Here, when the equation (33) is displayed as a phase, It is displayed as the following equation. Here, if the fault resistance is eliminated by taking the reactance, the following equation holds. However, θ = (phase of numerator) − (phase of denominator), and the reactance component of X ₁ = Z ₁ . The distance to the failure point can be calculated by this equation (35). Similarly, both the 2-wire ground fault and the 3-phase short-circuit can be determined by the equation (35). Moreover, even if it is standardized from the B end (1
Since each electric quantity at the branch point P shown in the equations (9) to (24) does not change, similar orientation can be performed. Note that (29), (3
If the result of the equation (5) shows the branch point P (the orientation value is zero), it is judged as a failure at the branch point P. If the C end is not the load end but the disconnection, the current normally does not flow in the section CP and is not affected by the C end, so (4)
The orientation result between the two terminals A and B by the formula becomes the orientation value as it is. In this case, if it is determined that there is a failure at the branch point P,
In the fault point localization in the section CP, since there is no shunt to the C end and the current flows into all the fault points, approximation with the fault point resistance << load is not necessary, and more accurate localization can be performed. In the above description of the embodiments, the one-line power transmission system has been described, but the present invention can be applied to the case where another line exists such as a parallel two-line power transmission system. For example,
In the case of a parallel two-line power transmission system, there is mutual impedance between lines, and therefore the same can be handled later by adding the voltage drop due to the mutual impedance between lines to the voltage drop shown in Eq. (1). In the above description of the embodiments, a three-terminal power transmission system with one end disconnected or the load end not grounded has been described, but it goes without saying that the present invention can be applied to a multi-terminal system having more than that.

【The invention's effect】

As described above, according to the present invention, first, by performing the orientation between the terminals where the terminal device is installed, the failure point is divided into the terminal where the terminal device is installed and the branch point. If it exists in any of the sections, the orientation value is obtained by a predetermined orientation calculation formula, and if it exists at the branch point, the voltage and current amount at the branch point are obtained and the orientation calculation expression from one end is obtained. Since it is configured to obtain the orientation value, it is possible to perform the orientation including the branch system in which one end of the system for locating the fault point is disconnected or the load end is ungrounded and there is no terminal device.

[Brief description of drawings]

FIG. 1 is a transmission line diagram of 1 line 3 terminals for explaining the present invention, FIG. 2 is an equivalent circuit diagram at the time of a phase 1 line ground fault, and FIG.
The figures are equivalent circuit diagrams when an a-phase 1-line ground fault occurs in the section AP, and FIGS. 4, 5, and 6 show the present invention when an a-phase 1-line ground fault occurs in each section. FIG. 7 is an explanatory diagram of the fault point locating system, and FIG. 7 shows an equivalent circuit diagram by the symmetric coordinate method when the b and c phases are short-circuited. A1, B1 ...... _{terminals, Z aa, Z bb, Z} cc ...... self-impedance per unit length of each phase, Z _ab, Z _bc, the mutual impedance per unit length between Z _ca ...... phases.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Mitsuo Saito, No. 1 Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Fuji Electric Co., Ltd. No. 1 within Fuji Electric Co., Ltd. (56) Reference JP-A-61-235767 (JP, A) JP-A-58-208675 (JP, A)

Claims (1)

[Claims] 1. In a fault point locating system for a transmission system consisting of multiple terminals, one end of which is disconnected or the load end is not grounded, a terminal device is installed at a terminal other than the disconnection or load end and is measured by each terminal device. Any section where the voltage and the current amount are collected at one place, and the fault point is distinguished between each terminal provided with the terminal device and the branch point by a predetermined orientation calculation formula based on the collected voltage and current amount. Alternatively, if it is not a branch point, it is determined.If it is not a branch point, the distance to the fault point is calculated by the orientation calculation formula according to the determined section. If it is a branch point, the voltage and current at this branch point are determined. A fault location method for a multi-terminal transmission system characterized by calculating the amount of the voltage and calculating the distance to the fault point of the branch system at the disconnection or load end from the location calculation formula from one end based on the calculated voltage and current .