JPS59204418A - Trestle multichannel ground-fault protecting relay - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power system protection device, and in particular, the present invention relates to a protection device for a power system, and in particular, a high-resistance grounding system (including an iPc system) of a shared multi-circuit line is connected to This invention relates to a ground fault protection relay that compensates for zero-phase circulating current.

Transmission lines with high resistance grounding systems that are co-extended with ultra-high-voltage transmission lines have a non-straight, anti-phase arrangement, so zero-phase circulation between lines occurs due to induction by the power flow of the ultra-high-voltage transmission lines. A current (simply referred to as zero-sequence circulating current) is generated, which causes the earth fault protection relay to malfunction or malfunction, so it is necessary to compensate for the zero-sequence circulating current.

Figure 1 (4), a3) shows a shared multi-line model system to which the present invention is applied. In Figure 1 (4), line 1 (1
A, IB, IC), line 2 (2A, 2B, 2C) is 1
87 to 500KV ultra-high voltage transmission line (hereinafter referred to as the guided system), A, B, and C indicate the phase sequence, bus 5 (5A, 5B
, 5C) are ultra-high voltage power transmission lines A and B.

This is the bus bar of the C phase. i is the current of each phase of a, b, and c.

In Figure 1 (B), line 3 (Sa, 6b, 3
c), line 4 (4a, 4b, 4c) is 66Kv~154
KV high resistance grounding system power transmission line (hereinafter referred to as guided system)
a, b, c indicate the phase Ill'e line 6 (6a, 6b.

6e) is the bus bar of the a, b, and c phases of the high-resistance grounding system power transmission line. 7 is a T-branch load of the power transmission lines 3a to 6C. 37a
~37e and 47a ~47c are current transformers, 3a
, 3b, 3c and 4a, 4b, 4c are connected to differential circuits via line difference current detectors 50a to 50c for each phase of a, b, e, respectively, and the power flow of the induction system shown in Figure 1 (5) is shown. These are the circulating currents of each phase of a, b, and c that circulate from line 3 to line 4 due to the induction of .

Let the electric station on the bus 6 side of the guided system be SA, and that on the opposite side be SB. The neutral points of SA and SB are each grounded to the earth through the neutral point grounding resistance RNA+RNB.

As shown in Figure 1, in the Juko resistance grounding system, a zero-phase circulating current is generated due to the current flowing through the upper thread, and when a single ground fault occurs, the internal direction (internal fault) and external direction (external fault) are mistaken. invite judgment. For example, when two circuits are used together in the system shown in the first report, when a load of 650OA is connected to the upper system, a circulating current of 267A flows, and a zero-phase input of 434A enters the ground fault line selection relay. In a normal high resistance grounding system,
There are many 10° to 400A grounding systems, but in such systems, the circulating current is larger than the ground fault current, making it impossible to determine the failure in the event of a one-wire ground fault. In addition, as a countermeasure against such circulating current, there is a relay that uses a changing current, that is, a method in which the circulating current in a steady state is memorized in advance, and the fault current is determined by subtracting the circulating current stored in advance from the circulating current in an abnormal state. However, this cannot be used during a prior interruption or in a 3-terminal system, and cannot be used when re-closing. Also, healthy 2
A method of estimating the circulating current from the phases, that is, excluding the positive phase component from the healthy 2 phases, and using the fact that the ratio of 'fCt and the zero-sequence circulating current is unrelated to the power flow of the induced system, the zero-sequence circulating current can be estimated from the healthy 2 phases. A relay that extracts the ground fault component by estimating the amount by removing the positive phase component from the phase and subtracting this value from the zero phase input is disclosed in Japanese Patent Application No. 54-67184 (Japanese Unexamined Patent Publication No. 55-16
No. 0929), we are already seeing a proposal. Although this relay can solve the above-mentioned problems, it may become a blind spot in the event of a phase failure in an ultra-high voltage system. This is because there is only one type of constant for estimating the circulating current, and it cannot cope with changes in the constant that change depending on the open phase state of the upper system.

The present invention has been made in view of the above points, and its purpose is to:
A shared multi-circuit ground system that can compensate for unreliable phase loss in the upper system, reliably determines failures, and eliminates these failures to ensure a stable supply of power. An object of the present invention is to provide a short circuit protection relay device.

The following is a second explanation of the shared multi-line ground fault protection relay of the present invention.
This will be explained with reference to FIGS.

FIG. 2 shows a schematic configuration of the earth fault protection relay of the present invention, and shows 1
00 is a determination unit that determines the system status of the upper system from the breaker condition of the upper system. If the upper system is in the same substation as the lower system, the relay conditions for the upper system are the same as the pallet conditions, and if the upper system and lower system breaker are not in the same substation, Obtain the cutoff conditions of the upper system using transmission means such as optical fiber or communication cables. In this case, the only information required is the breaker conditions, so transmission is relatively easy.

Reference numeral 200 is a constant setting unit having a function of changing the output depending on the system operation state. This constant is a constant for estimating the zero-sequence circulating current, as described later.Although it is possible to memorize a constant for each system operation case, it is better to memorize one constant for multiple cases with similar constants. It is advantageous in terms of storage space and configuration. In other words, the operational status of the upper system is grouped into several patterns for each case with similar constants. Also, this constant is Siminire-V
It can be determined in advance by a computer using vxn.

Reference numeral 600 denotes a zero-phase circulating current calculating section, and its inputs are the phase voltage V of the neutral point grounding, the healthy phase current generator, and the constant output S4 from the constant setting section 200. 400 is a compensation section, which is the zero-sequence component of the input current. a to the output S++' of the zero-phase circulating current calculation section 300
By subtracting ku, the zero-phase circulating current is eliminated (compensated). 500 is a ground fault line selection section and output S1 of the compensation section 400
．． and zero-sequence voltage■. Based on this, it is determined whether the fault is within the section or the fault is outside the section.

FIG. 3 shows a shared multi-line ground fault protection relay according to an embodiment of the present invention, and the same parts as in FIGS. 1 and 2 are designated by the same reference numerals. 9 is a breaker to which circuit breakers 9a to 9f are connected as shown, 10 is a first data converter, and the amount of electricity S1 from the current detector 8 is between the lines of each phase of a, b, and c. Performs differential current AD conversion. Reference numeral 11 denotes a voltage detecting section, which includes a first voltage detecting section 12 (zero-phase voltage detecting transformer) and a second voltage detecting section 16 (phase voltage detecting transformer) installed on the bus bars 6a to 6C. Reference numeral 14 denotes a second data converter which inputs the detection signal S of the first voltage detector 12, that is, the zero-phase voltage 0, at a constant cycle in synchronization with the first data converter! . is sampled and AD converted. 15 is a filter section and IB is the output of the first data conversion section 10;
By inputting each digital quantity 5sff of Bw Ibs+ice and calculating the difference current between the lines of the two phases, k IBB ”b
se ibs aICs, I(!!l ””6B
(However, a−εj2/3π) is performed to remove the positive phase component. Reference numeral 18 denotes an arithmetic unit for calculating the zero-phase circulating current, which includes the output S6 of the filter unit 15 and the constant circuit 200.
The calculation is performed by inputting the output S of and the output Sy of the ground fault phase determining section 16. 17 is a third data converter that converts the output voltage signal s0=* detected by the second voltage detector 16 into a digital quantity. These first data converters 10,
The filter section 15, the ground fault phase determination s16, and the third data conversion section 17 constitute a zero-phase circulating current calculation section 600.

Reference numeral 19 denotes a zero-phase circulation IT flow detection unit, which inputs the signal S directly and performs A/D conversion, or the A/D converted signal 5II.
After introducing th, the zero-phase portion of the line was delivered. 5(=Ias+ib
B + 1 cll) wo seek. The compensator 400 outputs all zero-phase components i of the zero-phase circulating current 600. , by subtracting from
Find the amount by which the zero-phase circulating current is eliminated.

The ground fault line selection unit 500 inputs the zero-sequence component of the inter-line difference current whose zero-sequence circulating current has been compensated by the first compensation unit 400 and the zero-sequence voltage Sta from the second data conversion unit 14. Perform all ground fault line selections. The ground fault line selection unit 500 outputs a ground fault line trip signal 5lllk, and this signal trips the breaker 9 of the ground fault line to protect the high resistance grounding system power transmission line of the shared multi-circuit from a ground fault.

In the ground fault protection W IJ relay with the above configuration, as an example, the circulating current of each phase and the line 6 of the a phase in the case of a ground fault of the a phase of the induced system
The distribution of the ground fault currents flowing in a and 4aK and the load currents flowing in lines 6 and 4 is shown in FIG.

Here, a circulates in the direction from line 6 to line 4.

The circulating current of each phase b, e is ia th * I b th
, ic th, and the load 'wL currents flowing through each phase of a, b, and c of line 6 and line 4 are i, , Ibe ■
Q and Ia+Ibe Ic. Further, the ground fault current flowing through the a-phase of the line 6 is 1, and the ground fault current flowing through the a-phase of the line 4 is I.

FIG. 3 shows only the guided system and the ground fault protection nM according to the present invention.
It is installed at IJ Shire Electric Station SA. The case where the guided system has a T-branch load 7 as shown is different.

Zero-sequence circulating current i during a ground fault. It is necessary to obtain the constant I'a+Rh+Rc in advance in order to perform the calculation according to the th i ground fault phase. These constants are determined by constant setting section 200 as shown in FIG.

That is, when the upper system breaker condition signal S0 is input to the system state detection section 100, the output S of the constant setting section 200
The setting value of 4 is changed. Circulating electricity IALXoth+ example.

Line difference current 1astIb of a, b, and c phases when the system is healthy
s-'as is output and converted into a digital quantity by the first data conversion section 10. The converted digital quantity - is filtered by the filter section 15
Perform the following calculation to remove the positive phase component.

The third data conversion section 17 converts the phase voltage detected by the voltage detection section 16 into a digital quantity and sends it to the ground fault phase determination section 16 . The determination unit 16 compares the input phase voltage with a predetermined set value and outputs a signal S to all calculation units 18 when determining a 1-ground fault. On the other hand, the determining unit 100 monitors the closing condition signal of the breaker of the upper system to determine the system status of the upper system, and notifies the constant setting unit 200 of the system operation status. The constant setting section 200 selects constants corresponding to the system operation state from a constant table stored in advance and outputs them to the calculation section 18.

Assuming that the a-phase has a ground fault, the output Ibs "Ic8" of the filter section 15 at the time of the a-phase ground fault is the circulating current 2 of the healthy phase.
(I b th a I c th ). The calculation unit 18 calculates the value R selected by the constant setting unit 200.
By multiplying a by the output Ibs aIc8 of the filter section 15, twice the zero-sequence circulating current is obtained.

The signal S6 when the system is healthy is equal to the correct zero-phase circulating current, but when the induced system has a ground fault, the line difference current of the ground fault phase includes a current component due to the ground fault. Therefore, ground fault detection can be performed by calculating the output S6 of the filter section 15 and the selected constant.

(3) holds when the system is healthy, but does not hold when there is a ground fault for the reasons mentioned above.

The calculation unit 18 performs ground fault detection by inputting and comparing two arbitrary calculation values of S6, a constant, and gold.

Similarly, in the case of b-phase ground fault, ea (= I(yB
'Ias) and the selected constant kb to obtain a zero-phase circulating current and output it to the compensator 400. The compensation unit 400 is for compensating for zero-sequence circulating current that causes malfunction of relays, and is for compensating for zero-sequence circulating current of line difference current. , is introduced through the zero-sequence circulating current detection unit 19, and a value that cancels the zero-sequence circulating current is obtained by subtracting the calculated value of the zero-sequence circulating current at the time of a ground fault, and a value that cancels the zero-sequence circulating current is obtained. It is output to the ground fault line selection section 500, which is a directional relay. The selection unit 500 selects a zero-sequence current containing almost no zero-sequence circulating current component and a second
The zero-sequence voltage converted into a digital quantity by the data conversion unit 14. From this, it is correctly determined whether the fault is within the section or the fault outside the section, and the circuit breaker 9a, 9b, 9c or 9d+9e*9f of the circuit breaker 9 is tripped by the trip signal Sl.

FIG. 4 shows an example of a processing flow when the principle of the present invention is realized by a microcomputer, and the main table processing will be described.

In FIG. 4, the block corresponds to the data converter and zero-sequence current detection section 1.2.3.

b, c voltage of each phase E, , Eb, i. and line opening current Ia
s*Ibs+I. 8 and zero-sequence voltage V. and zero-sequence current i
. S is measured by a current transformer and a voltage transformer, and is sampled and held at a constant period to perform AD conversion processing.

(However, Fig. 3 shows an embodiment in which a signal after AD conversion is input to the zero-phase circulating current detection section.) Block B3
corresponds to the filter section 15, and Ias + Ib5sics
The positive phase component is removed from the line difference current of two phases among the line difference currents of each phase. A, b phase, b, c phase, c, a phase The positive phase component is removed from the difference current between the same lines as ■ab + Ibe
+ Ica. Block B4 corresponds to the determination unit 100 and inputs the system operation status.

Block B corresponds to the constant setting section 200, and block B
Select constants that correspond to the system operation status determined in step 4.

Block B6 corresponds to the ground fault determination section 16, and this determination section 1
If the value calculated in step 6* is 9 less than the set value, the system is considered to be in a healthy state, and if it is smaller, it is considered to be a ground fault.

This corresponds to the arithmetic unit that determines a ground fault in block B6.

Block B, , B, , B, , B,. Detects ground fault phase. These blocks are block B, and B.

A calculated value obtained using the fC, a, b, and c phase ground fault detection signals and a constant is selected according to the ground fault phase, and the zero-phase circulating current i is determined. This is a block for deriving th.

Block Bll corresponds to the compensation section 400, and block B! I was calculated by converting it into a digital quantity. , and block B
Input the zero-sequence circulating current Iothk derived at 7-Bto and calculate the zero-sequence component i of the inter-line difference current. Compensate by S.

Block 13tt corresponds to the ground fault line selection unit 500, and block Bll calculates the zero-sequence portion of the inter-line difference current that compensated for the zero-sequence circulating current, and the zero-sequence voltage*. Enter all inputs, select the ground fault line, and issue a breaker trip signal to the ground fault line.

As explained above, according to the present invention, in a relay device that protects a high-resistance grounded two-circuit transmission line co-extended with an ultra-high voltage transmission line in digital quantities, the upper system interrupter conditions are obtained and detects the connected state of the upper system, switches several types of constants set in advance according to this detection signal, detects the ground fault phase when a one-wire ground fault occurs in the system, and connects the two healthy phases. The positive sequence component is removed from the current of The fault current is extracted and compensated by subtracting the computed zero-sequence circulating current value from the input zero-sequence, and the ground fault line is selected based on the direction and magnitude of this compensated amount of zero-sequence voltage. It is. According to the invention, therefore:
It is possible to compensate for the circulating current even in the case of an open phase in the upper system, and by reliably determining a failure and eliminating the failure, it is possible to ensure a stable supply of electric power.

[Brief explanation of drawings]

Figure 1, a3) is a system diagram of the shared multi-line circuit model, Figure 2 is a block diagram showing the principle of the ground fault protection relay according to the present invention, and Figure 3 is the shared multi-line earth fault protection relay according to the present invention. FIG. 4 is a processing flow diagram of an embodiment of the IJ system when the principle of the present invention is realized by a microcomputer. 1A~IC, 2A~2C...Ultra high voltage power transmission line, 3a~
3c, 4a~4c...High resistance grounding system power transmission line, 58~5
C... Bus bars of ultra-high voltage power transmission lines, 6a to 6c... Bus bars of high resistance grounding power transmission lines, 67a to 67c. 47a-470...Current transformer, 50a-50e...
- Line difference current detector of guided system, 7...T branch load, 8...Current detection unit, 51...Common steel tower, 9...
・Shutoff unit, 10...first data converter, 11...
・Voltage detection unit, 12... Zero-phase voltage transformer, 16...
Phase voltage transformer, 14... second data converter, 15.
...Arithmetic section, 16.. Judgment section, 17.. Third data converter, 18.. First selection section, 100.. Upper system judgment section, 200.. Constant setting section. 600...Zero-phase circulating current calculation section, 400...Compensation section, 500...
Ground fault line selection section.

Claims (1)

[Claims] In a relay device that digitally protects a high-resistance grounded two-circuit power transmission line co-extended with a power transmission line, there is provided a determination means for obtaining upper system breaker conditions and determining the operating state of the upper line based on the conditions; a constant setting means having a function of switching several kinds of constants set in advance according to the detection signal detected by the judgment means; A zero phase that calculates a zero-sequence circulating current by removing all the positive phase from the two-phase current, and multiplying the value obtained by dividing the switched setting constant according to the ground fault phase by the amount by which the positive phase was removed. A circulating current calculating means, a compensating means for extracting and compensating the fault current by subtracting the calculated value by the zero-sequence circulating current calculating means from the input zero-sequence, and a compensating means for extracting and compensating for the fault current, 1. A shared multi-line ground fault protection relay comprising: ground fault line selection means for selecting a fault line.