JPH069430B2 - Digital bus protection relay - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a digital ground fault bus protection relay device for protecting a double bus of a power system.

[Conventional technology]

FIG. 3 is a principle block diagram of a double busbar protection device called a conventional split protection system disclosed in, for example, Japanese Patent Publication No. 42-2986, in which (1-1) (1-2) are Busbars, (1-3) are busbar communication lines (referred to as (1) Shimomamaren) (101), (201)… (1n) (2n) are disconnectors, (3-1)… (3-n) (3-A) (3-B) is CT, (4) is input transformer with gap, (101X) (201X), (1nX) (2nX) are disconnectors respectively.
(101) (201), (1n) (2n) is an auxiliary relay contact that turns on when closed, (26) is an input device, (27) is a rectifier circuit, (28-1) (28-
2) is a busbar protection relay.

Next, the operation will be described. Bus 1 (1-1) or Bus 2 (1-
Two of CT (3-1) to (3-n) installed in each line connected to 2) and CT (3-A) and (3-B) installed in mother station (1-3). The secondary current is the input transformer with a gap built in each input device (26).
The voltage is converted in (4). The input transformer with a gap (4) has a secondary coil and a tertiary coil, the secondary coil output voltage is the operation amount, and the tertiary coil output voltage is the suppression amount via the rectifier circuit (27). Is a disconnector (101), (201)… (1n),
Contacts (101X), (201X) that open and close according to the operating state of (2n) ...
Busbar protection relay (hereinafter referred to as split relay A) (28-1) or busbar 2 (1-2) that protects busbar 1 (1-1) by (1nX) and (2nX)
Bus protection relay (hereinafter referred to as split relay B)
To be selected. That is, the operation amount V _DA of the split relay A (28-1) is proportional to the vector sum of the CT secondary currents of all lines connected to the bus 1 (1-1), and the suppression amount | V _RA | It is proportional to the maximum current of the CT secondary currents of all lines connected to 1-1). Similarly, the operation amount V _DB of the split relay B (28-2) is proportional to the vector sum of the CT secondary currents of all lines connected to the bus 2 (1-2), and the suppression amount | V _RB | is the bus 2 ( It is proportional to the maximum current of the CT secondary currents of all lines connected to 1-2). The split relay A (28-1) and the split relay B (28-2) are based on the ratio differential principle, and | V _DA | -η | V _RA | K or | V
It operates under the condition of _DB | −η | V _RB | K (where η and K are constants).

[Problems to be solved by the invention]

Since the conventional busbar protective relay device is configured as described above, an internal one-line ground fault occurs because the zero-phase circulating current Ioth of the transmission line concentrates on the busbar connection during busbar operation as shown in FIG. However, there is a problem that the zero-phase circulating current sum ΣIont of each line passing through the bus connection is effective as unnecessary suppression and the split relay does not operate or the detection sensitivity decreases.

The present invention has been made to solve the above problems, and an object thereof is to adopt a selective relay system that is not affected by the zero-phase circulating current at all.

[Means for solving problems]

According to the present invention, a collective relay for discriminating internal / external accidents on the bus bar and a differential amount ratio detection relay for detecting a ratio of differential amounts of each bus bar are provided as selection relays, and the logic of the collective relay output and the selection relay output is provided. The product is used as the final output.

[Action]

Since the selection relay according to the present invention is a differential amount ratio detection relay that detects the differential ratio of each busbar unit, the zero-phase circulating current passing through the busbar in the case of a one-line ground fault in the busbar is included in the differential amount. It is possible to select the accident busbar without fail. In addition, in case of an external accident, a malfunction can be prevented with a collective relay that does not use the mother continuous current.

Example of Invention

An embodiment of the present invention will be described below with reference to the drawings. First
In the figure, (4-1) to (4-n) (4-A) (4-B) are input transformers with a gap, (5) is a digital relay, (6) is a filter, (7)
Is a sample and hold device (hereinafter referred to as S / H), (8) is a multiplexer (hereinafter referred to as PX), and (9) is analog /
Digital converter (hereinafter referred to as A / D), (10) is a digital input circuit (hereinafter referred to as DI), (11) is a digital output circuit (hereinafter referred to as DO), (12) is a memory, (13) is It is a microprocessor (hereinafter referred to as CPU).

The secondary current of CT (3-1) to (3-n), (3-A) (3-B) is the input transformer with gap (4-1) to (4-n) (4-A) (4 -B) convert voltage and introduce to digital relay (5).

On the other hand, the open / closed state of the disconnector (101) (201)… (1n) (2n) is introduced to the digital relay (5) via its auxiliary relay contact (101X) (201X)… (1nX) (2nX). There is. Each of the input transformers with gaps (4-1) to (4-n) has a secondary coil and a tertiary coil, and the output of the secondary coil is the digital relay (5) as it is.
The third coil output is introduced into the digital relay (5) as a batch output in which all lines are vector-synthesized. The conventional example shown in FIG. 3 does not have the batch output.

Input transformer with gap (4-1) to (4-n) (4-A) (4-B) 2 each
The next output and the batch output are respectively S through the filter (6).
/ H (7) samples the analog value instantaneous value at the same time and at constant intervals. The MPX (8) sequentially switches the output of each S / H (7), converts the analog amount into a digital amount by the A / D (9), and stores it in the memory (12). On the other hand, the open / closed state of the disconnector is taken in from DI (10) and stored in the memory (12), and the CPU (13) performs the selection calculation of the digital current amount, the relay calculation, etc., and DO (11) outputs the operation output to the outside. It is something to put out.

FIG. 2 shows the operation principle of the digital ground fault bus protection relay device having the above-mentioned configuration.

Input _I 1 ~I _n each of the first view CT in FIG. 2 (3-
Digital quantities proportional to the secondary current instantaneous values of 1) to (3n), inputs I _A and I _B are proportional to the secondary current instantaneous values of CT (3-A) and (3-B) in FIG. The digital value and input _ID are connected to the combined value of the tertiary coil vectors of the input transformers (4-1) to (4-n) in FIG. 1, that is, the busbar 1 (1-1) and the busbar 2 (1-2). CT of all lines
A digital value proportional to the instantaneous value of the differential current that collectively includes the secondary current (hereinafter referred to as the collective differential current), input (101X), (201
X) to (1nX) (2nX) are the disconnectors (101) (201) to (1n) (2n) of Fig. 1.
Is a digital value that indicates the open / closed state of the
The signal D (9) and the disconnecting switch open / close state signal are temporarily stored in the memory (12) from DI (10). Using the above input data, the CPU (13) performs arithmetic processing according to a program permanently retained in the memory (12). Selection block
(14) is for selecting the current input data according to the open / close state of the disconnector. For example, if the line of CT (3-1) in Fig. 1 is in the disconnector (101) closed and (201) open state. For example, the current data I ₁ is selected on the bus 1 (1-1) side, and if the disconnector (101) is open (201) closed, the current data I ₁ is selected on the bus 2 (1-2) side. Similarly current data I ₂ ~I _n of selected result of the bus 1 (1-1) side current data group InA are shown in block (15-1) bus 2 (1-2) side current data group InB blocks ( It is shown in 15-2).

Naohaharen (1-3) Current data I _A block do not have to take the bus selection (15-1), I _B is introduced directly into the block (15-2). The operation blocks (16-1) and (16-2) are for obtaining the differential amounts I _DA and I _DB for the selection relay, and are bus 1 (1-1)
Differential amount for selection relay 87A proportional to the vector sum of the CT secondary currents of all circuits connected to Is obtained by adding all the current data group I _nA of the block (15-1), and similarly the differential amount for the selection relay 87B. Is obtained by adding all the current data groups I _nB of the block (15-2).

The operation block (17-1) is an operation determination operation block for the split relay 87-A that detects an accident on bus 1 (1-1).
(17-2) is an operation determination calculation block of the split relay 87B that detects an accident on the bus 2 (1-2). Computation block (17-1), (17
-2) shows the means for obtaining a selective relay that is not affected by the zero-phase circulating current, which is the object of the present invention.
The difference from the normal ratio differential relay is in the amount of suppression. That is, in the normal ratio differential relay, the amount proportional to the maximum value or the scalar sum of the absolute values of the respective line currents is used as the suppression amount as shown in the above-mentioned conventional embodiment. The amount proportional to the amount is defined as the suppression amount. If the amount proportional to the differential amount on the other bus side is used as the suppression amount as described above, it is clear that there is no influence of the zero-phase circulating current generated in the multi-circuit parallel transmission line, which will be described with reference to FIG. The problems that were done are solved. It should be noted that the differential amount of each busbar becomes zero in the event of an external busbar accident, and the suppression effect disappears. However, as a countermeasure against this, a collective relay described below is provided. The purpose of the selection relay of the present invention is to reliably select which busbar accident occurs in a busbar internal accident in a double busbar configuration. For example, in the case of a busbar (1-1) accident in FIG. 1, the selection relay 87A ( 17-1) operation amount (bus 1 (1-1) side differential value)
I _DA is an amount proportional to the fault current and is a suppression amount (bus 2 (1-2)
Since the side differential amount) I _DB becomes zero or the CT error component, if the constants η ₁ and K are set appropriately, | I _DA | −η ₁ | I _DB
|> K is established, and the selection relay 87A (17-1) operates. On the other hand, the operation amount (differential amount I _DB ) of the selection relay 87B (17-2) is zero or the CT error amount, while the suppression amount is proportional to the _fault current (differential amount I _DA ), which is sufficient. And the selection relay 87B (17-2) does not operate.

As described above, the selective relay of the present invention has the differential amounts I _DA and I _DB.
Is detected when the ratio is greater than or equal to a predetermined value. An example of the characteristic is shown in FIG.

Next, the operation block (18) is an operation block for deriving the absolute current value of each line except the currents I _A and I _B passing through the mother station (1-3), and the operation block (19) is an operation for obtaining the suppression amount. Yes,
In the example of FIG. 2, the maximum value suppression method is called, and the amount I _R proportional to the maximum value in each line current is derived as suppression. The calculation block (20) is a determination principle formula for the collective relay, and performs a ratio differential relay calculation with the collective differential amount | I _D | and the suppression amount I _R.

The calculation block (17-1), (17-2), the data used in _{(20) | I DA |,} | I DB |, | I D |, I R is known amplitude value which is not shown derived It is the result of the operation.

(21-1) and (21-2) are AND operation blocks, and make an AND condition between the collective relay (20) and the selection relay (17-1) or (17-2) to make the final operation judgment. It is a thing. Since it is not necessary to introduce the currents I _A and I _B of the mother station (1-3) to the suppression amount for collective relay, the sum of the zero-phase circulating currents ΣIoth passing through the mother station as shown in FIG. It will not be affected.

In the above embodiment, the CT for the collective relay and the selective relay is used.
The secondary current and the constituent hardware are shared, but it is also possible to use a collective + selective relay protection method in which this is completely separated, and the differential amount for collective relay can be calculated by the calculation (16-1) (16-2) in Figure 2 ) The results may be added to give I _D = I _DA + I _DB . Further, the suppression calculation (19) in FIG. 2 may be used as an addition calculation in a scalar sum suppression system.

〔The invention's effect〕

As described above, according to the present invention, a collective relay that protects the entire compound bus bar is provided for each bus bar unit that determines an internal / external bus fault and detects the ratio of the amount proportional to the differential amount of each bus line unit. Since the AND condition of the selection relay is used, the problems such as the inoperability of the selection relay due to the sum of zero-phase circulating currents passing through the mother station or the decrease in sensitivity are solved, and if the digital relay structure is used, all can be processed by software. Therefore, a highly reliable device can be obtained without increasing the cost.

[Brief description of drawings]

FIG. 1 is a block diagram of a digital ground fault bus protection relay device according to an embodiment of the present invention, and FIG.
FIG. 3 is a block diagram showing a conventional split protection system, FIG. 4 is a system diagram for explaining the problems of the conventional system, and FIG. 5 is a characteristic diagram of a selective relay according to the present invention. In the figure, (5) is a digital relay, (6) filter,
(7) is sample and hold, (8) is multiplexer, (9)
Is an A / D converter, (10) is a digital input, (11) is a digital output, (12) is a memory, and (13) is a microprocessor. The same reference numerals in the drawings indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A current transformer installed on each of a plurality of lines connected to a double bus composed of a first bus and a second bus and a bus connecting line connecting the first and second buses. First electric current data obtained by sampling the electric quantities proportional to the secondary currents at the same time and at the same intervals and converting them into digital quantities, and an analog proportional to the secondary currents of the current transformers of the plurality of lines. Second electric current data obtained by vector-synthesizing the electric quantities, sampling at the same time and at the same intervals as the sampling, and converting into digital quantities, and the disconnecting switch opening / closing state for selecting each of the lines to a digital quantity. In the digital type busbar protection relay device for inputting the switching status data obtained by the above, the first current data is transferred to each busbar unit of the first busbar or the second busbar according to the ON state of the switching status data. Selected result The first busbar differential amount I _DA and quantity proportional to the amplitude value of each of the differential amount I _DB of the second busbar obtained by adding operation _{| I DA |, | I DB} | from | I _DA | eta ₁ ｜ I _DB ｜-
A first busbar selection relay for discriminating K> 0 (where η ₁ and K are constants) and a second busbar selection relay for discriminating | I _DB | −η ₁ | I _DA | −K>0; The amount derived from the second current data is used as the operation amount, and all the line currents except the current data of the inner bus connecting lines of the first current data group are calculated as absolute values. Alternatively, a ratio differential relay in which an amount obtained by multiplying an amount derived from an added value of each absolute value current by a predetermined constant is used as a suppression amount is provided, and each of the selection relay output and the ratio differential relay output is provided. A digital bus protection relay device characterized by performing a logical product for each bus to obtain the final output.