JPH069428B2 - 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. 43-2986, in which (1-1) (1-2) are Busbars, (1-3) are busbar connecting lines (hereinafter referred to as busbars), (101), (201)… (1n) (2
n) is a disconnecting switch, (3-1) ... (3-n) (3-A) (3B) is CT, (4) is an input transformer with a gear cup, (101 ×) (201 ×), (1n ×)
(2n ×) are disconnecting switches (101) (201), (1n) (2)
n) is an auxiliary relay contact that turns on when closed, (26) is an input device, (27) is a rectifier circuit, and (28-1) and (28-2) are busbar protection relays.

Next, the operation will be described. Bus 1 (1-1) or Bus 2 (1-
Secondary of CT (3-1) to (3-n) installed on each line connected to 2) and CT (3-A), (3-B) installed on busbar (1-3) Each current is converted into a voltage by the input transformer (4) with a gear incorporated in the input device (26). Input transformer with gearup (4)
Has a secondary coil and a tertiary coil, the output voltage of the secondary coil is the operation amount, and the output voltage of the tertiary coil is the suppression amount via the rectifier circuit (27). These outputs are the disconnector (101). ， (201)…
Contact (101x) that opens and closes according to the operating status of (1n) and (2n),
(201 ×)… (1n ×), (2n ×) protects the busbar 1 (1-1) busbar protection relay (hereinafter referred to as split relay A) (28-1) or busbar 2 (1-2) Is selected as a bus protection relay (hereinafter, referred to as a split relay B) that protects the. That is, the split relay A
The operation amount V _DA of (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 |
Is proportional to the maximum current of the CT secondary currents of all lines connected to the bus 1 (1-1). Similarly, split relay B (2
The operation amount V _DB of 8-2) 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 | _VRB | is connected to the bus 2 (1-2). It is proportional to the maximum current of the CT secondary currents of all the lines that have been processed. The split relay A (28-1) and the split relay B (28-2) operate according to the ratio differential principle, and are | V _DA | −η | V _RA | K or | V _DB | −η |
It operates under the condition of V _RB | cmK (where η and K are constants).

[Problems to be solved by the invention]

Since the conventional busbar protection 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 when the busbar is operated as shown in FIG. However, there was a problem that the zero-phase circulating current sum ΣIoth of each line passing through the bus connection was effective as unnecessary suppression, and the split relay did not operate or the detection sensitivity was lowered.

The present invention has been made to solve the above problems, and an object thereof is to obtain a split 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 determining an internal / external accident on the bus bar, and a split relay having an operation amount of a differential differential for each bus bar and an amount proportional to the batch differential amount of the bus as a suppression amount are provided,
The trip output of each bus bar is generated by the logical product of the batch relay output and the split relay output.

[Operation] Since the split relay according to the present invention is a ratio differential relay that uses an amount proportional to the bus bar differential amount as the suppression amount, it is caused by the zero-phase circulating current passing through the bus station in the case of an internal one-line bus fault. Accident busbars can be reliably selected without unnecessary suppression. Further, for an external accident, a malfunction can be prevented by a collective relay in which the bus-line batch differential amount is the operation amount and the operation amount based on the absolute value of each line current is the suppression amount.

〔Example〕

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) and (4-B) are input transformers with gears, (5) is a digital relay, (6) is a filter, and (7) is a sample and hold device ( Hereinafter referred to as S / H), (8) is a multiplexer (hereinafter referred to as MP ×),
(9) is an analog / digital converter (hereinafter referred to as A / D) (1
0) 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, (1
3) is a microprocessor (hereinafter referred to as CPU).
The secondary current of CT (3-1) to (3-n), (3-A) (3B) is the input transformer with gap (4-1) to (4-n) (4-A) (4-B ) To convert the voltage and introduce it into the digital relay (5).

On the other hand, the open / close state of the disconnector (101) (201) ... (1n) (2n) is the digital relay (5) via the auxiliary relay contact (101x) (201x) ... (1nx) (2nx). Has been introduced to.

The input transformers with gears (4-1) to (4n) each have a secondary coil and a tertiary coil, and the secondary coil is used as a split output and is introduced to the digital relay (5) as it is. The next coil is to be introduced into the digital relay (5) as a batch output in which all lines are combined by a vector, and the conventional example shown in FIG. 3 does not have the batch output.

The secondary output of the input transformer with gaps (4-1) (4-n) (4-A) (4-B) and the output for batch are respectively passed through the filter (6) and S /
H (7) samples the analog value instantaneous value at the same time and at constant intervals. The MP × (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 from DI (10) and stored in the memory (12).
The CPU (13) performs selection calculation of the digital current amount, relay calculation, etc., and the DO (11) outputs the operation output to the outside.

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 I _D are connected to the composite value of the tertiary coil vector of the input transformers (4-1) to (4-N) in FIG. 1, that is, the bus bar 1 (1-1) and the bus bar 2 (1-2). C of all lines
Digital value proportional to the instantaneous value of the differential current that collectively includes the T secondary current (hereinafter referred to as the collective differential current), input 101 ×, 201 ×
〜 (1n ×) (2n ×) is the disconnector (101) (201) 〜 (1n) (2n)
It is a digital value that indicates the open / closed state of the
(9), disconnection switch open / close status signal is memorized from DI (10)
It is temporarily stored in (12). Using the above input data, the CPU (13) performs arithmetic processing according to a program permanently retained in the memory (12). Selection block (1
4) is for selecting the current input data according to the switching state of the disconnector. For example, the line of CT (3-1) in Fig. 1 is the disconnector.
If (101) closed and (201) open, the current data I ₁ is the bus
(1-1) split relay 87A (conventional 87A (28-1) shown in Fig. 3
Corresponding to ()) is selected as the input to perform the operation, and the disconnector (101)
If it is in the open (201) closed state, the current data I ₁ is the bus 2 (1-2)
Split relay 87B (corresponding to the conventional 87B (28-2) shown in FIG. 3) is selected as an input for calculation. Similarly shown divided relay 87B for current data group I _nB indicates division relay 87A for current data group I _nA of the result of selecting the current data I ₂ ~ _n to block (15-1) to block (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 to block (15-2). The arithmetic blocks (16-1) and (16-2) are for obtaining the differential amounts I _DA and I _DB for the split relay, and the bus bar 1 (1-
Differential amount for split relay 87A proportional to the vector sum of CT secondary current of all circuits connected to 1) Is obtained by adding all the current data group I _nA of the block (15-1), and similarly the differential amount for the split relay 87B. Is obtained by adding all the current data groups I _nB of the block (15-2).

The calculation block (17-1) is an operation discrimination calculation of the split relay 87-A that detects an accident on the bus 1 (1-1).
2) is an operation discrimination calculation of the split relay 87B for detecting an accident on the bus 2 (1-2). The principle formulas shown in the arithmetic blocks (17-1) and (17-2) show the means for obtaining a split relay that is not affected by the zero-phase circulating current, which is the object of the present invention. The difference between and is in the amount of suppression. That is, in the normal ratio differential relay, as shown in the above-described conventional embodiment, the amount proportional to the maximum value or the scalar sum of the absolute values of each line current is suppressed, but in the present invention, it is proportional to the collective differential amount. The amount is defined as the suppression amount. If the amount proportional to the collective differential amount is used as the suppression amount as described above, it is apparent that there is no influence of the zero-phase circulating current generated in the multi-line parallel transmission line, as described in FIG. 4 above. Problems are solved. It should be noted that the batch differential amount becomes zero in the event of an external accident on the bus, and the suppression effect is lost. However, as a countermeasure against this, a batch relay described later is provided. The purpose of the split relay of the present invention is to reliably select which busbar accident occurs in a busbar internal accident in a double busbar configuration. 17-1) The divided differential amount I _DA and the batch differential amount I _D have the same value, so if the constants η ₁ and K are set appropriately, | I _DA | −η ₁ | I _D |
> K is established, and the split relay 87A (17-1) operates. On the other hand, the split differential amount I _{DB of} split relay 87B (17-2)
Is zero or the amount of CT error, the suppression amount is proportional to the batch differential amount I _D , and a sufficient suppression effect is produced and the split relay 87B (17-2) does not operate.

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 block for obtaining the suppression amount. In the example of FIG. 2, this is called the maximum value suppression method, and the amount I _R proportional to the maximum value in each line current is derived as the suppression. The calculation block (20) is a block for calculating the discriminant principle formula of the collective relay, and the collective differential amount | _ID
The ratio differential relay calculation is performed using | and the suppression amount I _R.
(21-1) and (21-2) are logical product operations, and make an AND condition between the collective relay (20) and the split relay (17-1) or (17-2) to make the final operation judgment. Is.

In addition, the currents I _A and I _B of the mother stations (1-3) are included in the suppression amount for collective relay
Since it does not need to be introduced, it is not affected by the zero-phase circulating current sum ΣIoth passing through the mother station as shown in FIG.

It should be noted that in the above embodiment, the CT for the collective relay and the split relay
The secondary current and the constituent hardware are shared, but the differential amount for the collective relay in the collective + split double protection system in which this is completely separated is shown in the calculation (17-1) (17-2) in Fig. 2. Alternatively, the scalar sum suppression method may be used as the addition operation of the suppression operation (19) in FIG.

〔The invention's effect〕

As described above, according to the present invention, a collective relay that protects the entire compound bus is used to determine an internal / external bus fault, and a split relay that is provided for each bus unit whose suppression amount is an amount proportional to the collective differential amount. Since it is configured to be an AND condition, problems such as the inoperability of the split relay due to the sum of zero-phase circulating currents passing through the mother station or the decrease in sensitivity can be solved. There is an effect that a highly reliable device can be obtained without being up.

[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, and FIG. 4 is a supplementary diagram for explaining problems of the conventional system. The same reference numerals in the drawings indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A first current obtained by sampling secondary currents of current transformers installed in each line connected to a double bus and an inter-bus connecting line at the same time and at the same interval and converting them into digital quantities. Current data and second analog data obtained by vector-synthesizing analog quantities proportional to the secondary currents of the current transformers of the respective lines and then sampling at the same time and at the same intervals as the sampling and converting into digital quantities. A digital busbar protection relay device for inputting switching state data obtained by converting the switching state of the disconnecting switch that selects each of the lines into a digital amount, and the first current data according to the switching state data. Ratio difference in which the divided differential amount of each busbar unit obtained by adding and computing the results selected for each busbar unit is used as the operation amount, and the amount obtained by multiplying the second current data by a predetermined constant is the suppression amount. Dynamic relay A split relay is used for each bus, the second current data is used as an operation amount, and all the line currents except the current data of the inner bus connecting line of the first current data group are subjected to absolute value calculation and their absolute values are calculated. A ratio differential relay in which the amount obtained by multiplying the maximum value in the current value or the added value of each absolute value current by a predetermined constant is the suppression amount is a collective relay of the bus bar collectively, and the split relay output and the collective relay for each bus bar unit A digital bus protection relay device characterized in that a trip output of each bus is generated by a logical product with the output.