JPH069431B2 - Digital bus protection relay - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a digital bus protective relay device for protecting a double bus of an electric 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) (2n) are disconnectors, (3-1)… (3-n) (3- A) (3-B) is CT, (4) is input transformer with gear, (101 ×) (201 ×), (1n ×) (2n ×) are disconnectors (101) (201), (1n) Auxiliary relay contact (2n) turns on when closed, (26) input device, (27) rectifier circuit, (28-1) (2
8-2) 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 following currents are input transformers with gears built in the input device (26).
The voltage is converted in (4). The input transformer with gearup (4) has a secondary coil and a tertiary coil, and 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). Is a disconnector (101), (201)… (1n),
Contact (101 ×), (201 ×) that opens and closes according to the operating state of (2n)
… Bus protection relay (hereinafter referred to as split relay A) (28-1) or bus 2 that protects bus 1 (1-1) by (1n ×), (2n ×)
It is selected as a busbar protection relay (hereinafter referred to as split relay B) that protects (1-2). 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 | is the bus 1 ( 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 circuits connected to 1-2). Split relay A (28-1) and split relay B (28-2) are ratio differential principle, and | V _DA | -η | V _RA | K or | V _DB | -η | V _RB |
It operates under the condition of K (however, η and K are constants).

[Problems to be solved by the invention]

Since the conventional busbar protection device is configured as described above, since the zero-phase circulating current Ioth of the transmission line concentrates on the busbar connection during the busbar operation as shown in Fig. 4, an internal one-line ground fault accident occurs. However, the sum of the zero-phase circulating currents ΣIoth of each line passing through the bus connecting line is effective as unnecessary suppression, and there is a problem that the split relay does not operate or the detection sensitivity decreases. The present invention has been made in order to solve the above problems, and an object thereof is to obtain a split relay system which is not affected by the zero-phase circulating current sum ΣIoth passing through a bus connecting line.

[Means for solving problems]

In the split relay system according to the present invention, the amount proportional to the secondary current of each line CT of the bus connection other than the bus connecting line is set as the first suppression amount, and the split differential amount of each bus line is the differential amount of the bus side. The amount is the operation amount, and the sum of the divided differential amounts, that is, the amount proportional to the collective differential amount is the second suppression amount, and the first suppression amount and the second suppression amount.
This is a ratio differential relay that uses the sum of the suppression amounts as the total suppression amount.

[Action]

In the split relay system according to the present invention, since the current passing through the bus connecting line is not introduced as the suppression amount, the unnecessary suppression component due to the zero-phase circulating current sum ΣIoth is naturally excluded. Generally, in the conventional split relay, the amount proportional to the CT secondary current of the bus connecting line is introduced so as to always be effective as a suppression amount, but in the present invention, this is excluded to solve the above-mentioned problem, and replaced. Is added to the second suppression amount. That is, excluding the suppression amount of the busbar connecting line,
In the event of an internal busbar accident, the suppression effect of the sound busbar-side split relay becomes small and there is a risk of malfunction. Therefore, the present invention provides a second suppression amount as a countermeasure against this. During an internal bus accident,
Since the collective differential amount is proportional to the fault current, by properly selecting the suppression constant using this, a reliable suppression effect that replaces the conventional suppression amount of the bus connecting line for a healthy bus side split relay Is to get.

Example of Invention

An embodiment of the present invention will be described below with reference to FIG.
In Fig. 1, (4-1) to (4-n) (4-A) (4-B) are input transformers with gears, (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 MP ×), and (9) is analog /
Digital converter (hereinafter referred to as A / D), (10) is digital input circuit (hereinafter referred to as DI), (11) is digital output circuit (hereinafter referred to as DO), (12) is memory, (13) is It is a microprocessor (hereinafter referred to as CPU).

The secondary current of CT (3-1)-(3-n), (3-A) (3-B) is the input transformer with gearup (4-1)-(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 the digital relay (5) via its auxiliary relay contact (101x) (201x) ... (1nx) (2nx). ) Has been introduced. Each of the input transformers (4-1) to (4-2) with a gear has 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 tertiary coil is a digital relay (5) as a collective output that is vector-combined for all lines.
The conventional example shown in FIG. 3 does not have a batch output.

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

FIG. 2 shows the operation principle of the digital busbar protection device having the above configuration.

In FIG. 2, inputs I _{1 to In} are CT (3-1) to I _n in FIG. 1, respectively.
Digital value proportional to the instantaneous value of the secondary current of (3-n), input
I _A and I _B are digital values proportional to the secondary current instantaneous value of CT (3-A) and (3-B) in Fig. 1, and input I _D is the input transformer (4-1) ~ in Fig. 1. (4-n) tertiary coil output vector composite value,
That is, a digital amount proportional to the instantaneous value of the differential current (hereinafter referred to as the collective differential current) that collectively includes the CT secondary currents of all lines connected to the bus 1 (1-1) and the bus 2 (1-2), Input (101 ×),
(201 ×)-(1n ×) (2n ×) are the disconnectors (101) (201)-
(1n) (2n) is a digital value representing the open / closed state, the current input is temporarily stored in the memory (12) from the A / D (9) and the disconnector open / closed state signal from the DI (10). Using the above input data, the CPU (13) performs arithmetic processing according to the program permanently retained in the memory (12). The selection block (14) selects the current input data according to the open / close state of the disconnector. For example, the CT (3
If the line (-1) is in a state where the disconnector (101) is closed and (201) is open, the current data I ₁ is the split relay 87A for the bus 1 (1-1) (the conventional 87A (28- (Corresponding to 1)) If the disconnector (101) is opened and the (201) is closed, the current data I ₁ is the bus 2 (1-2) split relay 87B (see FIG. 3). (Corresponding to the conventional 87B (28-2) shown) is selected as the input for performing the operation. Similarly, the current data group I _nA for the split relay 87A, which is the result of selecting the current data I ₂ to _n , is shown in block (15-1).
The current data group _InB for the split relay 87B is shown in block (15-2).

Since the bus lines (1-3) do not need to select the bus bar, the current data I _A is introduced into the block (16-1) and I _B is directly introduced into the block (16-2). The arithmetic blocks (16-1) and (16-2) are for obtaining the differential amounts I _DA and I _DB for the split relay, and are used as the vector sum of the CT secondary currents of all the circuits connected to the bus 1 (1-1). Differential amount for proportional split relay 87A Is obtained by adding all the current data groups I _nA and I _A of the block (15-1). Similarly, the differential amount for the split relay 87B Is obtained by adding all the current data groups I _nB and I _B of the block (15-2).

Next, the calculation blocks (17-1) and (17-2) are the calculations for obtaining the suppression amount, and in the example of Fig. 2, the amount proportional to the maximum current in each line current called the maximum value suppression method. The current data group I _nA or I selected for each bus bar is derived as
_The absolute value of the instantaneous value of _nB is calculated and derived, and the maximum value is obtained from it. Computation blocks (18-1) and (18-2) show the operation judgment computation of the differential elements of the split relays 87A and 87B. The amplitude of the differential quantities I _DA and I _DB is calculated by the well-known vector method or area method. The values ‖I _DA ‖ and ‖I _DB ‖ are obtained and the magnitude is compared with the tap value constant K ₀ . The calculation blocks (19-1) and (19-2) show the operation judgment calculation of the ratio element of the split relays 87A and 87B, and judge the ratio of the differential absolute instantaneous value and the suppression instantaneous absolute value. .

Discriminant of split relay 87A | I _DA |-(η _| I _RA + η ₂ | I _DA + I _DB |)> 0… (1) Formula of split relay 87B | I _DB |-(η I _RB + η ₂ | I _DA + I _DB |)> 0 (2) where η ₁ and η ₂ are constants Indicates the maximum value of Of the above formulas (1) and (2) showing the maximum value of η ₁ I _RA or η ₁ I _RB as the first suppression amount η ₂ | I _DA + I _DB | The difference from the conventional split relay is that the first suppression amount is
-3) The point that the passing currents I _A and I _B are not included and the second suppression amount is provided separately. Regarding the operation determination principle of equations (1) and (2),
In more detail, in the event of an external accident on the bus, the differential amount I
_DA and _IDB are zero or CT error, but the suppression amounts I _RA and I _RB are proportional to the fault current passing through the busbar.
In the case of an internal bus accident, for example, in the case of bus 1 (1-1) in FIG. 1, the differential amount I _DA of the split relay 87A (18-1, 19-1) is proportional to the accident current I _F. Quantity and split relay 8
The differential amount I _DB of 7B (18-2, 19-2) is zero or an amount proportional to the CT error εI _F occurs. On the other hand, split relays 87A, 8
Since the first suppression amounts I _RA and I _RB of 7B are proportional to the fault current I _F , the formula (1) of the split relay 87A is | I _F |-(η ₁ | I _F | + η ₂ | I _F |) = | I _F | {1- (η ₁ + η ₂ )}… (3) Equation (2) for split relay 87B is | ε I _F |-(η ₁ | I _F | + η ₂ | I _F |) = | I _F | {ε- (η ₁ + η ₂ )}… (4)
It becomes clear that by selecting the constants η ₁ and η ₂ to appropriate values, it is possible to determine that Eq. (3) (split relay 87A) is operating and Eq. (4) (split relay 87B) is inoperative. Is. The block (20) is for discriminating the level of the batch differential amount I _D , and is similar to the differential elements (18-1) and (18-2) of the split relay. The block (21) is a ratio differential element of the collective relay, the operation amount is the instantaneous absolute value of the collective differential amount I _D , and the suppression amount is I _RA , I used for the first suppression amount of the split relays 87A, 87B. _RB
Value greater Max [I _RA, I _RB] Of the, | and eta ₃ Max [I _RA, I _RB]> 0 (5) where eta ₃ differential amount instantaneous absolute value of the constant | I _D The ratio of the suppression amounts is determined. Blocks (22-1) to (22-5) are AND operations, where the output of (22-1) is the final output of split relay 87A (22-2) is the final output of split relay 87B, and the output of (22 The output of (-3) is the final output of the batch relay, the output of (22-4) is the accident judgment of bus 1 (1-1), (22-
The output of 5) is the accident judgment of bus 2 (1-2).

In the above embodiment, the collective relay (blocks (20), (21))
Is provided, it is not necessarily required, and an example of the case of the conventional collective + division protection method is shown.

In addition, the calculation blocks (17-1) and (17-2) in Fig. 2 are used to calculate the suppression amount as the maximum value suppression method, but this is the instantaneous absolute value addition for each line. As good as. Furthermore, current data I ₁ ~I _n of FIG. 2 when applied to a cable system, I _A, I _B, may be data via each of the known active component derivation operation which does not show the I _D.

〔The invention's effect〕

As described above, according to the present invention, a bus with a zero-phase circulating current that passes through a bus connection that is a problem during system operation generally referred to as 1x2B operation of a transmission line in a system with a double bus configuration. It is possible to eliminate the effect that the split relay that performs the ground fault protection does not work or that the sensitivity decreases, and further, there is an effect that it has the same external accident performance as the conventional split relay system.

[Brief description of drawings]

FIG. 1 is a block diagram of a digital bus bar protector according to an embodiment of the present invention, FIG. 2 is a block diagram of the same operation principle, and FIG. 3 is a block diagram of an analog bus bar protector using a conventional double bus bar split protection system. , FIG. 4 is a system diagram for explaining the problems of the conventional method. 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 (2)

[Claims] 1. Current data obtained by sampling secondary currents of current transformers installed in each line connected to a double busbar and a connecting line between busbars at the same time and at the same interval and converting them into digital quantities. In a digital busbar protection relay device for inputting switching status data obtained by converting the switching status of the disconnecting switch for selecting each of the buses into a digital value, the current data is output according to the ON status of the switching status data. Means for deriving a divided differential amount for each busbar unit obtained by performing an instantaneous value addition operation for each busbar unit, and absolute value operation for each current data of the instantaneous value selected for the busbar unit for each of the above-mentioned lines Means for deriving a first suppression amount for each busbar unit that is proportional to the addition operation value of the maximum value or absolute value among the values, and each of the divided differential amounts for each busbar unit are obtained by instantaneous value addition operation Proportional to the absolute value of the collective operation amount Means for deriving a second inhibiting amount, and the operation amount of the divided differential amounts of the respective bus unit, first and second
And a means for calculating a ratio differential relay judgment calculation for each bus bar using the scalar sum of the above suppression amounts as a suppression amount. 2. Current data obtained by sampling secondary currents of current transformers installed in each line connected to a double busbar and a connecting line between busbars at the same time and at the same interval and converting them into digital quantities. In a digital busbar protection relay device for inputting switching status data obtained by converting the switching status of the disconnecting switch for selecting each of the buses into a digital value, the current data is output according to the ON status of the switching status data. Means for deriving a divided differential amount for each busbar unit obtained by performing an instantaneous value addition operation for each busbar unit, and absolute value operation for each current data of the instantaneous value selected for the busbar unit for each of the above-mentioned lines Means for deriving a first suppression amount for each busbar unit that is proportional to the addition operation value of the maximum value or absolute value among the values, and each of the divided differential amounts for each busbar unit are obtained by instantaneous value addition operation Proportional to the absolute value of the collective operation amount Means for deriving a second inhibiting amount, and the operation amount of the divided differential amounts of the respective bus unit, first and second
Determining means for performing a differential relay determination calculation for each bus line with the scalar sum of the suppression amount of S1 as the suppression amount, the collective differential amount, or an analog amount proportional to the secondary current of the current transformer of each line is vector-synthesized. The analog differential amount obtained by
An amount obtained by calculating an absolute value of the amount sampled at the same interval and converted into a digital amount is set as an operation amount, and a amount proportional to a maximum value or an amount obtained by addition calculation in each busbar unit of the first suppression amount. And a second determining means for performing a ratio differential relay determination calculation as a suppression amount, and operating under an AND condition of the operations of the first and second determining means.