JP3446775B2 - Bus short-circuit protection device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single bus circuit or a multi-bus circuit in which a plurality of upper power transmission lines are connected to a bus and one or a plurality of lower transmission lines extend from the bus. The present invention relates to a busbar short-circuit protection device that can cope with a short-circuit accident.

[0002]

2. Description of the Related Art A large number of transmission lines are connected to a low-voltage side busbar of a primary substation, and a current differential relay system using a differential current of each line is generally adopted for short-circuit protection of the busbar. Has been done. However, in order to improve the reliability of protection,
It is necessary to take measures for malfunction and malfunction at the same time as measures for malfunction. As a countermeasure against malfunctions, a self-end backup protection device is usually installed for the main protection device to provide backup when the main protection device is not operating.

The self-end protection device has a problem that it is more expensive than the far-end protection device in that it is a double equipment with the main protection device, but on the other hand, it has a higher sensitivity and a longer protection time. It has the advantage of preventing extension and is widely used. As the self-end backup protection method, in the present application, a short-circuit distance relay method
(44S) or short-circuit direction relay system (67S) is assumed, and the applicable busbar is assumed to be a single busbar or a plurality of busbars.

[0004]

In the application of the self-end protection system, it is possible to reliably prevent tripping in the event of an external accident, and to reliably determine the internal busbar accident so that the busbar internal accident can be reliably tripped. Must be a scheme. In particular, in a system using a plurality of busbars, it is necessary to determine which busbar has an accident during an internal busbar accident and perform selective cutoff.

Therefore, an object of the present invention is to solve the above-mentioned technical problems and to provide a busbar short-circuit protection device capable of reliably determining an internal busbar accident. Further, an object of the present invention is to provide a busbar short-circuit protection device capable of surely determining which busbar has an accident during an internal busbar accident.

[0006]

[Means and Action for Solving the Problems] (1) A busbar short-circuit protection device according to claim 1 for achieving the above object,
A busbar short-circuit protection device capable of coping with a short-circuit accident in a single-bus circuit in which a busbar is connected to a plurality of upper power transmission lines and one or more lower power transmission lines are output from the busbar. the sum current of the currents flowing from each of the wire
A first fault detection relay which performs a determination based on, is installed in each lower transmission line, a second fault detection relay which performs distance determination have groups Dzu <br/> the current flowing backward transmission line, wherein First
The determination means for determining a short-circuit accident in the busbar based on the logical product of the determination of the accident detection relay of No. 1 and the negative of the logical sum of the determinations of the second accident detection relays.
Accident detection relay of the motor element on the impedance plane, so a circle including the origin therein, a distance relay provided with Blinder elements such that the reactance axis Rights row.

According to the busbar short-circuit protection device described above, in the event of a short-circuit accident in the busbar, a large amount of current flows into the higher-order power transmission line, even though there is little current outflow from each of the power transmission lines extending from the busbar. Therefore, the determination means can determine that the internal failure of the bus. The first fault detection relay, which performs determination based on the sum current of the currents flowing from each of the upper transmission line, it means that detects a large current even when healthy. Therefore, the motor element on the impedance plane, so a circle including the origin therein, by providing a Blinder elements such that the reactance axis flat row, to prevent malfunctions, close-up fault such as an internal bus But I am trying to make sure it can be detected. (2) In the busbar short-circuit protection device according to claim 2 for achieving the above object, a plurality of busbars are connected to each other by a circuit breaker, and each of the busbars has one or more upper power transmission lines. A bus short-circuit protection device capable of responding to a short-circuit accident in a multi-bus circuit in which one or more low-order power transmission lines are connected to each bus and is connected to each bus. sum current
A first fault detection relay which performs a determination based on, is installed in each lower transmission line, a second fault detection relay which performs distance determination have groups Dzu <br/> the current flowing backward transmission lines, interrupted A third accident detection relay that detects a direction by detecting a current flowing into a bus bar through a container, a judgment of the first accident detection relay, and a negative logical sum of respective judgments of the second accident detection relay, Determination means for determining a short-circuit accident in any of the busbars based on a logical product with the judgment of the third accident detection relay, wherein the first accident detection relay includes a moh element on an impedance plane. , so a circle including the origin therein, a distance relay provided with Blinder elements such that the reactance axis Rights row.

According to this busbar short-circuit protection device, a large amount of current flows into the higher-order power transmission line even though there is little current outflow from each of the power transmission lines extending from the busbar. It is the same as the busbar short-circuit protection device according to claim 1 that the internal busbar failure can be determined by means. Further, along with this, it is possible to determine which busbar has an internal failure by determining the direction of the current flowing into the busbar through the circuit breaker.

[0009]

Embodiments will be described in detail below with reference to the accompanying drawings showing embodiments. (1) Example 1 (single bus) In FIG. 2, two upper power transmission lines F ₁ and F ₂ are connected to a bus, and two lower power transmission lines L ₁ and L ₂ are output from the bus. It is a figure which shows a single bus circuit. The currents I _F1 and I _F2 flowing through the upper power transmission lines F ₁ and F ₂ are converted into current transformers CT _F1 and CT _F2 , respectively.
And the currents I _L1 , I ₂ flowing through the lower transmission lines L ₁ , L _2
L2 is detected by current transformers CT _L1 and CT _L2 , respectively. The sum current I _F1 + I _F2 of the currents I _F1 and I _F2 detected by the current transformers CT _F1 and CT _F2 represents the total current flowing into the bus bar, and the current I _L1 detected by the current transformers CT _L1 and CT _L2. , I _L2 respectively represent currents flowing out from the bus bar. The sum current I _F1
Let + I _{F2 be written} as I _F1 + I _F2 = I _FT .

The sum current I _FT detected by the upper current transformers CT _F1 and CT _F2 and the secondary line voltage of the instrument transformer GPT connected to the bus are input to the short-circuit distance relay, The currents I _L1 and I _L2 detected by the current transformers CT _L1 and CT _L2 and the secondary line voltage of the instrument transformer GPT connected to the bus are input to other short-circuit distance relays, respectively. The reason why the sum current I _FT detected by the upper current transformers CT _F1 and CT _F2 is detected is to prevent malfunction due to the sneak current of the upper power transmission line in the case of a power supply failure or the like. Therefore, a short circuit of the upper transmission line itself cannot be detected by this short-circuit distance relay, but there is no problem because it is originally outside the protection range of the relay.

In this specification and the drawings, the short-circuit distance relay is hereinafter referred to as a 44S relay, and when attention is paid to the current I input to the 44S relay, it is referred to as a 44S (I) relay. Further, the determination of the 44S (I) relay will be simply written as 44S (I). The general operating characteristics of the 44S relay are shown in FIG. When the ratio of voltage to current (impedance) is represented by a polar coordinate vector, the operating characteristics are indicated by a circle (Moh element) that passes through the origin. If the impedance falls within this circle, it is determined that a short circuit has occurred in the planned direction. .

By the way, when a large load current (heavy current) flows even when the sound is normal, the impedance detected by the 44S relay enters the circle along the resistance axis (horizontal axis) on the impedance plane, and malfunction may occur. There is a nature. Therefore, normally, a voltage suppressing element (blinder element) is provided so that the relay does not operate unnecessarily even if it enters the circle. In this way, even if the impedance goes into the circle due to heavy current, it will not work unless it goes into the blinder. On the other hand, since the fault current is out of phase with the load current, it can be detected without being obstructed by the blinder.

However, in this embodiment, the above-mentioned 44
Since the S relay is used to detect the sum current I _FT flowing into the bus bar, a very large load current may flow. When a very large load current flows, as shown by the broken line in FIG. 3, the impedance in a normal state enters the blinder due to heavy power flow, and the relay malfunctions.

Therefore, as shown in FIG. 1, the Moh element is made to be a circle including the origin. Further, a blinder element is provided along the reactance axis (vertical axis). As a result, even if the sum current I _FT flowing into the bus becomes excessive, there is no risk of malfunction. Moreover, even when the voltage and impedance become almost 0 due to the short-circuit at the near end, that is, even when the vector comes near the origin, the origin is the center of the circle, so the operation is performed reliably. Therefore, it is most suitable as a backup protection relay.

Although the center of the circle is the origin in FIG. 1, the origin is not limited to this, and the origin may be within the circle. However, if the center of the circle is taken as the origin, even if a short circuit accident occurs inside the bus and the bus voltage is lost instantaneously,
As described above, the accident can be detected more reliably. Although the direction cannot be determined by adopting the characteristic including the origin as shown in FIG. 1, the sum current I _FT of the upper transmission line is originally detected, and when any one of the upper transmission lines fails, It does not work because the current wraps around. In other words, since this 44S relay is used exclusively for detecting lower-order failures, there is no inconvenience even if the direction cannot be determined.

The relay having such characteristics is generally called an overcurrent relay (51V) with voltage suppression, and the PT secondary line voltage which is the suppression voltage is subtracted from the voltage conversion value of the input current (CT secondary). Operates when the value exceeds the specified value. This relay can be easily realized as a digital type relay. The distance measuring element shown in FIG. 1 is not necessary, but if it exists, it is possible to know the failure position of the lower power transmission line, which is convenient for protection of the backup equipment.

The operation of the single bus circuit of FIG. 2 in the event of a failure is as follows. If a short-circuit failure (hereinafter simply referred to as “failure”) occurs in the upper power transmission lines F ₁ and F ₂ , 4
The current I _FT input to the 4S (I _FT ) relay is also 44 S
Since the currents I _L1 and I _L2 input to the (I _L1 ) relay and the 44S (I _L2 ) relay are also in the inoperative region of the relay,
The relay does not work.

When a failure occurs on the bus bar, 44S (I
_The current I _FT input to the _FT ) relay increases and enters the relay operating region, and the 44S (I _FT ) relay operates, but
The currents I _L1 and I _L2 input to the 4S (I _L1 ) relay and the 44S (I _L2 ) relay do not increase, and the 44S (I _L1 ) relay,
The 44S (I _L2 ) relay does not work. Therefore, it can be judged as an accident inside the bus.

[0019] When the failure in the lower transmission line L _1, L ₂ occurs, the increased current I _FT inputted to 44S (I _FT) relays, 44S (I _FT) relay operates, 44S (I _L1 )
Since any of the currents I _L1 and I _L2 input to the relay and the 44S (I _L2 ) relay increases, one of the 44S (I _L1 ) relay and the 44S (I _L2 ) relay operates. The above results are tabulated below.

[0020]

[Table 1]

Therefore, as shown in the following equation (1), 44S
The determination can be made based on the logical product of (I _FT ) and the negation of the logical sum of 44S (I _L1 ) and 44S (I _L2 ).

[0022]

[Equation 1]

(2) Second Embodiment (Single Bus + Single Bus) In this embodiment, the special 44S relay used in the first embodiment is used for the upper transmission lines F ₁ -F ₄ . Figure 4
Bus A is connected to _two upper power transmission lines F ₁ and F ₂ ,
Similarly, the bus B is connected to the two upper power transmission lines F ₃ and F ₄ , and the lower power transmission lines L ₁ and L ₃ are connected from the bus A.
A bus circuit in which the bus B is connected to the lower transmission lines L ₂ and L ₄ (of which L ₁ and L ₂ are parallel 2 lines)
FIG. This circuit looks like a double bus, but when protected it can be thought of as a combination of single and single buses.

That is, the upper transmission line F₁Or F₂Breakdown
Occurs, 44S (I_FTA) Relay, 44S
(I_FTBThe relay does not work. Also, 44S (I_L1)
Relay-44S (I_L4) The relay doesn't work either. On bus A
When a failure occurs, 44S (I_FTA) Detected by relay
Current I _FTAIncreases to 44S (I_FTA) Of the relay
Entering the operating area, 44S (I_FTAThe relay works, but
Lower 44S (I_L1) Relay, 44S (I_L3) The relay
Do not work. Therefore, it can be judged as an accident inside the bus A.
It

When a failure occurs on the bus B, 44S
(I_FTB) Current I detected by the relay _FTBIncreased to 4
4S (I_FTB) Enter the relay operating area 44S
(I_FTB) The relay works, but the lower 44S (I_L2)
Relay, 44S (I_L4The relay does not work. According to
Therefore, it can be judged as an accident inside the bus B. Lower power transmission line L₁, L
₃44S (I_FTA)relay
And 44S (I_L1) Relay, 44S (I_L3) The relay is moving
Made, lower transmission line L₂, L_FourWhen a failure occurs in
44S (I_FTB) Relay and 44S (I_L2) Relay, 4
4S (I_L4) The relay works.

The above results are tabulated below.

[0027]

[Table 2]

Therefore, as shown in the following equation (2), 44S
(I _FTA ), 44S (I _L1 ) relay, 44S (I _L3 ) relay
It is possible to judge that the accident inside the bus A by the logical product of the logical sum and the negative of the logical sum of 44S, as shown in the following equation (3).
(I _FTB ) and 44S (I _L2 ) relay, 44S (I _L4 )
It is possible to determine an accident inside the bus line B by the logical product of the logical sum of the above and the negation.

[0029]

[Equation 2]

(3) Third Embodiment (Complex Bus) In this embodiment as well, the special 44S relay used in the first embodiment is used for the upper power transmission lines F ₁ -F ₄ . Figure 5
Is connected to a bus line A to the _two upper power transmission lines F ₁ and F _{2, and} to a bus line B to two upper power transmission lines F ₃ and F ₄ as well. ₁ , L ₃ are connected, and lower transmission lines L ₂ and L ₄ are connected from bus B (of which L ₁ and L ₂ are parallel 2 lines), and bus A and bus B are connected. Busbars are connected to each other by a busbar breaker (referred to as a busbar CB) so that they can be selectively cut off. The current transformers CT _AB and C are sandwiched by the mother CB.
Although T _BA is arranged, the winding directions of CT _AB and CT _BA are opposite.

The currents I _F1 and I _F2 flowing through the upper power transmission lines F ₁ and F ₂ and detected by the current transformers CT _F1 and CT _F2 , and the currents CT _F3 flowing through the higher power transmission lines F ₃ and F ₄ , respectively. , CT _F4
Let I _{FT be} the sum of the currents I _F3 and I _F4 detected at 4
Detected by 4S (I _FT ) relay. Further, the currents flowing through the lower power transmission lines L ₁ -L ₄ and detected by the respective current transformers CT _L1 -CTL ₄ are 44S (I _L1 ) relay -44S, respectively.
(I _L4 ) Detected by the relay.

Furthermore, the current I _AB flowing through the bus B from the bus A through the mother communicating CB, (referred 67S) short-direction relay is detected in (I _AB) relays, bus A from the bus B through the base communication CB The current I _BA flowing through is detected by the 67S (I _BA ) relay. Thus, the current flowing from one bus bar through the circuit breaker toward the other bus bar is detected on the side closer to the one bus bar than the circuit breaker.
This is because the protection areas overlap on one side and the other side of the circuit breaker.

When a failure occurs in the upper power transmission lines F ₁ -F ₄ , none of the relays operates, as described above. When a failure occurs on the bus A, current flows from the upper power transmission lines F ₁ and F ₂ and also flows from the higher power transmission lines F ₃ and F ₄ through the mother CB. Therefore, the 44S (I _FT ) relay operates, and the 67S (I _BA ) relay also operates. However, 44S installed to the lower transmission line L ₁ -L ₄ (I _L1) relays -4
None of the 4S (I _L4 ) relays work.

When a failure occurs in the bus B, current flows from the upper power transmission lines F ₃ and F ₄ and also flows from the higher power transmission lines F ₁ and F ₂ through the mother CB. Therefore, the 44S (I _FT ) relay operates and 67S (I _FT ) relay operates.
_AB ) The relay also works. However, the lower transmission lines L ₁ -L ₄
None of the 44S (I _L1 ) relays-44S (I _L4 ) relays installed in

When the lower transmission line L ₁ or L ₃ fails, a current flows from the upper transmission lines F ₁ and F ₂ and a current also flows from the upper transmission lines F ₃ and F ₄ through the mother CB. . Therefore, a 44S (I _L1 ) relay or 4
The 4S (I _L3 ) relay operates, the 44S (I _FT ) relay operates, and the 67S (I _BA ) relay also operates. When the lower transmission line L ₂ or L ₄ fails, the upper transmission line F ₃ , F ₄
A current flows from the upper power transmission lines F ₁ and F ₂ through the mother CB. Therefore, 4
4S (I _L2 ) relay or 44S (I _L4 ) relay operates, 44S (I _FT ) relay operates, 67S (I _L )
_AB ) The relay also works.

The above results are shown in the table below.

[0037]

[Table 3]

Therefore, as in the following equations (4) and (5),
S (I _FT ), 67S (I _BA ), 44S (I _L1 ), 4
An accident inside the bus A can be determined by a logical product of 4S (I _L2 ), 44S (I _L3 ) and 44S (I _L4 ) and the negation of the logical sum, and 44S (I _FT ) and 67S (I _AB )When,
A bus B is formed by a logical product of 44S (I _L1 ), 44 S (I _L2 ), 44 S (I _L3 ), and 44 S (I _L4 ) AND the negation of the logical sum.
It can be judged as an internal accident. That is,
It can be judged by (4) or (5).

[0039]

[Equation 3]

In the judgment according to the equations (1)-(5), a timed relay may be further added. When it is determined that an accident has occurred inside the busbar using the busbar short-circuit protection device described in the above embodiment, it is necessary to disconnect the busbar. In this case, use a differential current relay (87S relay) as the main protection device for the busbar,
If you are using the busbar short-circuit protection device for backup protection,
To prevent malfunctions, the logical sum current (O
The trip may be performed based on R), or the trip may be performed based on a logical product (AND) of determinations of both relays to prevent malfunction.

The present invention is not limited to the above embodiment, and for example, the number of lower power transmission lines may be one. In addition, in FIG. 5, the bus stations CB may be installed at both ends of the bus lines A and B. In this case, two for each mother communicating CB current transformer 6, a total of four are provided, the sum of the currents flowing through the respective mother communicating CB in a predetermined direction I _AB1 + I _AB2
And I _BA1 + I _BA2 are taken, and the sum current of these is preferably detected by the 67S relay. By doing so, the equipment of the protection relay (67S) when the number of the mother stations CB is one can be used as it is, so that the configuration of the protection device is simplified.

[0042]

As described above, according to the busbar short-circuit protection device of the first aspect of the present invention, it is possible to identify the internal busbar failure in the event of a short-circuit accident in the busbar. Also, performing a first fault detection relay determination based on a sum current of the currents flowing from each of the upper transmission line, a motor element characteristic of the first fault detection relay on the impedance plane, and a circle including the origin inside so as to, it is provided with the Blinder elements such that the reactance axis flat row, without malfunction healthy during large current, at the time of the accident can be reliably detected by the close-up fault such as an internal bus.

According to the busbar short-circuit protection device of the second aspect, the busbar internal failure determination according to the first aspect is performed, and
Further, it is possible to reliably determine which bus bar has the internal failure.

[Brief description of drawings]

FIG. 1 is an operating characteristic diagram of a 44S relay used in the present invention.

FIG. 2 is a diagram showing a single bus circuit in which a bus is connected to _two upper power transmission lines F ₁ and F ₂ and two lower power transmission lines L ₁ and L2 are output from the bus.

FIG. 3 is an operating characteristic diagram of a general 44S relay.

[Fig. 4] Two upper power transmission lines F₁, F₂Bus A is connected to
Similarly, two upper power transmission lines F ₃, F_FourBus B is connected to
From each bus to the lower transmission line L₁-L_FourIs connected
It is a figure which shows the existing bus circuit.

FIG. 5: Two upper power transmission lines F₁, F₂Bus A is connected to
Similarly, two upper power transmission lines F ₃, F_FourBus B is connected to
From each bus to the lower transmission line L₁-L_FourIs connected
Busbar A and busbar B can be selectively cut off
Is connected by a busbar breaker (called mother CB).
It is a figure which shows the compound bus circuit currently provided.

FIG. 6 is a circuit diagram of a main part showing a state in which a bus station CB is provided at each end of a bus bar in FIG. 5;

[Explanation of symbols]

CT current transformer F Upper transmission line L lower transmission line A, B bus

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H02H 7/22 H02H 3/36 H02H 3/40

Claims (3)

(57) [Claims] 1. A bus short-circuit protection device capable of coping with a short-circuit accident in a single bus circuit in which a plurality of upper power transmission lines are connected to a bus and one or a plurality of lower power transmission lines are output from the bus. there are a first fault detection relay which performs a determination based on the sum current of the currents flowing from each of the upper transmission line is installed for each subordinate transmission line, current flowing backward transmission line
Based on the logical product of the second fault detection relay which performs distance determination, a determination of the first fault detection relay, the negation of logical sum of the determination of the second fault detection relay based on, bus and a determination means for determining short-circuit failure of the inner, the first fault detection relay, the motor element on the impedance plane, so a circle including the origin therein, so that the reactance axis Rights ascending A busbar short-circuit protection device, which is a distance relay provided with a blinder element. 2. A plurality of busbars are connected to each other by a circuit breaker, and one or a plurality of upper power transmission lines are connected to each of the plurality of busbars, and one or a plurality of lower power transmission lines are provided from each busbar. a busbar short-circuit protection device which can correspond to the short circuit in the double busbar circuits out this, the first fault detection relay which performs a determination based on the sum current of the current flowing from the upper transmission lines to the bus, It is installed in each lower transmission line, current flowing backward transmission line
A second accident detection relay for making a distance judgment based on the above, a third accident detection relay for making a direction judgment by detecting a current flowing into a busbar through a circuit breaker, a judgment made by the first accident detection relay, A determination means for determining a short-circuit accident in any of the busbars based on a logical product of the logical sum of the determinations of the two accident detection relays and the determination of the third accident detection relay; the first fault detection relay, and wherein the motional elements on the impedance plane, so a circle including the origin therein, a distance relay provided with Blinder elements such that the reactance axis Rights ascending Bus short-circuit protection device. 3. The moh element of the first accident detection relay comprises:
A circle centered on the origin on the impedance plane
The busbar short-circuit protection device according to claim 1 or 2.