JPH0619405B2 - Disconnection detection device for PT secondary circuit - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a disconnection detection circuit of a secondary circuit of a PT which is an input signal source of, for example, a digital protective relay device, and particularly to a positive-phase three-phase voltage. It is an invention suitable for use in a protective relay device that synthesizes and uses a zero-phase voltage.

[Conventional technology]

8 and 9 are conventional PTs shown in "Protective relay engineering" P235-P236 published by the Institute of Electrical Engineers of Japan on July 20, 1981, for example.
(Voltage transformer) This is a circuit that detects disconnection of the secondary circuit.
(28) is a PT, a parent-child PT is used, and its output circuit has two sets (2
There are 8A) and 28B. (29) is a voltage balancing relay, (29b) is the output b contact of this voltage balancing relay, (30) is an output relay device that receives the output of the output circuit (28A) of the PT (28), and (30a) is this output It is a contact for the output of the relay device (30).

Next, the operation will be described. Two sets of PT (28) output circuits (2
8A) (28B), and the output of one set (28A) is input to the original device that uses it, for example, the output relay device (30) and one input end of the voltage balancing relay (29). , The other pair
(28B) should be input only to the other input terminal of the voltage balancing relay. Here, if the output of the PT (28) connected to the output relay device becomes an abnormal value for some reason (for example, disconnection), a difference occurs between the two inputs of the voltage balancing relay (29). The difference is detected by the voltage balance relay (29),
Notifying the outside or setting up the sequence shown in Fig. 9 to open the b contact (29b) of the voltage balancing relay (29) and close the a contact (30a) of the output relay device (30). , The circuit of the a-contact (30a) is not closed.

[Problems to be Solved by the Invention]

Since the conventional PT failure detection device is configured as described above, two sets (1A) and (1B) of PT (1) output circuits must be provided, and a voltage balancing relay (2) must be installed. Must
There were drawbacks such as higher costs.

The present invention has been made to eliminate the above-mentioned drawbacks of the conventional ones.
The purpose is to detect the disconnection of the next circuit.

[Means for Solving the Problems]

The PT secondary circuit disconnection detection device according to the present invention is provided for each of the three phases, and three phases (A phase, B phase) input from the PT are provided.
Phase voltage determining means for determining whether or not each of the phase voltages V _A , V _B , V _C of the phase, C phase) is a predetermined value ε ₁ or more, and the phase voltage determining means provided for each of the phases. One of the voltages V _A , V _B , and V _C has a phase delayed by a predetermined angle ε ₂ or more from the line voltage (eg, V _BC ) between both phases other than the one phase voltage (eg, V _A ). Of the phase voltage line voltage phase difference determination means of each phase for determining whether or not, the corresponding phase voltage determination means and the phase voltage line voltage phase difference determination means provided corresponding to each phase When the phase voltage of the corresponding phase receives each output and is equal to or greater than a predetermined value ε ₁ and the phase voltage of the corresponding phase is delayed from the line voltage of the other two phases by a predetermined angle ε ₂ or more, PT2 First computing means for outputting a subsequent circuit disconnection detection signal, provided between each phase (for example, A phase) and the adjacent phase (for example, B phase, C phase) provided corresponding to each phase. First line voltage discriminating means for discriminating whether or not the line voltage (for example, V _AB , V _CA ) is a predetermined value K ₁ or less, the phase voltage discriminating means and the phase voltage discriminating means provided corresponding to each phase Receiving each output of the first line voltage determining means, the phase voltage (for example, V _A ) of the corresponding phase is smaller than the predetermined value ε ₁ and the line voltage between the corresponding phase and the adjacent two phases ( For example
If both V _AB and V _CA are less than or equal to the predetermined value K ₁ , the PT
Second computing means for outputting a secondary circuit disconnection detection signal, provided corresponding to each of the three-phase line voltages V _AB , V _BC , and V _CA input from the PT, and the corresponding line voltage is predetermined. Second line voltage determining means for determining whether or not the value is smaller than a value K _{2, and when} both of the line voltages are smaller than a predetermined value K ₂ upon receiving an output from each of the second line voltage determining means. Third computing means for outputting a secondary circuit disconnection detection signal of the PT, and the first to third
A PT secondary circuit having a fourth arithmetic means for receiving each output of the third arithmetic means and outputting a secondary circuit disconnection detection signal of the PT when at least one of the first to third arithmetic means outputs It is a disconnection detection device.

[Operation] In the PT secondary circuit disconnection detection device of the present invention,
From the next side, the phase voltage of three phases, the line voltage, and the phase voltage phase difference between the line voltage is obtained, and whether these phase voltage, line voltage, and phase voltage between the line voltage have a predetermined relationship. Determine if PT
It is designed to detect the disconnection of the secondary circuit. Therefore, the output circuit of the PT has 3
There is no need to provide two pairs of phases, and there is no need to provide a voltage balancing relay that compares the output voltage of these two sets of output circuits. The output of one set of three-phase output circuits of PT to the secondary circuit of PT The disconnection can be detected and the disconnection of the PT secondary circuit can be reliably detected even when there is another line load in the PT secondary circuit.

Example of Invention

An embodiment of the present invention will be described below with reference to the drawings. First
In the figure, (1) is the three-phase power transmission line to be protected, (2) is the three-phase bus of the substation to which the power transmission line is connected, and (3) is the voltage of the bus that is easy to use for relay devices. Convert to 3
Phase PT (voltage transformer), (4) is the input part of the device that receives the voltage input from PT, (5), (6), (7) are the three-phase phase voltages V _A , V _B , V
Phase voltage detecting means comprising a circuit for outputting a signal when the magnitude of _C is larger than a certain value ε ₁ , (8), (9), (10), (11), (1
2) and (13) are first line voltage determining means composed of a circuit that outputs a signal when the three-phase line voltages V _AB , V _BC , and V _CA are smaller than a certain value K ₁ , and (14) is a vector. Phase difference between phase voltage line and voltage which consists of a circuit that outputs a signal when _A is delayed from _BC by an angle corresponding to ε _2. Similarly, (15) and (16) are _B
But from the _CA, the circuit _(A × _BC issuing a signal when _{the C} is delayed by a certain angle from the _BAB represents an outer product. That is _A
× _BC = | _A | · | _BC | · sin θ, θ is the angle of _A with respect to _BC )
(17), (18) and (19) are second line voltage discriminating means composed of a circuit which outputs a signal when V _AB , V _BC and V _CA are smaller than a certain value K ₂ , and (20) and (21). , (22) is a first arithmetic means composed of an AND circuit, (23), (24), (25) is a second arithmetic means composed of an AND circuit in which one of the three input terminals is an INHIBIT terminal, ( 26) is a third arithmetic means composed of an AND circuit, (27) is a fourth arithmetic means composed of an OR circuit, S ₁ , S ₂ , S ₃ , S ₄ , S ₅ , S ₆ , S ₇ are of PT 2 This is the next circuit disconnection detection signal.

Next, the operation will be described, but before that, what happens to each voltage vector input to the relay device when the secondary circuit of PT (3) is disconnected will be described. When the secondary voltage of PT is a phase voltage, they are received by the phase voltage in the relay device, but naturally the secondary voltage of PT is not limited to the digital protection relay device but also various devices (meters, various measurement control devices, etc.). (Inter-load) is also used, and some of them receive it as line voltage. These are shown in FIG. In FIG. 2, (31) is a voltage generating portion of the PT, (32) is a relay device which is trying to detect disconnection of the PT secondary circuit, and (33) is another line load. Now, as shown in FIG. 3, when one output line of the phase voltage V _A of the PT secondary circuit is broken, the phase voltage V _A input circuit of the relay (32) is not broken as indicated by the arrow. A certain voltage is generated due to the sneak from the phase voltage. Of course, when the line load (3) shown in FIG. 2 is not provided, the sneak circuit is eliminated, so that the phase voltage V _A of the relay (32) becomes zero. The above is written in a vector diagram as shown in Fig. 4. That is, the phase voltage V _A is the impedance ratio between the relay (32) and the other line load (33), and is located in the shaded area due to the difference in impedance of each phase. The vector relationship at this time is clear.The phase voltage V _A is the line voltage V _BC
It will be later. The delay is -30 ° to -150 ° as shown in Fig. 5. To explain this relationship in the embodiment of the present invention shown in FIG. 1, the absolute value of the phase voltage | V _A | predetermined value epsilon ₁
If it is larger, the output signal of the circuit (5) is turned on and the output signal of the delay determination circuit for the phase voltage V _A and the line voltage V _BC of the circuit (14) is present, so that one-phase disconnection of PT can be detected. In addition, when the absolute value of the phase voltage | V _A | is a predetermined value ε ₁ or less, that is, when there is no other line load and the phase voltage V _A of the relay (32) is almost 0, at that time, The line voltage V _AB is approximately equal to the phase voltage V _B, and the line voltage V _CA is equal to the phase voltage V _C. Therefore, by setting the predetermined value K ₁ to 63.5 V or more, which is the rated voltage of the phase voltage, the output signals of the circuits (8) and (9) are output, so that the disconnection can be detected. The detection of one-line disconnection in the other phase is also possible.

Next, the two-phase disconnection will be described. As shown in Fig. 6, PT
Phase voltage V _B from the case where the signal line of V _C is disconnected, the phase voltage V _B of the relay device (32), the circuit of V _C is the phase voltage V _A from the phase that is not broken indicated by the arrow As described above, it is applied through a sneak circuit from another line load. The vector diagram is as shown in Fig. 7. That is, since the phase of the phase voltage V _A is not broken, it becomes the rated voltage (for example, 63.5 V), and the other phase voltage V _B ,
V _C becomes smaller than the phase voltage V _A by the phase voltage V _A and phase. Therefore, the line voltages V _AB , V _BC , and V _CA are 63.5 of the rated phase voltage.
Since it becomes smaller than V, if a predetermined value K ₂ of the second line voltage discriminating means (17), (18), (19) in FIG. Disconnection can be detected.

Next, an example of specific values of the constants (ε ₁ , ε ₂ , K ₁ , K ₂ ) of each predetermined value shown in FIG. 1 of the embodiment of the present invention will be shown below.

The predetermined value ε ₁ is set to, for example, 3 V in consideration of the fact that it is sufficient that there is a phase voltage that allows direction determination. The predetermined value ε ₂ is the fifth
As shown in the figure, the sacking judgment is over -30 °, so
If you look at the allowance 10 ° and the signal is output when it is more than 20 °, ε ₂ = | V _A ｜ × | V _BC ｜ × sin θ ＝ 3V × 110V × sin (-20 °) =- 113 is recommended. Further, the predetermined value K ₁ may be set to be equal to or higher than the rated voltage of the phase voltage, but the relay error is 5%, the PT error is 1%,
Furthermore, considering that there is a maximum voltage increase of 10% during operation of the power system, 63.5 × 1.06 × 1.1 = 74.04V Furthermore, if the phase voltage V _A reaches 3V, which is the prescribed value ε ₁ , the line voltage V _AB, V _CA or equal to a predetermined value K ₁ = 78V from K ₁ <74.04 + 3 = 77.04V becomes larger by epsilon _1. Predetermined value K ₂ is 63.5V or less between each line when the PT2 wire is broken. Therefore, considering the error between the relay and PT and the maximum voltage rise, K ₂ ＞ 63.5 × 1.06 × 1.1 = 74.04V Predetermined value K ₂ = 75V is recommended.

In the above embodiment, the detection signal S ₇ is used to detect various PT secondary circuit disconnections. However, only the detection signals S ₀ , S ₁ , S ₂ or S ₃ , S ₄ , S may be detected as required. Only ₅ or S ₆ may be used, in which case only the circuit that obtains S ₀ , S ₁ and S ₂ ,
Alternatively, only the circuit for obtaining S ₁ , S ₂ , S ₃ or only the circuit for obtaining S ₆ may be used, and two of these circuits may be combined appropriately. Further, the phase voltage detection, the line voltage determination, the phase voltage line voltage phase difference determination, and the first to fourth calculations in the above-described embodiment may be processed by S / W using an electronic computer. Good.

〔The invention's effect〕

As described above, the present invention determines whether or not each of the three-phase voltage V _A , V _B , and V _C provided corresponding to each phase and input from PT is a predetermined value ε ₁ or more. Phase voltage determination means of phase,
One of the phase voltages V _A , V _B , and V _C provided corresponding to each phase is different from the one phase voltage (for example, V _A ) and another line voltage between both phases (for example, V _A ). _BC ), the phase voltage line-to-line voltage phase difference determination means for each phase for determining whether or not the phase is delayed by a predetermined angle ε ₂ or more, and the phase voltage determination means provided corresponding to each phase. And the phase voltage of the corresponding phase upon receipt of each output of the phase voltage line voltage phase difference determination means is equal to or greater than a predetermined value ε ₁ , and the phase voltage of the corresponding phase is more phase than the line voltage between the other phases. Is delayed by a predetermined angle ε ₂ or more, the secondary circuit disconnection detection signal of the PT is output, and the PT is provided corresponding to each phase. 3 phases (A phase, B phase, C phase)
Phase voltage discriminating means for discriminating whether or not each of the phase voltages V _A , V _B , V _C is equal to or more than a predetermined value ε ₁ and provided for each phase (for example, A phase) Next to each other (eg phase B,
The voltage between lines (for example, V _AB , V _CA ) between the C phase) is a predetermined value K ₁
A line voltage discriminating means for discriminating whether or not the following, and a phase voltage of a corresponding phase which is provided corresponding to each phase and receives each output of the corresponding phase voltage discriminating means and line voltage discriminating means (Eg, V _A ) is smaller than a predetermined value ε ₁ and both line voltages (eg, V _AB , V _CA ) between the corresponding phase and adjacent two phases are equal to or smaller than a predetermined value K _1. In addition, the calculation means for outputting the secondary circuit disconnection detection signal of the PT is provided, and further, the three phases (A phase, B phase) provided corresponding to each phase and input from the PT are provided. Phase voltage V _A ,
Phase voltage discriminating means for each phase for discriminating whether or not each of V _B , V _C is a predetermined value ε ₁ or more, and each of the phase voltages V _A , V _B , V _C provided corresponding to each phase _A phase voltage line for each phase that determines whether or not the phase is delayed by a predetermined angle ε ₂ or more from a line voltage (eg, V _BC ) between other phases different from the one phase voltage (eg, V _A ). The inter-voltage phase determination means, the phase voltage determination means provided corresponding to each phase, and the phase voltage between the phase voltage line voltage phase difference determination means receive the respective outputs and the phase voltage of the corresponding phase is predetermined. A first computing means for outputting a PT secondary circuit disconnection detection signal when the phase voltage of the corresponding phase is delayed by a predetermined angle ε ₂ or more with respect to the line voltages of the other phases with a value ε ₁ or more; The phase (for example, A
First line voltage determining means for determining whether or not the line voltage (for example, V _AB , V _CA ) between a phase and an adjacent phase (for example, B phase, C phase) is less than or equal to a predetermined value K _1. , The phase voltage (for example, V _A ) of the corresponding phase is smaller than a predetermined value ε ₁ by receiving the outputs of the phase voltage determining means and the first line voltage determining means that are provided corresponding to the respective phases. And, when any of the voltages between both lines (for example, V _AB , V _CA ) between the corresponding phase and the two adjacent phases is less than a predetermined value K ₁ , the secondary circuit disconnection detection signal of the PT is output. The second computing means for determining whether or not the corresponding line voltage provided corresponding to each of the three-phase line voltages V _AB , V _BC , and V _CA input from the PT is smaller than a predetermined value K ₂ second line voltage determining means for determining secondary circuit disconnection of the PT wherein when both of該線voltage receives the output of the second line voltage determining means a predetermined value K ₂ is smaller than Third arithmetic means for outputting a detection signal, and the PT if at least one output of said third arithmetic means receiving the outputs of said first to third calculation means
Since the configuration is provided with the fourth arithmetic means for outputting the secondary circuit disconnection detection signal of No. 2, it is not necessary to provide two sets of three phases of the PT output circuit as in the conventional one, and the outputs of these two sets are provided. There is no need to install a voltage balancing relay that compares the output voltage of the circuit, and the output of the one-phase three-phase output circuit of PT is
The secondary circuit disconnection can be detected, and the PT secondary circuit disconnection can be reliably detected even when the PT secondary circuit has another line load.

[Brief description of drawings]

1 is a connection diagram showing a PT secondary circuit disconnection detection circuit according to an embodiment of the present invention, FIG. 2 is a diagram showing a load connected to a PT secondary circuit, FIG. 3, FIG. 4, and FIG. The figure is for explaining the 1-phase disconnection of the PT secondary circuit, and FIGS.
8 is a connection diagram showing a conventional PT secondary circuit, and FIG. 9 is a connection diagram showing a sequence for preventing malfunction of the output relay due to disconnection of the PT secondary circuit. In the figure, (3) is PT, (5) (6) and (7) are phase voltage detecting means,
(8) (9) (10) (11) (12) (13) are first line voltage discriminating means, and (1
4) (15) (16) are phase voltage line voltage phase difference determination means, (17) (1
8) (19) is the second line voltage determination means, and (20) (21) (22) is the first
Computing means, (23) (24) (25) and the second arithmetic means, (26) a third calculating means (27) is the fourth computing means, S ₁ to S ₇ are PT2 primary circuit disconnection Detection signals, V _A , V _B , V _C are phase voltages, V _AB , V _BC , V
_CA is the line voltage. In the drawings, the same reference numerals indicate the same or corresponding parts.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (71) Applicant 999999999 Meiden Co., Ltd. 2-17 Osaki, Shinagawa-ku, Tokyo (71) Applicant 999999999 2-3 2-3 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation (72 ) Inventor Yoshifumi Oura 1-3-1, Uchisaiwaicho, Chiyoda-ku, Tokyo, Tokyo Electric Power Company (72) Inventor Kazuyoshi Yoshida 1-3-1, Uchisaiwai-cho, Chiyoda-ku, Tokyo Tokyo Electric Power Company (72) Inventor Eijiro Ibaraki 1-1, Tanabe-Shinden, Kawasaki-ku, Kawasaki-shi, Kanagawa Fuji Electric Co., Ltd. (72) Inventor Yasuhiro Kurosawa No. 1, Toshiba-cho, Fuchu-shi, Tokyo Toshiba Fuchu Factory, Ltd. (72) Inventor Seya Minoru 1-1-1, Kokubun-cho, Hitachi-shi, Ibaraki Inside the Kokubun factory, Hitachi, Ltd. (72) Inventor Toshiro Fujimoto 5-chome Gotanda, Shinagawa-ku, Tokyo No. 5-5 Meidensha Gotanda Office (72) Inventor Toshiki Hattori 1-2 1-2 Wadazaki-cho, Hyogo-ku, Kobe-shi, Hyogo Mitsubishi Electric Co., Ltd. (56) Reference JP-A-55-152473 (JP, A) JP-A-1-122319 (JP, A) JP-A-63-186522 (JP, A)

Claims (3)

[Claims] 1. _{A method} for determining whether or not each of the three-phase voltage V _A , V _B , and V _C , which is provided corresponding to each phase and is input from PT, has a predetermined value ε ₁ or more. phase voltage determining means, each phase of each the provided corresponding said phase voltages V _a, V _B, V _C
Each of the phase voltages of each phase determines whether or not the phase lags the line voltage between both phases other than the one phase voltage by a predetermined angle ε ₂ or more. , And the phase voltage of the corresponding phase is greater than or equal to a predetermined value ε ₁ by receiving each output of the corresponding phase voltage determining means and the corresponding phase voltage line voltage phase difference determining means provided corresponding to each phase. Moreover, when the phase voltage of the corresponding phase is delayed from the line voltage between the other two phases by a predetermined angle ε ₂ or more, the PT secondary circuit provided with a calculating means for outputting the secondary circuit disconnection detection signal of the PT. Disconnection detector. 2. A corresponding to each phase of each input from PT kicked response (A phase, B phase, C phase) phase voltage V _{A of,} V _B, V
Phase voltage discriminating means for each phase for discriminating whether or not each _C is a predetermined value ε ₁ or more, and a line voltage between the phase and a phase adjacent to each phase is a predetermined value. A line voltage discriminating means for discriminating whether or not K ₁ or less, and a phase corresponding to each phase which is provided corresponding to each phase and receives the respective outputs of the corresponding phase voltage discriminating means and line voltage discriminating means. Phase voltage is a predetermined value ε ₁
If both of the line voltages that are smaller and that are between the corresponding phase and the adjacent phases are both less than or equal to a predetermined value K ₁ , the PT is 2
PT2 equipped with a calculating means for outputting a subsequent circuit disconnection detection signal
Disconnection detection device for the next circuit. 3. A phase voltage V _{A of} three phases (A phase, B phase, C phase) provided corresponding to each phase and inputted from PT,
Phase voltage discriminating means for each phase for discriminating whether or not each of V _B , V _C is a predetermined value ε ₁ or more, and each of the phase voltages V _A , V _B , V _C provided corresponding to each phase One phase voltage line-to-line voltage phase difference determination means for determining whether or not the phase is delayed by a predetermined angle ε ₂ or more from the other line-to-line voltage different from the one phase voltage. The phase voltage of the corresponding phase is given a predetermined value .epsilon. By receiving each output of the phase voltage determining means and the phase voltage line voltage phase difference determining means provided corresponding to each phase.
_If the phase voltage of the corresponding phase is ₁ or more and the phase is delayed from the line voltage of the other two phases by a predetermined angle ε ₂ or more, PT
A first calculating means for outputting a secondary circuit disconnection detection signal, a line voltage between the phase and a line voltage between adjacent phases, which is provided corresponding to each phase, is a predetermined value K. _{A first} line voltage determining means for determining whether or not it is ₁ or less, the corresponding phase voltage determining means provided corresponding to each phase, and receiving the respective outputs of the first line voltage determining corresponding phase. Of the secondary circuit disconnection detection signal of the PT when the phase voltage is less than the predetermined value ε ₁ and both line voltages between the corresponding phase and adjacent two phases are less than the predetermined value K _1. Second computing means for outputting
A second line voltage determination which is provided corresponding to each of the three-phase line voltages V _AB , V _BC , and V _CA input from the above and determines whether or not the corresponding line voltage is smaller than a predetermined value K _2. Means for receiving the output of each of the second line voltage determination means and outputting a secondary circuit disconnection detection signal of the PT when any of the line voltages is smaller than a predetermined value K _2. And a fourth arithmetic means for receiving the outputs of the first to third arithmetic means and outputting a secondary circuit disconnection detection signal of the PT when at least one of the first to third arithmetic means outputs. PT secondary circuit disconnection detection device provided.