JPH0520972B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a line selective relay device, and more particularly to trip prevention control of a stationary disconnector removal circuit.

[Technical background of the invention]

BACKGROUND ART In recent years, the trend toward digitalization aimed at power system control, staticization using transistors and semiconductor blocking for protection equipment, and even microcomputer applications has been increasing significantly with advances in elements and information and communication technology.

Under these circumstances, even in the power grid protection field, digital relays that use microcomputers as digital technology applications are moving from the research stage to the practical application stage. However, even if the relay unit, which is the central part of the protection device, has been digitalized, the reality is that the interface with the disconnector and external control equipment has not yet been made static. One example of this is the system called the low-level system in the electric power system.
A line selection protection system applied to protect two-line power transmission lines in a power grid will be described below.

FIG. 4 shows an example of a typical tripping circuit. In the figure,
152AX and 252AX are respectively 1LCB for the 1st line 1L and 2LCB for the 2nd line 2L.
Auxiliary relay 1 driven by the main detection relay (1M relay) and failure detection relay (1F relay) output from the first line digital relay 1A, which is the normally open contact of the auxiliary relay that operates when the Noshiya disconnector is closed.
The a contact that is “closed” when MX and 1FX are activated is 1L.
It is configured so that the breaker 1LCB can be tripped.
Also, at this time, the digital relay 2A operates on the second line 2L side, and as a result, the main detection relay 2M and failure detection relay 2F operate, and the auxiliary relay 2
Even if MX and 2FX are closed, the first line 1L
The blocking auxiliary relay 150 is triggered by the side tripping command.
Since TL is energized and the tripping circuit on the second line side is open, no tripping current flows through the disconnector on the second line 2L side. This is because if the relationship between the first line 1L side and the second line 2L side is reversed, the above-mentioned control circuit will be reversed.
It is a problem in the protection system that the first line 1L side shedding command and the second line 2L side shedding command need to output blocking signals to each other.

FIG. 5 shows the necessity of this function.
That is, it is a schematic explanatory diagram of a line selection protection method. This method is described in detail on pages 306 onwards in Denki Shoin's ``Protective Relay Technology'' (written by Susumu Kobayashi). Here, the first line 1L side and the second line in FIG.
Only the necessity of mutual blocking auxiliary relays 150TL and 250TL based on the disconnection command to the line 2L side disconnector will be explained. Figure 5a shows that when a fault occurs at point _F on the 1L side near the
The fault current _2F is taken in via the L-side current input transformer 2B, and its differential current _SF is synthesized.

_SF = _1F - _2F ... (1) The differential current _SF becomes a positive value because the fault current _1F on the 1L side of the 1st line is larger than the fault current on the 2L side of the 2nd line, and it is determined that the fault is on the line 1 side, and the main Detection relay operating output 1M, failure detection relay operating output 1F
As a result, the auxiliary trip relays 1MX and 1FX on the first line 1L side in FIG. 4 are driven. As a result, the fiber breaker on the first line 1L side is tripped, and the fiber breaker 1LCB is opened, as shown in FIG. 5b. After that, the fault current flowing to fault point F is:
The current that had previously been flowing to the first line 1L side disappears and flows to the second line 2L side, and as shown in Figure 5b, the fault current ' _2F flows through the X terminal 2L side and becomes Y
It flows from the terminal 2L side to the first line 1L side and flows to the fault point F. Therefore, in the digital relay of the X terminal, the main detection relay and failure detection relay on the 2L side will output the operating side due to the current flow on the second line 2L side, and the trip condition will be satisfied. Become. However, due to the operation of the blocking auxiliary relay 150TL in the tripping circuit on the first line 1L side, the tripping circuit on the second line 2L side becomes 150TL.
Since the circuit is opened by the b contact of TL, it is possible to prevent the second line 2L side from being accidentally disconnected. However, the fault current ' _2F remains in the transmission line. The reason why this current is quickly cut off is that the current on the first line 1L side of the Y terminal flows toward the inside of the power transmission line. The device is controlled to trip, and as shown in Figure 5c, X and Y on the fault line 1L side are
Only the terminals and disconnectors are opened, and the terminals and disconnectors on the healthy line 2L side remain as they are, and power transmission and reception remain in a healthy state.

The above is a function called sequential disconnection of the line selective relay system, and explains the effectiveness of the above-mentioned mutual blocking signals on the first line 1L side and the second line 2L side. However, as mentioned above, along with digital relay technology based on microcomputers, there is an urgent need to replace the mechanical mechanism of the tripping circuit and the auxiliary relay that utilizes electromagnetic force with semiconductor elements. Under such circumstances, the application of a controlled rectifier element with a control pole (hereinafter referred to as a semiconductor switching element) is attracting attention in order to make the tripping circuit stationary. The operating functions of this element are described in semiconductor books and the like. FIG. 6 shows an example of the characteristics of a semiconductor switching element. The symbol of the element is b in the figure.
Shown below. (A, K, G) are the symbol names of anode, cathode, and gate, respectively. The reverse blocking region shown in FIG. 5A has substantially the same characteristics as a normal diode. The forward blocking region is different from that of a normal diode, and the blocking voltage changes depending on the gate current control. However, when it is in the high conduction region shown in the figure, it is the same as the forward state of a normal diode, but at this time the gate current is changed to _G1. from
Even if the gate level is lowered to _{the G2} state, the blocking state does not return. Further, to return to the blocking state, the voltage between the anode and cathode may be released or a reverse blocking voltage may be applied. In other words, the relationship between the high conduction region characteristics and the forward blocking region of a semiconductor switching element is
As shown in the figure, when the auxiliary relays 152TX and 252TX operate according to the tripping command,
This mode is the same as the mode in which operation continues until the disconnector on the first line 1L side is opened. When a circuit breaker tripping circuit is constructed by utilizing the characteristics of such a semiconductor switching element, it becomes as shown in FIG. When the main detection relay operation output 1M and failure detection relay operation output 1F output from the digital relays 1A and 1B operate, the semiconductor switching element 5 is activated via the gate input interfaces 5A and 5B.
A current is input to the gates of semiconductor switching elements 5C and 5D, and both semiconductor switching elements 5C and 5D become highly conductive regions. As a result, the breaker is opened, and the anodes and cathodes of the semiconductor switching elements 5C and 5D are opened, so that the blocking state can be maintained even if the breaker is turned on after a predetermined period of time.

In addition, in the circuit shown in Fig. 7, when a system fault occurs outside the protected area and failure detection relay 1F operates, the main detection relay is inoperative and 1M is inoperative, current flows to the gate of semiconductor switching element 5C. The semiconductor switching element 5D remains in the forward blocking state, and even if current flows through the gate of the semiconductor switching element 5D, no forward current flows between the anode and the cathode. Therefore, when the accident disappears and the gate current of the semiconductor switching element 5D disappears, the original state is restored.

The above is an application circuit of a control rectifier with a control pole when aiming to make a circuit breaker trip circuit stationary.

[Problems with background technology]

However, when such a semiconductor switching element is used, a signal that can confirm that a tripping command has been issued to the circuit breaker, ie, 152TX in Fig. 4, is generated.
A signal corresponding to 252TX cannot be created. 7th
152 in Figure 4 to the static trip circuit in Figure 4.
There will be no problem if you can connect TX, but it will greatly deviate from the purpose of staticization.

[Purpose of the invention]

The present invention has been made to solve the above-mentioned problems, and even when a semiconductor switching element is applied to a line-selective protection type line-breaker tripping circuit, it is possible to ensure that the line-breaker tripping circuit on the fault line side is It is an object of the present invention to provide a line selection relay device that can prevent faulty or disconnection of a healthy line by confirming that a fault or disconnection current has flowed.

[Summary of the invention]

In the present invention, a trip circuit using a semiconductor switching element is used instead of the contacts of the conventional line selection relay and failure detection relay, and the on/off operation of the semiconductor switching element is performed using a flip-flop element and a logic circuit. A signal that becomes ``1'' when there is no command to trip the disconnector of the other line is input to the set side of the flip-flop element, and at least one of the disconnectors of both lines is closed. By using the signal that becomes ``1'' as the reset side input and holding the set side input when the reset side input is ``0'', each semiconductor switching element is operated, and in the case of conventional contact operation. The same selectivity can be obtained even when the system is stationary.

[Embodiments of the invention]

Examples will be described below with reference to the drawings. FIG. 1 is a diagram showing an embodiment of a line selective relay device according to the present invention.

In FIG. 1, 5C1 and 5D1 are semiconductor switching elements, which correspond to the contacts 1MX and 1FX of the main detection relay and failure detection relay explained in the conventional example. 5A1 and 5A2 are gate input interfaces connected to the gate circuits of the semiconductor switching elements 5C1 and 5D1, into which the input from the digital relay 1A on the first line side is introduced.
The digital relay 1A has inhibit circuits 63M and 63F, and the inhibit input terminals of the inhibit circuits 63M and 63F are commonly connected to the output terminal of the flip-flop FF1.
Main detection relay 1M and failure detection relay 1 are connected to the other input terminals of inhibit circuits 63M and 63F, respectively.
Furthermore, the 250TL output from the second line side, which will be described later, is connected to the set input terminal S of the flip-flop circuit FF1, and the reset terminal R is common to the flip-flop FF2 on the second line side. and is connected to the NAND circuit 62.
In addition, the NAND circuit 62 has an open/close signal 15 for each of the first line and the second line and a pallet switch for disconnection.
2A and 252A are input. Further, photocouplers 6A1 and 6B1 are connected in parallel to the semiconductor switching elements 5C1 and 5D1, respectively, via a resistor 64, and the phototransistors of the secondary example are connected to the digital relay for the second line via the NOR ₁ circuit 61. It is connected to the set input terminal S of the flip-flop FF2 located at the flip-flop FF2. Furthermore, 152-a, 252
-a is the pallet switch for the fence and disconnector. Although the above explanation concerns the first line side, the second line side is also completely similar. and NOR on the second line side
Output 250TL from circuit 61 ₂ is FF for the first line
It is input to the set input terminal S of 1.

The operation of the line selection relay device having the above configuration will be explained.

First, the steady state will be explained. When both the first line disconnector 1LCB and the second line disconnector 2LCB are closed, the logic signals 152A and 252A are both "1", and the output of the NAND circuit 62 is "0". Therefore, flip-flop (FF1,
A “0” signal enters the reset R side of FF2),
Both flip-flops (FF1, FF2) depend on the state of the SET signal. Further, both semiconductor switching elements 5C1 and 5D1 are in the OFF state (forward blocking state), and one of the photocouplers 6A1 and 6B1 is in the OFF state (forward blocking state).
Current flows to the next side via the limiting resistor 64, and the outputs of the photocouplers 6A1 and 6B1 are both "1",
It is taken into the digital relay 1B on the second line 2L side via the NOR gate 61, and the flip-flop
It is input to the set S side of FF2. 2nd line 2L
The same can be said about the side photocoupler. In other words, the photocoupler output 250TL from the second line 2L side is taken into the digital relay 1A.
is input to the set S side of flip-flop FF1. Therefore, flip-flop FF1
When the output of is "0", the inhibit circuit 63
It is input to M, 63F.

Next, the response when the accident shown in FIG. 5a occurs on the first line 1L side will be explained. That is, the first line 1
If an internal accident occurs in L, digital relay 1
The main detection relay 1M and failure detection relay 1F of A are activated, and the outputs of the inhibit circuits 63M and 63F of the digital relay 1A are both "1".
And gate input interface 5A1, 5B1
Semiconductor switching elements 5C1, 5D1 via
turn on together and enter the high conduction region with the characteristics shown in FIG.
Current flows through the TC and it operates. As a result, the first line 1L side disconnector 1LCB operates to disconnect the first line 1L.
Signal 152 that becomes “0” when the L-shaped circuit breaker 1LCB opens
A is input, and the output of the NAND circuit 62 is "1"
Therefore, "1" is input to the reset side of flip-flop FF2 mentioned above, the output of digital relay 1B is blocked to "0" side, and the first line 1L
Even if the breaker opens due to an accident on the side, a trip command is output to the 2L side breaker 2LCB on the 2nd line 2L side, even though the condition corresponds to b in Figure 5. It is possible to prevent damage and breakage. Digital relays 1A and 1B mentioned repeatedly in the above explanation
The flip-flops FF1, FF2, or the inhibit circuit 63 inside are all for explaining the functions, and in reality, the captured fault information, disconnection information, etc. are processed by a program to satisfy the above functions. will be processed. Figure 2 shows a configuration diagram of the digital relay. The current and voltage obtained through the current input transformer CT and voltage input transformer PD in FIG. 2 are input to an input converter 21 that converts them to a predetermined output level. The output is input to a filter 22 for removing undesired frequency components, and the output is input to a sample hold circuit (S/H) 23 that samples at a constant sampling period and holds it until the next sampling, and its parallel output is converted into serial data. It is converted into a digital quantity by an analog-to-digital converter (A/D) 25 via an MPX 24 which converts it into a digital quantity. The data converted into digital quantities is stored in a data memory (RAM) 26, and a predetermined protection calculation is executed by the CPU 28 according to a program memory 27 that stores a protection calculation program.
In addition, auxiliary relay contacts 152A and 25 indicate the opening/closing status of the 1L side and 2L side disconnectors necessary for protection calculation.
The state of 2A is taken into the input/output interface 30 via the interface 29. Further, the results of predetermined protection calculation and logic control are outputted as a trip circuit command via the input/output interface 30 and the external mechanism interface. That is, the tripping circuit command corresponds to the outputs 1M and 1F in FIG. 1 and the outputs passed through the inhibit circuit. Further, the setting section 31 in FIG. 2 has a built-in interface and dedicated memory for taking in setting values necessary for relay operation determination calculations, etc.

Although the present invention has been described with reference to a semiconductor switching element only, it goes without saying that similar effects can be expected in a tripping circuit in which a conventional auxiliary relay contact is applied in place of the semiconductor switching element.
An example is shown in FIG. Auxiliary relay 1 in Figure 3
It goes without saying that MX, 1FX and 2MX, 2FX have the same purpose as the auxiliary relay shown in Figure 4.

〔Effect of the invention〕

As described above, in the present invention, even when a semiconductor switching element is applied to a disconnector trip circuit of a line selection protection system for the purpose of protecting two-line power transmission lines, which is widely applied as a protection system for low-level systems, it is possible to prevent accidents. By confirming that the disconnection current has definitely flowed to the disconnector on the line side, it is possible to prevent errors and disconnections on the healthy line side.

[Brief explanation of the drawing]

FIG. 1 is an embodiment of an inter-line trip prevention circuit applied to a line selective relay device according to the present invention, and FIG.
Figure 3 is a block diagram of a digital relay, which is a relay to which the present invention is applied, Figure 3 is a diagram of another embodiment of an inter-line trip prevention circuit, Figure 4 is an example of a conventional tripping circuit, and Figure 5 is line selection protection. Figure 6 is a characteristic diagram of a semiconductor switching element, and Figure 7 is a diagram showing an example of a circuit breaker tripping circuit for a semiconductor switching element. It is. 1A, 1B...Digital relay, 5A, 5B
...Semiconductor switching element gate input interface, 5C, 5D...SCR circuit, 6A1,
6B1, 6C1, 6D1...Photocoupler circuit.

Claims (1)

[Claims] 1. In a line selection relay device that protects a two-line power transmission line, the first means has a function of selecting the faulty line, the second means has the function of detecting the occurrence of an accident, and has a function of tripping the fault line or disconnector of the other line. “1” because there is no command to do so.
The signal that becomes ``1'' when at least one of the wires and disconnectors of both lines is closed is the reset side input, and when the reset side input is ``0'', the set side input is input. a third means having a flip-flop function for holding; a fourth means having an AND function which inputs the not output of the third means and the output of the first means; and the not output of the third means; a fifth means having an AND function that takes the output of the second means as an input; a sixth means that takes the output of the fourth means as an input and converts it to a predetermined level; A seventh means for converting the input to a predetermined level, and a controlled rectifier with a control pole for inputting the outputs of the sixth means and the seventh means to each gate to flow a shear breaker tripping current between the anode and cathode. Eighth means consisting of an element and a ninth means
means, tenth means and eleventh means for detecting that a predetermined voltage is applied between the anode and cathode of the eighth means and the ninth means;
When the outputs of the means and the eleventh means are input and both are in the state of "0", it is judged as "1".
That is, a line selection relay device comprising a twelfth means for detecting that a tripping command is not output to the tripping circuit of its own line.