JPS61191229A - Current differential relay - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a plurality of AC transformers (hereinafter referred to as CT
It relates to a protective relay device that applies a current differential method by introducing an input amount from a current differential relay (hereinafter referred to as
The present invention relates to a current differential relay device that allows inspection of a current differential relay (referred to as a current differential relay) without being affected by current.

[Technical background of the invention and its problems] The current differential method is a method that uses the difference between multiple input currents as the operating amount, and is widely applied to busbar protection, transformer protection, generator protection, power transmission line protection, etc. This is a useful method. Although the present invention can be applied to any of these current differential systems, the following description will be made using a bus protection device as an example.

FIG. 4 shows a configuration in which a current differential relay device is applied to bus bar protection. In addition, in the figure, for simplicity, two power transmission lines Ll and 12, and 2v bus lines Bus-A and BLJS are shown.
-B, the power transmission line L1 is the disconnector LSIA and LS1B, and the power transmission line L2 is the disconnector LS2.
A and LS2B protect the bus line Bus as a protection target.
-A.

The configuration is such that it can be arbitrarily connected to either Bus-B. In the figure, 1.2 is the input converter, 3.4 is the current differential relay, and 5.6.7.8 is the respective disconnector LS.
IA, LS1B, LS2A.

It is a normally open contact that is linked to LS2B and closes when there is only one disconnector.

In FIG. 4, disconnectors LSIA and LS2A are "on", that is, power transmission line L1. When L2 is connected to BLJS-A, the grid current is transferred to the respective current transformer CT1. CT
2 into input transducers 1 and 2. Furthermore, after being converted into a predetermined quantity of electricity by input converters 1 and 2, it is introduced into current differential relay 3 via normally open contacts 5 and 7 which are interlocked with disconnectors LSIA and LS2A. on the other hand,
Power transmission line L1. If L2 is connected to Bus-8, the output of input converter 1.2 is disconnector LSIB.

The current will be introduced into the differential relay 4 via normally open contacts 6 and 8 linked to LS2B. That is, bus line B
Information on the power transmission line connected to us-A is introduced into the current differential relay 3, information on the power transmission line connected to the bus bus-B is introduced into the current differential relay 4, and the current differential relay 3 is introduced into the current differential relay 4. Relay 4 protects Bus-A and bus Bus-8.

FIG. 5 shows an example of the characteristics of the current differential relays 3 and 4. In the diagram, if we take the inflow current on the horizontal axis and the outflow current on the vertical axis, the current trajectory during normal power flow or an external fault is on the +45° line, that is, the broken line in the diagram, and the current trajectory during an internal fault is on the horizontal axis. Therefore, if the relay is configured to have characteristics 9 or 10 shown in the figure, it is possible to distinguish between internal and external accidents. In reality, it has a ratio differential characteristic as shown by the hatching in the figure where 9 and 10 are ANDed. This characteristic can be obtained to some extent by changing the operating formula, but since the characteristic itself is not the essence of the present invention, a detailed explanation thereof will be omitted.

FIG. 6 shows details of one phase of the input circuit to the input converter and current differential relay.

In the figure, 1 is the input converter, 1-1.1-2 is the primary winding of the input converter, 1-1 is the winding that introduces the CT secondary current, and 1-2 introduces the inspection current. winding wire, 1-3.
1-4 is the secondary winding of the input converter, 1-5.1-6.1-
7.1-8 is a rectifying element. Here, the polar side of the winding (
If the one marked with ○ is positive and the other is negative, secondary winding 1
-3 The current flowing through rectifying element 1-7.1- during the positive half wave
6 becomes conductive and the output of the input converter is 11+, and at the time of a negative half wave, the rectifying elements 1-8, 1-5 become conductive and the output of the input converter is 1-. On the other hand, the current generated in the windings 1-4 is a current 1 corresponding to the input current (strictly speaking, a current inversely proportional to the turns ratio). The same applies to the input converter 2, and if the normally open contacts 5.7 are both closed, all of them are introduced into the current differential relay 3.

The current introduced into this current differential relay 3 is Σ
1+-11" +12 +, ΣI-=Is-+I2-,
Id=Tt +I2, and the actual waveform is: ■1
and the magnitude and phase of 12.
). In the figure, (a) and '(C) are the same as when an internal accident occurs on the busbar, and (b) is the same as when an external accident occurs. . and 3 are arbitrary constants), a current differential relay having characteristics as shown in FIG. 2 is obtained.

On the other hand, if the normally open contact 6.8 is "closed", the output of the input converter is introduced into the current differential relay 4, but the response in this case is similar to that of the relay 3.

Note that although the above description has been made using an example in which there are two input converters, the same effect can be achieved even in the case of three or more input converters. In addition, in an actual busbar protection device, a busbar to which many power transmission lines and transformers are connected is protected, but even in this case, disconnections such as LSIA, LSIB, 'LS2A, and LS2B shown in Fig. The normally open contact that works with the bus allows only the current of the power transmission line/transformer connected to the bus to be introduced into the current differential relay that protects the bus, which allows reliable internal/external determination. It can be done. Furthermore, the sixth
Although the figure shows a circuit for one phase, in reality, a circuit for three phases is required, and an additional amount of electricity may be required depending on the operating formula of the current differential relay.

However, when performing automatic inspection of this type of current differential relay, the following problems may occur. That is, in general, when performing automatic inspection of the characteristics shown in Fig. 5,
The operating side is inspected by applying the inspection currents phased out from point A shown in FIG. 8, and the non-operating side is inspected by applying inspection currents corresponding to 8 points. In this case, in order to widen the scope of automatic inspection as much as possible, it is common to inspect the input converter as well.
A test current is applied from the test winding 1-2 shown in FIG.

Furthermore, since two input converters are required to simulate point A or point B, any two input converters in the busbar protection device are selected. Here, by changing the check current applied to each input converter, the normally open contact linked to the disconnector of the input converter to be selected is "closed" and the normally open contact of the selected input converter is "open". If shown in the figure
.

The magnitude and phase of I2 can be controlled arbitrarily.

In this way, points A and B in Fig. 8 can be easily controlled, but as is clear from Fig. 6, the CT secondary current is also introduced to the primary side of the input converter, so in reality In this case, the power flow will be superimposed on the inspection current. Therefore, point A,
Point B varies within the ranges each surrounded by a broken line due to the influence of the tidal current. For example, the current Ilj? Assuming that point A moves to point A1 or point B to point B1 due to i, it is near the operating limit of the relay, and there is a possibility that it will not work when inspected on the operating side and will operate when inspected on the non-operating side, resulting in a defective inspection. There is. Therefore, in order to avoid such problems, point A,
Point B is simulated at a point sufficiently ahead of the operating limit point so that there is sufficient margin even if it is affected by the tidal current, but on the other hand, the influence of the tidal current acts in the opposite direction and points A Assuming that point A2 and point B have moved to point 82, by moving further away from the relay's operating limit, even if the ratio characteristics of the relay are checked, even if there is a change in the ratio characteristics of the relay due to some malfunction, it will not be detected. That would be impossible.

As described above, the conventionally employed current differential relay system has a problem in that highly accurate inspection cannot be performed because the relay is affected by the current when inspecting the relay. On the other hand, possible ways to solve this problem include adding a circuit that cancels the power flow during inspection, or adding two input converters exclusively for inspection to which no power flow is applied, but both of these methods involve This method complicates the process and is not desirable.

[Purpose of the Invention] The present invention was made to solve the above-mentioned problems, and its purpose is to perform highly accurate inspection without complicating the device and without being affected by currents. The object of the present invention is to provide a current differential relay device that is capable of

[Summary of the Invention] In order to achieve the above object, the present invention introduces a plurality of system currents in a power system into a current differential relay via input converters provided correspondingly to each other, and In a current differential relay device that protects a power system by using the difference in current as an operating quantity, when inspecting the current differential relay, two of the input converters installed corresponding to each line of the power system are checked.
A first circuit that connects the next winding in three phases in parallel, and an iris switch that is installed on the secondary side of the input converter and connects the protection target of the power system, a second circuit for selecting the system current introduced into the differential circuit 1, and a third circuit provided with a test winding for applying a predetermined test voltage i provided on the primary side of the input converter. During inspection, the first circuit eliminates the influence of power flow, the second circuit selects each line, and the third circuit applies inspection current to check the current. A feature is that the differential relay is inspected.

[Embodiments of the invention] An embodiment of the present invention shown in the drawings will be described below.

FIG. 1 shows a configuration example of a current differential relay device according to the present invention. The same parts as in FIG. 6 are given the same reference numerals, and the explanation thereof will be omitted, and only the different parts will be described here.

In Fig. 1, 1A, IB, and IC are input converters that convert the three-phase grid currents of the power transmission line, that is, the R, S, and T phases, into appropriate magnitudes, and the secondary output is connected to the current differential relay. 3A
, 3B, 3G and 4A.

We are trying to introduce it to 4B and 4C respectively. Also, 11
are the above current differential relays 3A, 3B, 3C and 4A, 4
A normally open contact that closes during inspection of B and 4C, which closes the input converter IA and 1 provided corresponding to each of the above lines.
-8.1G secondary windings 1-3 and 1-4 are connected in 3 phases (R,
(S, T phase) constitutes a one-check circuit connected in parallel.

Although Fig. 1 shows the configuration of the power transmission lines and circuits, in reality, the system current of other lines is also introduced in the current differential relays 3A, 3B, 3C and 4A, 4B, 4C. This is what we do.

That is, the current differential relay device according to this embodiment includes the current differential relay 3A in addition to the original current differential relay device.

When inspecting 3B, 3C, 4A, 4B, and iG, input converters IA and IB installed corresponding to each line of the power system
, a first circuit having a normally open contact 11 that connects the secondary windings 1-3 and 1-4 of the IC in three-phase parallel; and the input converters 1A, 1B, the secondary side of the IC. and the objects of protection of the power system (here, the bus BUS
Disconnector LS1A, L as a switch connecting s-B)
a second circuit comprising the normally open contacts 5 and 6 that select the grid current introduced into the current differential relays 3A, 3B, 3C and 4A, 4B, 4C in conjunction with SIB and LS2A, LS2B; and the input converters IA, IB,
The present invention is constructed by adding an inspection device comprising a third circuit provided on the primary side of the IC and comprising the inspection winding 1-2 for applying a predetermined inspection current.

Next, the operation of the current differential relay device having such a configuration during inspection will be described using FIG. 2. Note that in order to make the explanation easier to understand, FIG.
One of the secondary windings 1-3 from 1C is omitted, and only the other secondary winding 1-4 is shown. Actually, 1-3
It also has the same configuration as 1-4.

In FIG. 2, two input converters IA, IB, and 1C each
In the next winding 1-4, when the normally open contact 11 is closed in response to an inspection command, the same poles are short-circuited.

As a result, three-phase alternating currents each having a phase shift of 120° are synthesized on the secondary side of the input converter.

0, the current is introduced into the differential relay, and the output 1d becomes zero. Next, in this state, when a check current (single-phase AC) is applied to the check windings 1-2, currents of the same phase are output to the secondary windings 1-4, and an output is obtained by combining the three phases. Id becomes a value equivalent to three times the inspection current and is introduced into the current differential relay.

In this way, by short-circuiting the secondary winding of each input converter with the normally open contact 11 that is closed during inspection, the influence of the grid current, that is, power flow, introduced into the current differential relay during inspection is eliminated. In addition, only the inspection current can be introduced. In other words, this means that in the conventional inspection of a current differential relay, an output in which the inspection current and mm are superimposed is introduced into the current differential relay.
The inspection point is A1. Although it was necessary to consider moving to the range of A2 and B1.82 points, by configuring the circuit of this embodiment, it becomes possible to introduce only the inspection current to the current differential relay.

In the above example, the inspection windings 1-2 are installed in each rough metal, but since the secondary windings of each phase are short-circuited by the normally open contact 11, the installation for only one phase is not necessary for the other phases. Although it is possible to omit this, all three phases are provided in order to inspect the windings as well.

In addition, although the secondary winding 1-4 was explained in Fig. 2,
Actually, as shown in Figure 1, the secondary winding 1-3 is also 1-4.
Similarly, it is short-circuited by the normally open contact 11. Therefore, the power flow of the secondary winding output 11"1ll-1■ is removed at the time of inspection and only the inspection current remains, and the current differential relay 3A~
Introduced into 3C14Δ~4C. As a result, since it is only necessary to consider the inspection points A and 8 points in Figure 8,
It is possible to perform inspections with extremely high precision. Furthermore, it goes without saying that the inspection can be performed either all at once or for each digit.

As described above, according to the current differential relay device of this embodiment,
Since the secondary windings 1-3゜1-4 of the input converters 1A to 1C are short-circuited during inspection, the current differential relay 3A
~3C, 4A~4C, only the inspection current is introduced without the influence of the current, which makes it possible to perform highly accurate inspection and improve the reliability of the device.

Additionally, in the past, when checking the characteristics in the small current range,
In order to eliminate the influence of tidal currents, a separate input converter for inspection was provided, but according to this embodiment, the input converter for inspection can be omitted, and an extremely low-cost device can be obtained. becomes possible.

Next, FIG. 3 shows another embodiment of the present invention.
The same parts as in the figures and FIG. 4 are designated by the same reference numerals. Although only one phase is shown in FIG. 3, three phase circuits are actually required.

In the figure, 1.2 indicates each power transmission line L1. In the input converter that introduces the L2 system current, the secondary winding 1-4 has a normally open contact 11.
When the terminal connected to is pulled out and the normally open contact 11 is closed during inspection, the secondary windings 1-4 having the same polarity are short-circuited.

Although the figure shows the case of two power transmission lines, in reality, the secondary sides of the input converters of all the power transmission lines connected to the double bus Bus-A or BIJS-B in Figure 4 are connected in the same way. The normally open contact 11 is configured to short-circuit between the two terminals.

Now, it is well known that normally, except for an internal failure of the bus, the total current of the power transmission lines connected to the bus becomes zero.

Therefore, by short-circuiting the secondary side of the input converter using the normally open contact 11 as shown in FIG. 3 during inspection, the output Id introduced into the current differential relay becomes zero. Next, in this state, if a check current is input in the same direction to the check windings 1-2 of input converters 1 and 2, the currents in the secondary windings 1-4 are in the same phase, so they are output as a summed current. will be done.

Therefore, by configuring as in this embodiment, it becomes possible to introduce only the inspection current into the current differential relay while eliminating the influence of power flow during inspection as described above.

[Effects of the Invention] As explained above, according to the present invention, a plurality of system currents in a power system are introduced into a current differential relay via input converters provided correspondingly to each other, and When inspecting the current differential relay, which protects the power system by using the difference in current as an operating quantity, two of the input converters installed corresponding to each line of the power system A first circuit that connects the secondary windings in three phases in parallel, and a switch that is provided on the secondary side of the input converter and that connects the protection target of the power system to the current differential relay. Equipped with an inspection device consisting of a second circuit that selects the system current to be introduced, and a third circuit provided on the primary side of the input converter and equipped with an inspection winding that applies a predetermined inspection current. With this configuration, it is possible to provide an extremely reliable current differential relay device that can perform highly accurate inspections without complicating the device and without being affected by power current.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is a block diagram for explaining the operation of the same embodiment, FIG. 3 is a block diagram showing another embodiment of the present invention, and FIG. The figure is a configuration diagram when a conventional current differential relay device is applied, Figure 5 is a characteristic diagram of a current differential relay, Figure 6 is a detailed diagram showing a specific example of an input conversion circuit, and Figure 7 (a ) to (C) are waveform diagrams showing the current introduced into the current differential relay, and a characteristic diagram showing the inspection points in FIG. 8. 1, IA, IB, IC, 2...input converter, 3゜4.
3A~3'C';'4A~4C...Current differential relay,
5.6.7.8...Normally open contact that works with the disconnector, 9゜10...Characteristics of current differential relay, 11...Normally open contact that closes during inspection, 1-2...・Inspection winding. Applicant's agent Patent attorney Takehiko Suzue Kuranuki + 1 Yanagi Ka ω IRQ-

Claims (2)

[Claims] (1) A current that protects the power system by introducing a plurality of system currents in the power system into a current differential relay via corresponding input converters, and using the difference between the system currents as an operating amount. In the differential relay device, when inspecting the current differential relay, a first circuit connects secondary windings of input converters provided corresponding to each line of the power system in three-phase parallel; a second circuit that is provided on the secondary side of the input converter and selects a system current to be introduced into the current differential relay in conjunction with a switch that connects the protection target of the power system; 1. A current differential relay device comprising: a third circuit provided on the primary side of a converter and provided with a test winding for applying a predetermined test current. (2) The current differential relay device according to claim 1, wherein the first circuit connects the same phases of each line of the power system in parallel.