JPS6230442Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement in an inspection method for a protective relay device.

In recent years, protective relay devices that protect power systems from abnormal accidents have been made stationary to achieve higher sensitivity, higher speed operation, and lower burden. However, due to the large number of parts used, measures have been taken to improve reliability. It is common to have an inspection function. To this end, various methods for inspecting protective relay devices have been proposed. When inspecting the relay connected to the main CT circuit, the secondary circuit of the main CT should never be opened, and the current should not affect the inspection performance, or even if it does, it should not interfere with pass/fail judgment. There must be a method that does not. A method that satisfies these conditions is to cancel the constant current and then apply a check current.

An example of a conventional inspection circuit is shown in FIG. 1 is the power system to be protected, 2 is the main CT,
5 is a relay, 3 is an input converter for the relay 5, 4 is the main winding of the relay, 6 is an operation determination section, 7 is a power source for inspection, 8a1 and 8a2 operate according to an inspection command given to inspect the relay 5. 8b is the normally closed contact of the auxiliary relay (not shown), 9 is the auxiliary current transformer (hereinafter referred to as cancel CT) for canceling the power flow, and 9-1 is the main CT
The winding connected to the circuit, 9-2 is its secondary winding,
9-3 is a winding connected to the inspection power source 7 via a normally open contact 8a1. 10 is a nonlinear resistance element that suppresses overvoltage in the cancel CT secondary circuit.

The secondary current I _M of the main CT circuit is always supplied to the input converter 3 of the relay 5 through the winding 9-1.
At this time, the secondary current i _M of the cancel CT 9 circulates through the normally closed contact 8b and the winding 9-2, and has no effect on the relay 5.

Next, when the normally open contacts 8a2 and 8b operate according to the inspection command given to inspect the relay 5, the secondary current i _M of the cancel CT9 changes from the winding 9-2 to
Contact 8a2 → main winding 4 of input converter 3 → winding 9-
2, and only the difference between I _M and the current i _M having the opposite phase flows through the main winding 4 of the input converter 3. At this time, if the turn ratio of the canceller CT 9 is selected so that |I _M |=|i _M .

On the other hand, when the inspection current I _T is applied to the winding 9-3 from the inspection power supply 7 as shown in the figure, the secondary current i _T flows to the main winding 4 of the input converter 3, so cancel CT9
By appropriately selecting the turns ratio of the windings 9-2 and 9-3, it is possible to obtain a check current of any current value and unaffected by the current. Moreover, according to this method, there is no direct contact in the secondary circuit of the main CT, so there is no risk of the CT secondary opening due to poor contact, etc., and a check current is not applied to the main winding of the input converter of the relay. This allows for a wide range of inspections and highly reliable inspections.

However, protective relay devices are generally configured by combining two or more types of relays with fail-safe considerations in mind, and considering the priority of accidents during inspection, it is not desirable to cancel the main CT secondary circuits of all relays at the same time. Therefore, as a conventional method of prioritizing accidents, for example, in the case of a device that issues a trip command to a disconnector under conditions where both a distance relay and an overcurrent relay are activated, inspection of the distance relay is canceled.
A CT is used to check the quality of distance measurement performance, but a method that does not use a cancel CT to check overcurrent relays is recommended, or a dedicated cancel CT is used for both relays.
By adopting a CT method, one of the relays is always connected to the main CT circuit during inspection.
They conducted independent inspections to ensure that they could respond to system accidents. In the former case, a cancel CT is not used to inspect the overcurrent relay, so the inspection uses an auxiliary winding for inspection, resulting in an inspection that is less reliable and less accurate than an inspection performed from the main winding of the relay. I have no choice but to do so. In the latter case, inspection can be performed from the main winding of the relay, which increases reliability and inspection accuracy, but doubles the number of cancel CTs, which goes against the trend toward downsizing of equipment. Figure 2 shows a circuit diagram of a conventional method in which a dedicated cancel CT is used for each relay. Subscripts A and B of 3, 4, 5, 6, and 9 indicate different relays 5A and 5B, and those having the same numbers as those in FIG. 1 are the same or have the same functions. Contacts 8a1, 8a2, 8b are contacts 11a1, 11a of an auxiliary relay (not shown) that operates according to an inspection command given to inspect relay 5A.
2, 11b is an auxiliary relay (not shown) that operates according to an inspection command given to inspect relay 5B.
8 and 11 are controlled so that they do not operate at the same time. The method of canceling the power flow of the relays 5A and 5B and the method of applying the inspection current are the same as in the case of FIG.

The present invention was developed in view of the above points, and aims to provide an inspection method that allows inspection from the main winding of a relay without increasing the number of cancel CTs.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 3 is a diagram showing an embodiment for reducing the number of cancel CTs by applying the present invention to the circuit shown in FIG. 2. Components with the same numbers as in FIGS. 1 and 2 are assumed to have the same or the same functions. In this embodiment, the relays are divided into two groups, and each group is provided with one relay. That is, the relay 5A is arranged in the first group, and the relay 5B is arranged in the second group.

A normally open contact of an auxiliary relay (not shown) that operates in response to an inspection command to inspect relay 5A is connected to 13a.
1, 13a2, and the normally closed contact is 13b. In addition, normally open contacts 14a1, 1 of an operating relay (not shown) that operates in response to an inspection command to inspect the relay 5B are connected.
4a2, and the normally closed contact is 14b. Now relay 5
The case of inspecting A will be explained. If the secondary current I _M of the main CT2 flows in the direction of the arrow in the primary winding 9-1 of the auxiliary CT9, then the secondary current i _M flows in the direction of the arrow in the secondary winding 9-2 of the auxiliary CT9. flows.
At this time, when the contacts 13a1, 13a2, and 13b operate due to the inspection command to check the relay 5A, the auxiliary
Secondary current i _M of CT9 is contact 13a2 → relay 5A
The main winding 4A → the contact 13a1 → the secondary winding 9-2 of the auxiliary CT 9 are circulated. Main winding 4A of relay 5A
The primary current I _M and the secondary current i _M of the auxiliary CT 9 flow in opposite phases, and the number of turns of the auxiliary CT 9 9-1 and 9-2 is adjusted so that |I _M |=|i _M | If the ratio is selected, the apparent current in the main winding 4A becomes zero. The secondary winding 9-2 of the auxiliary CT 9 is connected to 13a1 and 13a so as not to cause a secondary open in the auxiliary CT circuit.
2 and 13b use contacts whose operations overlap as shown in the time chart shown in FIG. In addition, in case the contacts do not wrap, the non-linear resistance element 1
Make sure that overvoltage does not occur due to zero voltage, etc.

On the other hand, a test current I _T is applied in the direction of the arrow from the test power source 7 to a winding 9-3 wound around the same core as the primary winding 9-1 of the auxiliary CT 9 through a contact 12a that is closed during the test. Then, a current i _T in the opposite direction to i _M flows through the secondary winding 9-2 of the auxiliary CT 9,
The inspection current flows through the main winding 4A of the relay 5A in the reverse order of _iM . In other words, main winding 4 of relay 5A
At A, the tidal current I _M is canceled and only the inspection current i _T is applied. If the magnitude of this inspection current i _T is appropriately selected, the inspection of the relay 5A can be carried out from the main winding without being affected by the current. Next, in order to inspect the relay 5B, the contacts 14a1, 14a2 of the auxiliary relay, which are activated by the inspection command to inspect the relay 5B in the same way as the inspection of the relay 5A, are
14b, only i _T is applied to the main winding 4B of the relay 5B using the same auxiliary CT 9 as used for inspecting the relay 5A, as in the case of inspecting the relay 5A. If other elements (for example, voltage) are required for these relay operating conditions, the elements taken out from the inspection power supply 7 may be used as the relay 5A or 5.
It is sufficient to apply it to B.

As described above, according to the method of the present invention, one cancel cell can be transmitted from the main winding of the CT circuit of the relay to two different groups of relays without being affected by the power flow.
Since inspection can be performed independently using CT, reliability is high, and since only a small number of cancel CTs are required, it is economical and extremely effective in downsizing the equipment. In this embodiment, we have explained the case where two relays are divided into two groups, but as shown in Fig. 6, relays with similar detection functions (for example, a short-circuit distance relay and a ground-fault distance relay) are grouped together as a group. You can cancel the current by doing so.

In FIG. 6, relays 5A1 and 5A2 are a short-circuit distance relay and a ground-fault distance relay, respectively,
The relays 5B1 and 5B2 may be combined as a short circuit overcurrent relay and a ground fault overcurrent relay. The relays to be combined are not limited to those in this embodiment, and any combination may be used.

Also, for n groups of relays, n/2
Similar inspection can be performed using (n: even number) or n+1/2 (n: even number) cancel CTs. 2 cancells for 4 relays 5A, 5B, 5A', 5B'
An example in which CT9 and CT9' are applied is shown in FIG.

Furthermore, if the present invention is applied to a dual-sequence device using the same main CT, it is also possible to independently inspect each one-sequence using one cancel CT.

FIG. 8 is a diagram showing an example of the embodiment. If 31A is the first series and 31B is the second series, each series can be inspected using one cancel CT. Even if a system fault occurs during inspection, the relays in the remaining series can respond normally and issue a trip command without any time delay, making it an extremely reliable protective relay device.

In this explanation, everything has been described for one phase, but it goes without saying that this can be multiplied by three to apply to a three-phase circuit.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an example of a conventional power flow cancel circuit, Fig. 2 is a diagram showing a conventional device for canceling the power flow of two relays, and Fig. 3 is a diagram for explaining an embodiment of the present invention. 4 are time charts showing the contact coordination of the circuit of FIG. 3, and FIGS. 5 to 7 are circuit configuration diagrams for explaining other embodiments of the present invention. 1...Protection target, 2...Main CT, 3...Input converter, 9...Auxiliary current transformer.

Claims (1)

[Claims for Utility Model Registration] (1) A main current transformer that inputs terminal current flowing through the protected object, transforms it, and outputs a secondary current, and is connected in series to the secondary circuit of this main current transformer. is,
and m relay input converters (m≧n) divided into n groups (n: an integer of 2 or more), and a main current transformer secondary circuit that connects each group of the input converters. The main current transformer 2 is inserted into the main current transformer 2.
an auxiliary current transformer comprising a primary winding through which a secondary current flows, a secondary winding electromagnetically coupled to the primary winding, and a check winding; and polarity of the current induced in the secondary winding of the auxiliary current transformer. Connect both terminals of the secondary winding of the auxiliary current transformer to both terminals of the relay input converter of each group so that the polarity of the current flowing through the relay input converter is opposite to that of the current flowing through the relay input converter. In each of these n closed circuits, the auxiliary current transformer 2
a pair of switch elements that are respectively inserted between both terminals of the next winding and both terminals of the relay input converter of each group, and are closed only when inspecting the relays in each group, and are normally open; Two switch elements are connected in series between both terminals of the secondary winding of the auxiliary current transformer, and these terminals are normally short-circuited and open only when inspecting the relays in the group. and a switch element for applying a test power source to the auxiliary current transformer test winding. (2) A protective relay device according to claim 1 of the utility model registration, characterized in that the number of relays in each group is one or more. (3) In the utility model registration claim described in paragraph 1, for relays divided into n groups, n/2 (where n is an even number) or (n+1)/2 (where n A protective relay device characterized by having an odd number of auxiliary current transformers.