JPS605728A - Differential protecting relaying device - 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 differential protection relay device (2) for detecting an internal fault occurring within a protection section of a power transmission line (2).

[Technical background of the invention and its problems]

There is a pilot relay type as a protective relay device for transmission lines, and one of them is an indicator line relay system.This indicator line relay system is shown in Figure 1 (2A). terminal (two currents flowing in and currents flowing out from the terminal IOA, Ion
'is: Input from each current transformer CTa e CTb I'', and introduce it through the display line PW to the display line relays RY, , RYb provided at each terminal (-), and connect the built-in differential circuit to each terminal (-). (= Yoshi zero phase difference ′ Flow is calculated, and this difference current determines whether there is a relationship between the amount of suppression and the schedule (υ), and whether it is an internal or external accident. In other words, under normal conditions (Secondly, the current flowing into the A terminal and the current flowing out from its own terminal are the same and no differential current occurs, so both relays RY and RYb are inoperative (-).On the other hand, in the event of an internal fault (2 is the A terminal (2 is the inflowing current and B
Since the current flowing out from the ends generates different differential currents, both relays RY, RYb and RYb operate.

However, if the general (2) cable is a cable system, the capacitance C of the (2) cable is large, so the charging current within the protection zone becomes large, which appears as a differential current and may cause malfunction. Therefore, it is necessary to take some kind of countermeasure. Conventionally, a relay as shown in Figure 2 (-) has been used to protect the high resistance grounding cable system from a ground fault.

In Figure 2, 1 is a current input conversion circuit, 1 is a current transformer C
Input the difference current factor 0 of the zero-sequence current detected by T, , c't'b, and output this (=proportional current factor 0'). 2 is a voltage input conversion circuit. Vessel RT.

(Input the zero-sequence voltage V at the A end detected from -,
This (; outputs a proportional voltage V.,'. 3 is a phase comparison circuit that compares the phases of υ, current I♂ and voltage V.,', and outputs when the phase difference is within a certain range. A relay output is produced via circuit 4. The operating characteristics of this relay are as shown in FIG.

However, in general C2, two compensation reactors are installed in the cable system (in order to compensate for the charging current), and in such a system, when recovering from a one-wire ground fault (inductance L and The dualized energy of the capacitance CCC is released through the resistor R.

Therefore, the transient zero-sequence voltage and current shown in FIG. 4 result.

The transient zero-sequence voltage and current at the time of accident recovery are determined by the system constant (=), but the frequency is generally not the commercial frequency, and the frequency f is given by the following equation.

In general (=, this frequency f is lower than the commercial frequency.The operating characteristics of the relay shown in Figure 2 (=) change as shown by the dotted line (b) in Figure 3) at low frequencies (2).Therefore,
The relay shown in FIG. 2 ζ 2 may malfunction due to transient voltage and current during failure recovery.

[Purpose of the invention]

The present invention was made in order to eliminate the above-mentioned drawbacks, and aims to provide a differential protection relay device that does not malfunction when recovering from an accident, even in systems with large charging currents such as cable systems. purpose.

[Summary of the invention]

In order to achieve the above objectives (2. At the time of accident recovery (
One of the difference currents between the zero-sequence voltage and the zero-sequence current that are compared in two phases is shifted by a predetermined phase angle to compensate for changes in operating characteristics at the time of recovery from an accident.

[Embodiments of the invention]

An embodiment of the present invention will be described with reference to FIG.

It should be noted that since the Shishi line connecting devices RY, , and RYb have the same configuration, they will be explained using two RY and + as representatives.

Figure 5 (22, 1 is a current input conversion circuit, 1st
Input the difference current Io of the zero-sequence current taken by the current transformers CT, , CTb in the figure, and calculate the proportional current ■
Output o'. 2 is a voltage input conversion circuit, and the zero-sequence voltage V at the A terminal is detected by the transformer PT in FIG.

1 is input, and a voltage Voa' which is proportional to it (2) is outputted. 5 is a change detection element, which operates when the zero-sequence voltage V changes in a decreasing tendency.

7 is a switching circuit, and the output of the current input conversion circuit 1 is 0'
At all times and when an accident occurs, the contact 7a side (2. When recovering from an accident, that is, when the change detection element 5 is activated, the opening is on the contact 7b side (:
Switch 9. 6 is a phase shift circuit, the input side is contact 7b
i=connected, voltage V. ′ by a predetermined phase angle, the voltage ■. 3 is a phase comparison circuit, and when the change detection element 5 is not operating, the current is 0' and the voltage is V.

a', and when the change detection element 5 is in operation, the current flow o' and °
The phase of the voltage V0□' is compared, and when the phase difference is within a certain range (=a relay output is generated via the output circuit 4).

Next (effects of the two embodiments) will be explained in two parts.

Within the protection zone 1: When an internal ground fault occurs, a zero-sequence current flows, and the difference current 0, which is the difference between the zero-sequence current at the A terminal (-) and the zero-sequence current at the B terminal (=), is the relay RY. , +2 people.At the time of an internal accident (2 is the zero-sequence voltage V.1 increases rapidly from 0 to a certain value (2), the change detection element 5 is inactive, and the phase comparator circuit 3 (: is , the output Io' of the current input conversion circuit 1, and the output vc, ' of the voltage input conversion circuit 2 are input.The phase difference between the current output O' and 'I@EEvO,' is indicated by the solid line in FIG. A relay output is generated when the signal is in the operating range indicated.

Second, after a system accident (internal or external) occurs,
Consider when the accident is removed. At the time of recovery from the accident, the zero-sequence voltage is V. Since there is a decreasing tendency (2), the change detection element 5 operates. Therefore, the phase comparison circuit 3 (2) shifts the output IO' of the current input conversion circuit 1 to the phase shift circuit 6 (= υ by a predetermined phase angle). The output current IO' and the output V of the voltage input conversion circuit 2
. , ′ are input. Current Io' shifted by a predetermined phase angle
and voltage V. When the phase difference between ``magnetic current Io'' and voltage V is in the operating range shown by the dotted line in Figure 4 (a relay output is produced. In other words, when the phase difference between the magnetic current Io' and the voltage V is in the operating range shown by the solid line) A relay output is generated (-).As mentioned above, the predetermined phase angle to be shifted by the phase shift circuit 6 is the zero-sequence voltage and current frequency at the time of accident recovery, which is lower than the commercial frequency. To compensate for the change in the operating range of relay C2 and relay RY, it is sufficient to set 2.

Furthermore, when the transient oscillation of the zero-sequence voltage Vat is attenuated to a steady state (=, the zero-sequence voltage V becomes zero and does not change, and the change detecting element 5 returns to its original state. Therefore, the phase comparator circuit 3
(2 is the output ♂ of the current input conversion circuit 1 and the output V of the voltage input conversion circuit 2.' produces an output.

In addition, the relay RYb is connected to the current input conversion circuit 1 (= is the difference current Io of the zero-sequence current) and the voltage input conversion circuit 2 (2 is the zero-sequence voltage at the b end. The structure may be the same as that of the relay RY shown in FIG.

According to this embodiment (2), at all times and when an accident occurs,
' and the voltages V, , l are compared in phase, and at the time of accident recovery, the voltage ■ is shifted by a predetermined phase angle from the 'magnetic current Io'. , ' are carried out for phase comparison (2), so that it is possible to prevent malfunction of the relay RY at the time of recovery from an accident. Therefore, reliability as a differential protection relay device is improved.

Next, another embodiment of the present invention will be described with reference to FIG.

FIG.
When not operating, the current is 0' and the voltage is V. , ' are phase-compared by the phase comparison circuit 3 (two people), and when the change detection element 5 is in operation, the voltage VA' and the current output is input to the phase comparator circuit 3 for phase comparison.

Even with this configuration (two relays RY, , RYb t-), malfunctions during accident recovery can be prevented as in the embodiment shown in Figure 5 (2). lags and advances a predetermined phase angle (two can be used and reversed).

In addition, in the embodiment (2) described above, whether or not it is the time of recovery from an accident is determined by detecting the change in the zero-sequence voltage v, 3, but the difference in the zero-sequence current The change in the current Io may be detected by the change detecting element 5 or may be determined.

Although the display line protection relay device has been described above, it is also applicable to a conveyor type protective relay system (2) such as an FM differential relay device.

〔Effect of the invention〕

According to the present invention (2), as explained above (2) systems with large charging currents such as cable systems (2), a differential protection relay device that does not cause false excitation during accident recovery (2). can be provided.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an example of a differential protection relay device, Fig. 2 is a block diagram showing a relay used in a conventional differential protection relay device, and Fig. 3 is a block diagram showing an example of a differential protection relay device. FIG. 4 is a waveform diagram showing the zero-sequence voltage and current at the time of accident recovery; FIG. 5 is a configuration diagram showing an embodiment of the present invention; FIG.
The figure is a configuration diagram showing another embodiment of the present invention. CT-, CTb...Current transformer, PT, , PTb・
...Transformer, 3.. Phase comparison circuit, 5.. Change detection element, 6.. Phase shift circuit, 7.. Switching circuit. (7317) Agent Patent Attorney Noriyuki Chika (and 1 others)
Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] Means for obtaining a zero-sequence difference current from the zero-sequence currents at the own end and the opposite end by transmitting the zero-sequence currents taken in at the own end and the opposite end through a transmission means, and a voltage transformer for taking in the zero-sequence voltage at the own end. When a change in at least one of the zero-sequence difference current and zero-sequence four voltages is detected and the change is on a decreasing trend (=
The operating change detection element inputs either the zero-sequence voltage or the zero-sequence difference current, outputs it to the first contact side when the change detection element is inactive, and outputs it to the first contact side when the change detection element is inactive ( 2-point side (a switching circuit that outputs -; a phase shift circuit that inputs the output of the second contact side and shifts the phase by a predetermined phase angle; A differential protection relay device comprising a phase comparator circuit that produces two outputs when the phase difference on the contact side is within a certain range.