JPS5970132A - Protecting 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] The present invention relates to a protective relay device for a DC line.

Conventionally, there has been a protection relay device for DC lines as shown in FIG. In Figure 1, an AC system 1 includes transformers 2 and 3.
A converter 3 consisting of a phase full-wave bridge, a reactor 4, a DC line 5, a reactor 6, and a converter 7 having the same configuration as the converter 3.
and is connected to an AC system 9 via a transformer 8. A DC transformer IQ, 1 is installed at both ends of the DC line 50, that is, at its own end and at the opposite end.
1 is provided, and the output of the DC transformer 10 is connected to a differential amplifier 12.
The output of the DC transformer 11 is supplied to the second power of the differential amplifier 12 via a transmitter 13, a transmission 113a, and a receiver 14, which constitute a transmission device. The output of the differential amplifier 12 is supplied to the level detection circuit 16 via the delay circuit 15, and when the output exceeds a predetermined value, the output is output from the DC line 5.
A protection operation signal for protecting the power supply is supplied to a relay (not shown). The level detection circuit 16 for the differential amplifier 12 constitutes a determination circuit for generating a protection operation signal.

In operation, unless a ground fault occurs in the DC line 5, the first and second power of the differential amplifier 12 are approximately equal, so the level detection circuit 16 does not output a protection operation signal.

By the way, the current in the DC line 5 may be significantly increased due to system operation requirements, but in this case, the current flowing through the DC transformers 10 and 11 increases in the same way; The output of the transmitter 13, transmission line 13
a and the receiver 14 to the differential amplifier 12 with a transmission delay. Due to this transmission delay, the differential amplifier 1
2, a difference occurs between the first and second human forces, causing the level detection circuit 16 to output a protection operation signal, causing the device to malfunction.

In order to prevent such inconveniences, measures are taken to increase the time constant of the delay circuit 150 in response to transmission delays. However, such measures have the disadvantage of slowing down the response of the device even to actual failures.

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and when a change of more than a predetermined value is detected in the voltage at each end of a DC line, the current of the DC line at that point is changed. By holding the value, transmitting the current value of the other end to the own end for comparison, giving priority to the transmission of other signals, and comparing the current values detected at both ends, accurate and high-speed response can be achieved. The purpose of the present invention is to provide a protective relay device that can be obtained.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A protective relay device according to an embodiment of the present invention will be described below with reference to the drawings. In FIG. 2, the same reference numerals as in FIG. 1 indicate the same parts, and a DC transformer 17.
18 is connected, and its output voltage signal is input to detection circuits 19 and 20 that detect voltage changes greater than a predetermined value. Detection circuit 19゜200 detection signal is detected by detection circuit 21.22
is input. The detection circuit 21.22 is the detection circuit 19.2.
When a detection signal of 0 is output, the DC current transformer 10.11
The voltage signal is compared with a reference signal Iref that provides a current reference, and a difference signal between the two is derived. The difference signal of the detection circuit 21 is directly supplied to the first power of the differential amplifier 12, and the difference signal of the force detection circuit 22 is directly supplied to the transmitter 13, the transmission line 13. a and a receiver 14 to the second input of the differential amplifier 12 . The components below the differential amplifier 12 are constructed in the same manner as in FIG.

Next, the operation will be explained. The graph shown in FIG. 3 shows the characteristics when the converter 3 is controlled as a forward converter and the converter 7 is controlled as a reverse converter with constant current. Converter 3 is the third
The converter 7 has a set value O3 shown in the figure, and the converter 7 has a set value 0. It has a setting value 02 that is larger by a current margin ΔId. I(
1 is the DC current of the DC line 5, and Vd is the DC voltage of the DC line 5. When the DC line 5 is healthy, the converters 3 and 7 have an operating point of 01. However, when a ground fault occurs in the DC line 5, the operating point of the converter 3 becomes 02,
The operating point of the converter 7 is 03, during which the current difference ΔI
d occurs. This will be explained using the timing diagram shown in FIG. When a ground fault occurs at time t1, the current IR of converter 3 becomes IR□ at time t2 after time T0, and converter 7
The current will be IN 7J″-IN.

On the other hand, since the voltage Vd of the DC line 5 rapidly decreases from time tl, as shown in FIG.
9.20 outputs a detection signal, and the detection circuit 21.22 detects the difference signal between the current IR0, IN and the reference signal Iref at this time. The difference signal of the detection circuit 22 is sent to the transmitter 13,
The signal is transmitted to the second input terminal of the differential amplifier 12 via the transmission path 13a and the receiver 14. Therefore, the differential amplifier 12 further detects the difference between the difference signals of the detectors 21 and 22 and supplies it to the level detection circuit 16. Since this difference is greater than a predetermined value, the level detection circuit 16 outputs a protective operation signal as shown in FIG. make it work.

In order to transmit the signal from the transmitter 13 to the receiver 14 as quickly as possible, the detection signal of the detector 22 is transmitted here according to a frame of a transmission format as shown in FIG. In the figure, the address indicates the address of the receiver 14. The flags (Fol and F2) are set to "1" by the transmitter 13 when the frame is occupied by the generation of the detection signal of the detection circuit 13.
Known priority transmission control is performed using the two bits F and F2. Here, the flag is given the highest priority code and sent. Data is from detector 2
The content is the difference signal between the two. Transmission speed 48 KBS
, cyclically in 44 pit frames (22 bits shown in FIG. 5), the transmission delay time until the difference signal is input to the differential amplifier 12 is 1 ms.
The value is as follows, which is a value that can be ignored in practice.

In the above embodiment, the detection circuits 19 and 20 detect a voltage change of a predetermined value or more, but they may also detect a voltage change rate, voltage change width, etc. of a predetermined value or more. In addition, the detection delay T1 in the detection circuit 19°20
The detection value is selected so as to reduce the detection circuit 19.
．． A predetermined delay time circuit may be added to 20.

As described above, according to the present invention, when a change of more than a predetermined value is detected in the voltage detected from both ends of the DC line, the difference signal between the current value of the special DC line and the reference signal is detected. The difference signal at the other end is transmitted with priority over other signals via a priority-controlled transmission line, and the two difference signals are compared, allowing accurate response to failures in the DC line. This has the effect of increasing the reliability of the device.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a conventional protective relay device, and FIG. 2 is a block diagram of a protective relay device according to an embodiment of the present invention.
Figure 3 is a graph showing the characteristics of the converter shown in Figure 2;
4 is a timing diagram of the operation of the protective relay device shown in FIG. 2, and FIG. 5 is a transmission format diagram of the transmission device shown in FIG. 2. 1.9...AC system, 3,7...Converter, 5...
DC line, 12... differential amplifier, 13... transmitter,
14...Receiver, 16...Level detector, 19.2
0.21°22...Detector. In addition, in the figure, the same - month sign indicates the same part. Agent Shin Kuzuno - (1 other person) ml 1
Figure 35 2. One procedural amendment (voluntary) Mr. Commissioner of the Patent Office 1. Indication of the case Japanese Patent Application No. 181014/1982 2
, Title of the invention Protective relay device 3, Relationship with the case of the person making the amendment Patent applicant's representative Hitoshi Katayama Department 4, Attorney 5, Detailed description of the invention in the specification subject to amendment 6, Amendment Contents (1) Does it say "DC transformer" on page 2, lines 6, 7, and 8 of the specification, and on lines 3 and 4 of statement box 3m? Correct it to "DC current transformer". (2) Ming #I @ page 3, line 18, replace “voltage” with “
Correct it as "current". (3) On page 4, line 14 of the specification, "voltage signal J" is corrected to "current signal." (4) In the third line of page 5 of the specification, the phrase "constant current control" should be corrected to "operation." (5) “Set value O5” on page 5, line 4 and line 5 of the specification
A certain request is corrected as "setting value 0." (6) On page 5, line 6 of the specification, it says "Large setting value 02", but it should be corrected to "small setting value 03-1". (7) On page 7, line 14 of the specification, it says "voltage" Correct it with "current".

Claims (1)

[Claims] A first detection circuit is provided at the own end and the opposite end of the DC line and generates a detection signal when the voltage of the DC line changes by a predetermined value or more; a second detection circuit that detects and holds the difference between the value and a reference signal; and a transmission device that transmits the output signal of the second detection circuit at the opposite end to the own end with priority over other signals. , when a difference of a predetermined value or more is detected by comparing the output signal of the second detection circuit at the own end and the output signal of the second detection circuit at the other end received via the transmission device. A protective relay device that protects the DC line from failure, comprising a determination circuit that generates a protection operation signal for protecting the DC line.