JPS5970131A - 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.
Converter consisting of phase full wave bridge 3. Reactor 4. DC line5. Reactor 6, converter 7 with the same configuration as converter 3
and is connected to an AC system 9 via a transformer 8. A DC transformer 10 is installed at both ends of the DC line 50, that is, at its own end and at the opposite end. i
t is provided, and the output of the DC transformer 10 is connected to the differential amplifier 12.
The output of the DC transformer 11 is supplied to a transmitter 13. which constitutes a transmission device. The signal is supplied to the second input of the differential amplifier 12 via the transmission line 13a and the receiver 14. The output of the differential amplifier 12 is sent to the level detection circuit 1 via the delay circuit 15.
6, and when the value exceeds a predetermined value, a protection operation signal is supplied to a relay (not shown). The differential amplifier 12 to the level detection circuit 16 form a determination circuit for generating a protection operation signal.

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

By the way, when the current in the DC line 6 is significantly increased due to system operation requirements, the current flowing through the DC transformers 10 and 11 increases in the same way. However, the DC transformer 11
The output of transmitter 13. The signal is transmitted to the differential amplifier 12 via the transmission line 13a and the receiver 14 with a transmission delay. Therefore, even though this is not a malfunction, this transmission delay becomes large, resulting in a large difference between the first and second inputs of the differential amplifier 12, causing the level detection circuit 16 to output a protective operation signal, which causes the device to fail. Make it 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 countermeasures are not desirable because they slow down the response of the device even to actual failures.

This invention was made 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 of the DC line, the current value of the DC line at that time is memorized. By detecting the memorized content in the same way at the other end, and comparing it with the current value at the other end, which has been transmitted with priority over other signals, it is possible to accurately and accurately detect the stored content without being affected by transmission delays. It is an object of the present invention to provide a protective relay device that can quickly respond to a fault in a DC line.

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 symbols as in FIG. 1 indicate the same parts, and DC transformers 17 and 18 are installed at both ends of the DC line 5.
are connected, and the output voltage signal is input to a detection circuit 19, 20 that detects a voltage change of a predetermined value or more. The detection signals of the detection circuits 19.20 are sent to the storage circuits 21.20. Transmitter 1
3 is input. The memory circuit 21 also receives the output of the DC transformer 10, stores this as a detection signal, and supplies the stored contents to the first input of the differential amplifier 12.

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. As shown in the figure, the converter 7 (7i current margin ΔId has a set value 03 smaller than the set value 02 of the converter 3. In the figure, Id
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 is 02, the operating point of the converter 7 is 03, and a current difference ΔId occurs between them. This will be explained using the timing diagram shown in FIG. When a ground fault occurs at time tl, at time t2 after a time Tl, the current IR of the converter 3 becomes IRl, and the current IN of the converter 7 becomes INI. On the other hand, since the voltage Vd of the DC line 5 rapidly decreases from time 11, the detection circuits 19 and 20 output a detection signal at time t2 as shown in FIG. is stored and output. Therefore, the difference between the first and second inputs of the differential amplifier 12 increases, and the level detection circuit 16 performs a protective operation as shown in FIG. 4d at time t3 after time F2 corresponding to the transmission delay time. A signal is output to operate a circuit breaker (not shown).

In order to transmit the signal from the transmitter 13 to the receiver 14 as quickly as possible, the detection signal of the detector 20 is transmitted here according to the frame of the transmission format shown in FIG. In the figure, the address indicates the address of the receiver 14. The flags (Fl and F2) are set to "1" and sent by the transmitter 13 when the frame is occupied by the generation of the detection signal of the detection circuit 13, and the two bits of Fl and F2 are used for known priority transmission control. will be done. Here, the flag is given the highest priority code and sent. The data includes current INs. When transmission is performed cyclically at a speed of 48 KBS and a 44-bit frame (Figure 5 shows the case of 22 bits), the transmission delay time until the difference signal is input to the differential amplifier 12 is less than 1 ms, which is not practical. The value above is negligible.

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 value is selected so as to reduce the detection delay T1 in the detection circuit 19.20, and the detection circuit 19.20
A predetermined delay time circuit may be added to.

As described above, according to this invention, when a change of more than a predetermined value is detected in the voltage of the DC line, the current value of the DC line at that time is memorized, and the stored content and the other end are processed in the same way. Since the detected current value is compared, DC line failures can be detected without being affected by transmission delay fluctuations.
Detection can be performed with high precision, and the reliability of the device can be improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional protective relay device, FIG. 2 is a block diagram of a protective relay device according to an embodiment of the present invention, and FIG. 3 is a graph showing the characteristics of the converter shown in FIG. 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, 19.20...Detector, 21...Storage circuit. Note that the same reference numerals in the figures indicate the same parts. Agent Shin Kuzuno - (1 other person) 1
Diagram 2 Diagram 3 Diagram 4 Diagram 2 3. Amendment to diagram procedure (voluntary) Commissioner of the Japan Patent Office 1, Indication of case Relationship to patent application No. 57-181013 Patent applicant address Seven generations, Tokyo En Ward Marunouchi-Tai 112 total,
3* Name (601): Ryoji Soki Co., Ltd. Representative Hitoshi Katayama 4, Agent Address Higashi Jji J Tokyo Chiyome 1 Ward Marunouchi 2 J゛ Item 2-3 Details of the invention in the specification Explanation column 6, contents of amendment (1) Page 2 of the specification, line 5, line 6, line 7, line 20, line 2 of 3rd edition, page 4 of the specification, line 11 Correct the phrase "DC transformer" in the first line to "DC transformer." (2) About page 4, line 18 of the specification [The setting value osJ smaller than the setting value 02 is corrected to "setting value 02 smaller than the setting value 03." (3) In the 3rd line of page 5 of the specification, the statement ``The operating point is 02J'' is corrected to ``The operating point is o+J.'' (-1) In the 4th line of page 5 of the specification, ``The operating point is 5" is corrected to "The operating point is 0."that's all

Claims (1)

[Claims] A 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 more than a predetermined value, and the current value at the own end of the DC line is stored by the detection signal. a storage circuit that transmits a current value detected at the opposite end of the DC line by the detection signal to the own end with priority over other signals; - the memory contents of the storage circuit and the transmission device; and a determination circuit that generates a protection operation signal for protecting the DC line when a difference of a predetermined value or more is detected by comparing the current value of the other end received via the DC line. A protective relay device that protects the device from failure.