JPS58204720A - Difference protecting relaying device for dc transmission line - 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 differential protection relay device that differentially protects currents at both ends of a DC power transmission line by transmitting them to each other in DC power transmission.

A conventional device of this type is shown in FIG.

In the figure, (1m) and (lb) are AC systems, (2a)
, (2b) is a converter consisting of an 8-phase full-wave bridge, (8a
), (8b) is a DC reactor, (4) is a DC transmission line,
(5) is return line, (6a), (6b), (?a), (7b
) is a DC current transformer, (8a) and (8b) are converters (2
In the control devices of a) and (2b), (9) is a DC current setting device, and a direct current setting value 1ref is given to the terminal X. Further, the current margin Δ is given to either one by the changeover switch θq from the terminal y. This selector switch Q (e is given to the right control device [(+ to 8),
The command value is (ref - Δ), and it is well known that the terminal serves as an inverse converter (hereinafter abbreviated as INV) and an opposite side as a forward converter (hereinafter abbreviated as RKO). . (
lla) and (llb) are signal transmission devices.

Figure 2 shows the voltage-current characteristics of this DC power transmission, where Kd is 1
A current voltage and d indicate blood flow current, and the intersection point N between the RKO side and the IMV side represents the normal voltage and current, and the respective values are Va and IN. Therefore, in normal times, an appropriate amount of current IN flows through the DC transmission line (4) and return line (5).

When a failure like the one shown at the 7 points in Figure 1 occurs, the operating point is
The current becomes Fa and Fb in FIG. 2, and the current has a magnitude of I, and a current of E=E from R1 flows through the DC current transformers (6sL) and (6b), respectively. Therefore, there is a difference of M-I l1 = I R-I X = Δ. As a means for detecting that a failure has occurred in the DC power transmission line (4), a method of detecting the difference between the M and the twist is adopted.

In Fig. 1, (12a) and (12b) are the differential protection relay device for this first feed line, and the DC current transformer output and signal transmission device b! it (18a), (18b)
2 of the free current transformer output of the mating terminal given through
Enter two and find the difference. Note that ', Ka,
Kb is its output steep terminal. ,.

FIG. 8 is a time chart showing the response of the differential protection network electrical equipment, in which (a) shows the current M on the REC side at the time of failure, and (b) shows the current on the INV side. There is. (
C) represents the difference between A-1B, and when the current control responds, it falls within a constant value as -ΔH from M-. Now, if the operating formula of the differential protection network electrical system is set from 1 m to 1 to -j, if a difference of 96 times greater than the fixed number of lawns occurs in the differential delta, it is determined to be a failure. The dashed line indicates K. Noe. ) outputs an output when the value of A- is greater than K・Δ, and after checking this condition for a certain period of time, the output is output (
(e) and sends it to terminals Ka and Kb in FIG.

Figure 4 is expressed in terms of ratio characteristics, where the dotted line indicated by ΔΔΔ is the current value at the time of failure, and the dash-dotted line indicated by the operating characteristic is the operating formula 1mu-IB. It is K・Δengineering.

Since the conventional differential protection relay device is configured as described above, the value indicated by K-cutting is small, and very strict management is required. In other words, ΔWork 4: is '#IeL margin approximately 10% of the rated current.
It is normal to be exposed to a certain degree, and it is common to have problems with turtle blood and set value engineering.
When ef is near the rated current, it is about 1096 for IR and IN. If the constant is set to about 0.6, K·Δ will need to be set to about 696 of the rated current. This value is a very strict value considering hardware errors and errors in the transmission device, and strict error management is required.

In the operation of the system, even if there is no failure, a difference occurs between the currents at both ends, and if this value exceeds K.DELTA., there is a possibility of malfunction.

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and takes advantage of the fact that the voltage is established during normal times, and uses this voltage to activate the differential protection relay device. It is an object of the present invention to provide a differential protection relay device that provides a suppressing force.

An embodiment of the present invention will be described below with reference to the drawings. Fifth
In the figure, (14a) and ('14b) are DC voltage transformers that detect the voltage of DC transmission wIL* (4) and apply it to differential protection network electrical equipment Tll (12a) and (12b). M is created by setting the voltage to Va. -■B≧K・Δtech +η・V'dη is a constant. From this equation, since Va is a large value in normal times, the right side can be set to a large value. Therefore, even if some error occurs in the machine 1, there is no risk of malfunction. If a failure occurs, as can be seen from Figure 2,
Since Va=O, the suppressing force is K・Noe+η・V(
Only 1=K・Δwork is the same as the conventional operation formula.

FIG. 6 is a time chart, and (a) and (b) are current waveforms on the RKO side and the INV side, respectively. (C) shows the voltage Va of the DC transmission line, and when a failure occurs, Vd=0
becomes. 4 shows kmu k1 and K・Δk+η・Va. (E) is the output for a period that satisfies the operating formula, and (F) is the output that was confirmed for a certain period of time.
@6 Output from terminals Ka and Kb in Figure.

FIG. 7 shows the ratio characteristics, and since the suppressing force of the operating type is strong in normal times, the operating characteristics are a one-point chain curve as shown when the voltage is normal. If a failure occurs, the operating characteristics shift to the dash-dotted line indicated by the voltage drop. Therefore, more =
The operating output will be output by covering the current at the time of failure as shown by EmuΔ.

In addition, if a fault other than the DC transmission line occurs, such as a ground fault within the converter station, a converter arm short circuit, or a commutation failure, the voltage of the DC transmission line may drop, and in this case, it is not shown in the diagram. By locking the output of the differential protection relay device of this invention in response to the premises ground fault detection device, arm short circuit failure detection device, and commutation failure detection device, This can prevent erroneous outputs from being output.

In addition, in the above embodiment, it was explained that the DC voltage value is multiplied by η and added to the suppressing force, but if the DC voltage value decreases below a certain value, the DC voltage is controlled to zero under the detection conditions. The suppressing force due to voltage may be changed stepwise.

As described above, according to the present invention, since the voltage component is added to the operating formula as a suppressing force, the suppressing force is large during normal operation, there is no malfunction, and the sensitivity is high in the event of a failure. This has the effect of providing a dynamic protection relay device.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram showing the differential protection line electrical equipment of a power transmission line in conventional DC power transmission, Fig. 2 is a current-voltage characteristic diagram, Fig. 8 is a time chart of a conventional differential protection relay device, and Fig. 8 is a time chart of a conventional differential protection relay device. FIG. 4 is a diagram showing the conventional ratio characteristic, FIG. 5 is a configuration diagram showing a differential protective relay device according to an embodiment of the present invention, FIG. 6 is a time chart thereof, and FIG. 7 is a diagram showing the ratio characteristic. . (la), (lb) - AC system, (2a), (2b)
- converter, (8a), (8b)...DC reactor, (4)...DC transmission line, (5)...return line, (6a
), (6b), (7a), (7b) ... DC current transformer, (8a), (8b) ... Control device, (9) ...
・Blood flow current setting device, 00... changeover switch, (ll
a), (llb), (18a), (18b)...signal transmission device, (12a), (12b)...differential protection relay device. In addition, in the figures, the same reference numerals indicate the same or equivalent parts. Agent Makoto Kuzuno - Figure 1, Figure 2; Figure 3, 0□0 "Immigration (, to) ---Continued from page 1 of 111 ■Applicant Mitsubishi Electric Corporation Tokyo 2-2-3 Marunouchi, Chiyoda-ku

Claims (2)

[Claims] (1) DC current transformers installed at both ends of the DC transmission line,
A transmission device that transmits the output of the DC current transformer of its own terminal to the other terminal, the difference between the DC current transformer output of its own terminal and the DC current transformer output of the other terminal sent via the transmission device, and this The differential protection relay device is designed to protect the DC transmission line by the difference, and a DC voltage transformer is provided to detect the voltage of the DC transmission line, and the obtained DC voltage value is transmitted to the differential protection relay device. 1. A differential protection relay device for a DC power transmission line, characterized in that it acts as a suppressing force. (2) When the blood flow voltage value acting as a suppressing force becomes less than a predetermined value, the DC voltage value is reduced to zero. Differential protection relay device for electric wires.