JPS59149719A - Dc line protecting 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 The present invention relates to a protection device for a DC power transmission line that can protect the DC power transmission line from high-voltage side ground faults.

Conventional protection methods include (1) protection by detecting voltage changes in DC transmission lines, (2) DC transmission lines? There was a method of detecting and protecting the voltage below 4 using an underpressure relay. However, in this type of system, voltage changes in the DC transmission line (v/dt or voltage 14-mode) can occur due to failures other than DC transmission line failures, so there is a high possibility that malfunctions will occur, and the rhythmic rate of the DC transmission system will change. This may cause a decrease in the temperature.

Therefore, recently, a current differential method has been used to detect a fault by utilizing the difference between the converter side current and the inverter side current at the time of a DC transmission line fault. FIG. 1 shows a conventional current differential protection device. In the figure, (1) is a rectangular converter (hereinafter referred to as a converter), and (2) is an inverse converter (hereinafter referred to as an inverter).
, (11) and (21) are DC reactors provided to smooth the DC current and suppress the increase in fault current.
(12), (22) is a DC CT1 (101) that converts into a minute current proportional to the current value flowing in the DC line,
(202) is a signal transmission device f which manually operates the electric cable of the DC CT and transmits its waveform; (201) and (102) receive a signal from the signal transmission device t=L; Signal conversion device for converting to (103), (2
03) is the signal conversion device (102), (201),
A differential relay, (1
05), (205) are Tome Calculator, (104), (20
4) shows a constant current control device which controls the DC flowing through the DC power transmission d (100) to a constant value '4.

Explain to Ward about VTB production.

When a 4wI fault (Fl) occurs in the DC transmission line (100), the converter side current IREC increases as shown in Fig. 2, but the converter (1) is not ignited due to the operation of the constant current control IIl device (104). By controlling the angle, the current direct load fVc can be returned to the value before the accident occurred. On the other hand, before the accident F1 occurred, the inverter side electrician TNV was controlled by a constant voltage control device (not shown in Fig. 1) that kept the DC voltage constant, so the constant '# of inverter (2) 11411 was controlled by the current control device. is not functioning at all. Therefore, before the accident fr1 occurred, the current value flowing through the DC line (100) was
) side, the current value is the same on both the converter side and the inverter side.

Simultaneously with the occurrence of accident F'1, the DC voltage drops significantly, so the constant voltage control device on the inverter side stops functioning, and the constant current control device comes into operation. Meanwhile, the inverter (2
) 11111 because the extreme pressure of the DC voltage is reversed, IJ:L
The current value INV on the impark side decreases to a current value of lr day f - work d due to the direct current side of the constant current control device.

The signal transmission devices (101), (202) and the signal conversion devices (201), (102) transmit the current waveforms at both ends to each other, and convert the current waveform name of one end and the current waveform of the other end into a differential relay (103). ), (203), differential output F can be obtained for each case, and DC transmission line accident F can be obtained.
This means that l can be detected.

Normally, Δ is called current margin and is 10% of the rated DC current.
a signal transmission device (101);
(202), signal conversion device (201), (102),
Considering the error of DC CT (12), (22) and constant current control device f (104), (204), differential relay (103), (203) d engineering RIC - engineering INV
Differential output under m5% condition? Determine.

Since the conventional protection device is configured as described above, the differential relays (103), (203) and the signal transmission device (
101), (202), signal conversion device f (201)
, (102) Since a high integration density is required for W, there is a drawback that the image quality of the device becomes high.

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and it increases the current margin setting value when an accident occurs, and increases the difference between the converter side DC current value RKC and the inverter side DC current value INV. It is an object of the present invention to provide a protection device that can detect DC line faults without using more sophisticated equipment.

An embodiment of the present invention will be described above with reference to the drawings. Third
In the figure, the same reference numerals as in FIG. 1 indicate the same or equivalent parts. 13) is a DC voltage F T that converts DC voltage into a certain minute nausea filter, (111) is an adder, and (112) is a cutter. s W , (106) is a current margin command value circuit that automatically increases and outputs the value of the DC' current margin according to the width of decrease in DC/voltage, and (110) is a DC current command value circuit. (1100) Fi current margin Δ
Current margin setting device to set the current margin.

Next, the operation will be explained.

The DC voltage value 1d output from the DC P T (13) is manually input to the current margin command value circuit (106).

The current margin command value circuit outputs a current margin command value in inverse proportion to the human-powered DC voltage. Therefore, the song where the DC line accident F1 occurred outputs a value of about 10% of the rated DC (DC). After the accident F'1 occurs, the DC voltage decreases significantly, so that the current margin command value Δf, which is larger than 0.1Pσ, is output from the '4 flow margin finger command value path. The output signal is sent from the current command value nθf from the current command value circuit (110) to the constant heel flow control circuit on the side of the converter operating the inverter via the switching S f (112). 111) and is given, the current on the inverter side becomes Ir5f - ΔE', which becomes significantly smaller.

Assuming that the f converter (2) is on the inverter side, the current of 1ull of the converter passes through the DC c'r (12), the transmission device (101), the TA converter (201), and the differential relay (203). ), and the difference between the inverter side current factor nef - Δfactor' is calculated. Here, since the inverse proportional material loss in the current margin command cycle vIr (106) set by Δf can be arbitrarily set, the above-mentioned No. 18 transmission device (
101), before signal f replacement (201), differential relay (20
3) By setting the above-mentioned constant according to the degree of extinguishment of the fire, it becomes possible to use a device that does not have a high degree of extinguishment to cause a failure of a hundred-flow yield route without error. .

As described above, according to the present invention, since the current margin is increased in accordance with the amount of decrease in the DC voltage, there is a problem that a high-grit device becomes unstable and the device becomes a cheap drawing.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a conventional DC transmission line protection device, Fig. 2 is a diagram showing a DC' warm current waveform at the time of an accident, Fig. 3 is a diagram illustrating an embodiment of the present invention, and Fig. FIG. 2 is a characteristic diagram illustrating an embodiment of the invention. (1)... Forward transform 4, (2)... Inverse transformer, (11
), (21)...DC reactor, (12), (
22) ・=DC CT, (101), (202) −
...Signal transmission device, (201), (102)...Signal conversion device, (103), (203)...Differential relay, (111), (105), (205)...Adder , (107) , (207) ... Adder, (10
4) , (204) ... Constant current control system agent Kuzuno
Communication - Figure 1

Claims (1)

[Claims] In a DC transmission system in which the converter converts alternating current into an IfL flow, the inverter converts direct current into alternating current, and the converter is connected by a DC line, a DC converter installed on both sides of the DC transmission line A current transformer, a transmission device that transmits the output of the DC current f of its own terminal to the other terminal, and a method for determining the difference between the outputs of the DC current transformer of the other terminal through the lf DC current transformer output transmission device of the own terminal. The DC power line protection device consists of a current margin command value circuit that increases the current margin according to the torrent signal of the DC voltage detector that detects the DC voltage, and the DC power line number fault chronological converter side A direct current and line protection device that acts to increase the difference between the direct current and the inverter side direct current.