JPS5851721A - Disconnection detector 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 disconnection detection device for a DC power transmission line.

FIG. 1 is a diagram showing an example of a DC power transmission system.

In the figure, (jli,, (121 is an AC/DC converter, @υ, @ is a converter transformer, buttons i and ruJ are DC reactors, and (4) is a DC transmission line. In Figure 1,
The AC/DC conversion rhyme 1111 is assumed to be a forward converter (RlcO), and - is assumed to be an inverse converter (RlcO).

Figure 2 shows the regulation V-yon curve showing the operating characteristics of DC power transmission.If the forward conversion side performs constant current control and the reverse conversion side performs constant margin angle control, the normal operating state is This will be point A.

Here, if a disconnection occurs at one point in Figure 1, then in the operating characteristics of Figure 2, the operating point is point B on the forward converter side, and 0 point on the inverse converter side (121 side). In other words, when a wire break occurs and the DC current becomes zero, the constant current control circuit works in both the converter and the inverse converter to reduce the control angle α.Therefore, the DC voltage on the forward converter side is controlled by the control angle limiter. αm
As a result of α shifting to 1!1, V6rollC at point B
, t on the inverse converter side, the operating point moves to vato at point %C as a result of α shifting up to the control angle limiter βmax.

Therefore, conventional methods for detecting disconnection include DC overvoltage relay 41D (Il), DC undervoltage relay 80D (61), and DC undercurrent relay 37D (Il), as shown in FIG.
．． As shown in Figure 3 (to), the forward converter side is 31
D.

45D ^MD condition, and the inverse converter side is S? D.80
Each transmits the AND conditions of D to the other end.

The method used was to determine disconnection based on the AND condition at both ends.

(8) is a DC transformer that derives a DC current; DC transformer a%+11 is a DC transformer that derives a DC voltage; 1101 is a signal transmission device.

0!1%64,651, (171%611.ea
t, -1 is an AMID circuit.

(2) % (goods) is OR@road.

Alternatively, as shown in FIG. 4, on the forward converter side, the minimum value αmin of the daughter control angle limiter and the inverse conversion l! -, there was also a method of detecting that the control angle limiter has shifted to the maximum value β maw and transmitting each signal to both ends to determine whether the p-wire is disconnected.

However, since conventional devices require transmission to both ends, it may be impossible to determine a disconnection accident when an abnormality occurs in the transmission system.

□ This invention was made in order to eliminate the above-mentioned drawbacks of the conventional device, and its purpose is to provide a device that can reliably detect a disconnection only at its own end even when there is an abnormality in the transmission system.

An embodiment of the present invention will be described below with reference to the drawings. 6th
The figure is a block diagram of a disconnection detection device according to the present invention, and -
%(2), (corporate) is an AND circuit, 輛 is an inhibit) circuit, a dOR circuit, and X is an operation delay timer.

The operation of the present invention will be explained. As mentioned above, when a disconnection occurs in the DC transmission line, the current becomes O, and the control angle limiter shifts to αmin on the forward converter side and βmax on the reverse converter side. Therefore, on the forward converter side, reaching the DC undercurrent relay "-171 and αwin limiter is determined to be a disconnection under condition □, and on the reverse converter side, reaching the DC undercurrent relay (71 and 2m x 9 limiter) is judged as a disconnection. It is determined that the wire is disconnected under the condition that the wire is disconnected.
Leap 1 size w! of r(m-・O] is expanded.As mentioned above, if it is protected using the disconnection detection Ka 2' fist 0v1111 transmission device, when an abnormality occurs in the transmission line. Since the delay-timer stretches the operation, it can be detected and protected only at its own end.

The echo diagram is a diagram showing another example. This uses a voltage V- to prevent overvoltage from occurring on the forward converter side and no voltage on the reverse converter side when a disconnection occurs in the DC transmission line. This serves as a substitute for using the above-mentioned DC overcurrent relay as a stopper.

As described above, according to the present invention, even if a disconnection occurs in a DC transmission line, both the forward converter and the reverse converter can detect it at their own end, so no transmission line is required and there is no problem even when there is an abnormality in the transmission line. It has the advantage of being able to detect disconnections.

[Brief explanation of the drawing]

Figure 1 is a diagram showing a DC power transmission system, Figure 5 is a diagram showing regulation characteristics during expanded DC power transmission, Figures 3 and 4 are diagrams showing a conventional disconnection protection device, and Figure S is a diagram showing a disconnection according to the present invention. FIG. 6, a gAI diagram of one embodiment of the detection device, is a diagram showing another embodiment of the present invention. In the tooth, (m, tJB is an AC/DC converter, @9
．． Converter transformer-H# @ is DC ripctor, 1
4) is a DC power line, (Ila DC overvoltage relay, 16)
is a DC undervoltage relay (71 is a DC undervoltage relay,
(81 is a DC transformer m% 1 is a DC transformer, m, @, @ is an input ND circuit, - is an operation delay timer. Agent Makoto Kuzuno: rI, 1 Figure Yari, -21'21 No. :<Figure 3 CB) Ei -4 Figure 0 (

Claims (1)

[Claims] Q) DC undervoltage of 9%/-, which operates when the required current derived from the DC transmission line is below a predetermined value, and A disconnection detection device for a DC power transmission line, comprising a device for detecting that a lower limit has been reached, and a logic circuit for detecting when a ζO device and the DC undervoltage relay are activated. (2) a DC overvoltage relay that operates when the voltage derived from the DC transmission line is equal to or higher than a predetermined value; a device that detects when the control angle of the DC transmission line has reached the lower limit; and this device and the DC overvoltage relay. A disconnection detection device for a DC power transmission line, which includes a logic circuit that detects activation of an overvoltage relay. 0) A DC undervoltage V- that operates when the voltage derived from the DC transmission line is below a predetermined value, a device for detecting that the control angle of the DC transmission line has reached an upper limit, and this device and the above A disconnection detection device for a DC power transmission line, comprising a logic circuit that detects that both DC undervoltage relays have operated.