JPS5851727A - 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 DC power line protection device, and particularly to a DC power line disconnection detection device.

In the case of a disconnection accident in the DC transmission line, power transmission becomes impossible in the 1L tortoise, so there is a pericardial sac that detects the disconnection and protects it.

As a conventional disconnection detection device, Japanese Patent Application Laid-Open No. iI861-1g1
There were some, such as No. 1h4, that detected by the voltage difference at one end of a DC transmission line that occurred when a disconnection occurred. The first factor is the DC transmission system diagram, where (1) is the AC system, (1) is the transformer, (
1) is a forward converter, Mouse) is a DC transmission line, and (S) is an inverse converter #!
It is kII. The conventional device described above focuses on the fact that when a wire breakage occurs, the rIi current voltage of the forward converter 11 (8) increases, and the DC voltage of the reverse converter (current) decreases, and detects a wire breakage based on the DC voltage difference between one converter. That is, *If the DC voltage of Conversion II (1) is "-", the DC voltage of Ss inverter (i) is -.

111-IIl≧K Ksia has a fixed value. However, the above relationship is not limited to only when there is a disconnection fault. For example, inverse transformation! When commutation of I (11,) fails, the phase in which commutation has failed becomes a DC short-circuit string, and the voltage E1 becomes almost zero, so that the Joki chest relation is established. Furthermore, in order to experience overvoltage, an operation may be performed to short-circuit the DC hook by giving a bypass pair command to the converter. In this case as well, the voltage of the converter of the bypass pair becomes zero, so the above-mentioned relationship holds true, and the line becomes ξ, which is determined to be a disconnection even though it is not a disconnection.

As described above, the conventional disconnection detection device for a DC power transmission line has the disadvantage of determining that the disconnection is new even though it is not a disconnection.

In addition to the DC voltage difference between both ends that occurs when a power transmission line is disconnected, the invention of H adds the condition that the DC voltage of the forward converter is positive and the DC voltage of the reverse converter is negative. This means that a disconnection can be detected correctly.

FIG. 2 shows typical voltage-current characteristics of a forward converter and an inverse converter. The forward converter has a constant current 11- at a set current 11. The inverse converter has constant margin angle l1lI1
There are 1 shi. The intersection r is II-controlled as in B. If a disconnection occurs in the DC transmission line here, the operating point of the lj degree converter moves from point 1 along the characteristic L1 and reaches point 8 of the no-load DC voltage. . Similarly, the groove inverter moves from one point along the characteristic L1, and the operating point reaches the point T where β of the inverter is maximum. Therefore, if the DC voltage of the converter is E2, and the DC voltage of the inverter is E2, then IsI! In the past, the absolute value I Es −ha I of the difference in the DC voltage application of the double-degree converter is greater than a predetermined value, and E, > O, E, < 0. This invention applies to such DC voltage characteristics. This paper proposes a device for detecting disconnections in DC transmission lines based on the above.

No. 81 is an example of a DC power line disconnection device according to the present invention.
FIG. 3 is a circuit configuration diagram showing an example Ii. In Figure 8, 1i
11. - is a DC voltage detector, (7) is a DC voltage detector -
A transmission device that transmits the detected value of
J circuit, -υ, - is a polarity discrimination circuit, αQ is an AND circuit,
(b) is a timer circuit.

When a disconnection accident occurs in the 6m power transmission II (4J), the detected voltage value of the DC voltage detector S- increases, and the detected voltage value of the @current tortoise pressure detector-1 decreases. - It is input to conclusion (8) and it is determined whether the detected value open!!IL-1ml is greater than or equal to the set value @I"!-"m
Even if l'≧, the differential circuit 1h (8) outputs. The DC voltage detected at the power transmission end is determined by the polarity determining circuit-1 to be of positive polarity or negative polarity. positive polarity (and I
Gender determination - road voice, @ is output. In the bit circuit so,
In other words, when the polarity discrimination circuit outputs an output and - does not output, in other words, when 11s-T≧, Σ is positive and E is negative □.

When the output of inhibit l % M continues for a certain period of time, the timer circuit 4 outputs an output, and this causes the DC transmission line 4 to be connected. 1 is a circuit diagram showing an embodiment of the llrIIM detection device of the blood flow sending IC4I according to the invention of Otsu.

(3) is a @dake i-wire, and (4) is a dc m-wire.

(i) i! Inverter, -1- is DC voltage detection -1 (2
) is a differential circuit, an', - is a polarity discrimination circuit, and a cap and a crack circuit.

Note that the h- symbol in each 1 indicates the same or similar part.

Agent Shin Kuzuno

Claims (1)

[Claims] a & IHl line current voltage detection #IJ7 which detects the DC voltage of the forward converter installed at one end of the power transmission line, and No. 2
The DC voltage detector and the output of both liquid exchangers are connected to
A wave circuit that detects ξ where the difference in current voltage is equal to or greater than a predetermined value, and a wave circuit that is provided corresponding to the DC voltage detectors @1 and @2 above, and that determines the polarity of the detected voltage of the corresponding DC voltage detector. do#! In response to the outputs of the first and second polarity discriminating circuits, these polarity discriminating circuits, and the primary differential circuit, the direct vibration pressure of the forward converter is of positive polarity, and the direct current voltage of the inverse converter is of negative polarity. and a circuit for determining that the DC transmission line is disconnected when the difference ki+1lWII is output.