JPS58201531A - Power controller for ac/dc parallel transmission system - 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 power control device for an AC/DC parallel power transmission system.

Figure 1 shows a block diagram of an AC/DC parallel power transmission system.

In the figure, αυ,@ is the AC system, QO2@ is the AC bus,
8 is the AC transmission line, Yu, Ni) is the AC system aiu, t5a is the DC system breaker, - is the converter transformer,
(2) is an AC/DC converter (e.g. thyristor converter), (
8) is a DC transmission line.

On the other hand, the AC/DC converter is equipped with a constant power control device that sets the power transmission power to a predetermined value, so that the power transmission power can be arbitrarily and quickly controlled.

FIG. 2 shows a block diagram of the constant power control device.

In the figure, (b) is a power detector that detects power from the current and voltage detected by the current transformer (9) and transformer 01), and its output is designated as Pd. The Foundation is a power setting device that gives commands for power transmission, and its output is PREF. So is an adder that adds PRKF and Pd with the polarity shown in the figure, (goods) is an amplifier, and the output of ■ is an AC/DC converter (7
) is the current command value (abbreviated as IdREp). On the other hand, a DC current Id is detected from a DC current transformer (2) and added by an adder (7) with the polarity shown. (b) is an amplifier, and the output of (2) is input to a phase control circuit (to) to determine the firing phase of the thyristor. That is, the current in the DC system is controlled by the power control device.

As mentioned above, in a DC power transmission system, Pd is detected and controlled to make it equal to PREF, so it is possible to control the power arbitrarily and quickly, which is not possible in AC power transmission. This is a major feature of

However, now suppose that an accident occurs in the AC system at point F shown in FIG. At this time, the AC system has a breaker @T), -
The accident will be removed by opening the
The transmission power of the AC system becomes zero.

As described above, the present invention uses a constant power control device of the DC system to compensate for the power transmission power of the AC system becoming zero when an accident occurs in the parallel AC line, so that even if an accident occurs in the AC system, the power transmission power is reduced to zero. It provides a device in which power does not change.

An embodiment of the present invention will be described below with reference to the drawings.

Figure 8 shows the output power setting value circuit (2) in Figure 2. The power line breaker (b) is opened when the circuit breaker is turned on and closed when the circuit breaker is turned off.

2) is a setting device that provides a constant bias, and 2) is an analog switch that operates when the breaker is activated and 2) is closed, transmitting the setting value of the setting device.

Let the set value of the setting device Q) be PF. The ring is po
@4 is a time constant circuit.

Next, another embodiment will be described with reference to FIG. The circle is a power detector for the parallel AC line, the circle is a first-order delay circuit with a large time constant, and the symbol - is a sample-and-hold circuit.

The operation of the present invention will be explained. When there is no accident in AC feed 4tw, the breaker is in the closed state, so the contact (
e) is not closed, and the power transmission power command value PREF of the DC system is
is equal to the set value PO. That is, PREF=PO. If an accident occurs on an AC power transmission line, the circuit breaker is turned off.
F, and the circuit is reclosed after a certain period of time.

Therefore, while the breaker is off, the contact is closed and the bias value py is added through the first-order delay circuit. That is, P-"Po+Pp.

Figure 4 shows the time chart. Here, the time constant circuit (incorporated) is used to raise or lower P with a certain time constant so that the output of the constant power control device does not transiently overshoot due to a sudden change in the command value P. It is a circuit.

In the other embodiment shown in Fig. 6, the power value flowing through the parallel AC line is used as the power correction value, and is sampled and held when the breaker is turned off, and the analog switch ■ is closed and inputted to the time constant circuit. do.

Furthermore, since the AC power value at the time the breaker is turned off may have changed from the value before the accident, a large first-order delay with a temporary constant is included to provide a memory function.

As described above, in the above embodiment, the 0N of the breaker is used to control the PF.
-OFF state was used, but the AC power line protection relay (
For example, if the contact is closed by the operation of a distance relay, and the contact is opened by the operation of a reclosing relay, P can be controlled faster by the trip time of the breaker. The time chart in this case is shown in FIG.

As described above, according to the present invention, since a fault in the parallel AC line is detected and the power command value of the DC system is increased, the power transmission power as an AC/DC parallel system is the same as when there is no fault in the AC system. This has the advantage that a constant amount of power can be transmitted at all times.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an AC/DC parallel power transmission system, Fig. 2 is a block diagram of a conventional constant power control device, Fig. 8 is a block diagram of a setting device device of a constant power control device according to the present invention, and Fig. 4 is a block diagram of the present invention. FIG. 5 is a block diagram showing another embodiment of the invention, and FIG. 6 is a time chart of FIG. 5. -〇...Setter, (G)...Contact, -...Analog switch, (Foundation)...Adder, ■, -...Time constant circuit, (2)...Electric power Setting device, 6υ, ■... Power tester, -... Sample and hold circuit The same reference numerals in each figure indicate the same or corresponding parts. Agent Makoto Kuzuno - Part ■1゛4 Figure 2 Figure j Figure 414

Claims (3)

[Claims] (1) In a device that controls power in a system that transmits power using an AC transmission line and a DC transmission line that are connected in parallel, when the AC transmission line is healthy, a predetermined setting value is set to the AC transmission line. When a failure occurs, a power setting device outputs the value obtained by adding the via filter value to the above set value as the power command value of the above DC transmission line, and a power setting device that outputs the value obtained by adding the Via filter value to the above set value as the power command value of the above DC transmission line, and outputs the measured value of the transmitted power of the above DC transmission line as the above power command value. A power control device for an AC/DC parallel power transmission system, comprising: a circuit for controlling the ignition of an AC/DC converter of a DC transmission line according to a deviation thereof. (2) The power control device for an AC/DC parallel power transmission system according to claim 1, wherein the bias value is a value corresponding to the power transmitted by the AC power transmission line in a healthy state. (3) The power control device for an AC/DC parallel power transmission system according to claim 1, wherein the power setting device includes a time constant circuit for smoothing changes in its output.