JPS5953024A - Dc transmitting 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 DC power transmission system.

As is well known, in a DC power transmission system, AC power is converted to DC by a thyristor forward converter and then supplied to the DC transmission line, and on the power receiving side, it is converted to AC by a thyristor reverse converter and then supplied to the load. do.

To start up such a DC power transmission system, set the control angle of the above-mentioned converter to around 90 degrees, which is close to the criticality of its operating range, and shift the control angle of each start-up converter to its respective control range. It is done by letting

That is, conventionally, limiters are provided on the forward converter side and the inverse converter side, and the control angle existence region is gradually opened by the forward converter side limiter as shown in Fig. 1. In this case, as shown in FIG. 2, current control is carried out on the forward converter side, and the DC voltage is raised by 2 in accordance with the limiter on the inverse converter side. In FIGS. 1 and 2, 102 represents the control characteristics on the inverse converter side, 104 represents the control characteristics on the forward converter side, and DEB represents the start time.

Therefore, the power transmitted by the above DC power transmission system changes as shown in Figure 3, and the minimum kinetic power determined by the minimum current and the rated DC voltage at a predetermined time constant after startup]) ml□ reach.

Here, the minimum operating current is set to the lowest value at which the DC current does not become intermittent, depending on the value of the DC reactor, etc. Therefore, the minimum value of the DC transmission power is determined by this.

However, when the generator is started, the power rise gradually increases like a ramp function, so it is preferable that the rise of the DC power transmitted by the DC power transmission system also corresponds to this.

For this purpose, it is possible to set the first-order delay constant of the limiter to a large value, but if such control is performed, the thyristor will be operated for a long time in the region where the control ffl + angle is large, and the damping circuit will be The problem arises of increased losses and increased cost of the stem/to cool the thyristor. In other words, since the loss of the damping circuit is affected by the thyristor control angle, the conventional inverter control of increasing the DC voltage by F must perform control in coordination with the loss limit value of the damping circuit. I couldn't do that.

The present invention has been made in view of the above-mentioned original problem,
The purpose is to provide a DC power transmission system that can start up a DC power transmission system together with a generator in a ramp function manner without increasing costs.

In order to achieve the above object, the present invention converts the electric power generated by a generator into DC using a thyristor converter, sends it to the DC wire, converts it into AC using a thyristor inverter, and supplies it to the load. In the supplied DC power transmission system, an IJ that limits the control angle of the forward converter thyristor immediately after startup to below the angle corresponding to the allowable loss of the damping circuit of the forward converter.
The present invention is characterized in that the transmitter is provided on the forward converter side, the voltage of the DC power transmission system is controlled on the forward converter side, and the current of the DC power transmission system is controlled on the reverse converter side.

Preferred embodiments of the present invention will be described below based on the drawings.

FIG. 4 shows the overall configuration of the DC power transmission system according to the present invention. The electric power generated by the generator 1 is transferred to the transformer 2,
It is applied to an AC/DC converter (forward converter) 6 via a breaker 3 , a bus bar 4 , and a converter transformer 5 , and its DC output is supplied to a DC power transmission line 7 .

The power transmitted to this DC power transmission line 7 is converted into AC/DC by an AC/DC converter (inverse converter) 6, and the power is supplied to the load via a converter converter 5, a breaker 3, and a bus 4. be done.

FIG. 5 shows the basic configuration of the control system for the AC/DC converter 60 shown in FIG.

In the figure, the DC current and DC voltage of the DC power transmission line 7 are detected by a DC current transformer 8 and a DC voltage transformer 9, respectively, and these detected values are sent to each comparison input of the current setting device 10. , the set values of the voltage setting device 11 are supplied to the other comparative inputs of the deviation detector 12, and the output of each deviation detector 12 is -1/7o. A control amplifier 14 is supplied, and their amplified output is supplied to a low value selector 15. This low]
The selected output of the direct selector 15 is supplied to a variable limiter 16, and the output thereof is converted into a shearth signal by an automatic pulse phase shifter 17, amplified by a pulse amplifier 18, and inputted to an AC/DC converter 6.

A preferred embodiment of the present invention has the above configuration, and its operation will be explained below.

In this embodiment, at startup, the control angle of the AC/DC converter 6 is limited by the variable limiter 16 to an angle equal to or less than the allowable loss of the damping circuit of the forward converter.

FIG. 6 explains the operation of this limiter 16. At startup, the limiter 16 reaches the damping loss limit of the thyristor.
By setting , it is possible to prevent the DC transmission voltage from exceeding the loss limit of the equipment.
As shown by 00, the transmitted power can be reduced by increasing it like a ramp function from the time of startup.

If such control is not performed, the inverse converter side performs constant current control, and the forward converter side performs DC voltage control based on the control angle, as shown in FIG.

As explained below, according to the present invention, it is possible to obtain transmitted power that is coordinated with the generated output at the time of starting the generator, and it is extremely suitable for direct current power transmission.

According to the present invention, the Zyristor control angle on the forward converter side is specially designed to operate as a limiter, so when the inverse converter fails and cannot be started, the power transmission line charge generated by the forward converter is reduced. Abnormal voltage caused by the phenomenon can be reduced.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of the operation of the limiter of the AC/DC converter in the conventional system; Figure 2 is the control characteristic diagram of the AC/DC converter in the conventional system; Figure 3 is the minimum operating power characteristic diagram immediately after startup of the conventional system; FIG. 4 is an overall configuration diagram of a preferred embodiment of the present invention, FIG. 5 is a configuration diagram of the control system of the AC/DC converter in FIG. FIG. 8 is a minimum operating power characteristic diagram immediately after startup of a preferred embodiment of the present invention, and FIG. 8 is a graph showing the power output during control of the AC/DC converter shown in FIGS. 4 and 5. l... Generator, 6... AC/DC converter, 7... DC transmission line, 1G... Variable limiter. Figure 1 (oL) III Tribute Hen Part I Odor 1p Nomi Suta (b) Reverse Transformation Pk Device I QIJ Rimig Figure 2 Territory Mutu Ox Figure 5 q Figure 6 (b) Yata Hen Kyo Rock Kai gl ) Mitta diagram

Claims (1)

[Claims] 1. A DC power transmission system that converts AC power into DC using a thyristor forward converter, sends it to a DC transmission line, converts it to AC using a thyristor inverse converter, and supplies it to a load, A limiter is provided on the forward converter side to limit the control angle of the forward converter thyristor immediately after startup to an angle corresponding to the allowable loss of the damping circuit of the forward converter, and the voltage of the DC power transmission system is controlled on the forward converter side. , A DC power transmission system characterized in that the current of the DC power transmission system is controlled on the inverter side. 2. In the system according to claim 1, the power transmission voltage is reduced immediately after startup. A DC power transmission system characterized in that the tap of the converter transformer of the forward converter is set to the lowest value.