JPS6260815B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a thyristor converter for AC/DC conversion such as DC power transmission or different frequency interconnection, and particularly relates to a water-cooled thyristor converter that is cooled by circulating a liquid.

[Technical background of the invention and its problems] Advances in semiconductor devices have been remarkable in recent years, and highly reliable high-voltage, large-current thyristor elements have been developed, and thyristor converters using these thyristor elements are increasing in capacity year by year. There is a tendency to Therefore, especially
As the current increases, the issue of how to efficiently cool the components of the device has become a problem. Conventionally, insulating oil, air, etc. have been used as the cooling medium for thyristor converters. However, the cooling performance of the above-mentioned cooling medium is limited. Therefore, many water-cooled thyristor converters have been developed that are air-insulated and cooled by water, which is easy to maintain and inspect, and has a high cooling effect.

Generally, a thyristor converter constitutes a three-phase bridge circuit as shown in FIG. That is, 1U,
1V, 1W, 2U, 2V, and 2W are thyristor valves, AC system 1 is connected to AC terminals U, V, and W, and 2 and 3 are DC terminals. Furthermore, with the recent increase in voltage and the shrinking of converter stations, as shown in Figure 2, the circuit in Figure 1 has been added to the valves 3U, 3V, 3W, and 4.
A three-phase bridge circuit consisting of U, 4V, and 4W is connected in cascade.

A conventional water-cooled thyristor converter in which the thyristor converter connected as shown in FIG. 2 is cooled with water will be explained with reference to FIGS. 3 to 5.

FIG. 3 shows a four-tiered thyristor converter and its cooling system in the circuit shown in FIG. 2, in which 2U is stacked on top of thyristor valve 1U, 3U is stacked on top of thyristor valve 1U, and then 4U is stacked on top of that to form an integrated structure. Each thyristor valve (1U will be explained here) consists of several thyristor elements 4 (6 in series in the figure) as shown in Fig. 4, an anode reactor 5, a voltage dividing resistor 6, and a capacitor. 7
A plurality of thyristor modules 8 containing such components are stacked with insulators 9 in multiple stages.

The components of the thyristor module 8 that require cooling with water are the thyristor element 4, the anode reactor 5, and the voltage dividing resistor 6, which have large power losses.

When cooling such a thyristor valve with water, the thyristor module 8 is used as shown in Figure 3.
Insulating main water pipes 10A and 10B are connected to both ends of the main water pipes by thyristor module water pipes 11A and 11B, respectively. In addition, at the ground level, an inlet water pipe 12 is connected to the main water pipes 10A and 10B.
A and an outlet water pipe 12B are connected, and a storage tank 13, a heat exchanger 14, an ion exchanger 15, and a pump 16 are connected to each.

Cooling water is supplied to the inlet water pipe 12A by the pump 16.
It is sent to the main water pipe 10A through the arrow 1.
As shown in FIG. 7, the water is distributed to each thyristor module 8 through the water distribution pipe 11A to cool each component, and the water warmed by heat loss is stored in the storage tank 13 through the main water distribution pipe 10B and the outlet water pipe 12B. A cooling system is provided in which the water is cooled again from the storage tank 13 by the heat exchanger 14, purified by removing ions and impurities by the ion exchanger 15, and sent again to the thyristor converter by the pump 16. Therefore, if the cooling system of FIG. 3 is plotted, it will become a cooling system diagram as shown in FIG. 5.

In FIG. 3, 18 is a frame of the thyristor valve, and 19 is an insulator that insulates and supports the entire four-stage thyristor valve. Normally, when the voltage of one stage of such a thyristor valve is 125KV, the height is about 3 m, and as shown in Fig. 3, the height is about 12 m when the thyristor valve is stacked in four stages. Furthermore, if the unit is 250KV class, the height will be nearly 20m when stacked in four tiers.

In a thyristor valve with a tower configuration like this, when cooling water is raised to a height of 10 m or more, if the pump 16 stops due to maintenance or inspection, or for some reason, the inside of the thyristor module 8 located above 10 m Water in pipes such as
Due to atmospheric pressure, for example, in the case of 1 atm
The water had fallen to a depth of 10.33m, and the inside of the pipe where the water had fallen naturally became a vacuum.

Therefore, most of the piping used for thyristor valves requires insulation, so insulated piping is used, and as mentioned above, insulated piping can collapse and break when vacuum is created, and further vacuum can cause discharge. This tends to cause problems such as dielectric breakdown and reduced reliability of the thyristor converter.

[Object of the present invention]

An object of the present invention is to eliminate the above-mentioned drawbacks and provide a highly reliable water-cooled thyristor converter without any adverse effects on the thyristor converter.

[Summary of the invention]

To achieve this objective, the present invention provides an inlet water pipe 12 so that the cooling water above the thyristor valve does not drop when the pump stops.
A, the outlet water pipe 12B is each provided with a valve, and the valve can be operated by a pump stop signal.

[Embodiments of the invention]

Hereinafter, the present invention will be explained with reference to FIG. 6, in which the same parts as in FIG. 5 are denoted by the same symbols.

In FIG. 6, a valve 20A provided in the inlet water pipe 12A and a valve 20B provided in the outlet water pipe 12B are, for example, electromagnetic valves whose opening and closing are controlled by an external signal. 16 is operating normally, it is opened,
When the pump 16 becomes abnormal or stops, this is detected and applied as an external operation signal to the valves 20A, 20B.
B is closed. Here, as a signal for detecting that the pump 16 has become abnormal, a signal detecting a power outage of the driving power source of the pump 16, a decrease in the number of revolutions of the pump, or a decrease in water pressure of the pump 16 may be used. I can do it. By configuring like this,
If the pump 16 becomes abnormal or stops, the valves 20A and 20B will be immediately closed, so the cooling water in the thyristor valve will not drop.

FIG. 7 is a system diagram showing another embodiment of the present invention. In the figure, reference numeral 21 is a check valve, which allows the cooling water to flow down from the valve without preventing the cooling water from rising toward the valve. It is a valve that prevents Therefore, in this case, by using a solenoid valve or an electric valve as the valve 20B, it is possible to prevent the cooling water from dropping when the pump 16 is abnormal.

In this way, the present invention allows the valves 20A, 20B, the valve 21, and the valve 20 to
The action of B can prevent the cooling water from dropping on the valve side.

〔Effect of the invention〕

As explained above, the present invention prevents the cooling water on the thyristor valve side from dropping even if the pump stops or malfunctions in a water-cooled thyristor converter, so the inside of the piping does not become vacuum. Therefore, a highly reliable water-cooled thyristor converter can be provided without causing damage to piping or dielectric breakdown due to discharge.

[Brief explanation of the drawing]

Figures 1 and 2 are configuration diagrams of a thyristor converter;
Fig. 3 is a configuration diagram of a cooling system for a thyristor valve that constitutes a conventional thyristor converter, Fig. 4 is a circuit diagram inside a thyristor module that constitutes a thyristor valve, and Fig. 5 is a cooling system diagram of Fig. 3. FIG. 6 is a cooling system diagram showing one embodiment of the present invention, and FIG. 7 is a cooling system diagram showing another embodiment of the invention. 1... AC system, 1U to 4W... Thyristor converter, 2, 3... DC terminal, U, V, W... AC terminal,
4... Thyristor element, 5... Anode reactor,
6... Partial voltage resistance, 7... Capacitor, 8... Thyristor module, 9... Insulator, 10A, 10B... Main water pipe, 11A, 11B... Water pipe, 12A... Inlet water pipe, 12B... Outlet water pipe, 13... Storage Tank, 14... Heat exchanger, 15... Ion exchanger, 16
...Pump, 17...Arrow, 18...Frame, 19...
Insulator, 20A, 20B... Valve, 21... Check valve, 22
...Signal, 23...Electric valve.

Claims (1)

[Claims] 1. Cooling of heat-generating parts such as thyristor elements of a thyristor valve constituting a thyristor converter is carried out by circulating cooling water through an inlet pipe and an outlet pipe provided at the lower part of the thyristor valve. In the water-cooled thyristor converter, each of the inlet pipe and the outlet pipe is provided with a valve, and the valve is a valve that closes when the pump for circulating the cooling water stops or when an abnormality occurs. type thyristor converter. 2. A water-cooled thyristor converter in which heat generating parts such as thyristor elements of a thyristor valve constituting the thyristor converter are cooled by circulating cooling water through an inlet pipe and an outlet pipe provided at the bottom of the thyristor valve. A water-cooled thyristor converter according to the invention, wherein the inlet pipe is provided with a check valve, and the outlet pipe is provided with a valve that closes when the pump for circulating the cooling water is stopped or there is an abnormality.