JPH10290561A - Power converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the size of a high voltage apparatus while enhancing the reliability by employing a cooling water anti-freeze heater not only for the essential purpose of anti-freeze but also for preventing dew formation, thereby optimizing the creeping distance of an insulator. SOLUTION: An anti-freeze heater 5 is turned on when the cooling water temperature drops below 5 deg.C, for example. The cooling water temperature is detected by a sensor. Even if the cooling water temperature is higher than a freezing point, e.g. 5-15 deg.C, the heater 5 is turned on when the room temperature (based on information from the sensor or other apparatus) is higher than the cooling water temperature in order to raise the cooling water temperature. Consequently, the temperature of indoor air is lowered to the cooling water temperature and the vapor is saturated, thus preventing dew formation on a converter 1. When the room temperature is 20 deg.C and the humidity is 70% or below, for example, no dew is formed for the cooling water temperature of 15 deg.C. Relationship between the cooling water temperature for turning on the heater 5 and the indoor is determined by the environmental conditions (air-conditioning capacity, settings) of a place where the converter 1 is installed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-voltage, pneumatically-insulated power converter, in particular, to improve the reliability and reduce the size of the power by preventing dew condensation which may cause deterioration of insulation characteristics. It concerns a converter.

[0002]

2. Description of the Related Art High-voltage, large-capacity power converters, including thyristor valves used for DC power transmission and frequency conversion equipment, are becoming higher in voltage and larger in capacity. In the case of a large-capacity converter, a water-cooling system with good cooling efficiency is often adopted as a system for cooling generated heat in order to reduce the installation area. In addition, a large-capacity converter is mainly of an air-insulated type, and it is necessary to pay attention to the use environment such as securing an insulation distance and humidity.

FIG. 1 shows an example of a simple cooling system diagram of a power converter.
Shown in The water that has cooled the power converter 1 is circulated in the cooling system by the pump 2. The cooling water whose temperature has risen by cooling the power converter is cooled by air or the like in the outdoor cooler 3 and enters the power converter again.

[0004] The cooling system of the power converter is designed so that the amount of heat generated when the converter is operated at the highest rated temperature under the strictest cooling conditions, that is, at high outside air temperature, can be sufficiently cooled. However, on the contrary, outside temperature is low in winter etc.
In addition, when the converter is stopped or the state where the output is small continues, there is a case where the cooling is performed. In this case, even if the operation of the outdoor cooler is stopped, the temperature of the cooling water falls outdoors due to natural heat radiation, and the cooling water may freeze. In order to prevent this, a heater is installed, and when the temperature falls below a certain value, the heater is turned on to prevent freezing.

On the other hand, in high-voltage, large-capacity devices, there is an increasing demand for smaller and lighter devices in order to reduce the installation area.
For this purpose, it is important not only to reduce the size of parts but also to optimally design the insulation distance in the air and the distance between the edges of the insulator to reduce the size. Water-cooled equipment is more advantageous in terms of downsizing components than air-cooled equipment, but care must be taken in the insulation design. For example, when the temperature of the cooling water is low and the room temperature is high, the temperature of the air around the cooling pipe drops to around the cooling water temperature, and there is a possibility that dew condensation may occur. In the case of condensation, the edge distance of the insulator needs to be longer than that in the dry state. Therefore, if the size is reduced, the edge distance may be insufficient. Conventionally, humidity is controlled to a certain value or less by air conditioning to prevent dew condensation. However, even in such a case, if the cooling water temperature is lower than room temperature, dew condensation may occur.

[0006] When the temperature and the relative humidity of the air are known, how much the temperature drops and the relative humidity reaches 100% (there is a possibility of dew condensation) is determined by a psychrometric chart ("Mechanical Engineering Handbook", The Japan Society of Mechanical Engineers). Knitting, etc.). This shows that the relative humidity of air at 20 ° C. and 70% relative humidity becomes 100% when cooled to about 14 ° C. or less. That is, under conditions of room temperature 20 ° C. and humidity 70%, if the cooling water temperature of the converter is 14 ° C. or less, dew condensation may occur.

[0007]

In order to promote the miniaturization of high-voltage equipment, it is essential to design the insulation distance optimally, and to increase the edge distance in consideration of condensation.
It is necessary to avoid as much as possible. In order to prevent dew condensation, it is sometimes insufficient to control the indoor temperature by air conditioning.

[0008]

According to the present invention, the cooling water freezing prevention heater is used not only for the purpose of preventing freezing, which is the original purpose, but also for preventing the formation of dew condensation. Optimization, and miniaturization of high-voltage equipment and improvement of reliability.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) FIG. 1 shows a configuration example of the embodiment. The heater is
For prevention of freezing, for example, the cooling water is supplied when the cooling water temperature becomes 5 ° C. or less. The temperature of the cooling water is determined by a sensor. Also,
Even if the temperature at which the cooling water does not freeze, for example, 5 to 15 ° C,
When the room temperature (according to information from a sensor or another device) is higher than the cooling water temperature, a heater is turned on to raise the temperature of the cooling water. This prevents the room air from being cooled down to the cooling water temperature, saturating the water vapor and preventing condensation on the converter. According to the aforementioned “humid air diagram”, if the room temperature is 20 ° C. and the humidity is 70% or less, no condensation occurs if the cooling water temperature is 15 ° C.

The relationship between the temperature of the cooling water supplied to the heater and the room temperature is determined by the environmental conditions (air-conditioning capacity, setting) where the converter is installed.

(Embodiment 2) FIG. 2 shows a configuration example of the embodiment. The temperature and humidity of the air are constantly monitored by the room temperature monitoring sensor and the indoor humidity monitoring sensor. From this data, a temperature at which dew condensation does not occur is calculated by the arithmetic unit. If the temperature of the cooling water is lower than that (if there is a possibility of dew condensation), the outdoor cooler is first stopped. If the temperature of the cooling water still does not rise to a temperature at which no dew condensation occurs, a heater is turned on to raise the temperature of the cooling water to prevent dew condensation.

[0012]

According to the present invention, in a water-cooled and air-insulated converter, it is possible to prevent dew condensation in the converter by controlling the cooling water temperature in comparison with room temperature. The edge distance of the insulator can be optimized, and the size and reliability of the converter can be reduced.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention.

FIG. 2 shows another embodiment of the present invention.

[Explanation of symbols]

1 ... Converter, 2 ... Cooling water pump, 3 ... Outdoor cooler, 4 ...
Water temperature gauge, 5 ... heater, 6 ... equipment equipped with room temperature meter, 7 ...
Room temperature meter, 8 ... Hygrometer, 9 ... Computing device, 10 ... Cooling control device.

Claims (2)

[Claims] 1. A water-cooled power converter comprising a pump for circulating cooling water, a cooler for cooling the cooling water, a heater for preventing cooling water from freezing in winter, and a sensor for monitoring the temperature of the cooling water. A sensor for monitoring the room temperature or a means for receiving the value of the room temperature from another device, and when the cooling water temperature is low in the power converter installed in the air-conditioned and air-conditioned equipment so as to have a constant humidity. In addition to turning on the heater to prevent freezing, power conversion that turns on the heater and raises the cooling water temperature to prevent condensation when the cooling water temperature is lower than room temperature and there is a possibility of condensation vessel. 2. A water-cooled power converter, a pump for circulating cooling water, a cooler for cooling the cooling water, a heater for preventing cooling water from freezing in winter, and a sensor for monitoring the temperature of the cooling water.
And a power converter equipped with a sensor for monitoring the temperature and temperature of the room. In the power converter, when the temperature of the cooling water is low, not only a heater is turned on to prevent freezing, but also an arithmetic unit that calculates a temperature at which dew condensation does not occur from room temperature and humidity. Equipped with a power converter that raises the cooling water temperature to a temperature that does not cause condensation.