JPS6123748B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a local overheating diagnosis device for a rotating electrical machine,
In particular, the present invention relates to a device for diagnosing local overheating of a portion covered with a thermally deteriorating organic insulating material, such as a stator core, in gas-cooled rotating electrical equipment.

BACKGROUND ART If local overheating occurs in a stator core in a large gas-cooled rotating electric generator, such as a turbine generator, there is a risk that the core will burn out and lead to a major accident. That is, when local overheating occurs in the stator core, the organic insulating material coated on the surface of each laminated iron plate is thermally decomposed, and the insulation between the laminated iron plates is destroyed. As a result, a short circuit occurs between each laminated steel plate, and a large current flows when the machine is under load.
Resistance heating occurs, and the amount of heat generated at this time is sufficient to melt the iron core. Accidents of this kind may actually occur, and therefore it is necessary to prevent them from occurring.

Currently, it is difficult to measure the temperature distribution by directly installing thermocouples in each part of the iron core, and methods of indirectly measuring temperature distribution are being considered. One of the reasons is that ultrafine particles are generated in the generator's refrigerant gas (in the case of large generators, hydrogen gas, which is a reducing gas, is usually used) during the thermal decomposition of the organic insulating material, and these particles are diffused. A method has been proposed to detect local overheating by detecting these particles. This kind of detection method is
Also found in US Pat. No. 3,427,880. In this patent, a detector constantly monitors the extracted portion of refrigerant gas. The detector is typically an ion chamber particle detector comprising an ionization section containing a radiation source;
and an electrode section that collects ions to a collector electrode. By extracting a portion of the refrigerant gas and passing it through this ion chamber particle detector, the particles in the refrigerant gas are ionized, and then collected at the collector electrode, causing an ionic current to flow, and from the amount of change in this ionic current. Changes in the concentration of particulates in the refrigerant gas, that is, the thermal decomposition of organic insulating materials, can be detected.

However, this detection method has the following problems.
First, organic insulation materials contain some moisture, which evaporates and diffuses into the refrigerant gas, and oil particles from the oil used in the seals of mechanical shafts also absorb into the refrigerant gas. Therefore, when some of the cooling gas is extracted to the ion chamber particle detector, these water particles and oil particles will be analyzed in the same way as particles produced by thermal decomposition. Therefore, the desired operation of the ion chamber particle detector to determine pyrolysis products based on local overheating is adversely affected. These pyrolysates therefore produce a signal similar to that of particulates, resulting in premature or unnecessary shutdown of the machine. Also, if oil particles or the like are present in the cooling gas, the readings of the ion chamber particle detector will be inaccurate, making it difficult to detect the correct signal indicating local overheating. On the other hand, a method can be considered in which these oil particles are removed by passing through a filter or the like and only the fine particles are guided to the ion chamber particle detector, but it is difficult to completely solve the above-mentioned problems. Therefore, in US Pat. No. 3,427,880, local overheating cannot be accurately determined because this problem always exists.

SUMMARY OF THE INVENTION An object of the present invention is to provide a local overheat diagnosis device for a rotating electrical machine that can solve the problems of the prior art described above, accurately diagnose local overheating, and prevent accidents.

To achieve this objective, the present invention analyzes the gas generated in a hydrogen gas atmosphere during thermal decomposition of organic insulating materials using gas chromatography, and as a result, carbon monoxide (CO), methane hydrocarbons, They found that hydrocarbons (HC) such as olefinic hydrocarbons were being generated, and focused on the fact that the latter accounted for the majority of these hydrocarbons. The present invention is characterized in that the hydrocarbon concentration in the refrigerant gas is monitored for detection.

Phenol resin,
Carbon and the mineral turpentine are used as the main components, but as a result of heating such a coating in a hydrogen atmosphere and analyzing the resulting gas by gas chromatography, it was found that carbon monoxide (CO), carbon dioxide ( It was found that the amount of CO ₂ ) generated was extremely small, and most of the amount generated was hydrocarbons represented by CnH ₂ n ₊₂ or CnHn. On the other hand, when filling a generator with hydrogen gas as a refrigerant gas, the air is first driven out with carbon dioxide (CO ₂ ), and then the hydrogen gas is sealed. The purity of hydrogen during normal operation is approximately 98% or higher, with approximately 1% remaining CO ₂ before replacement, carbon monoxide (CO), carbon dioxide ( Once diffused into the refrigerant gas, the amount of CO ₂ ) is on the order of ppb and impossible to detect. Also, the refrigerant gas is
At a temperature of 40-50°C, there are almost no hydrocarbons in the refrigerant gas in this temperature zone. Therefore, local overheating can be detected by detecting the hydrocarbon concentration during thermal decomposition of the organic insulating material. Note that this hydrocarbon concentration varies depending on the size of the thermally decomposed part of the organic insulating material, but even if thermal decomposition occurs in a relatively small part that does not destroy the insulation, it will be on the order of tens to hundreds of ppm. Can be detected.

Hereinafter, the present invention will be described in detail with reference to embodiments illustrated in the accompanying drawings.

FIG. 1 is an elevational view showing an embodiment in which the present invention is applied to a hydrogen gas-cooled power generator. generator 1
It is well known that the generator 1 is composed of a stator 2 and a rotor 3. Stator 2
and rotor 3 are all housed in an airtight casing 4 filled with cooling gas (hydrogen).
A fan 5 mounted on the rotor 3 circulates cooling gas along a passage arranged in the airtight casing 4. The cooling gas is cooled by a heat exchanger 6,
Return to the intake side of fan 5.

A portion of the cooling gas is taken out of the generator 1 via an extraction pipe 7. The extraction pipe 7 is attached to the high pressure side of the generator 1, and the analysis sample gas is configured to pass through the analyzer and return to the generator 1 via the return pipe 8 attached to the low pressure side. The extraction pipe 7 and the return pipe 8 are interconnected by a particle detector 11 for detecting particulate matter and a hydrocarbon detector 12. On the other hand, the circuits (flow paths) of the particle detector 11 and the hydrocarbon detector 12 are equipped with bypass pipes 9 and 10. Generally, at the beginning of flowing analysis sample gas to the analyzer and starting analysis, the temperature of the piping system of the analyzer is lower than the temperature inside the generator 1 (approximately 40°C), so this low-temperature piping system When a part of the warm cooling gas from inside the generator 1 flows as a sample gas, this sample gas is cooled and the moisture contained in it becomes water droplets and adheres to the inside of the piping system, causing each This adversely affects the operation of the detectors 11 and 12. In order to eliminate such adverse effects, in this embodiment, each detector 11, 12 is
The valves provided before and after the sample gas are closed, and the valves provided in the bypass pipes 9 and 10 are opened to allow the sample gas to flow from the extraction pipe 7 to the return pipe 8 via the bypass pipes 9 and 10. Thereafter, the piping system of the analyzer is warmed by the flow of the sample gas, and the water droplets adhering inside it are removed along with the sample gas, so at that point each valve installed in the bypass pipes 9 and 10 is closed, and each valve provided before and after each detector 11, 12 is opened.

Therefore, a portion of the cooling gas extracted from the extraction pipe 7 is transmitted to the particle detector 11 and the hydrocarbon detector 12.
Analysis of the particulate matter concentration and hydrocarbon concentration in the refrigerant gas is started when the generator is in a normal state. If local overheating occurs in the stator core of the generator 1, the organic insulating material will thermally decompose and generate ultrafine particles and hydrocarbons, which will be entrained in the hydrogen gas and the analysis sample extracted from the extraction tube 7. Since the particles are also entrained inside, an abnormal signal appears on the particle detector 11 and the hydrocarbon detector 12. The output signals from each of these detectors 11 and 12 are sent to a recorder 13.
is sent to and recorded. This recorder 13 is connected to an accumulating device 14, and the analysis results recorded by the recorder 13 are constantly monitored in this accumulating device 14, so that each detector 11,
When abnormal signals appear simultaneously from generator 12, integrated device 14 instructs alarm 15 to issue an alarm indicating that generator 1 is abnormal. Along with this warning, the power supply to the generator is cut off by the disconnector 16, and the generator is stopped. In this embodiment, local overheating is not diagnosed only when an abnormal signal appears in either one of the detectors 11 and 12, but only when abnormal signals appear from both detectors 11 and 12 at the same time. Since it is diagnosed that this has occurred, it is possible to prevent erroneous diagnosis due to malfunction or failure of each detector 11, 12 itself, and improve the reliability of monitoring.

The particle detector 11 and hydrocarbon detector 12 used here are of continuous analysis type. The reason for this is that when local overheating occurs, the organic insulating material thermally decomposes, and this thermal decomposition progresses over time.
Since the insulation will eventually break down, it is necessary to stop the generator 1 before the insulation breaks down. Therefore, it is necessary to continuously analyze the particulate matter concentration and hydrocarbon concentration in the hydrogen gas at all times, and the configuration must be such that the generator power can be immediately tripped if an abnormal signal is generated. If we were to monitor only the concentration of particulate matter and perform gas analysis to determine abnormalities after the concentration of particulate matter has increased, it would be a problem if the above-mentioned thermal decomposition progressed during that time and the insulation It is inappropriate as there is a risk of damage due to destruction. Therefore, it is not suitable to use discontinuous analysis type gas chromatography, which cannot perform continuous analysis, in conjunction with gas analysis. Therefore, in this embodiment, a hydrocarbon detector 12 is placed in parallel with the particle detector 11, and the hydrocarbon detector 12 is an analyzer that uses infrared absorption wavelength or a similar continuous measurement type analyzer. ing.

Next, the particle detector 11 used in this example will be explained in detail using FIG. 2. Unlike the ion chamber particle detector described in U.S. Pat. It is grounded, the internal electrodes are insulated, and a high voltage of several kV is applied from a DC power supply 19 to cause corona discharge. Countless ions are generated in this corona discharge field, and when the refrigerant gas passes through this particle charging section 17, the ions collide with particulate matter in the gas and are ionized. Next, the ionized particulate matter is sent to the particle detection section 18, where the ionized particulate matter is collected on a collector electrode, and its ionic current is detected. The ion current from the particle detection section 18 is a minute current on the order of 10 ^-12 (A), which is amplified by an electrometer 20, converted into a voltage signal, and recorded on a recorder 13. U.S. Patent No. 3,427,880 uses radiation (α rays) to ionize, so safety and
There is a problem in handling, and the ionization method of the particle detector, which is one of the configurations of this embodiment, is characterized by solving this problem.

In the embodiment described above, since monitoring only the hydrocarbon detector 12 may cause malfunction or failure of the detector itself, the particle detector 11 is also used to increase the reliability of monitoring. Of course, local overheating can be sufficiently detected using only the hydrocarbon detector 12.

As explained above, according to the present invention, in a rotating electric machine that includes a portion covered with an organic insulating material that thermally decomposes when exposed to high temperatures and uses reducing gas as a refrigerant, the concentration of hydrocarbons in the refrigerant gas can be reduced. A detection device is provided for detection, and when the hydrocarbon concentration detected by this detection device exceeds a predetermined value, it is diagnosed that local overheating has occurred. It is possible to accurately diagnose local overheating and prevent accidents without being affected by oil particles, etc.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a hydrogen gas-cooled power generation system equipped with a local overheating diagnostic device according to an embodiment of the present invention, and FIG. 2 is a block diagram showing the configuration of the particle detector shown in FIG. 1. be. 1...Hydrogen gas cooling type generator, 7...Extraction pipe, 8...
Return pipe, 9, 10... Bypass pipe, 11... Particle detector, 12... Hydrocarbon detector.

Claims (1)

[Scope of Claims] 1. A refrigerant comprising a part covered with an organic insulating material that thermally decomposes when exposed to high temperatures, and a refrigerant made of a reducing gas is brought into contact with the part covered with the organic insulating material and circulated within the machine. The rotating electrical machine is provided with a detection device that detects the concentration of hydrocarbons in the refrigerant gas, and when the concentration of hydrocarbons detected by the detection device exceeds a predetermined value, it is diagnosed that local overheating has occurred in the rotating electrical machine. A local overheating diagnostic device for a rotating electrical machine, which is characterized by: 2. The local overheat diagnosis device for a rotating electric machine according to claim 1, wherein the detection device is of a continuous spectroscopy type. 3. The local overheat diagnosis device for a rotating electric machine according to claim 2, wherein the continuous analysis type detection device is a spectrometer that uses infrared absorption wavelength. 4. A rotating electrical machine that includes a portion covered with an organic insulating material that thermally decomposes when exposed to high temperatures, and in which a refrigerant made of reducing gas is brought into contact with the portion covered with the organic insulating material and circulated within the machine, wherein the refrigerant A first detection device that detects the concentration of hydrocarbons in the gas and a second detection device that detects the concentration of particulate matter in the refrigerant gas are provided, and the carbonization detected by the first detection device is provided. When the concentration of hydrogen exceeds a predetermined value and the concentration of particulate matter detected by the second detection device exceeds a predetermined value, it is diagnosed that local overheating has occurred in the rotating electric machine. Local overheating diagnostic device for rotating electrical machines. 5. The local overheat diagnosis device for a rotating electrical machine according to claim 4, wherein the first and second detection devices are of a continuous spectroscopy type. 6 In claim 5, the first continuous spectroscopy type detection device is an analyzer that uses infrared absorption wavelength, and the second continuous spectroscopy type detection device is an analyzer that uses infrared absorption wavelength A device for diagnosing local overheating of a rotating electrical machine, characterized in that the device is a device for projecting ions into the particulate matter to ionize it, and detecting an ion current of the ionized particulate matter.