How to monitor temperature with capacitors-INNO

Mga sensor ng temperatura ng fiber optic hindi lamang may malawak na aplikasyon sa pagsukat ng temperatura ng switchgear, mga circuit breaker, at mga transformer, ngunit mayroon ding pagkakabukod, laban sa panghihimasok, at mga katangian ng paglaban sa mataas na boltahe na hindi maaaring makamit ng iba pang tradisyonal na mga sensor ng temperatura sa pagsubaybay sa temperatura ng kapasitor.

Ang high-voltage parallel capacitor bank device ay kasalukuyang napakahalagang reactive power source sa power system, gumaganap ng mahalagang papel sa pagpapabuti ng istraktura ng sistema ng kuryente at pagpapahusay ng kalidad ng kuryente. Ang pangunahing pag-andar ay upang magbigay ng reaktibong kapangyarihan sa sistema ng kuryente, bawasan ang pagkalugi ng linya, pagbutihin ang kalidad ng boltahe, at dagdagan ang paggamit ng kagamitan. Bilang isang reactive power compensation device, Ang mga power capacitor ay karaniwang ginagamit sa mga substation sa pamamagitan ng mataas na boltahe na sentralisadong kabayaran. The compensation capacitors are connected to the 10kV or 35kV busbar of the substation to compensate for the reactive power on all lines and transformers on the busbar side of the substation. They are often used in conjunction with on load tap changers to further improve the power quality of the power system.

The impact of temperature rise fault on high-voltage capacitors

Capacitors often encounter various faults during operation, na nagdudulot ng malaking banta sa ligtas at normal na operasyon ng power system. Common faults of capacitors in power operation include oil leakage, mahinang pagkakabukod, at nasunog na mga piyus. Sa kanila, the most harmful and frequently occurring fault is capacitor failure caused by heating. The heating caused by capacitor faults is divided into heating at the busbar connection point and heating at the fuse outside the capacitor, na ang huli ay mas malamang na mangyari. Sa mga nakaraang taon, the 35kV high-voltage parallel capacitor bank has experienced abnormal temperature rise due to aging or high load current during daily operation due to long operating years and construction and installation processes. If such abnormal situations are not detected and dealt with in a timely manner, they can easily develop and expand, leading to damage to individual capacitors and even group explosions and injuries. The high failure rate directly threatens the safety of 500kV power equipment and the personal safety of operation and maintenance personnel, resulting in significant fluctuations in grid voltage, increased active and reactive power losses, reduced service life of capacitors, and affecting the normal and stable operation of the grid. Power capacitors are mainly used for reactive power compensation in power systems to improve power factor. In order to make it operate more reliably, the current industry mainly considers connecting internal components of capacitors in series with internal fuses. When a capacitor experiences complete component failure due to weak dielectric points, the internal fuse connected in series with the component will activate, isolating only a portion of the damaged components. The capacitor will continue to operate with only a slight decrease in power. Sa puntong ito, the disturbance in the capacitor bank can be ignored, and the total capacity of the capacitor bank will not be significantly affected by the action of a fuse. The introduction of an internal fuse protects the capacitor components, but invisibly increases the fault points. Inside power capacitors, the internal fuse is the main heating point, but its volume and diameter are very small (about 135mm in length and 0.45mm in diameter), and it is generally hidden between capacitor components. Due to current measurement technology, it is difficult to accurately and objectively measure the surface temperature of the internal fuse under actual operating conditions.

Dry type capacitor temperature monitoring
Sa kasalukuyan, oil immersed capacitors and dry-type capacitors are commonly used in the field of high voltage. The latter has the advantages of environmental protection, material saving, mababang gastos, simple process, magaan ang timbang, small area, self-healing product, more reliable operation, good fire resistance, less likely to produce high voltage gas, and greatly reduced the possibility of explosive hazards.
A dry-type capacitor consists of a capacitor core, a casing, a sleeve, at iba pang mga accessories. The capacitor core is composed of capacitor elements and insulating components. Capacitor components are made by winding thin film insulating media and aluminum foil electrodes with a certain thickness and layers, or by evaporating a layer of metal on the thin film to form a metalized film. After the components are rolled up, they are loaded into the component housing, and several capacitor components are connected in series or parallel to form the entire capacitor core.
Dry type capacitors are usually used indoors or underground with poor ventilation conditions, and the internal heat dissipation of capacitors can only rely on gas. Compared with oil immersed capacitors, the heat transfer coefficient of gas is lower, kaya ang pagganap ng pagwawaldas ng init ng mga dry type capacitor ay mahirap. Ang lahat ng ito ay may masamang epekto sa pagpapatakbo ng mga dry-type na capacitor. Ang pagsasanay sa pagpapatakbo ng sistema ng kuryente ay nagpakita na ang rate ng pagkabigo ng mga capacitor ay makabuluhang mas mataas mula Hunyo hanggang Setyembre bawat taon kumpara sa iba pang mga buwan. Sa ilang rehiyon, ang mga regulasyon sa industriya ng kuryente ay nagsasaad na ang pinakamainit na temperatura ng punto ng buong film capacitor core ay hindi lalampas 80 ℃. Kapag lumampas ang temperatura 80 ℃, ang pagganap ng pagkakabukod ng polypropylene film (PP na pelikula) bilang isang dielectric ay bababa.
Sa kasalukuyan, ang patlang ng temperatura ng mga dry-type na capacitor ay karaniwang sinusukat ng tradisyonal na mga sensor ng temperatura upang masukat ang temperatura ng capacitor shell, at pagkatapos ay kinakalkula ang panloob na temperatura. Ang halaga ng temperatura na nakuha sa ganitong paraan ay may mga error sa pamamahagi ng panloob na patlang ng temperatura ng kapasitor, at hindi maaaring tumpak na makuha ang tunay na temperatura ng pinakamataas na punto ng temperatura.

Sa kasalukuyan, ang paraan ng pagsukat ng temperatura para sa panloob na proteksyon ng mga piyus ng mga power capacitor ay may kasamang pagsubok sa pagtaas ng temperatura, ngunit ang pagsubok na ito ay tinatantya lamang ang pagtaas ng temperatura ng panloob na piyus sa pamamagitan ng pagsukat ng kasalukuyang at paglaban ng panloob na piyus. Mahina ang katumpakan nito, at sa aktwal na proseso ng pagpasa ng kasalukuyang sa panloob na piyus, ang paglaban ng panloob na fuse ay magbabago sa temperatura. Sa isang banda, mahirap tiyakin ang patuloy na daloy ng kasalukuyang. Sa kabilang banda, ang pagsusulatan sa pagitan ng paglaban ng panloob na fuse at temperatura ay naaangkop lamang sa loob ng isang tiyak na hanay ng temperatura. Lampas sa saklaw na ito, magiging mahirap makakuha ng tumpak na mga resulta. Samakatuwid, this indirect method of measuring the temperature rise of the internal fuse in capacitors has limitations and low accuracy. Bilang karagdagan, the temperature rise of the internal fuse is measured through a thermal resistor, but due to the fact that the thermal resistor is much larger in both volume and diameter than the internal fuse, it will affect the actual temperature of the internal fuse during contact measurement, resulting in poorer measurement accuracy. In view of this, it is necessary to design a simple and feasible measuring device to accurately grasp the temperature of the fuse inside the capacitor under actual operating conditions, provide a basis for the design and selection of the fuse inside the capacitor, and effectively improve the reliability of the internal fuse protection action, ensuring that the temperature of the internal fuse will not cause damage to the internal insulation of the capacitor.

Disadvantages of infrared thermography for temperature measurement
Sa kasalukuyan, the heating maintenance of capacitors is mainly carried out through infrared imaging inspection. Gayunpaman, infrared thermal imaging cannot test the temperature inside a closed environment, and the test results are affected by the season, oras, and surface smoothness of the testing equipment. Infrared testing equipment is expensive and cannot continuously monitor the temperature of high-voltage electrical equipment for a long time. There is high voltage on the capacitor and strong electromagnetic interference around it, which often leads to false alarms and missed alarms in traditional detectors. Para sa layuning ito, highly reliable and high-performance temperature sensors are needed to monitor the temperature of capacitors in real-time and effectively, in order to avoid equipment burnout and power outages.

Bilang karagdagan, current temperature measuring equipment cannot detect the specific temperature inside the capacitor. The existing capacitors are used in environments with significant temperature changes. Prolonged use of capacitors at abnormal temperatures can seriously affect their service life and increase their damage rate.

Capacitor sistema ng pagsukat ng temperatura ng fiber optic
The FJINNO capacitor fluorescence fiber optic temperature measurement system not only solves the problem of traditional temperature sensors being unable to accurately measure the temperature of small internal fuses, ngunit nalulutas din ang potensyal na paghihiwalay sa pagitan ng malakas at mahinang kuryente at ang anti electromagnetic interference na problema ng komunikasyon ng data, pagbibigay ng isang mahusay na solusyon para sa komprehensibo at tumpak na paghawak sa hot spot temperatura ng panloob na core ng mga capacitor.

Ang fiber optic temperature monitoring host ay nilagyan ng temperature measurement alarm software, at ang computer sa pagsubaybay ay nangongolekta ng impormasyon sa temperatura na ipinadala ng fiber optic temperature signal demodulator sa pamamagitan ng port ng komunikasyon. Real time na pagpapakita ng data ng temperatura para sa bawat punto ng pagsukat ng temperatura, Ang software ng alarma sa temperatura ay nagbibigay ng mga function tulad ng graded monitoring, pagguhit ng curve ng temperatura, display ng pamamahagi ng temperatura, makasaysayang curve query, pagbuo ng ulat, at paglilimbag;