How to monitor temperature with capacitors

Optiese vesel temperatuur sensor, Intelligente moniteringstelsel, Verspreide optiese veselvervaardiger in China

Optiese vesel temperatuur sensors not only have wide applications in temperature measurement of switchgear, circuit breakers, En transformers, but also have insulation, anti-inmenging, and high voltage resistance characteristics that other traditional temperature sensors cannot achieve in capacitor temperature monitoring.

Die hoëspanning parallelle kapasitor bank toestel is tans 'n uiters belangrike reaktiewe kragbron in die kragstelsel, playing a crucial role in improving the structure of the power system and enhancing power quality. Die belangrikste funksie is om reaktiewe krag aan die kragstelsel te verskaf, verminder lynverliese, verbeter spanningskwaliteit, en verhoog die gebruik van toerusting. As a reactive power compensation device, Kragkondensators word gewoonlik in substasies gebruik deur middel van hoogspanning-gesentraliseerde vergoeding. 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

Kapasitors ondervind dikwels verskillende foute tydens operasie, wat 'n beduidende bedreiging vir die veilige en normale werking van die kragstelsel inhou. Common faults of capacitors in power operation include oil leakage, swak isolasie, en verbrande versmeltings. Onder hulle, 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, met laasgenoemde wat meer geneig is om te voorkom. In onlangse jare, 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. As sulke abnormale situasies nie betyds opgespoor en hanteer word nie, they can easily develop and expand, wat lei tot skade aan individuele kapasitors en selfs groepontploffings en beserings. 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, verhoogde aktiewe en reaktiewe kragverliese, reduced service life of capacitors, and affecting the normal and stable operation of the grid. Kragkondensators word hoofsaaklik gebruik vir reaktiewe kragvergoeding in kragstelsels om kragfaktor te verbeter. 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. Die kondensator sal voortgaan om te werk met slegs 'n effense afname in krag. Op hierdie punt, Die versteuring in die kapasitorbank kan geïgnoreer word, and the total capacity of the capacitor bank will not be significantly affected by the action of a fuse. Die bekendstelling van 'n interne lont beskerm die kapasitorkomponente, but invisibly increases the fault points. Binne krag kondensators, the internal fuse is the main heating point, but its volume and diameter are very small (ongeveer 135 mm lank en 0,45 mm in deursnee), en dit word gewoonlik tussen kapasitorkomponente versteek. Due to current measurement technology, dit is moeilik om die oppervlaktemperatuur van die interne lont akkuraat en objektief te meet onder werklike bedryfsomstandighede.

Dry type capacitor temperature monitoring
Op die oomblik, oil immersed capacitors and dry-type capacitors are commonly used in the field of high voltage. Laasgenoemde het die voordele van omgewingsbeskerming, materiële besparing, lae koste, eenvoudige proses, ligte gewig, klein area, selfgenesende produk, meer betroubare operasie, goeie brandweerstand, less likely to produce high voltage gas, en die moontlikheid van plofbare gevare aansienlik verminder.
A dry-type capacitor consists of a capacitor core, a casing, a sleeve, en ander bykomstighede. 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. Nadat die komponente opgerol is, they are loaded into the component housing, en verskeie kapasitorkomponente word in serie of parallel verbind om die hele kapasitorkern te vorm.
Dry type capacitors are usually used indoors or underground with poor ventilation conditions, en die interne hitte-afvoer van kapasitors kan slegs op gas staatmaak. In vergelyking met olie onderdompelde kondensators, die hitte-oordragskoëffisiënt van gas is laer, so the heat dissipation performance of dry type capacitors is poor. All of these have adverse effects on the operation of dry-type capacitors. Practice in power system operation has shown that the failure rate of capacitors is significantly higher from June to September each year compared to other months. In sommige streke, the power industry regulations stipulate that the hottest point temperature of the full film capacitor core shall not exceed 80 °C. Wanneer die temperatuur oorskry 80 °C, Die isolasieprestasie van polipropileenfilm (PP film) as 'n diëlektriese sal afneem.
Op die oomblik, the temperature field of dry-type capacitors is generally measured by traditional temperature sensors to measure the temperature of the capacitor shell, and then the internal temperature is calculated. The temperature value obtained in this way has errors in the distribution of the internal temperature field of the capacitor, and cannot accurately obtain the true temperature of the highest temperature point.

Op die oomblik, the temperature measurement method for internal protection fuses of power capacitors includes temperature rise test, but this test only estimates the temperature rise of the internal fuse by measuring the current and resistance of the internal fuse. Its accuracy is poor, and in the actual process of passing current to the internal fuse, the resistance of the internal fuse will change with the temperature. Aan die een kant, it is difficult to ensure its constant current flow. Aan die ander kant, die korrespondensie tussen die weerstand van die interne lont en temperatuur is slegs van toepassing binne 'n sekere temperatuurbereik. Buite hierdie reeks, dit sal moeilik wees om akkurate resultate te verkry. Dus, Hierdie indirekte metode om die temperatuurstyging van die interne lont in kapasitors te meet, het beperkings en lae akkuraatheid. Bykomend, 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, wat lei tot swakker meet akkuraatheid. In die lig hiervan, 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, voorsien 'n basis vir die ontwerp en seleksie van die lont binne die kondensator, 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
Op die oomblik, the heating maintenance of capacitors is mainly carried out through infrared imaging inspection. Egter, infrared thermal imaging cannot test the temperature inside a closed environment, en die toetsuitslae word deur die seisoen beïnvloed, Tyd, en oppervlak gladheid van die toets toerusting. Infrarooi toetstoerusting is duur en kan nie die temperatuur van hoëspanning elektriese toerusting vir 'n lang tyd deurlopend monitor nie. 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. For this purpose, 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.

Bykomend, current temperature measuring equipment cannot detect the specific temperature inside the capacitor. Die bestaande kapasitors word gebruik in omgewings met beduidende temperatuurveranderinge. Prolonged use of capacitors at abnormal temperatures can seriously affect their service life and increase their damage rate.

Capacitor fiber optic temperature measurement system
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, but also solves the potential isolation between strong and weak electricity and the anti electromagnetic interference problem of data communication, providing a good solution for comprehensively and accurately grasping the hot spot temperature of the internal core of capacitors.

Die veseloptiese temperatuurmoniteringsgasheer is toegerus met alarmprogrammatuur vir temperatuurmeting, en die moniteringsrekenaar versamel temperatuurinligting wat deur die optiese veseltemperatuurseindemodulator deur die kommunikasiepoort oorgedra word. Real time display of temperature data for each temperature measurement point, temperature alarm software provides functions such as graded monitoring, temperatuur kromme tekening, temperatuur verspreiding vertoon, Historiese kurwe-navraag, report generation, and printing;