How to monitor temperature with capacitors-INNO

Sensorer za joto za fiber optic not only have wide applications in kipimo cha joto cha switchgear, wavunja mzunguko, na transfoma, but also have insulation, kupambana na kuingiliwa, and high voltage resistance characteristics that other traditional temperature sensors cannot achieve in capacitor temperature monitoring.

The high-voltage parallel capacitor bank device is currently an extremely important reactive power source in the power system, playing a crucial role in improving the structure of the power system and enhancing power quality. The main function is to provide reactive power to the power system, reduce line losses, improve voltage quality, and increase equipment utilization. As a reactive power compensation device, capacitors nguvu ni kawaida kutumika katika substations kupitia high-voltage fidia ya kati. 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

Mara nyingi capacitors hukutana na makosa mbalimbali wakati wa operesheni, ambayo ni tishio kubwa kwa uendeshaji salama na wa kawaida wa mfumo wa nguvu. Common faults of capacitors in power operation include oil leakage, insulation mbaya, na fusi zilizochomwa. Miongoni mwao, 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, with the latter being more likely to occur. Katika miaka ya hivi karibuni, 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, kuongezeka kwa upotezaji wa nguvu hai na tendaji, reduced service life of capacitors, and affecting the normal and stable operation of the grid. Vibanishi vya nguvu hutumiwa hasa kwa fidia tendaji ya nguvu katika mifumo ya nguvu ili kuboresha kipengele cha nguvu. 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. Capacitor itaendelea kufanya kazi na kupungua kidogo tu kwa nguvu. Katika hatua hii, 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
Kwa sasa, 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, gharama ya chini, simple process, uzito mwepesi, 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, na vifaa vingine. 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, na vipengele kadhaa vya capacitor vinaunganishwa katika mfululizo au sambamba ili kuunda msingi wote wa capacitor.
Dry type capacitors are usually used indoors or underground with poor ventilation conditions, na uharibifu wa joto wa ndani wa capacitors unaweza tu kutegemea gesi. Ikilinganishwa na capacitors ya mafuta, mgawo wa uhamisho wa joto wa gesi ni wa chini, 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. Katika baadhi ya mikoa, the power industry regulations stipulate that the hottest point temperature of the full film capacitor core shall not exceed 80 ℃. Wakati joto linapozidi 80 ℃, utendaji wa insulation ya filamu ya polypropen (filamu ya PP) kwani dielectric itapungua.
Kwa sasa, 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.

Kwa sasa, 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. Kwa upande mmoja, it is difficult to ensure its constant current flow. Kwa upande mwingine, the correspondence between the resistance of the internal fuse and temperature is only applicable within a certain temperature range. Beyond this range, it will be difficult to obtain accurate results. Kwa hiyo, this indirect method of measuring the temperature rise of the internal fuse in capacitors has limitations and low accuracy. Aidha, 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, kusababisha usahihi duni wa kipimo. Kwa kuzingatia hili, 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, kutoa msingi wa kubuni na uteuzi wa fuse ndani ya 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
Kwa sasa, the heating maintenance of capacitors is mainly carried out through infrared imaging inspection. Hata hivyo, infrared thermal imaging cannot test the temperature inside a closed environment, and the test results are affected by the season, wakati, 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. Kwa kusudi hili, 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.

Aidha, 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 mfumo wa kipimo cha joto la 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, 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.

The fiber optic temperature monitoring host is equipped with temperature measurement alarm software, and the monitoring computer collects temperature information transmitted by the fiber optic temperature signal demodulator through the communication port. Real time display of temperature data for each temperature measurement point, temperature alarm software provides functions such as graded monitoring, temperature curve drawing, temperature distribution display, historical curve query, report generation, and printing;