The series resonant withstand voltage testing system has a wide range of application scenarios in the field of power. The following is a detailed introduction to its main application scenarios:
1. Voltage withstand test of power cables
Medium and low voltage power cables: For power cables with a rated voltage of 10kV, a series resonant high voltage test system based on direct digital frequency synthesis technology can generate a continuous high-resolution frequency sine signal, which is amplified and used as a resonant excitation power supply. By continuously adjusting the output frequency of the signal, it meets the resonance requirements of the series system. Through voltage withstand testing of a 10kV power cable with a length of 1km, it was found that the system design meets the requirements of regulatory testing and has broad application prospects in this field.
High voltage power cables: In the 220kV cable withstand voltage test, the use of variable frequency series resonance technology can greatly reduce the capacity of power testing equipment, which helps to improve testing quality and work efficiency. This technology has proven its feasibility and effectiveness in long-distance high-voltage XLPE cable AC withstand voltage testing.
2. GIS equipment withstand voltage test
The voltage withstand test of GIS (gas insulated metal enclosed switchgear) is the main method to test its insulation level and the most effective means to detect internal abnormalities in GIS. Due to its small size, light weight, and convenient use, frequency modulated series resonant equipment has become the preferred choice for voltage withstand testing. For example, when conducting GIS voltage withstand tests on site, by introducing the application of frequency modulation series resonance equipment, summarizing the standardized practices of on-site work preparation, equipment selection, test steps, and pressurization process, reasonable equipment selection is calculated before the test in engineering examples, and verified in on-site measurement test data.
3. Voltage withstand test of switchgear
① Medium and high voltage switchgear: Various high voltage tests are required for newly installed and overhauled electrical equipment. AC withstand voltage test, as a handover test item, is of decisive significance in determining whether the equipment can be put into operation. The application research of frequency conversion series resonance withstand voltage test equipment in engineering shows that this technology can be used for AC withstand voltage testing of electrical equipment in high-voltage cable engineering and substation engineering. Firstly, introduce the basic concept of the variable frequency series resonant AC withstand voltage test technology, analyze its basic principles, the characteristics of the current devices used, and the method of parameter calculation in the test; Secondly, analyze the problems encountered in its practical application process, explore the safety issues during the experimental process, and find ways to avoid the occurrence of problems; Finally, by studying the application of this technology in engineering, standardizing the working methods of withstand voltage testing, guiding on-site operations, and providing ideas for the development of the application of testing technology.
500kV switchgear: With the increasing voltage values of on-site AC withstand voltage tests, the safety testing distance of 500kV switchgear has been greatly affected. Although scholars at home and abroad have conducted extensive research on air gap breakdown tests under power frequency voltage, there is relatively little research on air gap breakdown and safety distance assessment based on the principle of series resonance. By establishing a simplified model of 500kV HGIS bushing bushing, the discharge and breakdown phenomena at different resonance frequencies were studied using a series resonance test device, and the air breakdown voltage at different voltage frequencies was obtained. It was found that under the same gap testing conditions, the breakdown voltage of high resonance frequency was lower than that of low resonance frequency, and the difference between the two increased with the increase of air gap. Based on the probability distribution of air gap breakdown and test data, a calculation method for the safe distance of on-site AC withstand voltage test is proposed, and the safe distance under typical test scenarios is given.
In summary, the series resonant withstand voltage testing system has important application value in fields such as power cables, GIS equipment, and switchgear.
The ZCVF-A series variable frequency series resonant withstand voltage test device adopts the method of adjusting the power supply frequency to achieve resonance between the reactor and the tested capacitor, thereby obtaining high voltage and high current on the tested object. Due to its low required power supply, light weight and small size, it has been widely praised and applied at home and abroad, and is a new method and trend of high voltage testing. This device is mainly designed for AC withstand voltage testing of cross-linked cables, hydroelectric generators, main transformers, busbars, GIS, etc. It has a wide range of applications and is an ideal withstand voltage equipment for high-voltage testing departments and power installation and maintenance engineering units at the local, municipal, and county levels. The equipment mainly consists of a variable frequency control power supply, an excitation transformer, a reactor, a capacitive voltage divider, and a compensation capacitor (optional).
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