Due to the needs of production, there are a large number of pump loads in the petrochemical industry, and many pump loads are equipped with frequency converters. The large number of applications of frequency converters greatly increase the harmonic content of the distribution system in the petrochemical industry. At present, most of the rectifier links of the frequency converters are the application of 6 pulse rectifier to convert AC into DC. Therefore, the harmonics produced are mainly the 5th, 7th and 11th harmonics.
1. Analysis of load characteristics in the oil industry
More than 85% of the power load in the oil industry grid is inductive load, such as various oil pumps, motors and so on. In recent years, as the oil field has put forward higher requirements for energy conservation, many units have adopted a large number of energy-saving devices. Because of its obvious energy-saving effect, easy adjustment, easy maintenance and network, the frequency converter has been widely used in oil exploitation. The pump, pump, step-down pump and mixing pump in the oil production station are driven by the frequency converter, but the frequency converter will produce a large number of harmonics to interfere with the load and its adjacent equipment, and the harmonics will also affect the public power grid through the input power line.
2. Harm of harmonics to oil field power grid
1) Harmonics affect the stable operation of the oilfield power grid and reduce the power supply quality of the oil field power grid.
2) Harmonics increase the loss power of the capacitor, shorten the service life of the power capacitor, and in the case of serious harmonics, it will also make the capacitor bulge, breakdown or explosion. Harmonics can also increase the power loss of the transformer.
3) Harmonics will cause the power loss of the rotating motor to increase, cause overheating, produce mechanical vibration, noise and harmonic overvoltage, which will shorten the life of the equipment, and even damage in serious cases; Harmonics will cause relay protection misaction or rejection action; The harmonics in the power system are coupled to the weak current system by electromagnetic induction, electrostatic induction and conduction, which will also cause interference to the weak current system.
With the wide use of frequency converter in oil field water injection system, it not only solves the problems of traditional water injection pressure variation, high energy consumption and low efficiency, but also brings the increase of harmonic content in power grid. The existence of a large number of harmonics threatens the reliability and security of the power supply system. In order to eliminate the harm caused by harmonics, the use of manufacturing, improve the power supply quality of the power grid, to ensure the normal production.
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Post time: Jun-30-2023