Dissertation
Dissertation > Industrial Technology > Electrotechnical > Transmission and distribution engineering, power network and power system > Theory and Analysis > Network analysis,power system analysis

Analyzing Harmonic and Harmonic Wave Harness of Low Voltage Power Network

Author ZengHui
Tutor KangLongYun; YuanZhou
School South China University of Technology
Course Electrical Engineering
Keywords Quality of electric energy Frequency converter The harm of harmonics Harmonic control
CLC TM711
Type Master's thesis
Year 2012
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Quality of supply, including system voltage, frequency pass rate, peak, voltagegauge the duration of power outages, as well as harmonic content and so on. As therapid development of power electronics technology, various power electronic devicesin power systems, industrial, transportation and the increasingly widespreadapplication of the family, so that a large number of power system non-linear loadsincrease, the grid disturbance caused by serious and increasingly complex, lead tolower quality power supply. Currently, power system harmonics and power factor toreduce pollution, electromagnetic interference, power system has been tied to threemajor hazards.In the field of industrial variable speed drives, mechanical speed control,compared with the traditional, with the inverter has many advantages, so itsapplication is very extensive. South of a heat distribution system in the company10KV/0.4KV use a lot of drive, but because of the inverter switching characteristicsof the inverter circuit, its power supply to form a typical non-linear load. The inverterpower electronic devices, represented by the utility grid are the most important sourceof harmonics, its power system has an important impact on power quality, anddistribution network is also a major source of harmonics.To improve system power factor, the company installed on the low voltage buscapacitor compensation equipment. However, during operation, the device oftenoverload trip, serious and even cause an explosion capacitor, resulting incompensation device can not be put into operation. As the capacitor impedance is verysmall for high harmonics, harmonic current in the capacitor increases the fundamental,so that the capacitor’s total operating current increases, causing the capacitor andoverload protection trip. Meanwhile, the harmonic parameters match the impact of thecapacitor, it is possible to cause the power grid high-order harmonic resonance,increasing the fault harmonics in the power system, transmission, distribution, supply,use the various links. The company since production began in the production process,there has been reactive power compensation device can not be normal switching, DCSsystem board damage to the pump motor bearings burn, burn plant transformer,inverter motor cooling fan control the bursting of the capacitor phenomenon, a directimpact on the company’s safety and give the company a reliable heat supply tocomplete the task to bring potential problems.Through the distribution network harmonic test, and test results were analyzed,preliminary treatment plan, the harmonics of governance, to improve the distributionnetwork power quality, extend equipment life, protect the company’s safety.

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