| Summary: | 碩士 === 和春技術學院 === 電機工程研究所 === 99 === The current electricity distribution system supplies power together with power generation of renewable energy such as the equipment of solar power generation, wind power generation, fuel-cell power generation, etc. Electricity generated by generating equipment of renewable energy are converted into alternating current and then incorporated into utility power which can not only supply power to loads but also can be sold to power companies for additional rewards.
Power generation of renewable energy is generally divided into single-phase and three-phase according to connection modes of converters. Three-phase connection is made by three single-phase converters distributed like Y or △. Power generated by single-phase connection constitutes three-phase power. Power generated is different in the same energy field, therefore, three-phase power has unbalanced current. This thesis investigates balance of three-phase current by connecting single-phase current with renewable energy in parallel on distant islands and three-phase power supply of parallel system because the issue of imbalance of three-phase current emerges when single-phase power generation of renewable energy is incorporated into three-phase electricity distribution system. This thesis sets 27 power generation of distributed renewable energy which is then blended into three-phase electricity distribution system. Power supply system is divided into three-phase power supply on distant islands and three-phase parallel power supply for investigation. Three-phase power supply system on distant islands takes complex current with the same loads and actual current as the input, in which loads of complex current has both conjugated number and non-conjugated number based on current amount and unbalance rate is calculated both including phase and excluding phase. Three-phase parallel power supply system calculates unbalance rate of three-phase current under the circumstance of the original power supplied both with loads and without loads by Taipower and with the same amount of complex current and actual current as its input and current amount as its judging criterion. In conclusion, with the same amount of complex current and the same current mode as the input, effect of balance rate can be determined by calculation results based on actual current and complementation degree of three-phase current.
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