| Summary: | 碩士 === 國立中山大學 === 電機工程研究所 === 85 ===
Phase unbalance is one of the prime reasons to cause extra line loss and ground relay tripping in the distribution system. In Taiwan, the feeder unbalance introduced by the open wye-open delta transformers could be one of the most serious reason for feeder imbalance in a practical three phase distribution system. Many researchs used feeder reconfiguration and capacitor placement to minimize power loss. This research tries to minimize power loss by changing the prime phase sequencing of the open wye-open delta transformers to.
Studies of changing the prime phase sequence of the distribution transformers for load balance are not vary popular. In Taiwan, a practical distribution system could have many open wye-open delta transformers to supply power. This research will focus on the optimal transfer of phase sequence to solve the above problem. Feeder balance and loss minimization will both be considered.
Optimization by changing the phase sequence to balance load and minimize loss is a complicated mathematical formulation. It is not easy to define a direct correlation between the variables, .i.e. the phase sequence, cost of loss reduce, and the objetives. However with the fitness function and the concept of chromosome provided by Genetic Algorithms (G.As), the formulation can be greatly simplified. This research will try to formulate a G.As to determine the optimal phase sequencing for load transfer. By using the characteristic of G.As, the performance of all the combinations of the open wye-open delta transformers with their phase sequence can be evaluated. A parallel process can also be developed by the G.As to avoid the convergence to a local optimum. The developed method will provide a tool for making strategies for the power company to achieve the feeder balance and reduce power loss.
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