| Summary: | 碩士 === 國立中正大學 === 電機工程所 === 95 === Voltage stability assessment and loss improvement are important issues in power system planning and operation. The voltage stability of a system depends on the network topology, generation and load patterns, availability of reactive power reservation etc. Voltage collapse may occur, if the system does not have reactive power compensation immediately after a contingency due to load increasing or transmission line trip. As situation is worsening, it may excite domino effect. Then blackout happens.
This thesis aims at presenting a novel calculation index of voltage stability. The voltage stability index is easy to use and quick to calculate. Besides, in order to resolve multi-objective optimization problems, a concept of per-unit system to determine weighting factor for every sub-objective is provided.
This research presents a new method using the hybrid differential evolution (HDE) to determine the tap setting of on-load tap changing transformers (OLTCs) for adjusting reactive power flow and determining the location and size of the added Static Var Compensators (SVCs) for reactive power compensation on transmission systems. This technique would be able to improve voltage stability in the system and reduce the system losses. The above-mentioned techniques consider three different operation modes, and every mode considers three different load conditions.
The performance of this technique is tested using the IEEE 14-bus Power Flow Test System. The results show that the OLTCs with the tap setting identified and the SVCs with the location and size identified by the proposed technique have been able to improve voltage stability of the system and reduce the losses.
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