| Summary: | 博士 === 淡江大學 === 電機工程學系博士班 === 95 === Power System consists of generation, transmission and distribution systems to deliver the power service to customers. Typical distribution systems operate in a radial configuration which is supplied from substations and feeds to distribution transformers. Distribution systems cover a very wide area with components such as main transformers, primary feeders, laterals, distribution transformers, low tension lines and meters. All these components contribute distribution line loss to deteriorate system operation efficiency. Numerous shunt capacitors are installed along distribution feeders to compensate for reactive power to regulate the voltage, reduce energy, correct the power factor, and release system capacity, for both urban and rural areas.
The general capacitor placement problem is to locate and determine the sizes of capacitors to be installed at the nodes of a radial distribution system under various loading conditions. This dissertation formulates the capacitor placement problem as a multi-objective problem, including operational requirements. Furthermore, the single-tuned filter design is also presented to improve the harmonic distortion of the distribution feeders. The problem formulation presented in radial distribution system considers four objectives including of minimizing the cost of installing capacitors, minimizing the real power loss, minimizing the deviation of the bus voltage, and maximizing the capacity margin of the feeders and the transformer. The problem formulation presented in distorted distribution networks considers four objectives including of minimizing the cost of installing capacitors, the real power loss, the deviation of the bus voltage, and the total harmonic distortion of the bus voltage. A new problem formulation model of all objective functions with fuzzy sets to reflect the imprecise nature of objectives and incorporate the multiple requirements on planning is presented.
This dissertation presents a two-staged immune multi-objective method to solve the constrained multi-objective problem. The artificial immune algorithm simulates the operating relationship between the antigen and antibody in human immune system, which are in corresponding to the optimal solution and objective function of the optimization problem, to solve the optimization problem of reactive power and voltage control. The affinity among the antibodies is applied to increase the diversity among them to avoid the local optimal solution such that the quick convergent speed and the global optimal solution can be achieved. This dissertation proposes the fuzzy-based artificial immune multi-objective method embedded with the compromise programming to the multi-objective optimal capacitor placement. The proposed method finds a set of non-inferior (Pareto) solutions rather than any single aggregated optimal solution for the decision maker to choose one particular solution. Besides, this proposed method eliminated the need of any user-defined weight factor for aggregating all objectives.
Finally, to demonstrate the effectiveness of the proposed method, comparative studies are conducted on an actual system with rather encouraging results. To find out the changes of each objective function between before and after the placement of capacitors, 69-BUS distribution system is used to test in this method. It proves that the proposed method is the most effective method to solve the optimal capacitor placement problem.
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