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- Type of Document: M.Sc. Thesis
- Language: Farsi
- Document No: 44991 (05)
- University: Sharif University of Technology
- Department: Electrical Engineering
- Advisor(s): Vakilian, Mehdi
- Abstract:
- Feeder reconfiguration is one of the most prominent tasks for loss reduction, reliability improvement and also congestion alleviation in distribution networks. Besides improving abovementioned operational issues, during a long period of time, proper switching in appropriate times can causes a lot of economic savings. Furthermore, it can be intensified when capacitors are implemented and controlled in the network. To reach this purpose, most of the previous literature focuses merely on the power grid reconfiguration. Few of these researches have considered this problem as a dynamic one and studied that in a period of time, e.g. one day, considering fixed level of loads despite the others that have investigated this problem on a fixed amount of loads. Because of time-varying nature of loads in distribution networks, these assumptions lead to suboptimal solutions. Another group of literature has concentrated on reconfiguration with fixed capacitors placement. Considering all the previous literature, in this thesis, a novel method for feeder reconfiguration with switching switchable capacitor banks is proposed. Furthermore, this problem is considered as a dynamic problem, that for any time interval determines which switches should be closed and how much capacitor should be entered the grid in each capacitor bank. The switching operation should be cost effective and the reconfiguration and capacitor switching scheme should balance the costs of switching against benefits in system loss reduction, reliability improvement, and those benefits earned because of enhancing the transformers life caused by alleviating their load congestion. Moreover, this is a dynamic problem and switching operations of time intervals over a month are not independent. In this thesis two scenarios are considered: 1) without considering distributed generation units, and 2) with considering distributed generation units. In first scenario, in the first stage of the proposed method, to obtain the effective configurations and capacitor switching scheme, optimal switching scheme for reconfiguration switches and capacitors for each hour of month is determined independently using harmony search algorithm (HSA) and graph theory. In fact this stage is considered as a scenario reduction stage to reduce the different states of switches and capacitor banks in order to improving the efficiency and decreasing the computation time. After determination of effective scheme for the network in each hour, in the second stage, year is divided into multi equal periods and considering loss cost, interruption cost, benefits due to transformers aging enhancement, and also switching cost from one state of switches to another one, Ant Colony Optimization (ACO) is used to find the optimum annual switching scheme. Furthermore, in the second scenario, this procedure is repeated considering stochastic nature of distributed generation units in the grid. The proposed method has been tested on the IEEE 33-bus distribution test system and the obtained results denote that to have an optimum solution it is necessary to compare operation costs dynamically
- Keywords:
- Capacitors ; Reconfiguration ; Ant Colony Algorithm ; Harmony Search Algorithm ; Dispersed Generation ; Distribution Line Carrier
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