چكيده به لاتين
Existence of nonlinear loads and faults in distribution networks can lead to harmonic voltage distortion and network voltage sag, respectively. Harmonics and voltage sags can cause damage to network loads, especially sensitive ones. In addition to harmonic and voltage sag problems, the distribution network also suffers from high losses due to its relatively high resistance. In order to confront the above-mentioned problems, among the existing methods, reconfiguration is emphasized as a cheap method that can simultaneously control the entire three operational problem. Reconfiguration means changing the topology of the distribution network using the tie and sectionalizing switches to achieve a specific goal. This is actually happening by changing the impedance and the path of current flow from source to loads.
Reconfiguration of the distribution network depends on two factors: one is to use an optimization algorithm for reconfiguration, and the other is the objective of the reconfiguration. The innovations of this thesis are in both parts. In this thesis, the Particle Swarm Optimization algorithm combines with a radial configuration method and the Modified Particle Swarm Optimization algorithm is created. The proposed algorithm in this thesis eliminates the vulnerability of localized trapping to the local optimal localization of the classical particle swarm algorithm and, moreover, has a faster convergence speed than the classical particle swarm algorithm. The efficiency of the proposed algorithm is evaluated on the IEEE 69 bus and real feader of Isfahan-Iran . the results indicate that the proposed algorithm is capable of finding better configuration in comparison to previous researches.
In this study the total loss (sum of fundamental frequency and harmonic losses), harmonic distortion of the system and the voltage sag are considered as objective function. The results show that in the case of loss reduction, it is necessary to consider the harmonic losses along with the basic losses. In addition, the results show that reconfiguration of the distribution network by changing the path impedance can improve the harmonic distortion of the voltage and degrade the voltage sag of the network. In addition, the effect of daily short-term reconfiguration on energy saving is evaluated in order to improve the total losses when the network load is not constant during the day. It is shown that short-term reconfiguration can save more energy in the distribution network.
