PhD thesis defense to be held on April 3, 2023, at 14:00 (Virtually in MS Teams)
Picture Credit: Panagiotis Karafotis
Thesis title: Contribution to the Reliability and Power Quality of Electric Power Distribution Networks
Abstract: This PhD thesis contributes to the reliability and power quality of electric power distribution systems.
At the first phase, the term of power system’s reliability is presented, the most appropriate reliability-oriented indices are discussed, and the technique of distribution network reconfiguration (DNR) is indicated as an effective reliability improvement strategy. Then, the research focuses on the development of a novel optimization model to improve system’s reliability through DNR. Towards this direction, an innovative mixed-integer second-order cone programming model is proposed for solving the problem of optimal reliability-oriented DNR. The objectives that are optimized are the improvement of power system’s reliability indices and/or the minimization of network active power losses. This model introduces an original methodology for the determination of the upstream path of each network node, which is necessary for calculating system’s reliability indices. Then, the proposed model is enriched with a scenario-based stochastic programming framework, to encounter the variability of load and production from renewable energy sources when solving the reliability-oriented DNR problem. The standard 33-nodes distribution system and a real-world 83-nodes distribution system are employed to prove the efficiency and applicability of the model. Finally, the obtained results are compared with those of recently published works.
At the second phase, the typical phenomena as well as the appropriate indices concerning the power quality of power distribution networks are presented. Then, the technique of Wavelet Packet Transform (WPT) is indicated for analyzing and processing the voltage and current signals of three-phase power systems. In that context, a WPT-based model is developed for the calculation of the power quality indices of three-phase systems, which operate under both stationary and non-stationary conditions. In addition, an innovative methodology is introduced to calculate the contribution of each harmonic component of voltage and current waveforms to the unbalance of three-phase systems, especially with the presence of non-stationary disturbances. The proposed model is applied to synthetic voltage and current waveforms, simulation and typical networks, and a laboratory experimental setup. The results are compared with their true values and those obtained using Fourier Transform, demonstrating the accuracy and the superiority of the proposed model in calculating power quality indices of distribution networks, which operate under non-stationary conditions.
In conclusion, the proposed models introduce an innovative framework of methodologies to improve the reliability and estimate the power quality of power distribution networks.
Supervisor: Professor Pavlos Georgilakis
PhD Student: Panagiotis Karafotis