Mohammad Ghanaatian Jobzari – Doctoral Final Exam
About the event
Advisor: Dr. Saeed Lotfifard
Degree: Ph.D. Electrical & Computer Engineering
Dissertation Title: MODELING AND MONITORING OF FAULTED POWER DISTRIBUTION SYSTEMS WITH INVERTER INTERFACED DISTRIBUTED GENERATORS
Abstract: This dissertation studies the regular faults and high impedance faults in power distribution systems with inverter interfaced distribution generators. Chapter one proposes a method for calculating short circuit current in distribution systems with Inverter Interfaced Distributed Generators (IIDG). It is capable of calculating the short circuit in a multi-phase distribution systems based on the symmetrical components without obtaining the complete impedance matrix. Furthermore, it considers the load effect and the pre-fault state of the system for the fault analysis and is able to handle unbalanced systems with mutually coupled phases. The problem is formulated as an iterative linear system calculation and is solved by Generalized Minimal Residual (GMRES) approach. The validity of the proposed algorithm is verified through the simulation of IEEE 13-node, 123-node, 478-node, 954-node and 1430-node distribution systems. Simulation results demonstrate the effectiveness of the proposed algorithm and the advantages of using GMRES method to calculate the short circuit current in a distribution system with IIDG.
Chapter two considers the high impedance faults. High impedance faults (HIF) generate low fault current that makes the fault detection task challenging. Moreover, non-fault events like capacitor switching may have relatively similar behavior as arcing faults which can confuse HIF detection methods. This dissertation proposes a multi-criteria high impedance fault detection method. The proposed method is based on the change in the amplitudes of harmonics and interharmonics of measured current signal, change in the roots of characteristics equation, damping factor value of appeared current harmonics and interharmonics, and the existence of interharmonics. To extract these features from the measured current, the Prony method is utilized. To evaluate the performance of the presented method, capacitor bank switching, power electronic loads, inrush current, load switching, and HIF are simulated. The simulation results demonstrate that the proposed method successfully detects high impedance faults and distinguishes them from other disturbances.