Unbalanced power converter modeling for AC/DC power distribution systems.

摘要

In power distribution systems, the installation of power electronics based equipment has grown rapidly for ac/dc system coupling, system protection, alternative energy source interface, etc. This thesis will focus on power electronic component and system modeling techniques and three-phase ac/dc power flow analysis for power distribution systems. First, mathematical models are developed for unbalanced power electronic converters, such as thyristor converters, diode rectifiers, and Pulse-Width-Modulated (PWM) converters. The modeling approach captures the imbalance of distribution systems using three, delta-connected, single-phase converters. In order to perform system analysis, these models have been incorporated into two types of ac/dc power flow solvers: (i) a three-phase backward/forward sequential solver and (ii) a three-phase unified solver using the modified nodal analysis method. Both solvers have been applied to unbalanced radial and weakly meshed distribution systems. Finally, an ac/dc system hardware test bed was created to validate the mathematical models and the performance of the power flow solvers. Extensive hardware tests, time domain simulations, and steady-state analysis have been performed.