Abstract

Concerns for the rising cost of electricity, environmental impact, and the difficulty in obtaining new right-of-ways results in the use of smaller environmentally-friendly power sources such as photovoltaic (PV), wind-driven or gas-fired micro-turbines located closer to the end consumers, which are connected directly to the distribution system in what is commonly referred to as distributed generation (DG). The protection schemes of the distribution systems were designed under the assumption that power flows from the substations to the end users. If a fault takes place and a breaker opens all circuits downstream would be de-energized. However this is not the case when DG is used. Under fault condition, an island condition with power generation and consumption threatens both equipment and personnel safety. Thus, islanding detection methods (IDMs) must be developed and tested. A number of IDMs has been developed to prevent this situation. The goal of this thesis is to investigate a means for comparing the effectiveness of active type IDMs used in an inverter based DG. Unlike standard passive IDMs, the use of non-detection zones (NDZ) in a power imbalance plane is not adequate. This thesis proposes a new load parameter space based on the load quality factor Q f and resonant frequency f 0 . Equations that describe the NDZs of three of the most used active IDMS, namely active frequency drift (AFD), slip-mode phase shift (SMS) and Sandia frequency shift (SFS) have been derived. Simulation and experimental results are presented to corroborate the theoretical analysis