| Due to technology development and continued increase in energy demand while keeping the environment protected, renewable resources started emerging rapidly within the distribution system. Renewable resources help to maintain power quality and reliability, but in high penetration, they can adversely affect the system operation by causing overvoltage issues or interfering with existing fault protection technologies. The existing fault protection methods do not always apply in these new distribution networks because of various reasons including cost, complexity of the system due to mesh-like network topology, presence of power electronics converters, and bidirectional power flow. In a system containing renewable resources, most fault protection technologies ignore the presence of the renewable resources by assuming either low penetration level or no power injection from renewable resources during a fault. The few fault protection technologies that consider the presence of renewable resources have not considered a network with power electronics (PE) converters that limit the fault current in the system. A fault protection system includes detection, location, and isolation of the faulted section and possible reconfiguration of the system. The work here is focused on fault detection and location because they present the challenging component of fault protection in a converter based distribution system with fault current limited. Isolation and reconfiguration are system dependent as they occur according to the physical arrangement of the system and the availability of resources.;This thesis focuses on the design of a comparison framework which aims to help in choosing the most appropriate protection strategy for the system of interest. Because of the massive penetration of power electronics devices that interface with the renewable resources, the system of interest considered in this thesis is a fault current limited system. Considering the power rating, the line parameters, the converters, and the topology of the system, identify quantifiable characteristics of the system and derive a selection tree to help establish the most suitable protection scheme for the system.;First, various meaningful influencing factors of existing fault protection detection and location are identified. In order to design a comparison framework, we consider the governing criteria for each protection scheme including some of the most common fault protection systems based on current only, voltage only, and current and voltage measurements. The sensitivity and selectivity of the protection scheme are also taken into consideration, and those characteristics are mapped to the current limiting system under study: the FREEDM system.;"Smart Grid" concept is used to describe the idea of intelligently controlling renewable resources in the distribution system and all the other assets. Future Renewable Electric Energy Delivery and Management (FREEDM) system, which is one example of developing smart grid systems, is suitable for the study of the challenges related to fault protection technologies in a current limited system and the development of a fault location technology for significantly limited fault current system.;Given the characteristics of the FREEDM system and the comparison framework developed, the differential pilot protection , the directional overcurrent protection, the directional overcurrent pilot section protection, and the voltage profile based protection were all chosen to be implemented on a fault current limited distribution system. The directional overcurrent pilot section protection was proposed to overcome the coordination issues that arise with the directional overcurrent protection therefore, making it faster. However, the small residual voltage remains a challenge for both directional protection technologies while the differential pilot protection is challenged by the large amount of measurements that need to be synchronized and processed. Thus, another fault location strategy is developed for converters based systems with fault current limited. This strategy takes advantage of the system topology, the presence of the controllable PE converters, and the change of the voltage profile with the presence of the fault. |
