Protection analysis tool for distribution networks with a high embedded generation penetration
The protection design philosophy of distribution networks is predicated on the inherent radiality that exists in such networks. However, the increased presence of inverter-interfaced embedded generation is compromising the radial nature of distribution networks. Hence, the increasing importance of accurately modelling the fault response of inverter-interfaced embedded generation is becoming apparent. Presently, the impacts of large penetrations of inverter-interfaced embedded generators on protection adequacy are determined through time-domain modelling. This paper proposes a tool for determining a snapshot of the expected protection response of distribution networks with inverter-interfaced embedded generation. The tool automatically simulates all fault types at the extremities of each protection zone and compiles the data to generate a report that showcases important information from a protection adequacy perspective. The tool can simulate fault responses in orders of magnitude faster than time-domain analysis using a load-flow like algorithm. This algorithm is designed to have a high convergence in fault scenarios and also approximate the fault behaviour of inverter-interfaced embedded generators. Finally, the tool investigates whether a new embedded generator installation may require an upgrade of network infrastructure or an amendment of protection settings. The tool is implemented using MATLAB and compared with time-domain simulations for verification purposes.