The modern grid codes for fault ride through specifications in transmission and distribution grids specify that Distributed Generation (DG) must remain connected to the grid even at voltages well below the nominal voltage. This is contrary to the traditional approach, whereby the power plants were not required to stay connected. The reliable operation of the grid during this period is challenging as the inverter based DGs are designed to operate reliably at nominal voltages and does not function well under the abnormal conditions. This paper presents a new fault ride through scheme that limits fault current within the system limits. The microgrid (MG) model considered here is studied under normal and fault situation and a fault analysis on an islanded microgrid with two wind sources and a Photovoltaic (PV) source. Different types of faults are considered at random points to study the effect of fault location and recovery time. A novel control strategy for the interface converter is proposed where a master-slave control is adopted for the sources, which enables the power sharing between the DGs and a fault ride through logic that addresses the fault current limiting is developed. The scheme has been validated with simulation results in MATLAB/Simulink.
J. R and Sruthy V., “Fault ride through augmentation of microgrid”, in International Conference on Advancements in Power and Energy (TAP Energy), 2015, Kollam, India, 2015.