Fault Ride-Through Capability of Voltage-Controlled Inverters

An auxiliary voltage controller is proposed for the fault ride-through (FRT) control of voltage-controlled inverters used in distributed energy resources. The proposed auxiliary controller can be added to different existing voltage control strategies with minimum or no need to alter the original structure of the voltage controller. The proposed controller prevents the transient overcurrent during grid faults and controls the exchange of real and reactive powers according to the governing grid standard. A fault detection algorithm is also implemented to detect the fault instant and determine the interval of fault during which the real and reactive power references are adjusted accordingly. Complete stability analysis of the proposed controller is performed through a new model. Successful performance of the proposed controller in achieving FRT requirements of German and Danish codes are illustrated by simulations. Extensive real-time and experimental results are also presented and discussed.