A nonlinear model predictive controller design for residual current compensation inverters in rapid earth fault current limiters to mitigate powerline bushfires

This paper presents a nonlinear model predictive control scheme for residual current compensation inverters in rapid earth fault current limiters to inject appropriate current to the neutral so that the fault current is compensated in distribution networks. The proposed nonlinear model predictive controller is designed to limit the fault current within a level that powerline bushfires do not ignite due to single line-to-ground faults on power distribution systems in bushfire prone areas. The nonlinear model predictive controller is designed for a T-type residual current compensation inverter in rapid earth fault current limiters based on its dynamical model where the control objective is to inject current for compensating the fault current. The control law for the residual current compensation inverter is obtained by solving an optimal control problem while using the concept of the receding horizon control scheme. The performance of the controller is evaluated through standard software-based computer and processor-in-loop simulations where results are benchmarked against backstepping and sliding mode controllers in terms of compensating both faulty phase voltage and fault current.