Enhancement of Grid Connected PV Arrays Fault Ride Through and Post Fault Recovery Performance

In this paper, a novel nonlinear control system for enhancing the low-voltage ride through capability and post-fault recovery performance of two-stage grid connected PV arrays (GCPAs) is proposed. The proposed control scheme is composed of two controllers: 1) finite-time sliding mode control (FTSMC) and 2) proxy-based sliding mode control (PBSMC). The FTSMC, which assures the finite time convergence of the tracking error, controls the dc/dc converter of GCPA during voltage sags to assure the dc-link capacitor voltage does not exceed its limits. PBSMC controls the dc/ac inverter. PBSMC provides accurate and fast tracking feature during normal condition (similar to PID controller) and is capable of very smooth resuming to the desired reference value/trajectory after large disturbances that may lead the control signal to exceed the limits. Therefore, during post-fault voltage recovery period, PBSMC exits saturation faster and smoother which significantly enhances the recovery performance of GCPA. The advantages of the proposed control schemes are demonstrated using simulation results.