A Novel Fault Ride Through Scheme for Hybrid Wind/PV Power Generation Systems

This article proposes a cost effective and simple design for hybrid wind/PV systems. Its main objective is to endow the system with fault ride through capabilities in accordance to the new grid code requirements while eliminating the need for inverters for the PV units. The proposed topology connects the PV system to the DFIG's DC-link via a DC-DC converter, thus reducing cost be eliminating the need for a dedicated inverter for PV power processing. During normal conditions, the DC-DC converter controls the active power of the hybrid wind/PV system. When grid faults occur, the GSC is operated as a STATCOM, thus injecting reactive power to the grid, while the DC-DC converter controls the DC-link voltage of DFIG. To ensure optimum performance, the gains of the controllers for the RSC, GSC and DC-DC converters were auto-tuned using a fuzzy PI approach. The performance of the proposed scheme was assessed in the presence of severe single and three phase voltage sag condition, three-phase grid faults and parameter variations. Its performance was also compared to that of conventional voltage ride through approaches. The proposed scheme was shown to minimize rotor over-currents, optimize the converter's performance, reduce voltage, power and torque fluctuations and protect the hybrid wind/PV system during voltage disturbances. Additionally, it was able to support the grid by injecting reactive power during voltage sags.