Coordinative Low-Voltage-Ride-Through Control for the Wind-Photovoltaic Hybrid Generation System

The wind-photovoltaic (PV) hybrid renewable energy system (HRES), which consists of permanent-magnet synchronous generators (PMSG) and PV arrays, is becoming a cost-effective electric source for powering islanded areas. However, high penetration of renewables makes the power system vulnerable to transient voltage faults, which undermines the stability of the future inverter-dominated grid. To address this issue, a coordinative low-voltage-ride-through (LVRT) control scheme is proposed for the operation of the wind-PV HRES in this article. This control scheme will exploit the maximum energy inertia of the HRES for incorporating the power imbalance between the faulted grid and the renewable generators. An optimization problem is formulated to maximize the renewable energy harvesting within the operational and environmental limitations. To cope with different working conditions, four control processes are coordinated in an optimized manner during the LVRT period: 1) adaptive dc-link voltage control; 2) PMSG rotating speed control; 3) PV energy curtailment control; and 4) blade pitch angle control. Besides, this control scheme applies a direct output control that can generate stable and accurate current as per grid code requirements. The results of the hardware-in-the-loop (HIL) experiment and the MATLAB/Simulink simulation are provided to verify the effectiveness of the proposed control scheme.