Application of feedback linearization strategy in voltage fault ride-through for photovoltaic inverters

Fault ride-through specifications listed in modern transmission and distribution grid codes specify that photovoltaic system have to operate under grid faults. In the classic strategies used in photovoltaic systems the power delivered to the grid remains constant when a fault occurs. As a consequence, the system should operate with increasing inverter current, which may result in damage. Noticing the PV array´s special characteristics,this paper presents new strategy for photovoltaic systems which ensures the current levels remaining within the designed limits. In addition,a nonlinear feedback controller based on feedback linearization is used to control the inverter. Simulation results are presented in order to validate the proposal. The results include performance of different voltage dips. The proposed control strategy permits the inverter operates in any fault situation without over currents as well as delivering sinusoidal currents. In addition, The dynamic performance of LVRT is improved by using the proposed controller.