Analysis of sensorless MPPT method for hybrid PV-Wind system using DFIG Wind Turbines

In this paper, a sensorless Maximum Power Point Tracking (MPPT) method for a hybrid Photovoltaic-Wind system, which consists of Photovoltaic (PV) system and Doubly-Fed Induction Generator (DFIG) Wind Turbine (WT), is proposed. In the hybrid system, the DC/DC converter output of the PV system is directly connected to the DC-link of DFIG's back-to-back converter. Therefore, the PV inverter and its associated circuit can be removed in this structure. Typically, the PV power is monitored by using PV current sensor and PV voltage sensor for MPPT. In this research, the powers of converters on grid side and rotor side of DFIG are used to estimate the PV power without the PV current sensor. In the other words, the available sensors of DFIG are applied to track the maximum power of the PV system without the measured value of the PV power. That can efficiently reduce the cost of system compared to two separate systems with traditional MPPT method. Simulation studies are conducted to investigate the performance of the proposed method. The sensorless MPPT hybrid system can work very well under changes of operational conditions, such as irradiation and input power. As illustrated in the simulation results, the proposed system can handle powers in various direction harmoniously. The DC-link is also maintained stable during these variations. Overall, the proposed method can be utilized to harness the maximum power of PV system without the PV power information. (C) 2015 Elsevier Ltd. All rights reserved.