Design and control of wind-solar energy system with DFIG feeding a 3-phase 4-wire network

This paper presents the design and control of a distributed generation system using wind and solar PV (Photovoltaic) energy sources feeding to a 3-phase 4-wire network. The wind energy conversion system consists of a wind turbine coupled to DFIG (Double Fed Induction Generator) equipped with MPPT (Maximum Power Point Tracking). The MPPT demands speed control which is realized using vector control of the rotor side converter. The voltage and frequency control is achieved through load side converter connected to the common DC bus. Solar PV power is fed to the same DC bus using DC-DC boost converter which is also equipped with MPPT algorithm to extract maximum energy from the incident solar energy. The system is modeled in Sim-Power System tool of MATLAB and its performance under all the practical conditions e.g. varying wind speed and radiation; unbalanced and nonlinear load is presented. Under all these conditions; the stator currents flowing through DFIG are balanced and sinusoidal. The harmonics in load voltage under all conditions are within requirement of IEEE 519 standard. The scheme doesn't envisage measurement of any mechanical quantities e.g. wind speed or rotor position. Finally the effectiveness of the system is demonstrated experimentally using a 3.7 kW DFIG and a 5 kW solar array simulator.