Design and control of autonomous hybrid wind solar system with DFIG supplying three-phase four-wire loads

Abstract

This paper presents the design, control and evaluation of an Autonomous Hybrid Wind Solar System (AHWSS) energy system feeding into three-phase, four-line loads and an array of batteries. Wind Energy Conversion System Connected to the Grid (WECS) contains Doubly Fed Induction Generator (DFIG) and two PWM voltage source converters i.e. Grid Side Converter (GSC) and Rotor Side Converter (RSC) connected back to back at DC-link and are provided with an algorithm for Maximum Power Point Tracking (MPPT). The grid voltage-oriented control algorithm is used to maintain a steady DC bus voltage for the GSC and to balance the reactive power at the power grid even the divergence in frequency and voltage can be regulated with this novel approach. The stator voltage-orientated vector control is implemented in the RSC control strategy, delivering effective controlling of active and reactive power at the stator, and also a MPPT is achieved through controlling the Tip Speed Ratio. The photovoltaic (PV) system along with the boost converter is fed to the DC link. A Perturb & Observe method is used for tracking maximum power in a solar PV system. The model is implemented in MATLAB's Sim-power-system toolkit with ode3 solver and is presented in different scenarios, e.g., solar irradiation, differing wind velocity, dynamic, and unbalanced nonlinear loads. In these all constraints, DFIG's stator winding currents are balanced with low Total Harmonics Distortion (THD), value less than 4% in all scenarios.