Autonomous wind—Hydro hybrid system using cage generators and battery storage

Abstract

This paper deals with a new autonomous wind-hydro hybrid generation system consists of one squirrel-cage induction generator (SCIG) driven by a variable-speed wind turbine and another SCIG driven by a constant-power hydro turbine feeding three-phase four-wire medium loads. The proposed system consists of two back-to-back-connected pulse width modulation controlled insulated-gate-bipolar-transistor based voltage source converters (VSCs) with a efficient battery energy storage system at their dc link. The main purpose of the control algorithm for the VSCs are to acquire maximum power tracking (MPT) by rotor speed control of a wind turbine driven SCIG under varying wind speeds and control of the frequency and magnitude the of the load voltage. This wind hydro hybrid system has the ability of bidirectional reactive and active power flow, by which it controls the magnitude and the frequency for voltage. The proposed system using cage generators, MPT controller, and a voltage and a frequency controller are studied and simulated in MATLAB using Simulink and SimPower System toolboxes, and the proposed system are studied for various types of linear and nonlinear, under balanced and unbalanced conditions. The performance of the proposed system is presented to demonstrate its voltage and frequency control (VFC), harmonic elimination, and load balancing.