Autonomous micro-grid based on micro hydro power plants

This paper presents a control strategy that aims to improve the parallel operation of two micro hydro power plants (MHPPs) on an islanded micro-grid (MG). The two MHPPs are equipped with fix-speed turbines that drive induction generators (IG). The proposed control system is a combination between active elements - a voltage source inverter (VSI) with a dump load (DL) on its DC side - and passive ones (stepped capacitors). The VSI operates at constant frequency, thus stabilizing the MG frequency. The voltage regulation is accomplished by the DL, by dissipating the exceeding active power. The stepped capacitors compensate the reactive power, minimizing its circulation through the VSI in steady-state regime. The value of the VSI DC side capacitor, critical during transitory regimes, is computed and tested thorough a series of simulations. Other simulations are carried to reveal the control system overall efficiency.