Control of micro hydro power stations using nonlinear model of hydraulic turbine applied on microgrid systems

Over the last few years the interest in microgeneration has increased once it represents the nearest solution for the current problems faced in electricity generation filed. Among different technologies available in microsources field, micro hydro power stations with induction generators (IG) represent one interesting choice, mainly considering its application in isolated areas or connected to the grid. This paper presents an approach to full modeling and control of micro hydro power stations based on the nonlinear model of hydraulic turbine applied on induction generators. Constant frequency control is obtained by a speed governor applied to the turbine feed system while constant voltage control is reached through reactive power control using a voltage source inverter (VSI) connected in parallel to the grid. The proposed system is as well able to connect to the main utility grid being the synchronism previously established. Simulation results considering step changes in load and frequency reference setting have been considered. Grid connection and disconnection is as well established. Experimental results related to reactive power control and voltage regulation are presented and have shown satisfactory dynamic performance.