Background: Recently, with the increasing shortage of energy, researchers paid more attention
to wind power, photovoltaic, hydroelectric and other renewable energy technologies. As one
of the most important renewable energy sources, hydro energy is widely used, as described in the
various patents. Meanwhile, the scholars put forward the concept of micro-grid which is a controllable
unit consisting the generator, load, energy storage device and control device, micro-hydro generator
as one of the most important micro sources has been getting more and more attention. So, in this
paper, a grid-connected topology circuit of micro hydropower system based on self-excited induction
generator is proposed.
Methods: Micro hydropower system based on self-excited induction generator drives the turbine by
the fixed amount of hydraulic potential difference, and then drives the induction generator to generate
stabilization power. This controller includes the AC/DC module and DC/AC module. The
AC/DC module uses hysterics PWM current control, while DC/AC module uses voltage outer loop,
and current inner loop of double closed-loop control.
Results: In this paper, a resistive load which can be varied from 0 to 4.5kW in steps is used as consumer
load and the variety of grid voltage and grid current when the load is changed. When the system
starts running, the grid voltage can be tracked by grid current with the same frequency and
phase, the power factor is 1. And the current has a small impact on voltage. the waveforms of grid
voltage and grid current when the load is added from 0W to 300W. The power of generator is used
by load, so gird current is reduced.
Conclusion: A topology structure of micro hydropower based on self-excited induction generator
has been proposed. It has been presented in an economical and energy-efficient way. A comparative
study of both the rectifier is uncontrolled and controlled in the system has been demonstrated by
simulation. The system of excited capacitance has been proposed which gives a steady voltage. The
experimental investigation shows that the grid voltage can be tracked by grid current with the same
frequency and phase, and the result of the grid is an excellent option for micro-hydro applications.