Control of Grid Connected Micro Hydro Power System
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Date
2020-01
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Addis Ababa University
Abstract
For a grid connected micro hydropower (MHP) system, power electronics and phase locked loop
was designed and simulated in this research. The grid interconnection of MHP improve the
reliability of the grid and helps to decrease transmission and distribution losses. However, the
synchronization with the utility grid is the main concern of the inverter control design because the
grid frequency, phase and voltage need to be tracked. If the inverter output cannot meet the local
grid connection criteria, the power will not be allowed to deliver.
In this research, mathematical modeling of micro hydro power plant has been done. The full bridge
three phase diode rectifier, boost converter, inverter and LC filter are designed to connect the power
generated to the grid. Then, by injecting the grid voltage signal in to the PLL, the phase voltage
frequency and phase angle has been tracked to synchronize phase, frequency and voltage of the
generated power with different grid condition.
It is observed from the simulation results that for ideal grid conditions the phase angle was tracked
and relatively faster and also precisely. Also the system can easily track the phase when the
frequency was changed from 50Hz to 55Hz or 45Hz. The only difference from the ideal case is that
the PI-regulator now approaches 2π*5rad/s for 55 Hz and -2π*5rad/s for 45Hz instead of zero.
Moreover, different non-ideal grid conditions were simulated and almost handled by the system.
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Keywords
Micro Hydropower, Power Converters, PI Regulator, Phase Locked Loop