10 research outputs found
Back-to-back Converter Control of Grid-connected Wind Turbine to Mitigate Voltage Drop Caused by Faults
Power electronic converters enable wind turbines, operating at variable
speed, to generate electricity more efficiently. Among variable speed operating
turbine generators, permanent magnetic synchronous generator (PMSG) has got
more attentions due to low cost and maintenance requirements. In addition, the
converter in a wind turbine with PMSG decouples the turbine from the power
grid, which favors them for grid codes. In this paper, the performance of
back-to-back (B2B) converter control of a wind turbine system with PMSG is
investigated on a faulty grid. The switching strategy of the grid side
converter is designed to improve voltage drop caused by the fault in the grid
while the maximum available active power of wind turbine system is injected to
the grid and the DC link voltage in the converter is regulated. The methodology
of the converter control is elaborated in details and its performance on a
sample faulty grid is assessed through simulation
Weather Forecasting Error in Solar Energy Forecasting
As renewable distributed energy resources (DERs) penetrate the power grid at
an accelerating speed, it is essential for operators to have accurate solar
photovoltaic (PV) energy forecasting for efficient operations and planning.
Generally, observed weather data are applied in the solar PV generation
forecasting model while in practice the energy forecasting is based on
forecasted weather data. In this paper, a study on the uncertainty in weather
forecasting for the most commonly used weather variables is presented. The
forecasted weather data for six days ahead is compared with the observed data
and the results of analysis are quantified by statistical metrics. In addition,
the most influential weather predictors in energy forecasting model are
selected. The performance of historical and observed weather data errors is
assessed using a solar PV generation forecasting model. Finally, a sensitivity
test is performed to identify the influential weather variables whose accurate
values can significantly improve the results of energy forecasting
Semi-valley switching method for buck LED driver to increase its efficiency and performance
Valley switching is one of the most efficient methods to decrease the switching losses in DC/DC converters. It uses a resonance between the converter's inductor and parasitic output capacitance of a metal–oxide–semiconductor field-effect transistor. In this study, the drawbacks of the valley switching in buck light-emitting-diode (LED) drivers are investigated. It shows that in spite of decreasing the switching losses, the valley switching method reduces its efficiency in some conditions. Also, it is clarified that the valley switching method not only causes current fluctuation in boost power factor correction converters but also malfunctions the buck LED drivers' performance. In this study, a semi-valley switching and its implementation are introduced to solve these problems. In general, it is shown that the proposed method improves both the efficiency and the performance of the buck LED driver, simultaneously. The methodologies are implemented in an experimental prototype to verify the proposed method.Peer reviewe