Andrejs Stepanovs

Development of a Modular Power Converter

Development of a Modular Power Converter This report describes the most important details of elaboration of a versatile power module that can be utilized as a part of various converters. Two or more modules connected together can form a frequency converter or multilevel converter or 3-phase inverter/rectifier etc. Initially the module was developed for fast prototyping of uninterruptible power supplies and energy systems with alternative energy sources. The module can be used also as a basis for laboratory equipment of the power electronics course.

Analysis of using a heliostat with non-rotating solar energy receivers

The use of solar energy in Northern countries is not as obviously reasonable as in the countries that are located closer to the Equator due to bigger differences of daytime during changes of seasons, as well as lower solar irradiance. This paper investigates the advantages of using a heliostat with non-rotating solar energy receivers (like water/air heating collectors, stationary PV panels or solar illumination collectors). The optimal orientation of the solar receiver and the heliostat is discussed in detail for two different optimization strategies - maximal energy and maximal operation period with irradiance higher than 400 W/m2. The results of the analysis demonstrate that the heliostat allows prolonging the operation of solar receivers for 20 % of time during the year, or allows extracting 30 % more energy per annum if proper orientation angles are selected.