11 research outputs found
Single-loop all-pass-filter-based active damping for VSCs with LCL filters connected to the grid
LCL filters are commonly used to connect Voltage Sourced Converters (VSCs) to the grid. This type of filters are cheaper than a single inductor, but they can generate resonance problems if no active or passive damping method is used. Active damping methods are becoming popular in the literature because they improve efficiency, but they are sometimes difficult to implement and additional measurements are required. This paper proposes a method to provide active damping for VSCs connected to the grid that is based on making zero the openloop phase at the resonance frequency. It will shown that this strategy provides adequate damping of oscillations and that it can be achieved in two different ways: at the design stage (if the design constraints make it possible) or with an all-pass filter in series with the current controller. All the proposed control algorithms are verified by simulation and in a 15 kW prototype of a three-phase VSC connected to the grid with an LCL filter
Geodetic Research on Deception Island and its Environment (South Shetland Islands, Bransfield Sea and Antarctic Peninsula) During Spanish Antarctic Campaigns (1987-2007)
Since 1987, Spain has been continuously developing several scientific
projects, mainly based on Earth Sciences, in Geodesy, Geochemistry, Geology or
Volcanology. The need of a geodetic reference frame when doing hydrographic and
topographic mapping meant the organization of the earlier campaigns with the
main goals of updating the existing cartography and of making new maps of the
area. During this period of time, new techniques arose in Space Geodesy
improving the classical methodology and making possible its applications to
other different fields such as tectonic or volcanism. Spanish Antarctic
Geodetic activities from the 1987/1988 to 2006/2007 campaigns are described as
well as a geodetic and a levelling network are presented. The first network,
RGAE, was designed and established to define a reference frame in the region
formed by the South Shetlands Islands, the Bransfield Sea and the Antarctic
Peninsula whereas the second one, REGID, was planned to control the volcanic
activity in Deception Island. Finally, the horizontal and vertical deformation
models are described too, as well as the strategy which has been followed when
computing an experimental geoid