This paper presents a low-frequency ac (LFAC)
transmission system for offshore wind power. The LFAC
system is interfaced with the main power grid with a
cycloconverter. The wind power plant collection system is dc
based, and connects to the LFAC transmission line with a 12-
pulse thyristor converter. The main advantage of the LFAC
technology is the increase of power capacity and transmission
distance for a given submarine cable compared to 50-Hz or
60-Hz HVAC. This leads to substantial cost savings due to the
reduction in cabling requrments (i.e, less lines in parallel for
a desired power level) and the use of normal AC breakers for
protection. A method to design the system’s components and
controls is set forth. Simulation results are provided to
illustrate the system’s performance.
Published In : IJCAT Journal Volume 3, Issue 1
Date of Publication : January 2016
Pages : 48 - 57
Tables : --
Publication Link :HVAC Transmission for Offshore Wind Power
T. Rajesh : M.Tech Student Lenora College of Engineering- Rampachodavaram
M. Chandra Sekhar : Asst. Professor Lenora College of Engineering- Rampachodavaram
Under-Water Power Cables
A low-frequency ac transmission system for offshore wind
power has been proposed. A method to design the
system’s components and control strategies has been
discussed. The use of a low frequency can improve the
transmission capability of submarine power cables due to
lower cable charging current. The proposed LFAC system
appears to be a feasible solution for the integration of
offshore wind power plants over long distances, and it
might be a suitable alternative over HVDC systems in
certain cases. Furthermore, it might be easier to establish
an interconnected low-frequency ac network to transmit
bulk power from multiple plants. In order to make betterinformed
decisions, it is necessary to perform a complete
technical and eco- Fig. 14. Transient waveforms during a
wind power ramp event. side of the cycloconverter is 34.9
, which is close to the design requirement. Fig. 14 depicts
the results of a transient simulation where the power from
the wind turbines ramps from 0 to 180 MW, at a rate of 60
MW/s (perhaps unrealistically fast, but chosen to
demonstrate that the system is stable even for this large
transient). Shown are the transient responses of the dc bus
voltage at the sending end, the magnitude of the
fundamental component of the 20-Hz voltage generated by
the cycloconverter, the active nomic comparison among
HVAC, HVDC, and LFAC, evaluating factors, such as the
transmission efficiency, investment and operating costs,
and the performance under system transients.
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