Page 216 - Renewable Energy Devices and System with Simulations in MATLAB and ANSYS

Power Electronics and Controls for Large Wind Turbines and Wind Farms 203

Controls
Simulink VHDL- Maxwell/
TurbSim Fast AMS RMxprt Simplorer

FIGURE 8.29 The comprehensive simulation of a wind turbine system using a framework of freeware and
commercially available software. (Based on Novakovic et al., IEEE Indus. Appl. Mag., 22(5), 73, 2016.)

The gearbox was modeled in the VHDL-AMS language within the ANSYS Simplorer software.
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The back to back AC/DC and DC/AC power electronics converters, together with their associated
generator side and grid side controllers, was also modeled using this software, but in an approach
that considers the electric circuit schematics and details including those of the IGBTs used for prac-
tical implementation. As such, the model is able to simulate with very small steps time transients
and can be successfully employed in order to estimate the converter power losses, and, based on this
and on an additional simulator for the thermal field, can predict the temperature variation for the
power electronic semiconductor devices. The permanent magnet (PM) generator can be modeled
using the ANSYS Maxwell software for electromagnetic finite element numerical analysis (FEA)
®
or the analytical and equivalent circuit based ANSYS RMxprt module. The former is superior in
®
terms of detail and accuracy, while the latter is advantageous in terms of high computational speed
and reduced effort.
Such a framework of tightly coupled software modules supports the complex design process at
the component and system level, including the interactions involved in the implementation of maxi-
mum power point tracking (MPPT) controls that require the variable speed operation of generators
below the rated wind speed and the pitch blade control at high speeds. The comprehensive model
also supports high fidelity transient and stability studies under large power variations and grid fault
conditions.

8.8 SUMMARY

The individual power rating and the installations of WTs have been significantly increasing over
the decades, such that wind energy now plays an important and growing role in power systems.
A main driving factor is represented by the continuous need for sustainable and renewable energy
at competitive prices.
The review of state-of-the-art solutions indicates that power electronic technologies, including
associated controls and variable speed generators, have significantly improved the operation and
performance of the WTS. Through proper selection and configuration, controls, and grid regula-
tions, it is now possible for the WTS and for wind farms to act similar to conventional power plants
and actively contribute to the frequency and voltage control in the power grid.
These capabilities create opportunities for a continued large-scale deployment of WTs.
Furthermore, driven by the need to lower the cost of energy and enhance the performance of
energy conversion, there are yet many new possibilities for the advancement of power electronics
and electric generator technologies, including the development and application of new topologies
and power devices, the increase of reliability, and the incorporation of energy storage and power
system control capabilities.