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Doubly-fed induction generators (DFIG) still play an important role in wind-energy applications. One of the major challenges concerning their operation is to meet not only steady-state, but also dynamic requirements. State-of-the-art DFIGs are often controlled applying dq-control structures to guarantee steady-state power-quality requirements. The need of(More)
Simulating complex offshore grids including connected devices and independent control algorithms (e.g. in DLL form) is essential for the assessment of global system stability. In power-electronic applications - due to independently controlled and independently switching inverters - only time domain simulation can give meaningful results. This paper presents(More)
The modular multilevel converter (MMC) topology is characterized by excellent scalability. Converters with direct connection to high voltages in the range of several 100 kV can be built by stacking comparatively simple modules. The drawback of the technology is the single-phase structure, causing, among others, oscillations of the capacitor voltages which(More)
Induction machines are affordable and robust, presenting a valid option for electric vehicles. Many control schemes for such machines are known and have been published. With regard to fast torque dynamics and robustness against parameter variation, stator-flux-oriented control is a very favorable option. This paper presents a stator-flux oriented control(More)
A novel approach to flux-based control, `assessment-based flux trajectory optimization' (AFO), is presented and analysed, which directly takes the properties of the converter into account. It seamlessly integrates stationary operation, slow and fast dynamics. The optimal flux trajectory is defined, based on the relatively few possibilities resulting from(More)
Connecting renewable energy sources to the grid requires stable and reliable control algorithms. Especially in case of solar-energy systems, single-phase connection is often used at low power levels. This can be achieved by using a four-quadrant converter. For optimal reaction to variations of infeed (e.g. by shading by clouds) and grid disturbances, a fast(More)
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