Impact of Wind Generation Mix on Transient Stability for an Interconnected Power System

The rapid growth of wind generation in many European countries is pushing power systems into
uncharted territory. As additional wind generators are installed, the changing generation mix may
impact on power system stability. This paper adopts the New England 39 bus system as a test
system for transient stability analysis. Thermal generator models are based on a likely future plant
mix for existing systems, while varying capacities of fixed-speed induction generators (FSIG) and
doubly-fed induction generators (DFIG) are considered. The main emphasis here has been placed
on the impact of wind technology mix on inter-area oscillations following transient grid
disturbances. In addition, both rotor angle stability and transient voltage stability are examined, and
results are compared with current grid code requirements and standards. Results have shown that
FSIGs can reduce tie-line oscillations and improve damping following a transient disturbance, but
they also cause voltage stability and rotor angle stability problems at high wind penetrations. In
contrast, DFIGs can improve both voltage and rotor angle stability, but their power output
noticeably oscillates during disturbances.

Idealized Operation of Third-Harmonic-Peaking Class-Ef Power Amplifier with Extended Maximum Operating Frequency

A new variant of Class-EF power amplifier (PA), the so-called third-harmonic-peaking Class-EF, is presented. It inherits a soft-switching operation from the Class-E PA and a low peak switch voltage from the Class-F PA. More importantly, the new topology allows operations at higher frequencies and permits deployment of large transistors which is normally prohibited since they are always accompanied with high output capacitances. Using a simple transmission-line load network, the PA is synthesized to satisfy Class-EF impedances at fundamental frequency, third harmonic, and all even harmonics as well as to simultaneously provide an impedance matching to 50-Ω load.

Moving with Beats and Loops: The Structure of Auditory Events and Sensorimotor Timing

Traditionally, audio-motor timing processes have been understood as motor output from an internal clock, the speed of which is set by heard sound pulses. In contrast, this paper proposes a more ecologically-grounded approach, arguing that audio-motor processes are better characterized as performed actions on the perceived structure of auditory events. This position is explored in the context of auditory sensorimotor synchronization and continuation timing. Empirical research shows that the structure of sounds as auditory events can lead to marked differences in movement timing performance. The nature of these effects is discussed in the context of perceived action-relevance of auditory event structure. It is proposed that different forms of sound invite or support different patterns of sensorimotor timing. Hence, the temporal information in looped auditory signals is more than just the interval durations between onsets: all metronomes are not created equal. The potential implications for auditory guides in motor performance enhancement are also described.