This paper presents dynamic modeling of selfexcited induction generator (SEIG) using state space approach. The proposed dynamic model consists of induction generator, self-excitation capacitance and load model are expressed in stationary d-q reference frame with the actual saturation curve of the machine. The dynamic performance of SEIG is investigated under no load, with load and perturbation of load. To predict the performance of the purposed system, a MATLAB/ SIMULINK based simulation study is carried out. Viability of the excitation process is ascertained through experimental results obtained from the laboratory prototype.
The control characteristics of the ac/dc grid-side voltage source converter (VSC) used to connect wind power systems with the grid are of significant grandness for the overall grid execution. In this paper, voltage oriented control PI and phase locked loop (PLL) are used to regulate grid-side dc voltage and system power factor by decoupled control theory. The mathematical models of grid-side converter and the control strategy of grid-side converter based wind power generation system are analyzed. The control performance is assessed through simulation approach using MatLab SimPowerSystem, which verifies that the developed control mechanism is feasible to apply for grid-side converter based wind power generation system and the grid-side converter is controlled well.Keywords -Grid side voltage source converter, wind power generation, voltage oriented control, phase locked loop, decoupled control theory.
Purpose: To determine the effect of depth of scleral tunnel incision measured by anterior segment OCT on postoperative corneal astigmatism by comparing the change of magnitude of corneal astigmatism between superficial and deep sclerocorneal tunnel incision in manual small-incision cataract surgery (SICS). Methods: Depths of sclerocorneal incision of 72 eyes of patients undergoing uncomplicated manual SICS and attending regular follow-up schedule were assessed with anterior segment OCT at 6-week post-op follow-up. Results: The overall mean ± standard deviation (SD) change of astigmatism for superficial incision, that is, ≤399 mm, was 0.44 ± 0.30 and that for deeper, that is, ≥400 mm, was 0.13 ± 0.48 and the change was significantly higher in ≤399 mm group than in ≥400 mm group ( P = 0.003). In both superior and temporal incision locations, the mean ± SD change of astigmatism for ≤399 mm incision was 0.48 ± 0.29 and 0.40 ± 0.30, respectively, and that for ≥400 mm was 0.03 ± 0.34 and 0.23 ± 0.57, respectively. The change of astigmatism was significantly higher in ≤399 mm incision group overall ( P = 0.003) and also higher in both superior and temporal incision location groups ( P = 0.001 and P = 0.479, respectively). Conclusion: The depth of sclerocorneal incision had a statistically significant effect on the change of astigmatism following manual SICS, with superficial incision (≤399 μm) causing a higher change than deeper incision (≥ 400 μm).
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