Modelling and control of a wind energy conversion system

The dynamical model of a novel low power wind energy conversion system consisting of a wind turbine, an induction generator, a PWM a.c. inverter and a d.c. battery group is obtained. A feedback control law is developed to provide optimum power conversion and arbitrarily fast responses at steady-state. The feedback does not require measurement of the wind speed and therefore is suitable for real applications. The stability of the closed-loop system is analysed using a Liapunov-type practical stability criterion, and it is shown that the system remains stable for wind speed variations that are not both large and fast at the same time. Digital computer simulation studies on a 1 kVA test system verify the theoretical results.     

Statistical investigation of hydraulic driven circular interpolation motions

In this study, a twin-axis gantry has been structured to examine hydraulic driven positioning skills of the curvilinear motions based on ISO 230-4 standard entitled ??Circular tests for numerically controlled machine tools??. The system is controlled by a path and position control module of a PLC device. As a result of the experiments conducted based on the full factorial design, the effects of piston diameter, feed rate, radius and their two-way interactions on the circularity error are determined through analysis of variance. Accordingly, minimum circularity error is obtained with the piston diameter of 63 mm, inertia load of 12.5 kg, radius of 5 mm and feed rate of 50 mm/min as 0.345 mm. Circularity error increases with the increase of inertia load, radius and feed rate, and declines with the increase of piston diameter. Lastly, piston diameter has the greatest effect on the circularity error change and followed by radius, feed rate, piston diameter?Cradius, radius?Cfeed rate, piston diameter-feed-rate, inertia load, piston diameter?Cinertia load, and inertia load?Cradius factors and interactions.