A liquid-crystal-infiltrated microcavity structure is proposed as a variable-refractive-index material. It has the advantages over previously considered nanostructured materials of having a larger phase-angle change and lower driving voltage. Two-dimensional liquid-crystal director and finite-difference time-domain optical simulations are used to select liquid crystal material parameters and op...

This paper proposes a multi-stage power generation system suitable for renewable energy sources, which is composed of a DC-DC power converter and a three-phase inverter. The DC-DC power converter is a boost converter to convert the output voltage of the DC source into two voltage sources. The DC-DC converter has two switches operates like a continuous conduction mode. The input current of DC-DC...

damping of a full-scale cable with a pair of passive–on magnetorheological (mr) dampers was tested. a cable of 215.58m long with the first mode frequency of 0.658hz was tensioned horizontally in cable prefabrication factory. two mr dampers were attached to the cable in an angle in the plane perpendicularly to the cable axis in 5m length from the cable anchorage. the applied voltage level was 0v...

Voltage sags in the electric power system are mostly due to faults in the power system. Voltage sag is characterized by its magnitude (the retained voltage), phase-angle jump, unbalance in the sag in the three phases, and duration. Type of transformers in the electrical system is the important parameter influencing the characteristic of sag at the node where sensitive loads are connected. For s...

Nowadays power quality is term widely used in power systems wherein the voltage, current, and phase angle are widely discussed and used. The Time Frequency Representation (TFR) provides a powerful method for identification of the non-stationary of the signals. This paper proposes a Discrete Orthogonal S-Transform (DOST) for analysis and visualization of voltage distortions with timevarying ampl...

Dynamic Voltage Restorer (DVR) restores the distribution system load voltage to a nominal balanced sinusoidal voltage, when the source voltage has distortions, sag/swell and unbalances. DVR has to inject a required amount of Volt-Amperes (VA) into the system to maintain a nominal balanced sinusoidal voltage at the load. Keeping the cost effectiveness of DVR, it is desirable to have a minimum VA...

In this paper, a novel control scheme of three-phase PWM rectifiers eliminating both the ac input voltage and current sensors is proposed. The phase angle and the magnitude of the source voltage are estimated by controlling the deviation between the rectifier current and its model current to be zero. The input currents can be reconstructed from switching states of the PWM rectifier and the meas...

A technique for selecting the element values of the PWM AC chopper circuits to improve the input power factor is presented. This technique analyzes the phase angles of input current, output current and voltage for selecting the optimal value of the filter capacitance. This produces the phase angle of input current in phase with that of input voltage. Therefore, the PWM AC chopper can operate at...

The DSTATCOM (Distribution STATic synchronous COMpensator) is being increasingly popular in power system applications. In general, compensation of reactive power in a power distribution network of a power utility and industry plays a major role in reducing distribution loss and maintaining constant distribution voltage. A simple transformation and steady state and transient analysis are achieve...