A circuit configuration of a single-phase nonisolated online uninterruptible power supply (UPS) with 110-V/220-V input–output voltage ratings is proposed, allowing the bypass operation without a transformer even if the input voltage is different from the output voltage. The converter consists of an ac–dc/dc–dc three-level boost converter combined with a double half-bridge inverter. In this type...

Standard lowand medium-power induction motor drives are based on the pulsewidth modulation (PWM) voltagesource inverter fed from a diode rectifier. The dual topology, based on the current-source inverter/rectifier structure is used in mediumand high-power applications. This paper analyzes the existing motor drives based on current-source topologies and proposes a control strategy that addresses...

Distributed generators are very much beneficial in reducing the losses effectively compared to other methods of loss reduction .In this paper optimal size of DG unit operated at optimal power factor is dealt. DG unit placement using fuzzy logic and sizing of DG at any power factor is calculated using analytical method . Voltage and power loss reduction indices of distribution system nodes are m...

This paper presents a newly developed approach to find the optimal location of distributed generations (DGs) to improve power system voltage stability margin and reduce losses incorporating the constraints. The loadability limit index is used to assess the static voltage stability security margin, which is associated with the point of voltage collapse limit. Based on this, a toolbox is develope...

Voltage-Source Converters have brought numerous advantages to HVDC transmission. However, they suffer from high losses and are usually weak against faults on the DC-side. In this paper, a new topology which brings together some concepts from traditional Current Source Converters and multi-level converters, is presented. Two stacks of Hbridge cells alternate to construct the converter voltage us...

Introduction The important considerations in the design and operation of a transmission line are the determination of voltage drop, line losses and efficiency of transmission. These values are greatly influenced by the line constants R, L and C of the transmission line. For instance, the voltage drop in the line depends upon the values of above three line constants. Similarly, the resistance of...

ARTICLE INFO ABSTRACT ARTICLE HISTORY: Received 15 September 2012 Revised 15 August 2013 Accepted 22 August 2013 This paper presents a novel control method to improve the efficiency of low-voltage DC-DC converters at light loads. Pulse Width Modulation (PWM) converters have poor efficiencies at light loads, while pulse frequency modulation (PFM) control is more efficient for the same cases. Swi...

The main aim of this paper is to improve the performance of high current dual active bridge converters when operated over a wide voltage range. A typical application is for fuel cell vehicles where a bi-directional interface between a 12V battery and a high voltage DC bus is required. The battery side voltage ranges from 11V to 16V while the fuel cell is operated between 220V and 447V and the r...

This paper presents a new hybrid particle swarm optimization (HPSO) method for solving multi-objective real power optimization problem. The objectives of the optimization problem are to minimize the losses and to maximize the voltage stability margin. The proposed method expands the original GA and PSO to tackle the mixed –integer nonlinear optimization problem and achieves the voltage stabilit...