http://ieeexplore.ieee.org/iel5/5610941/5624686/05624745.pdf

Power electronics

The aim of this paper is to present a review of current control techniques for three-phase voltage-source pulsewidth modulated converters. Various techniques, different in concept, have been described in two main groups: linear and nonlinear. The first includes proportional integral (stationary and synchronous) and state feedback controllers, and predictive techniques with constant switching frequency. The second comprises bang-bang (hysteresis, delta modulation) controllers and predictive controllers with on-line optimization. New trends in current control-neural networks and fuzzy-logic-based controllers-are discussed, as well. Selected oscillograms accompany the presentation in order to illustrate properties of the described controller groups.

Current control techniques for three-phase voltage-source PWM converters: a survey

Solid-state switch-mode rectification converters have reached a matured level for improving power quality in terms of power-factor correction (PFC), reduced total harmonic distortion at input AC mains and precisely regulated DC output in buck, boost, buck-boost and multilevel modes with unidirectional and bidirectional power flow. This paper deals with a comprehensive review of improved power quality converters (IPQCs) configurations, control approaches, design features, selection of components, other related considerations, and their suitability and selection for specific applications. It is targeted to provide a wide spectrum on the status of IPQC technology to researchers, designers and application engineers working on switched-mode AC-DC converters. A classified list of more than 450 research publications on the state of art of IPQC is also given for a quick reference.

/pdf/a-review-of-single-phase-improved-power-quality-ac-dc-2pm6h4zjxq.pdf

A review of single-phase improved power quality AC-DC converters

The authors discuss high-voltage power conversion. Conventional series connection and three-level voltage source inverter techniques are reviewed and compared. A novel versatile multilevel commutation cell is introduced: it is shown that this topology is safer and more simple to control, and delivers purer output waveforms. The authors show how this technique can be applied to either choppers or voltage-source inverters and generalized to any number of switches.<<ETX>>

Multi-level conversion : high voltage choppers and voltage-source inverters

With rapid development of wind power technologies and significant growth of wind power capacity installed worldwide, various wind turbine concepts have been developed. The wind energy conversion system is demanded to be more cost-competitive, so that comparisons of different wind generator systems are necessary. An overview of different wind generator systems and their comparisons are presented. First, the contemporary wind turbines are classified with respect to both their control features and drive train types, and their strengths and weaknesses are described. The promising permanent magnet generator types are also investigated. Then, the quantitative comparison and market penetration of different wind generator systems are presented. Finally, the developing trends of wind generator systems and appropriate comparison criteria are discussed. It is shown that variable speed concepts with power electronics will continue to dominate and be very promising technologies for large wind farms. The future success of different wind turbine concepts may strongly depend on their ability of complying with both market expectations and the requirements of grid utility companies.

Overview of different wind generator systems and their comparisons

An optimum dispatch strategy using set points for a photovoltaic (PV)–diesel–battery hybrid power system

Voltage source inverters (VSI) have been widely used in uninterruptible power supplies, unified power flow controllers or unified power quality conditioners, and distributed generation systems (DGS) VSIs are inherently efficient, compact, and economical devices used to control power flow and provide quality supply VSIs can be classified as voltage-controlled VSIs (VCVSIs) and current-controlled VSIs (CCVSIs), depending on their control mechanism In this paper, a detailed comparison of VCVSIs and CCVSIs for DGS applications is presented This paper examines the advantages and limitations of each control technique in a single-phase DGS, without incorporating additional hardware and/or extra complex control techniques Discussions on the concepts, hypotheses, and computer simulations of different VSIs in the presence of different loads and conditions are presented The experimental results confirm the validity of the analysis and simulations outlined The paper provides design recommendations for the use of VCVSIs and CCVSIs in various applications

Application of voltage- and current-controlled voltage source inverters for distributed generation systems

This paper presents the design and finite-element analysis of a permanent-magnet generator using neodymium-iron-boron magnets for directly coupled wind turbines. For the sake of small size and light weight with extra low speed for direct coupling, the outer rotor structure is used. The simple magnetic equivalent circuit approach is used for initial design iteration, and the finite-element method is applied to analyze the detailed characteristics. Comprehensive experimental tests were conducted to verify the theoretical predictions. Agreement between the theoretical work and testing results was good.

Design and finite-element analysis of an outer-rotor permanent-magnet generator for directly coupled wind turbines

A multilevel pulse-width modulated (PWM) single phase voltage-source inverter topology for photovoltaic applications is discussed in this paper. The use of the phase opposition (PO) carrier disposition multicarrier PWM switching technique for this topology is presented. Inverter switch control signals are derived. A 5-level and a 3-level PWM voltage waveform across the load is generated, for high and low modulation indexes respectively. Performance characteristics including total harmonic distortion for a range of operating conditions of the inverter are provided. Theoretical considerations discussed in this paper are supported with simulation and experimental results taken from a low power laboratory prototype.

A multilevel PWM inverter topology for photovoltaic applications

This paper presents a practical implementation of a grid interactive photovoltaic uninterruptible power supply (UPS) system using battery storage and a back up diesel generator. The system incorporates 2.5 kWp of photovoltaic arrays, a 10 kVA power conditioning unit capable of operating in both inverting and charging modes, and a 300-Ah battery bank. Two such systems were installed in two Indian cities. The project was implemented using soft loans available in India through a World Bank Loan for photovoltaic market development. The system has been working satisfactorily since May 1997 and has demonstrated the capability of the system to provide uninterrupted power, demand side management function and load voltage stabilization in a grid which experiences frequent blackouts and under/over voltage problems. Some results from the field installation are also included in this paper.

C.V. Nayar

Papers

An optimum dispatch strategy using set points for a photovoltaic (PV)–diesel–battery hybrid power system

Application of voltage- and current-controlled voltage source inverters for distributed generation systems

Design and finite-element analysis of an outer-rotor permanent-magnet generator for directly coupled wind turbines

A multilevel PWM inverter topology for photovoltaic applications

A grid-interactive photovoltaic uninterruptible power supply system using battery storage and a back up diesel generator