Summary
Grid-connected photo voltaic (PV) systems are being developed very fast and systems from a few kW to tenths of a MW are now in operation. As an important source of distributed generation (DS) the PV systems need to comply with a series of standard requirements in order to ensure the safety and the seamless transfer of the electrical energy to the grid. Multilevel voltage source converters (VSC) is a heart of the PV system and are emerging as an important power converter options for low, medium, and high-power applications. These VSCs have bought numerous advantages, especially in renewable energy systems such as PV and wind energy systems. In this article, several topologies of VSCs, which brings together some concepts from traditional converters and multi-level converters, are presented. Also, several control strategies for controlling current, voltage, active power and reactive power have also been reviewed. Various topologies with their technical aspects have been reviewed and the best suitable topology and control scheme for grid connected PV and wind energy systems has been suggested. Copyright © 2016 John Wiley & Sons, Ltd.

Power conversion in renewable energy systems: A review advances in wind and PV system

This paper describes a push-pull parametric transformer constructed using a pair of orthogonal-cores. The operating characteristics of the parametric transformer with a rectifier load were analyzed based on SPICE simulations. The analysis results show good agreement with experiment. It was found that the input surge current of the full-wave rectifier circuit with a smoothing capacitor can be compensated by the parametric transformer. Use of the parametric transformer as a power stabilizer is anticipated owing to its various functions, such as for voltage regulation and overload protection.

Analysis of Parametric Transformer with Rectifier Load

Analysis of a Phase Converter with a Frequency-Divide Function.

Analysis of Parametric Transformer with Rectifier Load.

Frequency-dividing three-phase inverters, which consist of a single-phase square wave inverter and a three-phase ferroresonant circuit, have excellent efficiency, constant voltage characteristics, and three-phase balance. These advantages make them suitable for use as dc-ac converters and uninterruptible power supplies (UPS). However, when such three-phase inverters are used as UPS devices, a startup circuit with a complicated sequence is needed to reduce the capacitance of the single-phase inverter. If the sequence is simplified a separate problem emerges?the phase sequence of the voltage cannot be determined. In this work, the relationship between circuit imbalance and the phase sequence of three-phase voltages is clarified through both experiments and analyses. The results provide useful information on circuit constants which can be used to reduce costs through simplification of startup circuits for these applications.

Frequency-Dividing-Type Three-Phase Inverter with Adjusting Capacitor

The ferro-resonant type power supply has high reliability, and is therefore used for power supply to electronic devices. Recently, a three phase inverter has been proposed (called the phase conversion type), which is a combination of a single phase squarewave inverter and a phase converter utilizing the phase conversion function of the ferro-resonant circuit. However, the phase conversion type causes difficulties in that the output voltages are not balanced and that the efficiency remains at about 60%. This paper reports experiments, analysis and review made on a three phase inverter (called the frequency divide type) having a phase converter utilizing the frequency divide function and a single phase square wave inverter in a combination. As a result, the characteristics of the device are clarified, and a high output balance and system efficiency are realized.

3-Phase Inverter Using Frequency Divide Function of Ferro-Resonant Circuit.

Ferro-resonant type power supplies are highly reliable, and are therefore used as power supplies for electronic devices. Recently a three-phase inverter (called a phase-conversion type inverter), a combination of a single-phase square-wave inverter and a phase converter utilizing the phase conversion function of a ferroresonant circuit, has been proposed. However, the use of a phase converter causes difficulties, in that the output voltages are not balanced and the efficiency remains at about 60%. This paper reports experiments, analyses and reviews three-phase inverters (frequency-divide type inverters) which combine a phase converter utilizing a frequency-divide function with a single-phase square-wave inverter. As a result, the device characteristics were determined, and a high output balance and high system efficiency were achieved.

H. Satoh

Papers

3-Phase Inverter Using Frequency Divide Function of Ferro-Resonant Circuit.

3-Phase Inverter Using Frequency Divide Function of Ferro-resonant Circuit