This paper is intended to review the development of active power filter (APF) technologies that are commonly used to mitigate harmonics in utility power lines. This review can also be considered as a "tutorial-type paper" as it provides a holistic coverage of the APF technologies by omitting the tedious details, but without losing the main essence of the subject matter. It is hoped that by this approach, it would be possible to lure more power engineering readers to be involved in this important and growing field. The discussion starts with a brief overview of harmonic distortion problems and their impacts on electric power quality. The operation of common APF topologies, namely the shunt, series and hybrid APFs are described in detail. This is followed by a review on different types of reference signal estimation extraction techniques. In particular, the application of the p-q and extension p-q theorems to extract the reference signals are elaborated, as they are the most commonly found in practical APF systems. Finally, an overview of the APF control strategies is provided. A brief discussion on the APF-solar photovoltaic system is also given. At the end of the paper, important references are cited to assist readers who are interested to explore the subject in greater detail.

Harmonics mitigation using active power filter: a technological review

An apparatus and method for supplying energy to a load includes an energy recharge unit, an energy storage unit, an energy converter connected to the energy recharge unit, the energy converter being capable of transferring energy at a power level from the energy recharge unit to an output node, the power level being determined by a power transfer controller, and a bi-directional energy converter connected to the energy storage unit and to the output node. The bi-directional energy converter is capable of converting energy of varying voltages from the energy storage unit to energy of varying current levels to supplement the transferred energy with energy from the energy storage unit so as to maintain a constant voltage on the output node. The bi-directional energy converter is capable of converting the transferred energy to provide charging energy to the energy storage unit when the transferred energy exceeds a demand level of the load while maintaining the constant voltage at the output node.

Modular System for Unattended Energy Generation and Storage

An electronics module docking system includes docking member removably coupled to a photovoltaic module. The docking system includes a first connector port electrically coupled to one or more photovoltaic cells of the photovoltaic module. The photovoltaic module is selectively coupleable to the docking member. The docking system includes a housing to enclose an electronics module. The housing may include second connector port that is selectively engageable to the power electronics module. The power electronics module and the photovoltaic cells are electrically coupled to one another upon selective engagement of the connector ports. The inverter housing is receivable by and removably coupleable to the docking member allowing the inverter housing to be removably coupleable to the photovoltaic module.

Power inverter docking system for photovoltaic modules

An apparatus and method for controlling the delivery of a pre-determined amount of power from a DC source to an AC grid includes an inverter and an inverter controller The inverter includes an input converter, an energy storage capacitor, and an output converter The inverter controller includes an input converter controller and an output converter controller The input converter controller includes feedforward controller configured to perform a calculation to determine a value for the duty cycle for the input converter such that: (1) the input converter delivers the pre-determined amount of power and (2) the magnitude of a ripple signal reflected into the input source is attenuated toward zero The input converter controller may also include a quadrature corrector configured to determine the effectiveness of the calculation in attenuating the ripple and to adaptively alter the calculation to improve the effectiveness

Quadrature-Corrected Feedforward Control Apparatus and Method for DC-AC Power Conversion

An apparatus and method for controlling the delivery of power from a DC source to an AC grid includes an inverter configured to deliver power from the unipolar input source to the AC grid and an inverter controller. The inverter includes an input converter, an active filter, and an output converter. The inverter controller includes an input converter controller, an active filter controller and an output converter controller. The input converter controller is configured to control a current delivered by the input converter to a galvanically isolated unipolar bus of the inverter. The output converter is configured to control the output converter to deliver power to the AC grid. Additionally, the active filter controller is configured to control the active filter to supply substantially all the power that is deliver by the output controller to the AC grid at a grid frequency.

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Apparatus and method for controlling dc-ac power conversion

This paper presents the analysis of a static conversion system for treatment of the solar energy from photovoltaic panels. This system is interconnected with the mains power supply, contributing to the generation of the electrical energy. The power structure is composed by a current-fed push-pull converter, a buck converter and a current inverter. The main features of the system are: simple control strategy, robustness, lower harmonic distortion of the current and natural isolation. The principle of operation, design procedure and experimental results are presented.

D. Cruz Martins

Papers

Usage of the solar energy from the photovoltaic panels for the generation of electrical energy