Jakson Paulo Bonaldo

Multi-functional use of single-phase power converters

This work deal with multi-functional use of electronic power converters as interface between utility grid and local power sources. The Conservative Power Theory is used to simultaneously injecting power into the grid and performing selective disturbance compensation.

Control strategies for high frequency voltage source converter for ozone generation

This paper presents a resonant converter for ozone generation developed for corona discharge processes. The switching frequency is adjusted near the series resonance between the leakage inductance of transformer and the equivalent capacitance of the ozone generation cell, allowing high efficiency, due to high power factor and power switches soft-switching. Power regulation is provided by Pulse Density Modulation - PDM. As the converter is a voltage source inverter it is necessary to limit the instantaneous current and its average value in order to avoid the saturation of the highvoltage transformer. Simulation and experimental results show the behavior of the proposed circuit and controller.

Flexible operation of grid-tied single-phase power converter

This work presents a technique to allow the use of single-phase power converter tied to the grid utility both as active power filter (APF), mitigating power quality disturbances due to the load, and as distributed generation (DG) interface, connecting a local renewable power source into the grid. The main goal is to ensure that the power processed by the power electronic converter (PEC) is lower than its rated power, contributing to increasing the lifetime and safety of the converter. The load current is decomposed, by using the Conservative Power Theory, in current components related to the non-active power consumed by the load. Then, this non-active current is weighted by a factor, which is calculated based on the load power factor, generating the reference for disturbances compensation. The reduction in the power processed by the PEC is achieved by adjusting the power factor desired in the grid side, which leads to a partial compensation of the PQ disturbances.

Digital control system for high precision power supplies of the new Brazilian synchrotron source

This paper proposes an architecture of digital current regulator intended to be used to control the power supplies of the new Brazilian synchrotron light source, called Sirius. It is based on a high-precision Digital to Analog Converter and a modern System on Chip device, which has the capability of performing realtime control tasks together with managing and interface tasks. Despite this system will be used to control many kinds of power supplies, it was validated in a 100 W power supply, which was previously developed to be used in the present Synchrotron Light Source.

Adaptive saturation system for grid-tied inverters in low voltage residential micro-grids

Provision of ancillary services, like power quality improvement is a key to attain higher utilization of multifunctional grid-tied inverter. However, the power quality improvement is mainly limited by the power capacity the grid-tied inverter. This paper explores integration issues of the next-generation intermittent power sources. In particular, two different strategies for enhancing power quality given the residual power capacity of the inverters are developed. One strategy aims to obtain the expected power quality exploiting the dynamic saturation of the inverter rated apparent power and another strategy is based on peak current detection. Both strategies offer the possibility to generate appropriate references for the inner current control loop. The two proposed strategies are compared in performance, and a discussion on their practical implementation for the best performance of the inverters is provided.

Single-phase multifunctional grid interface converter without grid sincronization

VSI are largely used as grid interface device for DG sources. Extra features have been added to the interface converters, mainly to deal with power quality issues, configuring its use as a multi-function device. In general, the converter acts as a power interface when the DG source is supplying energy and as a power conditioner when the DG source is inactive. In this paper the VSI converter is able to simultaneously operate both as APF and power interface between the grid and the DG source. Also it is possible to operate solely as APF or as an power interface. No synchronization with the grid voltage is required, contributing to the simplicity of the proposed strategy. A single-phase system is simulated validating the strategy.

Power Equalization Techniques for Three-Phase VSI-Driven Single-Phase Ozone Generators

The purpose of this article is to present a method to equalize power imbalances in single-phase loads driven by three-phase voltage source inverters. The objective is to unbalance the line-to-line voltages in order to equalize the individual load power. The method is evaluated under non-linear loads, considering the dispersion of the high-voltage transformer electrical parameters values usually found in ozone generating systems. Two methods are considered for equalizing the load power. In the progressive method, the power equalization is performed by a microcontroller and works setting up the voltage applied over each load in response to power feedback from the other loads. In addition, Fuzzy Logic concepts are also applied, permitting a fast response, in spite of lower precision in the power balancing. Analytical, simulation and experimental results validate both methods.

Multifunctional converter for power quality and power flow control in wind distributed generation systems directly connected to the grid

This paper presents a shunt-connected converter for interfacing a distributed generation system and the grid, with focus on uncontrolled small power wind generators. The objective is to show that the converter, with a suitable control strategy, is able to impose sinusoidal voltage and, in most cases, guarantee the compliance of the grid voltage with the THD standard levels. The strategy allows, simultaneously, the power flow regulation and current harmonic.