Andre A. Ferreira

Analysis of voltage droop control method for dc microgrids with Simulink: Modelling and simulation

This work presents a performance study of a dc microgrid when it is used a voltage droop technique to regulated the grid voltage and to control the load sharing between different sources. A small model of a dc microgrid comprising microsources and loads was implemented in the Simulink/Matlab environment. Some aspects about centralized (master-slave) and descentralized (voltage droop) control strategies as well as the procedures to design the controllers, with and without droop control, are presented and discussed. Simulation results obtained with the digital model of the dc microgrid with three microsources will be presented to validate the effectiveness of the voltage droop strategy, applied to proportional and proportional-integral controllers, to regulate the microgrid voltage.

A study of shunt active power filter based on modular multilevel converter (MMC)

This paper presents a study of a shunt active power filter based on the modular multilevel converter (MMC) topology. The current controller of the shunt active power filter uses a PI-MRI (PI with multi reference frame integrators) technique to assure that the APF current tracks the reference signal. It is also investigated the performance of the method of selection and classification used to choose and to control which submodule (SM) of the MMC will become active. Simulation results will be used to evaluate and to demonstrate the behavior of MMC as active power filter.

Integrated bidirectional single-phase vehicle-to-grid interface with active power filter capability

This work proposes and describes the integration of a bidirectional grid interface, capable to simultaneously operate as an active power filter and a battery charger (or a power generator), to the on-board power electronics of an electric vehicle. The integration of additional functions to electric vehicles is a very desirable feature, since it can result on cost reduction (in comparison to the separated implementation of the integrated functions). Simulation results based on a small-scale system provide evidence of the feasibility of the proposed concepts.

Comparative analysis of current and voltage-controlled photovoltaic Maximum Power Point tracking

Maximum Power Point tracking (MPPT) in photovoltaic (PV) systems may be achieved by controlling either the voltage or current of the PV device. There is no consensus in the technical literature about how is the best choice. This paper provides a comparative analysis performance among current and voltage control using two different MPPT strategies: the perturb and observe (P&O) and the incremental conductance techniques.

Simultaneous active power filter and G2V (or V2G) operation of EV on-board power electronics

This work proposes the application of a battery or plug-in electric vehicle on-board power electronics on the mitigation of possible residential electricity network power quality problems simultaneously to its use as a battery charger or a power generator. The integration of additional functions to an electric vehicle is a very desirable feature, since it can result on cost reduction (in comparison to the separated implementation of the integrated functions). Simulation results provide evidence of the feasibility of the proposed system and concepts.

Analysis of non-linear adaptive voltage droop control method applied to a grid connected DC microgrid

Currently, the standards of reliability and power quality indicate a new design of the Electric Power Systems (EPS), in which the model of centralized generation gives way to the Distributed Generation (DG). One way to achieve the integration of sources in DG is using DC microgrids, since renewable energy sources can be integrated into systems using DC as well as energy storage and UPS, eliminating conversion stages. The voltage control in these systems is of paramount importance. Therefore, this paper proposes the use of a methodology for nonlinear control associated with the concept of voltage droop control in a grid-connected DC microgrid. Simulation results are presented and the behavior of the system is analyzed.

Active power filter operation of an electric vehicle applied to single-phase networks

This work proposes the application of a battery or plug-in electric vehicle powertrain on the mitigation of possible residential electricity network power quality problems by means of the integration of a shunt active power filter into its power electronics circuitry. The integration of additional functions to an electric vehicle is a very desirable feature, since it can result on cost reduction (in comparison to the separately implementation of the integrated functions). Simulation results provide evidence of the possible employment of power electronics converters, inherent to the vehicle propulsion system, in order to reduce harmonic content and improve power factor in single-phased electric networks.

Contribution To The Study Of A Single-Phase And Single Stage Photovoltaic System

This paper deals with grid-connected single-phase photovoltaic (PV) systems and presents the design steps of a fully functional prototype, based on the full-bridge voltage-source inverter, being controlled by means of a low-cost integrated circuit (IC). Two-stage and single-stage arrangements are described with the aid of a didactic approach. It is shown that the average current control technique enables tracking the maximum power point of PV panels and allows attaining a low distortion, high power factor output current. The main contribution of this work is to demonstrate that those main functions, maximum power point tracking and low-distortion current synthesizing, can be accomplished by means of the IC UC3854. Since this integrated circuit is commonly employed in high power factor ac-to-dc pre-regulators it is required to provide an adaptation, which is described in the paper. Digital simulation as well as experimental results of a 720 W prototype are presented and validate the intended proposition.

A linear quadratic control applied to buck converters with H-infinity constraints

This paper provides a control design algorithm to get state feedback controllers for DC-DC buck converters with input voltage disturbances. The algorithm is based on the linear quadratic regulator and on the H∞ norm, ensuring a prescribed settling time for the transient responses and a prescribed attenuation for disturbances on the input voltage. Results show that the proposed algorithm can provide control gains with suitable time and frequency responses for the closed-loop system.

An alternative to charging stations for electric vehicles

The increase of eletric vehicle numbers would lead a considerable reduction in polluting gases emittion. However, there are several challenges related to the connection of electric vehicles and renewable sources to the electrical power system. The main objective of this work is to study the behavior of an electric vehicle battery recharging system composed of a set of photovoltaic solar panels connected to the electric power grid. Thus, the energy generated by the solar panels is preferably used to recharge the electric vehicle where the generated energy is injected into the power grid. In situations where the generation of energy by the panels is less than the demand of the electric vehicle, the grid complements the required energy. The topology and operation of the system studied in this paper consists essentially of the power management of three static converters, which share the same DC link. The simulation results indicate that the system works properly even on days of small power production at photovoltaic solar panels.