Enio R. Ribeiro

Harmonic Voltage Reduction Using a Series Active Filter Under Different Load Conditions

This paper proposes a series active filter using a simple control technique. The series active filter is applied as a controlled voltage source contrary to its common usage as variable impedance. It reduces the terminal harmonic voltages, supplying linear or even nonlinear loads with a good quality voltage waveform. The operation principle, control strategy, and theoretical analysis of the active filter are presented. These aspects were proven by the results of numerical simulations. Experimental results of the series active filter demonstrated its good performance under different load conditions

Reconfiguration methodology of shaded photovoltaic panels to maximize the produced energy

This paper presents the development of an automatic reconfiguration system for photovoltaic panels operating under shaded conditions in order to maximize power output. The main goal of the proposed system is to minimize the negative effects of shading, through the reconfiguration of the electrical connections of the panel. The automatic reconfiguration system is built with the aid of Rough Set Theory and its results are evaluated with computer simulations.

Relationship between the shading position and the output power of a photovoltaic panel

This paper presents a research about the harmful effects of partial shading on a photovoltaic panel. The analysis begins with the study of the electrical model of the solar cell and is extended to the module and the photovoltaic panel. The computational evaluations determine the relationship between the position of shade on the photovoltaic array and its electrical efficiency. An experimental photovoltaic panel is built and tested for various situations of shading. The experimental results were consistent with computational predictions.

Harmonic voltage reduction using a series active filter under different load conditions

This paper proposes a series active filter using a simple control technique. The series active filter is applied as a controlled voltage source contrary to its common usage as variable impedance. It reduces the terminal harmonic voltages, supplying linear or even nonlinear loads with a good quality voltage waveform. The operation principle, control strategy, and theoretical analysis of the active filter are presented. These aspects were proven by the results of numerical simulations. Experimental results of the series active filter demonstrated its good performance under different load conditionsThis paper proposes a series active filter using a simple control technique. The series active filter reduces the terminal harmonic voltages, supplying linear or even non-linear loads with a good quality voltage waveform. The operation principle, control strategy and theoretical analysis of the active filter are presented. These aspects were proven by the results of numerical simulations. Experimental results of the series active filter demonstrated its good performance under different load conditions.

Photovoltaic Array Reconfiguration Strategy for Maximization of Energy Production

This paper presents a dynamic reconfiguration method for electrical connections in a Series-Parallel connected photovoltaic array under partial shading conditions. It is desirable to extract the maximum energy from the array, but it does not occur in situations where the modules have different points of operation caused by shading. The proposed method is then characterized by the maintenance of the PV array dimensions, that is; no module is removed or added to the array. Furthermore, the control algorithm is based on the Rough Sets Theory, which allows the fast and efficient implementation of a control system, comprising rules that identify the system optimal configuration.

MPPT Technique Based on Current and Temperature Measurements

This paper presents a new maximum power point tracking (MPPT) method based on the measurement of temperature and short-circuit current, in a simple and efficient approach. These measurements, which can precisely define the maximum power point (MPP), have not been used together in other existing techniques. The temperature is measured with a low cost sensor and the solar irradiance is estimated through the relationship of the measured short-circuit current and its reference. Fast tracking speed and stable steady-state operation are advantages of this technique, which presents higher performance when compared to other well-known techniques.

Small-signal modeling of a single-phase DVR for voltage sag mitigation

Voltage sags are sudden voltage reduction that may be present among power systems. It persists from milliseconds to a minute of duration. Different causes may produce voltage sags such as lightning, presence of non-linear equipment connected to the power grid or presence of short circuit faults. Sensitive loads, like electronic equipments, may be damaged or present malfunctioning during the voltage sag, generating economical losses. A suitable solution to mitigate this voltage disturbance is the Dynamic Voltage Restorer (DVR). It is a power electronics-based solution that provides power compensation to sensitive loads during the sag occurrence. The DVR must operate with control loops, monitoring the load voltage and generate the compensation during the sag. Those control loops must be tuned with aid of a mathematical model, a performance criteria and a proper design procedure of the controller. This paper presents a small-signal modeling for a single-phase transformerless DVR. A small-signal equivalent circuit will be obtained and its analysis will produce the control-to-output transfer function. Using the control-to-output transfer function a PID voltage controller will be designed. This PID design methods will be described and the proper operation will be verified through computer simulation.

Thyristorized rectifier bridge controlled through a PSoC

This work presents the design and implementation of a control system for a thyristorized rectifier bridge held by PSoC (Programmable System-on-Chip), which is able to maintain the output current of the circuit in a predetermined reference supporting changes in input voltage, as well as changes in load. Using the PSoC — an integrated circuit that has programmable analog and digital resources — it is possible to reduce the external circuitry. The project built with the PSoC, compared with a conventional implementation, is smaller and has lower costs. Another important aspect is related to the decrease in energy consumption due to the use of fewer components. The rectifier and its control system were designed and simulated. Additionally, a prototype was built and the tests proved the feasibility of using PSoC.

A review of solar photovoltaic array reconfiguration methods

Shading causes significant reduction in energy production in photovoltaic (PV) systems. The negative effects caused by shadowing can be reduced through different techniques, among them, the reconfiguration of PV array electrical connections, stands out. This paper presents an overview of the main techniques used to perform the photovoltaic array reconfiguration, as well as the key features of each method.

Small-signal model of a single-phase series active filter

Electrical power supplies or networks containing voltage harmonics cause harmful effects to the electrical equipments and thus economic losses to their users. Series active filters are an alternative to reduce or even eliminate these voltage distortions. They produce opposing voltages to the harmonic voltages from the power supply and therefore loads are fed with an almost sine wave signal. This paper presents a development of a small-signal model of a single-phase series active filter. The model takes in account parasitic elements of energy storage components and semiconductors devices of the series active filter. Due to this fact, that model makes possible an investigation of their influence on the dynamic behavior of the series active filter and on its controllers design. Simulation results are presented to validate the proposed small-signal model, control scheme and series active filter effectiveness.