Salvador Pérez Litrán

A Control Strategy for Hybrid Power Filter to Compensate Four-Wires Three-Phase Systems

A control algorithm is proposed for a three-phase hybrid power filter constituted by a series active filter and a shunt passive filter. The control strategy is based on the dual formulation of the compensation system principles. It is applied by considering a balanced and resistive load as ideal load, so that the voltage waveform injected by the active filter is able to compensate the reactive power, to eliminate harmonics of the load current and to balance asymmetrical loads. This strategy improves the passive filter compensation characteristics without depending on the system impedance, and avoiding the series/shunt resonance problems, since the set load-filter would present resistive behavior. An experimental prototype was developed and experimental results are presented.

A Converter for Bipolar DC Link Based on SEPIC-Cuk Combination

This letter describes a new application of single-ended primary converter (SEPIC) and Cuk converter for dc bipolar network. A dc-dc converter configuration based on a combination of both converters is proposed. In the resulting topology, the switching node is shared by the SEPIC and Cuk converter since they have the same instantaneous duty cycle. The main advantage of this topology is that synchronization of various switches is not required and control terminal is connected to ground which simplifies the design of the gate drive. On the other hand, this configuration allows the connection of renewable energy sources to microgrids (MG)-type bipolar dc link and to cover the current needs of new distributed generation units with efficient, economical, and easy way. To verify its performance, a prototype was designed. Experimental results show as this combination of two converter topologies with appropriated modulation schemes are adequate to use in dc MG.

Reference Voltage Optimization of a Hybrid Filter for Nonlinear Load Compensation

The harmonic problem in electric power systems, far from improving, has been increasing in recent years. To mitigate this problem, active filters have been proposed; however, they do not present a complete solution for any type of load and system. This paper develops a control strategy for a compensator based on a hybrid filter topology. This topology is formed by an active power filter of series connection and a passive filter of parallel connection. The proposed strategy is based on minimizing the root-mean-square value of the voltage at the point of common coupling so that the source transfers the power demanded by the load. Thus, the determination of the reference signal is posed as a constrained optimization problem. The strategy was proposed for four- and three-wire systems, and it allowed the compensation of current harmonics and reactive power of harmonic current source and harmonic voltage source loads. An experimental prototype was developed, which has allowed verification of their performance.

Instantaneous Reactive Power Theory to N Wire Systems

The control strategy derived from the instantaneous reactive power theory is one of the most commonly used in the Active Power Filters (APFs). For the last decades other formulations have been developed in order to achieve compensation objectives different to the proposed in the original one. Nevertheless, all of them can be only applied to three-phase systems, i.e.: in those formulations frameworks, they can not be used to obtain the control strategy for a polyphase system. This paper presents a new approach which can be applied to n wire systems. The powers and currents expressions derived from the formulations presented up now can be obtain applying this new approach. In this paper, the original p-q and the modified p-q formulation expressions are obtain in the new approach framework.

New Single-Input, Multiple-Output Converter Topologies: Combining Single-Switch Nonisolated dc-dc Converters for Single-Input, Multiple-Output Applications

This article presents a methodology that allows the development of new converter topologies for single-input, multiple-output (SIMO) from different basic configurations of single-input, single-output dc-dc converters. These typologies have in common the use of only one power-switching device, and they are all nonisolated converters. Sixteen different topologies are highlighted, and their main features are explained. The 16 typologies include nine twooutput-type, five three-output-type, one four-output-type, and one six-output-type dc-dc converter configurations. In addition, an experimental prototype of a three-output-type configuration with six different output voltages based on a single-ended primary inductance (SEPIC)-Cuk-boost combination converter was developed, and the proposed design methodology for a basic converter combination was experimentally verified.

A SEPIC-Cuk converter combination for bipolar DC microgrid applications

This paper describes a new application of SEPIC (Single Ended Primary Converter) and Cuk converter for distributed generation systems. A DC/DC converter configuration based on a combination of both converters is proposed. In the resulting topology the switching node is shared by the SEPIC and Cuk converter, since they have the same instantaneous duty cycle. This topology allows the connection of renewable energy sources to microgrids type bipolar DC link and to cover the current needs of new distributed generation units with efficient, economical and easily way. Simulation results show that this combining of two converter topologies with appropriated modulation schemes are adequate for the functions of voltage balance and current redistribution in DC microgrid (MG).

A New Control for a Combined System of Shunt Passive and Series Active Filters

A new control algorithm for a hybrid filter formed by a series active filter and a passive filter connected in parallel with the load is proposed. The new control strategy is based on the dual formulation of the vectorial theory of electric power, so that the signal injected by the active filter is able to compensate the reactive power and the harmonics of the load current. To verify the developed theoretical analysis, the proposed control scheme has been simulated in the platform MATLAB-Simulink and applied to a three-phase three-wire system. The simulation results to verify the effectiveness of the proposed control algorithm are presented.

A Zeta-Buck-Boost converter combination for Single-Input Multiple-Output applications

This paper presents and describes a new DC-DC converter combination based on Zeta and Buck-Boost single inductor converters for Single-Input Multiple-Output (SIMO) applications. This converter combination provides a three-output type with DC bipolar voltage (two outputs with the same voltage, but different polarities) with only one controllable switch. The main advantage of the proposed converter is the low number of components used in the combination which reduces its size, manufacturing costs, and provides high efficiency in power conversion. An analysis of the proposed configuration for different performance modes and load conditions has been carried out. Simulation results show that this combination of two Single-Input and Single-Output (SISO) converter topologies, with appropriated modulation schemes, is suitable for SIMO applications.

Load compensation active conditioner for power quality

This paper presents the obtained experimental results with a single-phase experimental prototype of a load compensation active conditioner, sLCAC. The sLCAC is composed by a series-parallel combination of active power filters, to provide a global conditioning of the load against harmonic distortion: to isolate the load voltage vL from the harmonics of the supply voltage vS, as well as to regulate it to the rated value; and also to enhance the supply current iS, compensating the harmonic and reactive components of the load current iL. The control and components design of the LCAC allows to apply it to different types of load, with an efficient and robust behavior. Experimental prototype results are presented, applied to two types of non-linear loads with distorted supply voltage. The analysis of these results show the validity of the proposed design for the development of active conditioners with a wide load range in highly distorted environments

Assessment on apparent power indices with hybrid active power filters

This paper presents a method for assessing the quality improvement of the electric power, when compensation equipment based on hybrid active power filters is applied. Power quality indicators that allow to separate the contribution to unbalance of each harmonic and interharmonic of voltages and currents are introduced, calculated with an enhanced procedure. To characterize the behavior of these indices, a hybrid series - active parallel - passive filter, SAPPF, is used for the compensation of a load in a system with unbalance and distortion. The results obtained with the practical cases have allowed to verify the validity of the proposed procedure, and to clarify the interpretation of the unbalance and harmonic distortion indices with this kind of compensation.