Strategies for extracting the three-phase reference currents for shunt active power filters are compared, evaluating their performance under different source and load conditions with the new IEEE Standard 1459 power definitions. The study was applied to a three-phase four-wire system in order to include imbalance. Under balanced and sinusoidal voltages, harmonic cancellation and reactive power compensation can be attained in all the methods. However, when the voltages are distorted and/or unbalanced, the compensation capabilities are not equivalent, with some strategies unable to yield an adequate solution when the mains voltages are not ideal. Simulation and experimental results are included

/pdf/comparison-of-control-strategies-for-shunt-active-power-2h9dyoalqf.pdf

Comparison of Control Strategies for Shunt Active Power Filters in Three-Phase Four-Wire Systems

This article gives a survey of the commonly used methods for harmonic detection in active power filters (APFs). The work proposes a simulation setup that decouples the harmonic detection method from the active filter model and its controllers. In this way, the selected methods can be equally analyzed and compared with respect to their performance, which helps in anticipating possible implementation issues. A comparison is given that may be used to decide the future hardware setup implementation. The comparison shows that the choice of numerical filtering is a key factor for obtaining a good accuracy and dynamic performance of an active power filter.

Detection is key - Harmonic detection methods for active power filter applications

A shunt active filter based on the instantaneous active and reactive current component i/sub d/-i/sub q/ method is proposed. This new control method aims to compensate harmonics and first harmonic unbalance. To evaluate its relative performance, it is compared with the instantaneous active and reactive power p-q method under various mains voltage conditions and for different harmonic injection high-pass filters. Both methods are completely frequency-independent, however under distorted mains voltages the proposed method presents a better harmonic compensation performance. The system synthesis and implementation are performed. Simulation and experimental results are presented.

An instantaneous active and reactive current component method for active filters

The simulation and experimental study of a fuzzy logic controlled, three-phase shunt active power filter to improve power quality by compensating harmonics and reactive power required by a nonlinear load is presented. The advantage of fuzzy control is that it is based on a linguistic description and does not require a mathematical model of the system. The fuzzy control scheme is realised on an inexpensive dedicated micro-controller (INTEL 8031) based system. The compensation process is based on sensing line currents only, an approach different from conventional methods, which require harmonics or reactive volt-ampere requirement of the load. The performance of the fuzzy logic controller is compared with a conventional PI controller. The dynamic behavior of the fuzzy controller is found to be better than the conventional PI controller. PWM pattern generation is based on carrierless hysteresis based current control to obtain the switching signals. Various simulation and experimental results are presented under steady state and transient conditions.

Fuzzy logic controlled shunt active power filter for power quality improvement

In this paper, the five main formulations of the instantaneous reactive power theory have been chosen to study nonlinear load compensation. They are p-q original theory, d-q transformation, modified or cross-product formulation, p-q-r reference frame, and vectorial theory. The obtention of the compensation current according to each formulation has been established. Next, the behavior of an active power filter (APF) that is implemented with those different control algorithms has been studied. On one hand, a simulation platform with control, APF, and load has been built to test them. Results obtained in an unbalanced and nonsinusoidal three-phase four-wire system have been compared by means of the most adequate indexes. On the other hand, the APF control strategies have been implemented in an experimental platform constituted by a 20-kVA power inverter and a 400-MHz digital signal processing controller board. The final analysis shows that, in general, the five theories present a different behavior, which depends on supply voltage, with respect to distortion. However, all of them widely decrease the waveform distortion. Moreover, a more general compensation objective is possible. It obtains balanced and sinusoidal source current in any conditions of the supply voltage.

Instantaneous Reactive Power Theory Applied to Active Power Filter Compensation: Different Approaches, Assessment, and Experimental Results

This paper presents the control circuit of a shunt active power filter based on the instantaneous active and reactive current i/sub d/-i/sub q/ method The presented method is compared with the instantaneous active and reactive power p-q method under several mains voltage conditions and for different harmonic injection highpass filters The i/sub d/-i/sub q/ method as an excellent harmonic compensation performance and presents the advantage of being frequency-independent The DC voltage regulation system is analysed and its synthesis is performed Extensive simulation results are used to show the stability of the voltage regulation system and to establish the superior performance of i/sub d/-i/sub q/ method based compensator

Active power filter control circuit based on the instantaneous active and reactive current i/sub d/-i/sub q/ method

This paper presents a unity power factor PWM voltage rectifier control circuit. This control circuit is based in the instantaneous active and reactive current i/sub d/-i/sub q/ method. The rectifier DC voltage is controlled acting in the instantaneous active current. In order to obtain a unity power factor the instantaneous reactive current is controlled in a null value. This control method is analysed under several mains voltages conditions: balanced sinusoidal conditions; balanced nonsinusoidal conditions and unbalanced sinusoidal conditions. Under those mains voltages conditions the control circuit proposed is compared with another one where the converter input currents have the same template as the mains voltages. Under distorted mains voltage conditions better results are obtained with the control circuit proposed. The two control systems' design is presented in the paper.

http://ieeexplore.ieee.org/iel4/5230/14143/00648977.pdf

V. Soares

Papers

An instantaneous active and reactive current component method for active filters

Active power filter control circuit based on the instantaneous active and reactive current i/sub d/-i/sub q/ method

A unity power factor PWM voltage rectifier based on the instantaneous active and reactive current i/sub d/-i/sub q/ method