Active filtering of electric power has now become a mature technology for harmonic and reactive power compensation in two-wire (single phase), three-wire (three phase without neutral), and four-wire (three phase with neutral) AC power networks with nonlinear loads. This paper presents a comprehensive review of active filter (AF) configurations, control strategies, selection of components, other related economic and technical considerations, and their selection for specific applications. It is aimed at providing a broad perspective on the status of AF technology to researchers and application engineers dealing with power quality issues. A list of more than 200 research publications on the subject is also appended for a quick reference.

A review of active filters for power quality improvement

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

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

Existing definitions for power terms in alternating current systems work well for single-phase and three-phase systems where both voltages and currents are sinusoidal with respect to time. This paper clarifies and proposes definitions for power terms that are practical and effective when voltage and/or currents are distorted and/or unbalanced. It also suggests definitions for measurable values that may be used to indicate the level of distortion and unbalance.

Practical definitions for powers in systems with nonsinusoidal waveforms and unbalanced loads: a discussion

IEEE Std 1459–2010. IEEE Standard Definitions for the Measurement of Electric Power Quantities under Sinusoidal, Nonsinusoidal, Balanced or Unbalanced Conditions

The author expands on the physical meaning of the reactive power in nonsinusoidal situations. The sinusoidal waveform case is surveyed, viewing the active current as a component of identical waveform with the voltage. This approach, when extended to nonsinusoidal waveforms, supports Fryze's model for apparent power, S/sup 2/=p/sup 2/+Q/sup 2//sub F/. It is proved that the total reactive power Q/sub F/ is composed from four distinctive types of elementary reactive powers. Each of the basic reactive powers is identified as the amplitude of an oscillation of instantaneous power. The separation of Q/sub F/ in Q/sub 1/, the reactive power at the system frequency, and in Q/sub H/, the reactive power at harmonic frequencies, is recommended as an effective mean for monitoring filter efficacy and power-factor compensation. Two major recommendations are supported by the results of this study: abolish the power model using distortion power, and measure the active power of the system frequency separately from the active power of the harmonics. >

Powers in nonsinusoidal situations-a review of definitions and physical meaning

This tutorial paper discusses the drawbacks of the definitions of various types of powers found in the IEEE Standard Dictionary of Electrical and Electronics Terms (IEEE Std. 100-88). With the exceptions of instantaneous power and active power, all remaining kinds of "powers" are nonphysical. The concept of power factor in polyphase circuits is ambiguous. Examples that illustrate the shortcomings of many power definitions are included. The impact of these definitions on current power/energy metering practices are discussed. It is recommended that some definitions be either changed or eliminated from the IEEE Dictionary. >

Discussion of power definitions contained in the IEEE Dictionary

Four reactive power meters, operating on different principles, were tested under nonsinusoidal conditions. Different definitions of the reactive power are discussed. Because the definition and meaning of the nonsinusoidal reactive power are still being actively debated, the readings of the tested meters were compared with four nonsinusoidal reactive powers and the first harmonic reactive power, to verify whether these readings can be interpreted as approximate measures of the different definitions. A digital instrument, programmed to measure each of these powers, was used as a reference. >

Evaluation of reactive power meters in the presence of high harmonic distortion

The influence of harmonics on commonly used three-phase watthour and kVA demand meters was studied using a computer-controlled three-phase test system capable of generating nonsinusoidal voltages and currents. A description of the three-phase test system and results of preliminary tests of several revenue meters are presented. The performance of the tested meters is compared with the response of time-division and thermal reference meters for different harmonic conditions, primarily field-recorded data. Errors up to 2% were observed during the testing of energy meters and up to 35% for kVA demand meters. >

Application of a three phase nonsinusoidal calibration system for testing energy and demand meters under simulated field conditions

It is pointed out that the term apparent power does not have a unique meaning when used to describe polyphase, nonsinusoidal systems; in a general case it is an artificial concept with no physical interpretation. It is shown that this ambiguity can have implications for power factor calculations, reactive current compensation, and revenue metering. The time-domain based method of defining and measuring the apparent power is discussed. The necessity of a critical revision of terms relating to apparent power in the IEEE Standard Dictionary is pointed out. >

P.S. Filipski

Papers

Practical definitions for powers in systems with nonsinusoidal waveforms and unbalanced loads: a discussion

Discussion of power definitions contained in the IEEE Dictionary

Evaluation of reactive power meters in the presence of high harmonic distortion

Application of a three phase nonsinusoidal calibration system for testing energy and demand meters under simulated field conditions

Polyphase apparent power and power factor under distorted waveform conditions