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

Preface. 1. Introduction. 1.1. Concepts and Evolution of Electric Power Theory. 1.2. Applications of the p-q Theory to Power Electronics Equipment. 1.3. Harmonic Voltages in Power Systems. 1.4. Identified and Unidentified Harmonic-Producing Loads. 1.5. Harmonic Current and Voltage Sources. 1.6. Basic Principles of Harmonic Compensation. 1.7. Basic Principles of Power Flow Control. References. 2. Electric Power Definitions: Background. 2.1. Power Definitions Under Sinusoidal Conditions. 2.2. Voltage and Current Phasors and the Complex Impedance. 2.3. Complex Power and Power Factor. 2.4. Concepts of Power Under Non-Sinusoidal Conditions -Conventional Approaches. 2.5. Electric Power in Three-Phase Systems. 2.6. Summary. References. 3 The Instantaneous Power Theory. 3.1. Basis of the p-q Theory. 3.2. The p-q Theory in Three-Phase, Three-Wire Systems. 3.3. The p-q Theory in Three-Phase, Four-Wire Systems. 3.4. Instantaneous abc Theory. 3.5. Comparisons between the p-q Theory and the abc Theory. 3.6. Summary. References. 4 Shunt Active Filters. 4.1. General Description of Shunt Active Filters. 4.2. Three-Phase, Three-Wire Shunt Active Filters. 4.3. Three-Phase, Four-Wire Shunt Active Filters. 4.4. Shunt Selective Harmonic Compensation. 4.5. Summary. References. 5 Hybrid and Series Active Filters. 5.1. Basic Series Active Filter. 5.2. Combined Series Active Filter and Shunt Passive Filter. 5.3. Series Active Filter Integrated with a Double-Series Diode Rectifier. 5.4. Comparisons Between Hybrid and Pure Active Filters. 5.5. Conclusions. References. 6 Combined Series and Shunt Power Conditioners. 6.1. The Unified Power Flow Controller (UPFC). 6.2. The Unified Power Quality Conditioner (UPQC). 6.3. The Universal Active Power Line Conditioner (UPLC). 6.4. Summary. References. Index.

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Instantaneous power theory and applications to power conditioning

Attention has been paid to active filters for power conditioning which provide the following multifunctions: reactive power compensation; harmonic compensation; flicker/imbalance compensation; and voltage regulation. Active filters in a range of 50 kVA-60 MVA have been practically installed in Japan. In the near future, the term "active filters" will have a much wider meaning than it did in the 1970s. For instance, active filters intended for harmonic solutions are expanding their functions from harmonic compensation of nonlinear loads into harmonic isolation between utilities and consumers, and harmonic damping throughout power distribution systems. This paper presents the present status of active filters based on state-of-the-art power electronics technology, and their future prospects and directions toward the 21st Century, including the personal views and expectations of the author.

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New trends in active filters for power conditioning

This paper deals with unified power quality conditioners (UPQCs), which aim at the integration of series-active and shunt-active power filters. The main purpose of a UPQC is to compensate for voltage flicker/imbalance, reactive power, negative-sequence current and harmonics. In other words, the UPQC has the capability of improving power quality at the point of installation on power distribution systems or industrial power systems. This paper discusses the control strategy of the UPQC, with a focus on the how of instantaneous active and reactive powers inside the UPQC. Experimental results obtained from a laboratory model of 20 kVA, along with a theoretical analysis, are shown to verify the viability and effectiveness of the UPQC.

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The unified power quality conditioner: the integration of series- and shunt-active filters

This paper discusses the modular multilevel cascade converter (MMCC) family based on cascade connection of multiple bidirectional chopper cells or single-phase full-bridge cells. The MMCC family is classified from circuit configuration as follows: the single-star bridge cells (SSBC); the single-delta bridge cells (SDBC); the double-star chopper cells (DSCC); and the double-star bridge cells (DSBC). The term MMCC corresponds to a family name in a person while, for example, the term SSBC corresponds to a given name. Therefore, the term “MMCC-SSBC” can identify the circuit configuration without any confusion. Among the four MMCC family members, the SSBC and DSCC are more practical in cost, performance, and market than the others although a distinct difference exists in application between the SSBC and DSCC. This paper presents application examples of the SSBC to a battery energy storage system (BESS), the SDBC to a static synchronous compensator (STATCOM) for negative-sequence reactive-power control, and the DSCC to a motor drive for fans and blowers, along with their experimental results.

Classification, Terminology, and Application of the Modular Multilevel Cascade Converter (MMCC)

The conventional reactive power in single-phase or three- phase circuits has been defined on the basis of the average value concept for sinusoidal voltage and current waveforms in steady states. The instantaneous reactive power in three-phase circuits is defined on the basis of the instantaneous value concept for arbitrary voltage and current waveforms, including transient states. A new instantaneous reactive power compensator comprising switching devices is proposed which requires practically no energy storage components.

Yoshihira Kanazawa

Papers

Instantaneous Reactive Power Compensators Comprising Switching Devices without Energy Storage Components

Generalized Theory of the Instantaneous Reactive Power and its Application

A Study on Analysis and Design of a Harmonic Reactive Power Compensator using a Voltage Source Type PWM Converter