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

Recently utilities are continuously seeking cost-effective and accurate power quality (PQ) improvement techniques in order to achieve customer satisfaction. This paper intends to provide a comprehensive review on the status of topological aspects of techniques used to improve the power quality in distribution network for the researchers, designers and engineers working in this area. This review helps to select a PQ improvement technique that suits a specific application in terms of technical and economical aspects. More than 300 research publications on the state of the art of PQ improvement techniques have been rigorously analyzed, classified and listed for quick reference.

Topological aspects of power quality improvement techniques: A comprehensive overview

A reactive power compensation (RPC) system which uses a three-phase current-source force-commutated PWM (pulsewidth-modulated) rectifier is presented and analyzed Pulsewidth modulation is also investigated as a means of reducing the size of reactive components The proposed RPC system can compensate for leading and lagging displacement power factor Other areas of investigation include the selection of rectifier input and output filter components and the closing of the loop around the reactive power command signal finally, predicted results are verified experimentally >

Analysis and design of a three-phase current source solid-state VAR compensator

A unified approach to the compensation of multiple power quality phenomenon is described in this paper. It is shown that the converter-based power quality mitigation device is a viable solution to power quality problems on power networks since more than one power quality problem can be compensated by the same hardware. These devices should be capable of harmonic compensation or isolation, improving dynamic voltage regulation and flicker simultaneously, while capable of controlling power factor and power flow through the network. These functions can also be implemented independently. These power quality mitigating devices can be hybrid devices comprising passive components and converters. The drive is to minimize the converter power rating while maximizing the compensating performance. Several projects where this approach has been implemented are discussed in this paper.

Unified approach to power quality mitigation

A novel control approach that utilizes both thyristor-controlled-reactive sources (TCR), and dynamic power filters (DPF), is proposed for applications in fictitious power compensation. The network parameters for the control loops are calculated from digital-time-domain, cross-correlation signal processing techniques, implemented with the aid of a microcomputer. A measurement system for fictitious power and a converter for dynamic power filters are described. Experimental results obtained with a 150 kVA three-phase passive dynamic power filter are presented. >

A new control philosophy for power electronic converters as fictitious power compensators

The paper deals with a switching system used to improve the waveform of current drawn by thyristorized loads. A practical circuit is presented, and its operation is described in detail. Suitable equations are used, from which formulas are derived for choice of its components. Analytical results were verified on an experimental circuit.

Analysis of a Reactive Current Source Used to Improve Current Drawn by Static Inverters

This paper analyzes a single-phase static VAR compensator, based on the current source-forced commutated inverter. Emphasis is given to the subject of energy storage in the circuit.

Analysis of a Static VAR Compensator with Optimal Energy Storage Element

The paper presents a new method of synchronization of the pulse delay control circuits for, triggering thyristors in line commutated converters, where an exact 180° phase difference is ensured between the firing ing pulses sent to the thyristors in the same mains phase. In 3-phase systems, it provides small deviation from the desired ± 120° difference with respect to the other two phases. The delay angle is, proportional to the control voltage; and can be varied throughout the appropriate interval for phase controlled rectifiers and AC voltage controllers. The circuit consists of integrated linear and logic elements and is suitable both for manually-controlled and closed-loop systems.

Improved Pulse Delay Circuit for Phase-Controlled Rectifiers and Ac Voltage Controllers

The currents and load voltage of a two-branch resistance-inductance parallel circuit controlled by an ac switch in series with the supply are derived. It is shown that the extinction angle is a transcendental function of the ratio of the absolute values of the load impedances, the load phase angles, and the triggering angle, but not (as claimed by another author) of the supply voltage.

Steady-State Analysis of a Two-Branch Resistance--Inductance Parallel Circuit Controlled by a Bidirectional ac Switch

A new approach to the analysis of a high-frequency rectangular wave inverter provides a simple means for determining the commutation circuit components.

Alexander Yair

Papers

Analysis of a Reactive Current Source Used to Improve Current Drawn by Static Inverters

Analysis of a Static VAR Compensator with Optimal Energy Storage Element

Improved Pulse Delay Circuit for Phase-Controlled Rectifiers and Ac Voltage Controllers

Steady-State Analysis of a Two-Branch Resistance--Inductance Parallel Circuit Controlled by a Bidirectional ac Switch

Guidelines for Adaptation of High-Frequency Rectangular Wave Inverter to Inductive Load