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A novel variable reactor is presented in this paper. The principle of the novel variable reactor is simply addressed. The equivalent impedance of primary winding of the transformer will vary with the ratio between the primary and the secondary voltages. For the proposed variable reactor, a novel series power quality controller (SPQC) is developed and its principle is analyzed in detail. The SPQC greatly improves the power utility impedance to harmonics instead of the fundamental and plays the role of isolating the harmonics. Because the novel SPQC is with very high impedance to harmonics, the passive power filter can be reduced. Accordingly, three kinds of reduced single-phase passive power filters are presented. The comparison criterion of reducing passive power filter is described. The SPQC is characterized by perfectly isolating the harmonics, simplified passive power filter design, small rating, and being suitable for two kinds of harmonic sources. The validity of the novel SPQC and excellent filtering characteristic are verified by the experimental results. [ABSTRACT FROM PUBLISHER]

A novel variable reactor based on transformer is proposed in the paper. In the variable reactor, a transformer with air gap is chosen, and the primary voltage is detected and used as the reference signal. A voltage-sourced inverter is applied to track the reference signal in order to yield a controllable voltage, which is applied across the secondary winding of the transformer. When the secondary-controlled voltage and the primary voltage satisfy a proportional condition, the equivalent impedance of primary winding of the transformer will vary continuously. According to the novel variable reactor, a novel shunt power quality controller is proposed and its principle is analyzed in detail. The shunt power quality controller is characterized by parallel topology and single frequency control. The approaches of decreasing the transformer leakage inductance are addressed. The experimental results verify the validity of the shunt power quality controller. [ABSTRACT FROM AUTHOR]

A novel variable reactor based on magnetic flux control is proposed in this paper. The system configuration of the novel variable reactor is presented, while its operational principle and dynamic performance are analyzed. Based on the developed variable reactor, a novel integrated power quality controller (IPQC) suitable for microgrid is proposed, which can cater for the peculiar requirements of microgrid power quality, such as the harmonic high penetration, frequent voltage fluctuation and overcurrent phenomenon, and bidirectional power flow and small capacity. For the fundamental, the equivalent impedance of the primary winding is a variable reactor or capacitor. For the $n$th-order harmonic, the equivalent impedance is very high impedance and acts as a “harmonic isolator.” The system control strategy is also analyzed in detail. A set of three-phase IPQC has been constructed. The experimental test results verify the validity of the novel variable reactor and the IPQC. [ABSTRACT FROM PUBLISHER]