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Design and implementation of a current source converter based active power filter for medium voltage applications

Terciyanlı, Alper
This research work is devoted to the design, development and implementation of a Current Source Converter (CSC) based Active Power Filter (APF) for Medium Voltage (MV) applications. A new approach has been proposed to the design of the CSC based APF for reducing the converter kVA rating considerably. This design approach is called the Selective Harmonic Amplification Method (SHAM), and is based on the amplification of some selected harmoniccurrent components of the CSC by the input filter, and the CSC control system, which is specifically designed for this purpose. The proposed SHAM has been implemented on the first industrial CSC based APF for the elimination of 11th and 13th current harmonics of 12-pulse rectifiers fed from Medium Voltage (MV) underground cables in order to comply with IEEE Std. 519-1992. 450 kVA rated APF with only 205 kVA CSC rating has been connected to the MV bus via a coupling transformer of 600kVA, 34.5/1.1 kV. The power stage of the CSC based APF is composed of water-cooled high voltage IGBT and diode modules. Reference currents to be generated by the CSC are obtained by the use of a selective harmonic extraction method, by mploying synchronously rotating reference frames for each selected harmonic component. An Active damping method is also used to suppress the oscillations around the natural frequency of the input filter, excluding the harmonic components to be eliminated by APF. Simulation and field test results have shown that SHAM can successfully be applied to a CSC based APF for reduction of converter kVA rating, thus making it a cost- competitive alternative to voltage source converter based APFs traditionally used in industry applications.