A Grid-Level High-Power BTB (Back-To-Back) System Using Modular Multilevel Cascade Converters WithoutCommon DC-Link Capacitor

Author

Sekiguchi, Kazuma ; Khamphakdi, Pracha ; Hagiwara, Manabu ; Akagi, Hirofumi

Author_Institution

Dept. of Electr. & Electron. Eng., Tokyo Inst. of Technol., Tokyo, Japan

Volume

50

Issue

4

fYear

2014

fDate

July-Aug. 2014

Firstpage

2648

Lastpage

2659

Abstract

This paper provides an intensive discussion on analysis, simulation, and experiment of a back-to-back (BTB) system unifying two modular multilevel cascade converters based on double-star chopper cells (MMCCs-DSCCs). Each of the two DSCCs connected back-to-back consists of multiple cascaded chopper cells and a center-tapped inductor per leg. Low voltage steps bring significant reductions in harmonic voltage and current to the BTB system. Neither dc-link capacitor nor voltage sensor is required for regulating the dc-link voltage and controlling the dc-link current. A three-phase 200-V, 10-kW, 50-Hz downscaled BTB system with phase-shifted PWM is designed, constructed, and tested to verify its operating principles and performance. Analytical, simulated, and experimental results agree well with each other in steady and transient states. Experimental waveforms confirm the effectiveness of a self-starting/restarting procedure.

Keywords

PWM power convertors; electric current control; power grids; voltage control; DC-link capacitor; DC-link current control; Dc-link voltage control; MMCCs-DSCCs; back-to-back system; cascaded chopper cells; center-tapped inductor; double-star chopper cells; downscaled BTB system; frequency 50 Hz; grid-level high-power BTB system; harmonic current; harmonic voltage; low voltage steps; modular multilevel cascade converters; phase-shifted PWM; power 10 kW; self-restarting procedure; self-starting procedure; voltage 200 V; voltage sensor; Capacitors; Choppers (circuits); HVDC transmission; Inductance; Inductors; Pulse width modulation; Voltage control; Asynchronous intertie; back-to-back (BTB) systems; back-to-back systems; grid-connected power converters; gridconnected power converters; modular multilevel cascade converters; modular multilevel cascade converters (MMCCs);

fLanguage

English

Journal_Title

Industry Applications, IEEE Transactions on

Publisher

ieee

ISSN

0093-9994

Type

jour

DOI

10.1109/TIA.2013.2290867

Filename

6663638