Dynamic Behavior of a 21-Level BTB-Based Power-Flow Controller Under Single-Line-to-Ground Fault Conditions

This paper deals with the dynamic behavior of a 21-level (line-to-line) back-to-back (BTB) system based on series connection of 16 converter cells under a single-line-to-ground (SLG) fault condition. The BTB system is an ac-dc-ac power conversion system intended for achieving asynchronous power-flow control between transmission networks. When the SLG fault happens, an imbalance in the supply voltage brings an amount of negative-sequence current to the BTB system. The negative- sequence current should be mitigated because it would result in an increased supply current and a dc-capacitor voltage fluctuation. This paper intends for reducing both the negative-sequence current and the dc-voltage fluctuation to acceptable levels. A laboratory system rated at 200 V and 20 kW confirms the validity of the reduction scheme. In addition, this paper addresses the issue of magnetic saturation in the 16 three-phase converter-transformers.

[1]  S. Halen,et al.  High-frequency impacts in a converter-based back-to-back tie; the Eagle Pass installation , 2003 .

[2]  G. Asplund.  Application of HVDC Light to power system enhancement , 2000, 2000 IEEE Power Engineering Society Winter Meeting. Conference Proceedings (Cat. No.00CH37077).

[3]  H. Fujita,et al.  A 21-level (line-to-line) BTB system based on series connection of sixteen converter-cells for power flow control: experimental verifications by a 200-V, 10-kW laboratory system , 2004, Conference Record of the 2004 IEEE Industry Applications Conference, 2004. 39th IAS Annual Meeting..

[4]  Hidetoshi Ito,et al.  Enhancement of continuous operation performance of HVDC with self-commutated converter , 2000 .

[5]  Boon-Teck Ooi,et al.  Force commutated HVDC and SVC based on phase-shifted multi-converter modules , 1993 .

[6]  P. Cartwright,et al.  VSC transmission operating under unbalanced AC conditions - analysis and control design , 2005, IEEE Transactions on Power Delivery.

[7]  B. Blazic,et al.  Improved D-StatCom control for operation with unbalanced currents and voltages , 2006, IEEE Transactions on Power Delivery.

[8]  S. Sugimoto,et al.  Development of a control system for a high-performance self-commutated AC/DC converter , 1998 .

[9]  H. Fujita,et al.  Design and Experimentation of a Dynamic Voltage Restorer Capable of Significantly Reducing an Energy-Storage Element , 2008, IEEE Transactions on Industry Applications.

[10]  Hirofumi Akagi,et al.  Instantaneous Reactive Power Compensators Comprising Switching Devices without Energy Storage Components , 1984, IEEE Transactions on Industry Applications.

[11]  B. Banerjee,et al.  Assessment of Voltage Unbalance , 2001, IEEE Power Engineering Review.

[12]  Makoto Hagiwara,et al.  Performance of a self-commutated BTB HVDC link system under a single-line-to-ground fault condition , 2003 .

[13]  A. Ekstrom,et al.  Applying PWM to control overcurrents at unbalanced faults of forced-commutated VSCs used as static VAr compensators , 1997 .

[14]  Makoto Hagiwara,et al.  An approach to regulating the DC-link voltage of a voltage-source BTB system during power line faults , 2003 .

[15]  M. Noroozian,et al.  The Potential Use of Voltage-Sourced Converter-Based Back-to-Back Tie in Load Restorations , 2002, IEEE Power Engineering Review.

[16]  A. Ekstrom,et al.  Multiterminal HVDC systems in urban areas of large cities , 1998 .

[17]  L. Sainz,et al.  Symmetrical and unsymmetrical voltage sag effects on three-phase transformers , 2005, IEEE Transactions on Power Delivery.

[18]  Robert H. Lasseter,et al.  Statcom controls for operation with unbalanced voltages , 1998 .