Title :
Enhancing the Ride-Through Capability of DC-Link Voltage in NPC Multilevel Unified Power-Flow Controllers
Author :
Santos, Natalia M. R. ; Silva, Jorge F. ; Verveckken, Jan ; Pires, Vitor M. Fernao ; Castro, Rui M. G.
Author_Institution :
Escola Super. Tecnol., Polytechnics Inst. of Setubal, Setubal, Portugal
Abstract :
Multilevel converters are attractive for unified power-flow controller (UPFC) applications, due to their high-voltage and power capability. Among multilevel topologies, the three-level neutral-point-clamped (NPC) converter allows back-to-back connection as the UPFC shunt and series converters. Besides the pulsewidth-modulated (PWM) multilevel control schemes, UPFCs require constant dc-link voltage and balanced voltages in the NPC multilevel dc capacitors. This paper proposes three main contributions to increase the dc-link voltage steadiness of multilevel UPFCs under line faults: 1) decoupled active and reactive linear power controllers; 2) real-time PWM generation; and 3) double balancing of dc capacitor voltages. A case study using part of the Portuguese transmission network is presented. The results show the effectiveness of the real-time PWM generation and dc-link capacitor voltages balancing included in NPC series and shunt converters to keep the dc-link voltage steadiness under line faults, overall enhancing the UPFC ride-through capability.
Keywords :
PWM power convertors; load flow control; power capacitors; power transmission control; reactive power control; real-time systems; NPC multilevel dc capacitors; NPC multilevel unified power-flow controllers; PWM multilevel control; Portuguese transmission network; UPFC shunt converters; back-to-back connection; balanced voltages; dc-link voltage; decoupled active power controllers; double balancing; high-voltage capability; multilevel converters; multilevel topology; power capability; pulsewidth-modulated multilevel control; reactive linear power controllers; real-time PWM generation; ride-through capability; series converters; three-level neutral-point-clamped converter; unified power flow controller; Capacitors; Pulse width modulation; Reactive power; Real-time systems; Shunts (electrical); Vectors; Voltage control; Decoupled power controller; flexible ac transmission systems (FACTS); power flow; power-flow control; unified power-flow controller;
Journal_Title :
Power Delivery, IEEE Transactions on
DOI :
10.1109/TPWRD.2014.2326774
