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Robust control of an autonomous four-wire electronically-coupled distributed generation unit

Karimi, H ; Sharif University of Technology | 2011

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  1. Type of Document: Article
  2. DOI: 10.1109/TPWRD.2010.2064184
  3. Publisher: 2011
  4. Abstract:
  5. This paper proposes a control strategy for the autonomous (islanded) operation of a four-wire, electronically-coupled distributed generation (DG) unit which can feed a highly unbalanced load, e.g., due to the presence of single-phase loads. In the grid-connected mode, the power-electronic interface of the DG unit enables the exchange of real and reactive power with the distribution network, based on the conventional dq-frame current control strategy. The current control scheme is disabled subsequent to the detection of an islanding event, and the proposed controller is activated. The proposed control strategy utilizes: i) an internal oscillator to maintain the island frequency and ii) a feedback control system to regulate the island voltage. The proposed control strategy provides a set of balanced three-phase voltages for the load, despite the load imbalance and parameters uncertainties. The proposed control strategy also guarantees robust stability, fast dynamic response to disturbances, and zero steady-state error. A stability analysis is also carried out to determine the robust stability margin of the closed-loop islanded system. Effectiveness of the proposed control strategy is evaluated based on time-domain simulation studies in the PSCAD/EMTDC software environment and verified based on laboratory experiments
  6. Keywords:
  7. Autonomous operations ; Distributed Generation ; Four-wire system ; islanded system ; Robust stability analysis ; Unbalanced condition ; Adaptive control systems ; Computer software ; Distributed parameter networks ; Dynamic response ; Electric current control ; Feedback control ; Galerkin methods ; Robust control ; Time domain analysis ; Wire ; System stability
  8. Source: IEEE Transactions on Power Delivery ; Volume 26, Issue 1 , September , 2011 , Pages 455-466 ; 08858977 (ISSN)
  9. URL: http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=5565538