Double-Frame Current Control with a Multivariable PI Controller and Power Compensation forWeak Unbalanced Networks

Authors

  • D. Siemaszko PESC-CH (Power Electronics & Systems Consultancy Switzerland), Geneva
  • A. Rufer EPFL (Ecole Polytechnique Fédérale de Lausanne), Lausanne

DOI:

https://doi.org/10.5170/CERN-2015-003.97

Keywords:

Asymmetric networks, weak networks, PLL, double frame control, multivariable PI control, power theory.

Abstract

The handling of weak networks with asymmetric loads and disturbances implies the accurate handling of the second-harmonic component that appears in an unbalanced network. This paper proposes a classic vector control approach using a PI-based controller with superior decoupling capabilities for operation in weak networks with unbalanced phase voltages. A synchronization method for weak unbalanced networks is detailed, with dedicated dimensioning rules. The use of a double-frame controller allows a current symmetry or controlled imbalance to be forced for compensation of power oscillations by controlling the negative current sequence. This paper also serves as a useful reminder of the proper way to cancel the inherent coupling effect due to the transformation to the synchronous rotating reference frame, and of basic considerations of the relationship between switching frequency and control bandwidth.

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Published

2016-02-03