Voltage Unbalance Compensation with Smart Three-phase Loads

Philip Douglass, Ionut Trintis, Stig Munk-Nielsen

Research output: Contribution to book/anthology/report/conference proceedingArticle in proceedingResearchpeer-review

7 Citations (Scopus)


This paper describes the design, proof-of-concept simulations and laboratory test of an algorithm for controlling active front-end rectifiers to reduce voltage unbalance. Using
inputs of RMS voltage, the rectifier controller allocates load unevenly on its 3 phases to compensate for voltage unbalance originating in the power supply network. Two variants of the algorithm are tested: first, using phase-neutral voltage as input, second, using phase-phase voltage. The control algorithm is described, and evaluated in simulations and laboratory tests. Two metrics for quantifying voltage unbalance are evaluated: one metric based on the maximum deviation of RMS phaseneutral voltage from the average voltage and one metric based on negative sequence voltage. The tests show that controller that uses phase-neutral voltage as input can in most cases eliminate
the deviations of phase voltage from the average voltage, but it does not reduce the negative sequence voltage. The controller that uses phase-phase voltage as input eliminates negative sequence voltage, and reduces voltage deviations from the average to approximately half their initial value. Current unbalance is reduced when the voltage unbalance is caused by asymmetrical loads. These results suggest that the optimal algorithm to reduce system unbalance depends on which system parameter is most important: phase-neutral voltage unbalance, phase-phase voltage unbalance, or current unbalance.
Original languageEnglish
Title of host publicationProceedings of 19th Power Systems Computation Conference (PSCC), 2016
Number of pages7
PublisherIEEE Press
Publication dateJun 2016
ISBN (Electronic)978-88-941051-2-4
Publication statusPublished - Jun 2016
EventPower Systems Computation Conference (PSCC 2016) - Genoa, Italy, Genoa, Italy
Duration: 20 Jun 201624 Jun 2016


ConferencePower Systems Computation Conference (PSCC 2016)
LocationGenoa, Italy


  • Voltage control
  • Load modeling
  • Voltage measurement
  • Algorithm design and analysis
  • Power systems
  • Prototypes

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