## Abstract

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.

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 language | English |
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Title of host publication | Proceedings of 19th Power Systems Computation Conference (PSCC), 2016 |

Number of pages | 7 |

Publisher | IEEE Press |

Publication date | Jun 2016 |

ISBN (Electronic) | 978-88-941051-2-4 |

DOIs | |

Publication status | Published - Jun 2016 |

Event | Power Systems Computation Conference (PSCC 2016) - Genoa, Italy, Genoa, Italy Duration: 20 Jun 2016 → 24 Jun 2016 |

### Conference

Conference | Power Systems Computation Conference (PSCC 2016) |
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Location | Genoa, Italy |

Country | Italy |

City | Genoa |

Period | 20/06/2016 → 24/06/2016 |

## Keywords

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