A Comparative Analytical Study on Low-Voltage Ride-Through Reference-Current-Generation (LVRT-RCG) Strategies in Converter-Interfaced DER Units

• Author / Creator

  Mohammadalizadeh Shabestary, Masoud

• Recently, riding through grid faults and supporting the grid voltage under faults have become major requirements in distributed energy resource (DER) units. There have been also extensive efforts in academia and industry to develop and implement control strategies to ride through voltage disturbances, and even to support the grid under such faulted conditions which can be named as low-voltage ride-through (LVRT) technology. Therefore, a comprehensive and comparative study seems to be very useful in order to analyze and discuss available LVRT reference-current-generation (LVRT-RCG) strategies in converter-interfaced DER units, compare their performances, and introduce their pros and cons. This thesis studies all existing (nine) LVRT-RCG strategies available in the literature. These strategies are categorized into two main groups. The analytical evaluations and mathematical assessments of all LVRT-RCG strategies are performed. For a comprehensive evaluation of these strategies, the following important parameters are used in this study: instantaneous active/reactive powers oscillation and maximum phase currents. Analytical expressions of these parameters are formulated, evaluated and used to conduct several evaluation and comparative studies on different strategies. Based on the obtained formulas for the maximum phase currents, the maximum allowable reactive power delivery (MARPD) equations are proposed specifically for each of the nine LVRT-RCG strategies. Proposed equations help each LVRT-RCG technique to provide their best voltage support under the specific maximum phase current restrictions imposed by DER owners. Using different test cases, the strategies are compared and the proposed equations are validated. This thesis can be helpful to evaluate the performance of existing LVRT-RCG strategies, solve their existing drawbacks, exploit the best performance out of each, combine their individual capabilities, and improve them.

• Subjects / Keywords

  • Voltage Dip
  • Voltage Sequences
  • Positive Negative Sequences
  • Maximum Reactive Power Injection
  • Asymmetrical Grid Faults
  • Unbalanced Current Injection
  • Distributed Energy Resource
  • Power Oscillations
  • Fault Ride Through
  • Voltage Support
  • Unbalanced Voltage
  • Ancillary Services
  • Grid Fault
  • Flexible Voltage Support
  • Fault Current Limitation
  • Positive Negative Sequence Control
  • Power Converters
  • Reactive Current Injection
  • Distributed Generation
  • Instantaneous Power Theory
  • Flexible Power Control
  • Voltage Sag
  • Instantaneous Power Control
  • Reference Current Generation
  • Flexible Positive Negative Sequence Control
  • Symmetrical Components
  • Low Voltage Ride Through
  • Smooth Power Injection
  • Negative Sequence Current
  • Grid Converter

• Graduation date

  Spring 2015

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3M08G

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.