Reliable & selectable islanding detection techniques for low inertia power system

Rights statement
Awarding institution
  • University of Strathclyde
Date of award
  • 2022
Thesis identifier
  • T16240
Person Identifier (Local)
  • 201751643
Qualification Level
Qualification Name
Department, School or Faculty
  • With the development of inverter-based distributed generator (DG) connected to the distribution network, utilities are becoming concerned about the risk of unintentional islanding formation. Unfortunately, many existing methods are unable to detect islanding for loads that closely match the DG capacity, particularly for higher loading quality factors. Other methods, on the other hand, reduce the power quality. The complexity and cost of the other methods are also disadvantages, making them unsuitable. This thesis proposes three innovative methods for islanding detection. They are classified in the active methods for equipping inverter-based DG in connection to the grid along with the local loads. They are based on Q-f droop curve method, voltage amplitude variation (VAV) method and hybrid method of Q-f and VAV methods respectively. The operation of these proposed methods is investigated and simulated for detection of unintentional islanding when the grid is disconnected. Also, their performance are simulated for maintaining stable operation during the grid connection, even with the load switching. Q-f droop curve method has a good performance with zero NDZ. Also, VAV method has a fast detection time, however, there is small NDZ for VAV method. To compensate for the disadvantages of the VAV method, a hybrid method with a short detection time is developed. The operation of the proposed methods, when the DG is generating only active power or generation simultaneously active and reactive power for both balanced and unbalanced loads, are simulated. All aforementioned cases are simulated to validate three proposed methods have the effective operation for both outside and inside the non-detection zone (NDZ). Due to the importance of microgrids in the advancement of decentralised electricity generation, three proposed methods are considered to prove their robustness under multiple-DGs connection. As realistic loads, such as motors, which constitute a substantial portion of the distribution system, the performance of the proposed islanding detection methods are simulated with a motor load as well. It is confirmed that the proposed methods can recognise between islanding detection and motor starting to avoid any unnecessary disconnection from the grid. The proposed methods are supported by theoretical, simulation, and Q-f droop curve method is validated by experimentation.
Advisor / supervisor
  • Ahmed, Khaled
  • Booth, Campbell
Resource Type
Alternative Title
  • Reliable and selectable islanding detection techniques for low inertia power system
Embargo Note
  • The electronic version of this thesis is currently under moratorium due to copyright restrictions. If you are the author of this thesis, please contact the Library to resolve this issue.