Document Type : Research Paper


1 Department of Electrical Eng., University of Technology, Baghdad, Iraq

2 Electrical Engineering Department, University of Technology, Baghdad, Iraq

3 State Company of North Distribution Electricity, Iraq


Electrical supply safety and quality represent targets that Iraqi power distribution companies always strive to meet. Load-side broken conductor fault LSBC is one of the greatest faults affecting both targets. Stand out since the magnitudes of the impact on the system are too small to activate the relevant system protection devices in Iraqi substation 33/11kV. Therefore, protection from LSBC faults has been one of the biggest challenges in the Iraqi electrical distribution system. In this context, the main aim of this article is to present a method for detecting LSBC faults by unbalanced three-phase currents faults measured in a 33/11kv distribution substation. Using computer simulations based on an actual distribution 11kV feeder model, this method was qualitatively tested. Then, a relationship between mathematical and simulation results was made. Finally, A comparison of the proposed method and recent literature was written. According to the obtained results of case studies, the protection devices in the Iraqi substations cannot efficiently sense the LSBC fault. The overcurrent relay is completely not sensitive to LSBC, and the neutral current fault relay is only sensitive (0-70)% of the different types of feeders under the study. While the proposed unbalance, the current method had been detected with 87% -93% of 11 kV feeders. The proposed techniques are applicable and compatible with the existing traditional protection of the overcurrent and earth fault protection system in the Iraqi 33/11kV substation.

Graphical Abstract


  • Design of a MATLAB model capable of simulating the real distribution 11kv feeder.
  • The over-current relay is completely not sensitive to LSBC, and the neutral current fault relay is only sensitive to (0-70) % of the feeders.
  • Using the unbalanced current method, 87% - 93% of feeders can be protected.
  • Use mathematical methods to analyze LSBC fault.
  •  A comparison between the suggested approach with current research is written.


Main Subjects

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