Experimental results and technique evaluation based on alienation coefficients for busbar protection scheme

• The present work proposes a busbar protection algorithm based on alienation coefficients.
• The three phase coefficients of alienation are used to implement relay logic.
• The performance of the proposed algorithm has been investigated on a physical model.
• The model is tested under different operating conditions of internal and external faults.
• The alienation technique shows reliable and efficient method to detect busbar faults.

In modern digital power protection systems, statistical coefficients technique is recently used for fault analysis. An alienation technique is developed for busbar protection against all ten types of shunt faults, which may locate in busbar protection zone, under different loading levels, fault resistances and fault inception angle. It does not need any extra equipment as it depends only on the three-line currents measurements, of all feeders connected to the protected busbar, which are mostly available at the relay location. It is able to perform fault detection, fault confirmation, faulty phase selection and determine the fault location in about a half-cycle period. Thus, the alienation technique is well suited for implementation in digital protection schemes. The technique is efficient to detect current transformer saturation conditions without needing any additional algorithm. The effects of DC components and harmonics are eliminated with estimation of alienation coefficients. The proposed scheme is applied for an experimental circuit. LABVIEW program and MATLAB package are used to implement the proposed technique.