Adaptive differential current relay based on form/ripple factors for busbar current signals

Area of Science:

• Electrical Engineering
• Power Systems Protection

Background:

• Traditional differential relaying schemes face challenges with Current Transformer (CT) saturation and DC components during fault currents.
• Accurate fault detection and discrimination are crucial for power system stability and reliability.

Purpose of the Study:

• To develop an adaptive protection algorithm for differential relaying schemes.
• To improve fault discrimination by accounting for CT saturation and DC components.
• To ensure reliable operation during internal faults and prevent maloperation during external faults.

Main Methods:

• Estimating tripping characteristic slope using form and ripple factors of current signals.
• Implementing the algorithm in MATLAB, integrating with ATP simulations for validation.
• Simulating diverse fault scenarios, including CT saturation and DC offset.

Main Results:

• The algorithm accurately differentiates internal from external faults under various conditions.
• Achieved a rapid response time of approximately 10.0 ms for internal faults.
• Demonstrated high accuracy (>99.40%) in dependability, security, and reliability.

Conclusions:

• The proposed adaptive algorithm offers a robust solution for digital protection relays.
• It is highly effective, stable, accurate, and reliable for Smart Grids and Substation Automation Systems.
• The technique successfully addresses CT saturation and current distortion issues in fault analysis.