Experimental results and technique evaluation based on correlation function for a backup protection of synchronous generator stator windings

Abstract

Unbalanced loads and faults cause power quality problems in power grids, which may lead to system elements failure, particularly to synchronous generators. Faults detection and identification of the disturbance severity level are essential in the grids. Important equipment are often protected with dual protection systems. A backup protection operates and trips appropriate circuit breaker(s) only if the main protection fails to detect the disturbance presence or miss opening the breakers. This paper proposes a backup protection scheme for detecting and evaluating the disruption severity of voltage and current signals for protecting the synchronous generators. This scheme is based on a numerical technique of correlation applied for the electrical signals to detect and assess the fault situation. Different fault types are experimentally conducted on a motor-generator set to test the proposed algorithm effectiveness using Data Acquisition Card (DAC) and LABVIEW software. The scheme has proven to be successful for fault detection and assessment. The algorithm has shown high reliability at various faults and operating conditions. Moreover, the practical results reveal that the scheme is able to evaluate the severity degree of disturbances/unbalances, and it is effective and secure considering the acceptable overloading, harmonics and temporary faults in power grids.