New M-robust algorithm for the calculation of the negative sequence current of a synchronous generator

A novel algorithm for the calculation of the negative sequence current of a synchronous generator is presented in this paper. The algorithm is based on the M-robust methodology of signal processing for the estimation of the rotor endangerment of a synchronous generator during unbalanced conditions. This paper, in light of state-of-the-art methods, presents a novel M-robust algorithm and its application in a system of synchronous generator protection. Under real operating conditions, in which a generator may be in the asymmetrical regime, it is possible that a rotor negative sequence current persists longer than it is allowed to. This current may lead to serious permanent damage to the rotor of the synchronous generator and catastrophic consequences for the synchronous generator, which is the most important component in the process of power generation. As a result, it is important to have algorithms and devices that can prevent operation in dangerous regimes to avoid both serious damage and high financial losses for power-generation utilities. Notably, regarding the unallowable rotor negative sequence current, unbalanced conditions caused by open-circuit faults are more critical than those caused by short-circuit faults because the negative sequence current is lower in the first case, and therefore, detection is more difficult, making it impossible to realise another efficient backup rotor protection function for these types of faults.