Investigations for Transient Stability Enhancement of Multi-machine Power System Integrated with Large Scale Renewable Energy Sources using Modified Series Resonance type Fault Current Limiter

Abstract

The electrical power generation is augmented by the deployment of renewable energy sources apart from the conventional synchronous generators (SGs). The wind energy, one of the extensively extracted renewable resource is mainly derived using induction generators (IGs). The IGs have different electrical performance characteristics depending on its type and hence their behaviour under faulty conditions are quite different as compared to synchronous generators. The researchers have proposed the peak current contribution of IGs during various faults at point of common coupling (PCC) when connected to the single machine infinite bus (SMIB) system. A number of researchers are pursuing to improve the low voltage ride through (LVRT) capability of wind farms i.e. ensure them to remain in synchronism with the grid despite of the power system disturbance. The literature available attempts various techniques for low voltage ride through improvement of grid-connected wind farms - either by modifications in control technique or by using various fault current limiters (FCLs) mainly for various faults at PCC with SMIB. This research work presents investigations on performance evaluation of different types of IGs operating in synchronism with SGs in a multi-machine power system by considering a high penetration of wind energy. The reactance diagram of multi-machine power system is deliberated. A 3L-G fault is simulated at weak bus of the system and results are presented and analysed for induction generators and their short circuit current contributions. The research work proposes a novel series resonance type fault current limiter and its implementation to improve LVRT performance of wind farms connected in the multi-machine power system. The authors have analysed the system behaviour in case of symmetrical fault at point of common coupling in the SMIB and at the weak bus in a multi-machine system. To check the effectiveness of the proposed FCL, its performance is compared with the FCLs in the literature. The simulation based results are presented and discussed.