Improving Multi-Machine Power System Stability having High Penetration of Wind Energy Resources

Better tomorrow of mankind is envisaged by reducing the carbon footprint. To attain carbon-free environment-friendly energy sufficiency is one of the keys to sustainable development and it is a major driving force to energy-related research. As per United Nations 17 sustainable development goals to transform the world, goal seven refers to the availability of affordable and clean energy. Moreover, the fast depletion of fossil fuel-based resources and exponential rise in energy demand has made renewable energy research inevitable. The electrical power generation is augmented by the deployment of renewable energy sources apart from the conventional synchronous generators (SGs). Wind energy is one of the extensively extracted renewable resources that is mainly derived using induction generators (IGs).

The IGs have different electrical performance characteristics depending on their types. The behaviour of IGs under system disturbances (faults) are quite different as compared to synchronous generators. One of the aims of this doctoral research work is to investigate the 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. A symmetrical fault is considered at a weak bus of the system. It is observed that the fault location has an impact on the short circuit current contributions by these generators, as it affects the voltage at each generator bus.

Another avenue of this research is to improve the low voltage ride through (LVRT) capability of wind farms i.e. to ensure the wind farms remain in synchronism with the power grid despite the power system disturbances. The literature available attempts various techniques for low voltage ride through the 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 single machine infinite bus (SMIB) system.

The second aim of the doctoral research work is to propose a novel fault current limiter and its implementation to improve the LVRT performance of wind farms connected in the multi-machine power system. The multi-machine power system comprises of SGs, Wind farms and photovoltaic (PV) solar farms. The analysis of the system behaviour in case of symmetrical fault at the point of common coupling in the SMIB system and the weak bus in a multi-machine system is carried out.

The effectiveness of the proposed FCL is verified by comparing it with the other FCLs by considering SMIB and multi-machine power systems. The series resonance type FCL improves the transient stability of the multi-machine power system and also provide the LVRT improvement in the SMIB system. This doctoral research work is carried out by Mr Chintan Mehta and supervised by Dr SC Vora, Professor and Head of Electrical Engineering Department, Institute of Technology, Nirma University.