Enhancement of Power System Dynamic Performance by Coordinated Design of PSS and FACTS Damping Controllers

Abstract

Due to environmental and economical constraints, it is difficult to build new power lines and to reinforce the existing ones. The continued growth in demand for electric power must therefore to a great extent be met by increased loading of available lines. A consequence of
this is reduction of power system damping, leading to a risk of poorly damped power oscillations between generators. To suppress these oscillations and maintain power system dynamic performance, one of the conventional, economical and effective solutions is to
install a power system stabilizer (PSS). However, in some cases PSS may not provide sufficient damping for the inter-area oscillations in a multi-machine power system. In this context, other possible solutions are needed to be exposed. With the evolution of power electronics, flexible AC transmission systems (FACTS) controllers turn out to be possible solution to alleviate such critical situations by controlling the power flow over the AC transmission line and improving power oscillations damping. However, coordination of conventional PSS with FACTS controllers in aiding of power system oscillations damping is still an open problem. Therefore, it is essential to study the coordinated design of PSS with FACTS controllers in a multi-machine power system.
This thesis gives an overview of the modelling and operation of power system with conventional PSS. It gives the introduction to emerging FACTS controllers with emphasis on the TCSC, SVC and STATCOM controllers. The basic modelling and operating principles of the controllers are explained in this thesis, along with the power oscillations damping (POD) stabilizers.
The coordination design of PSS and FACTS damping controllers over a wide range of operating conditions is formulated as an optimization problem. The objective function of this optimization problem is framed using system eigen values and it is solved using AAPSO and
IWO algorithms. The optimal control parameters of coordinated controllers are obtained at the end of these optimization algorithms. A comprehensive approach to the hybrid coordinated design of PSS with series and shunt FACTS damping controllers is proposed to enhance the overall system dynamic performance. The robustness and effectiveness of proposed hybrid coordinated designs are demonstrated through the eigen value analysis and
time-domain simulations. The proposed hybrid designs provide robust dynamic performance under wide range in load condition and providing significant improvement in damping power system oscillations under
severe disturbance. The developed hybrid coordinated designs are tested in different multimachine power systems using AAPSO and IWO algorithms. The IWO based hybrid designs and AAPSO based hybrid designs are more effective than other control designs. In addition
to this, the proposed designs are implemented and validated in real-time using Opal-RT hardware simulator. The real-time simulations of different test power systems with different proposed designs are carried out for a severe fault disturbance. Finally, the proposed controller simulation results are validated with real-time results.