Proportional Integral Power System Stabilizer Research Articles

Model based PI power system stabilizer design for damping low frequency oscillations in power systems

This paper explores a two-level control strategy by blending local controller with centralized controller for the low frequency oscillations in a power system. The proposed control scheme provides stabilization of local modes using a local controller and minimizes the effect of inter-connection of sub-systems performance through a centralized control. For designing the local controllers in the form of proportional-integral power system stabilizer (PI-PSS), a simple and straight forward frequency domain direct synthesis method is considered that works on use of a suitable reference model which is based on the desired requirements. Several examples both on one machine infinite bus and multi-machine systems taken from the literature are illustrated to show the efficacy of the proposed PI-PSS. The effective damping of the systems is found to be increased remarkably which is reflected in the time-responses; even unstable operation has been stabilized with improved damping after applying the proposed controller. The proposed controllers give remarkable improvement in damping the oscillations in all the illustrations considered here and as for example, the value of damping factor has been increased from 0.0217 to 0.666 in Example 1. The simulation results obtained by the proposed control strategy are favourably compared with some controllers prevalent in the literature.

Power system feedback stabilizer design via optimal subeigenstructure assignment

Power system stabilizer (PSS) design is addressed using an optimal reduced order model whose state variables are torque angles and speeds. System damping can be improved by using eigenvalue assignment, and the coordination of stabilizers can be achieved through eigenvector assignment by maintaining system mode shapes. The proportional-integral PSSs are derived by the optimal reduced order model. The effectiveness of the stabilizer is evaluated. By using the output feedback only, the result of eigenstructure assignment is more stable and much better than the assignment method based on the whole system model. Examples, a single-machine to infinite bus system and a multimachine system, are given to illustrate the advantages and effectiveness of the proposed approach. Results based on the whole system model are included for comparative analyses.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>