Selection of input/output signals for wide area control loops

This paper studies the various aspects of input/output selection for wide-area damping controllers, targeted at the power system inter-area oscillation modes. The objectives is to choose a control loop which has large impact to a few selected modes, while does not affect the other system modes, hence the interactions problem can be greatly reduced. For this purpose, a new modal interaction index is proposed. Non linear simulations are also carried out to validate the modal analysis results.

I. Introduction

ELECTROMECHANICAL oscillation is a common problem in large electric power sytems. These oscillations limit the power transfer capacity, and at times, may cause severe grid failures [1]. Damping of these oscillations is therefore important for a secure operation of power systems. The conventional damping device is the Power system Stabilizer [2]. Emerging electronic based devices (FACTS) can also be equipped with auxiliary control mode to provide oscillation damping [3] [4].