1 Abstract— In this paper, the potential benefits of a Wide Area Control System for coordinated power oscillation damping control is investigated for the Nordic power system, with an overall motivation to facilitate increased power transfer limits. Several approaches to the design of power system stabilizers making use of phasor measurements from a wide area monitoring system are presented and compared with conventional stabilizers using locally measured control feedback signals. Linear analysis and time domain simulations illustrate the performance of these PSS designs when applied to selected SVCs in the Norwegian power transmission grid. Utilizing remote signals available recently through wide area monitoring systems enables selection of the best feedback control signal with highest modal observability of the modes of interest. Preliminary conclusions indicate that this leads to a higher performance and robustness of the power system stabilizer control. Index Terms--Controllability, linear analysis, observability, power system stabilizers, static VAR compensation, wide area measurements I. INTRODUCTION igher demand on inter-area power transfer results as new and larger power markets evolve and as a general consequence of load increase. Congestion issues leading to unwanted price differences in the markets are getting more and more attention. Transfer limits are determined from power system security considerations and are either constrained by thermal, voltage or stability limits [1]. Improved damping of inter-area power oscillations is identified as one of the means to increase stability limits on transmission corridors. This can be achieved by installations and proper tuning of Power System Stabilizers (PSSs) in the system. Many studies are performed with the goal to increase damping of low damped oscillations, often with focus on generator applications, FACTS equipment using local measurements, and damping of local modes [2] - [5]. In this study the focus is on damping improvements through SVCs. This area is of high interest since SVCs are E. Johansson is with SINTEF, Trondheim, Norway, (emil.johansson@sintef.no) K. Uhlen is with Sintef, Trondheim, Norway, (kjetil.uhlen@sintef.no) A. B. Leirbukt is with ABB, Oslo, Norway (albert.leirbukt@no.abb.com) P. Korba is with ABB, Baden, Switzerland (petr.korba@ch.abb.com) J. O. Gjerde is with Statnett, Oslo, Norway (jan.gjerde@statnett.no) L. K. Vormedal is with Statnett, Oslo, Norway (lars.vormedal@statnett.no) fully controlled by the Transmission System Operators (TSOs). The availability of generators and their PSSs, on the other hand, depends on the market settlements at any given hour. The main objective of the work has been to investigate the design and tuning of SVC stabilizers with the motivation to increase transfer limits on Power Transmission Corridors (PTCs) between main areas. More specifically the goal has been to • investigate coordinated stabilizer design to fully exploit the potential of SVCs in providing damping of inter-area power oscillations, • with the possibility to use input signals from wide area measurements utilizing Phasor Measurement Units (PMUs), • and finally to identify potential benefits and challenges of using wide area measurements compared to traditional local power measurements. This paper presents a computer simulation study on the use of WAMS measurements in a damping control scheme, exploring the effectiveness of using voltage phasor angle difference as input signals to PSS controllers. Several SVCs are installed in the Norwegian power transmission grid shown in Fig. 3. Some of these SVCs are also equipped with PSS to damp power oscillations. These PSSs are fed with local branch power measurements as input signals, and have successfully been in operation for decades. Local measurements for damping control purposes are convenient since there is no need to communicate a real time control signal over a large geographic distance. However, local measurements are not always favorable when inter-area modes are concerned [6] & [7]. Phasor measurements provided by WAMS provide new opportunities for designing damping control schemes. With high performance communication infrastructure, WAMS provides the opportunity to select a control feedback signal from any PMU-equipped substation in the transmission grid. Voltage phasor angle signals are well suited to measure power system oscillations, since there is no need to monitor a particular branch or multiple branches. In the power transmission community, it is therefore widely expected that WAMS can enhance the damping performance of PSSs, however little field experience exists to support this. Coordinating Power Oscillation Damping Control using Wide Area Measurements E. Johansson, K. Uhlen, Member, IEEE, A. B. Leirbukt, Member, IEEE, P. Korba, Member, IEEE, J. O. Gjerde, Member, IEEE, L. K. Vormedal, Member, IEEE, H 978-1-4244-3811-2/09/$25.00 ©2009 IEEE