Published in IET Generation, Transmission & Distribution Received on 7th September 2009 Revised on 26th February 2010 doi: 10.1049/iet-gtd.2009.0505 Special Issue on Wide Area Monitoring, Protection and Control ISSN 1751-8687 Wide area control for improving stability of a power system with plug-in electric vehicles P. Mitra G.K. Venayagamoorthy Real-Time Power and Intelligent Systems (RTPIS) Laboratory, Missouri University of Science and Technology, MO 65409, USA E-mail: gkumar@ieee.org Abstract: The integration of plug-in electric vehicles (PEVs) to power systems has impacts on the stability characteristics of the integrated systems. Wide area controllers (WACs) are used in power systems to provide auxiliary control signals to the generators or other devices in order to improve the stability of the system. The necessity of WACs becomes more relevant during grid-to-vehicle (G2V) or vehicle-to-grid (V2G) power transactions, that is, charging and discharging cycles of the PEVs respectively. The design of a WAC for providing damping to three generators in a 12-bus power system with PEVs is presented in this study. Each WAC signal is obtained based on the aggregation of modulated local and remote power system stabilisers’ signals. The modulation indices associated with those signals are tuned using the particle swarm optimisation technique to provide the maximum damping to the three generators. The 12-bus power system with the PEVs and WAC has been implemented on the real-time digital simulator (RTDS). Typical results have been presented to show the improvement in the stability of the power system when PEVs are integrated using transient simulations and Prony analysis. 1 Introduction As increasing numbers of plug-in electric vehicles (PEVs) enter the market, the effects of adding large numbers of small power electronic devices to the grid become more and more predominant. Many of these vehicles can also be adopted to participate in vehicle-to-grid (V2G) applications in the proposed smart grid framework which calls for increased amount of bidirectional power flows between vehicles and utility grids [1, 2]. Vehicles providing auxiliary services coordinate their power flows with the utility to change grid conditions in some predetermined way. If vehicle owners try to buy and sell power according to varying prices, there will be large swings in power as groups of vehicles switch the direction of their power flows. Therefore the PEVs are going to have significant impact on the stability of the power grids. Several measures have been taken in the recent decades to provide better stability and reliability to the stressed systems. Local compensators like power system stabiliser (PSS) are installed to damp out low-frequency oscillations. But, it is observed that the local controllers have good performance when local measurements provide all the information about the dynamics of disturbances. But, if there are adverse interactions between multiple adjacent areas of the power system, or between the grid and the power electronics devices associated with the distributed generations or storage, only a wide-area measurement-based controller can provide better stabilising control [3, 4]. Wide-area controllers (WACs) coordinate the actions of the distributed agents using supervisory control and data acquisition, phasor measurement unit or other sources providing wide-area dynamic information [5, 6]. The WAC receives information/data of different areas in the power system and based on some predefined objective function, sends appropriate control signals to distributed agents for enhancing system’s dynamic performance [7]. Several researchers have contributed in the area of wide area monitoring and control. A hierarchical WAC for damping post-disturbance oscillations has been reported in [8]. The other control strategies based on linear matrix inequality [9], gain scheduling and H 1 -based control [10, 11] have also been used to provide effective auxiliary IET Gener. Transm. Distrib., 2010, Vol. 4, Iss. 10, pp. 1151–1163 1151 doi: 10.1049/iet-gtd.2009.0505 & The Institution of Engineering and Technology 2010 www.ietdl.org