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Unformatted text preview: DETECTION OF INTER AREA OSCILLATIONS IN THE TUNISIAN INTERCONNECTED POWER SYSTEM USING PHASOR MEASUREMENT UNITS Khadija Ben Kilani 1 , Hajer Ben Hamouda 1 and Mohamed Elleuch 1 Electric Systems Laboratory, National Engineering School of Tunis, Tunisia Email: [email protected], [email protected], [email protected] ABSTRACT The Tunisian power system rely more on tie line power interchange. Unstable inter-area oscillations restrict power transfer between areas and may endanger the system security. In this paper we perform a study on the oscillation phenomena in the interconnected Tunisian power system and their detection by the global positioning system. The detection of the frequency is based on the equivalent relation machine rotor speed- terminal voltage angle. The placement of the phasor measurement units (PMUs) is optimized by the Recursive Security N Algorithm and several power exchanges events are simulated. The results of this paper can help solve some of the existing interconnexion problems and demonstrate how to improve the operation of the overall system behaviour by phasor measurement technology. Index Terms — Power system interconnections, inter-area oscillations, small signal stability, PMU. 1. INTRODUCTION In the view of an interconnected Euro- Mediterranean power system, the Tunisian power system rely more on tie line power interchange. Recent extensions of the European synchronous zone which currently include the Magrebien regions via the Spain-Morocco two 400 kV ac connexion, aim at establishing the closed Mediterranean loop. The Tunisian power system has four tie line connexions with the Algerian (ALG) network: two 90 kV lines of 70 MVA and 80 MVA capacities, a 150 kV of 160 MVA capacity, and a 225 kV line of 240 MVA capacity. With the Libyan (LYB) network, two 225 kV tie lines of 720 MVA each are established, the connexion not closed. Reinforcement projects aim at upgrading the TUN-ALG 400 kV tie line of 600 MVA capacity in 2009, to a capacity of 1070 MVA in 2011 -. On one hand, a high interchange capacity can improve the Tunisian network security; on the other hand, unstable electromechanical inter-area oscillations restrict power transfer between areas and may endanger the system operation. Power transfer from the ALG to the LYB system is vehicled via the Tunisian transmission grid which may be split two major areas each holding about 50 % of the total system power pool capacity estimated at 3 GW (see Fig. 1). Area 2 is split into two sub- regions representing the center sub-region and the Figure 1 . The Tunisian Transmission grid of 2011 south sub -region as shown in Figure 1. Moreover, the deregulated electricity market causes rather quick changes in the system’s operational conditions and new, unknown load flow patterns show up more frequently for the system operator. There is a general trend to include both normal operation issues and disturbance handling into power system control....
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This note was uploaded on 01/29/2011 for the course ENGR 52 taught by Professor Mcmillan during the Spring '10 term at Baylor Med.
- Spring '10