Power System Stability

SCYR 2010 - 10th Scientific Conference of Young Researchers – FEI TU of Košice

Stability of Power System (May 2011)
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Vladimír KRIŠTOF, 2Stanislav KUŠNÍR, 3Matúš KATIN

Dept. of Electric Power Engineering, FEI TU of Košice, Slovak Republic Dept. of Electric Power Engineering, FEI TU of Košice, Slovak Republic 3 Dept. of Electric Power Engineering, FEI TU of Košice, Slovak Republic
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[e-mail], [e-mail], [e-mail] change rapidly, but the mechanical power into the machine is relatively slow to change. Because of this difference in speed of response, there exists a temporary difference in the balance of power. This power unbalance causes a difference in torque applied to the shaft, which causes it to accelerate or decelerate, depending on the direction of the unbalance. As the rotor changes speed, the relative rotor angle changes. Fig. 2 shows the relationship between the rotor (torque) angle δ, the stator magnetomotive force (MMF) F1, and the rotor MMF F2. The torque angle δ is the angle between the rotor MMF F2 and the resultant of the vector addition of the rotor and stator MMFs R, as shown in Fig. 2

Abstract— Due to increase of electric power demands, power systems are larger and more complicated, and the dependence of people on electricity increases. Outages in electric supply have an increasing social and economic impact. Therefore it is necessary to minimize the effect of disturbances that arise in the power system so as to have minimum impact on the reliable and safe supply of electricity. Stability of power system is one of the most important area of power system operation. Loss of stability (loss of synchronism) can lead to outages of transmission lines, loss of loads, cascading failures, and eventually to black-out. This paper discusses power-system instability and the importance of fast fault-clearing performance to aid in reliable production of power.

Keywords—power system, steady-state

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