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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vladimir.kristof@tuke.sk, 2stanislav.kusnir@tuke.sk, 3matus.katin@tuke.sk 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
Stability of Power System (May 2011)
1
1
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
2 1
vladimir.kristof@tuke.sk, 2stanislav.kusnir@tuke.sk, 3matus.katin@tuke.sk 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
References: Krištof, V.: Riadenie ES v krízových situáciach. Minimová práca. Košice: Technická univerzita v Košiciach, Fakulta elektrotechniky a informatiky, 2010. [2] Basler, M.J. – Schaefer, R.C.: Understanding Power system stability. In:Industry applications, IEEE Transactions on. March 2008. ISSN: 0093-9994 [3] Kundur, P. – Paserba, J.- Ajjarapu, V. – Andersson, G.- Bose, A. – Canizares, C. – Hatziargyrou, N. – Hill, D.- Stankovic, A.- Taylor, C. – Van Custem, T. – Vittal, V. : Definiton and clasification of power system stability. In: Power Systems, IEEE Transactions on. August 2004. ISSN: 0885-8950 [4] Krištof, V. – Kušnír, S.- Hlubeň,D.- Kolcun, M.: Modeling of transient phenomena in PSLF. In: Electrical power engineering 2010 : international scientific and technical conference : 14-16.10.2010, Varna, Bulgaria. - Varna : TU, 2010 P. 186-190. - ISBN 978-954-20-0497-4 [5] Mešter, M.: Analýza hraničných podmienok stability elektrizačnej sústavy pri rôznych typoch skratov. Dizertačná práca. Košice: Technická univerzita v Košiciach, Fakulta elektrotechniky a informatiky, 2004. [6] CIGRE: Advanced Angle stability controls. CIGRÉ Technical Brochure. International Conference on Large High Voltage Electric Systems 1999. [7] Mešter, M. – Hvizdoš, M. – Rusnák, J. – Szathmáry, P. – Vargončík, M: Stabilita elektrizačnej sústavy. Equilibria 2006. ISBN 80–969224– 9-1 [8] Prabha, K.: Power System Stability and Control. United States of America. 1993. 0-07-035958-X [9] Machowski, J. − Bialek, J. W. − Bumby, R. J.: Power system dynamics and stability. England, 1997. 484 s, 978-0-471-95643-3 [10] Yorino, N. – Priyadi, A. – Kakui, H. – Takeshita, M. : A new method obtaining critical clearing time for transient stability. In: Power Systems, IEEE transactions on. August 2010. ISSN 0885-8950 . [1] Fig. 8. Influence of fault clearing time: a) slow fault clearing time b) fast fault clearing time Power-system stability depends on the clearing time for a fault on the transmission system. Comparing the two examples in Fig. 8 shows this point. In the example of slower fault clearing (a), the time duration of the fault allows the rotor to accelerate so far along the curve of PE that the decelerating torque comes right to the limit of maintaining the rotor in synchronism. The shorter fault-clearing time (b) stops the acceleration of the rotor much sooner, assuring that sufficient synchronizing torque is available to recover with a large safety margin. This effect is the demand placed on protection engineers to install the fastest available relaying equipment to protect the transmission system. IV. CONCLUSION Due to the increasing electricity consumption and economic and time consuming construction of new power lines, existing networks are operated more at the limits of their possibilities and they are just an ultimate of stability of power system. Therefore it is necessary pay close attention to power system stability and control.