Title :
Synchronism versus stability in power systems: Frequency dependent loads
Author :
Alberto, Luís F C ; Bretas, Newton G.
Author_Institution :
Dept. of Electr. Eng., Sao Paulo Univ., Brazil
Abstract :
In this work, considerations about current power system modeling methods, related to transient stability analysis are presented. It is shown that the swing equations do not present equilibrium solutions if damping coefficients are neglected. It is not possible to characterize the stability of the power system in the Lyapunov sense due to some structural problems. Those structural problems are made clear using power mismatch concepts. Stability studies using one machine as reference (OMR) and the center of angle as reference (COA) are in fact equivalent and do not eliminate the aforementioned structural problems. A possible solution for these difficulties is developed, that is, modeling the system loads as frequency dependent. A structure preserving model with the loads as frequency dependent is presented. In the presence of these loads the system can reach equilibrium solutions in velocities other than the synchronous frequency. The equilibrium frequency is calculated through the solution of a structure preserving power flow added to the equation of equilibrium frequency
Keywords :
damping; load (electric); power system transient stability; synchronisation; center of angle as reference; damping coefficients; equilibrium frequency equation; equilibrium solutions; frequency dependent loads; one machine as reference; power mismatch concepts; power system modelling; power system transient stability analysis; structural problems; structure preserving model; structure preserving power flow; synchronism; Equations; Frequency dependence; Frequency synchronization; Load modeling; Power system analysis computing; Power system modeling; Power system stability; Power system transients; Stability analysis; Transient analysis;
Conference_Titel :
Power System Technology, 1998. Proceedings. POWERCON '98. 1998 International Conference on
Conference_Location :
Beijing
Print_ISBN :
0-7803-4754-4
DOI :
10.1109/ICPST.1998.729304