000000255 001__ 255
000000255 037__ $$aENY-ARTICLE-2008-201
000000255 041__ $$aeng
000000255 100__ $$aWiszniewski, A$$uInstitute of Power System Engineering, Wroclaw University of Technology, Wroclaw, Poland
000000255 245__ $$aNew Criteria of Voltage Stability Margin for the Purpose of Load Shedding
000000255 260__ $$c2006-02-23
000000255 300__ $$a5p
000000255 500__ $$aIEEE Transactions on Power Delivery, Vol. 22, No. 3, July 2007, pp. 1367-1371
000000255 520__ $$aVoltage instability is a phenomenon which often contributes to the development of power system disturbances. While increasing load admittance, bus voltage decreases to such a degree that the apparent power (V^2 Y) does not increase. As a result, voltage collapses with all consequences resulting from it. During the large-scale power system disturbance, the last line of defense is the load shedding at the stations, where the stability margin becomes dangerously low. To do that, there is a need to use automatic devices which process local signals, detect the decreased margin, and activate the load shedding. As a criteria of operating such devices, the voltage level is adopted. The disadvantage of such an approach results from the fact that the relations between the voltage level and the stability limit depend very much on the load power factor. To overcome this weakness, this paper presents a criterion which is directly based on the definition of voltage stability. It calculates the derivative of apparent power against the admittance (dS/dY). It may be easily accomplished, because both the power and the admittance are measurable, and the changes of load occurs continuously, as a result of switching on and off the impedances, and/or actions of the transformer on load tap-changing devices.
000000255 6531_ $$adisturbances
000000255 6531_ $$aload shedding
000000255 6531_ $$apower systems
000000255 6531_ $$avoltage collapse
000000255 6531_ $$avoltage stability
000000255 8560_ $$fleon99@pwr.wroc.pl
000000255 8564_ $$uhttp://zet10.ipee.pwr.wroc.pl/record/255/files/$$zAccess to Fulltext
000000255 909CO $$ooai:zet10.pwr.wroc.pl:255$$pglobal
000000255 980__ $$aARTICLE