Abstract
In electrical power systems, saddle node bifurcation (SNB) is the voltage stability margin at which voltage collapse takes place. It plays an important role in power system planning and operation as economic and environmental pressures force to operate always closer to the limit of stability. Voltage collapse is associated with the reactive power demands not being met because of limitations in the generation and transmission of reactive power. Determination of the SNB point greatly assists planning and operation of power system. Among various voltage stability analysis (VSA) methods, this paper specifies the continuation power flow (CPF) method as it accurately identifies the SNB point and the critical or the weaker bus. In this paper, power system of Sri Lanka is assessed for diverse applications of VSA by concerning about single element outage or (N-1) criterion and the role of voltage compensation devices. Furthermore, the optimum at the SNB point is verified by eigenvalue analysis.
Highlights
The continuing electricity demands associated with shortages in installed capacities, brought about by economic and environmental pressures, have led to an increasingly complex system that must operate ever nearer to limits of stability
The maximum saddle node bifurcation (SNB) point of a system without violating active and reactive power limits of generators is defined as the optimal operation condition (OOC)
The solution is obtained from University of Waterloo Power Flow (UWPFLOW) software and the system optimality is verified with the eigenvalue analysis where the smallest eigenvalue, ηmin of the power flow Jacobian should be zero at the SNB point
Summary
The continuing electricity demands associated with shortages in installed capacities, brought about by economic and environmental pressures, have led to an increasingly complex system that must operate ever nearer to limits of stability. Saddle node bifurcation (SNB) is the voltage stability limit at which voltage collapse arises. All events of voltage collapse are not associated with SNB. Some voltage collapse problems may be due to fast dynamic events that have nothing to do with bifurcation, such as large disturbances that push the system outside its stability region, initiating voltage problems [1]. Voltage collapse typically occurs in power systems, which are heavily loaded, faulted and/or lack of reactive power. Voltage collapse is associated with the reactive power demands of loads not being met because of limitations in the generation and/or transmission of reactive power. The major limitations on the transmission of reactive power are the high reactive power loss on heavily loaded lines and line outages. Reactive power demands of loads increases with the increasing of load or changes in load composition [2]
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