Static Voltage Stability
This is a stability phenomenon, where the power system looses its ability to control
load bus voltage due to various reasons. This phenomenon can lead to failure of
the total or partial power system due to interventions of various control and protection
The reasons for voltage instability could be
Failure to provide necessary power support to the
loads as a consequence of power transfer limit. The power transfer limit is determined
not only by the bus voltage phase angle, but also by bus voltage magnitude
Failure to meet power requirements due to equipments
reaching their control and operating limits. Examples are transformer tap limits,
generator reactive power supply capabilities.
Inconsistency in the load power requirements as
function of bus voltage and power supply characteristics.
PowerApps provides various analytical tools for assessment of static voltage stability
using load flow solution or output from static state estimation. Further the reactive
power optimization algorithm provides a method of improving static voltage stability.
The analytical tools are
V-P (nose) curves or PV curves
Sensitivity Indices. Sensitivity of bus voltage magnitude for active (P) and reactive
(Q) injection at a bus.
Sensitivity of net reactive power generation for a given bus reactive power injection.
Minimum Singular Value Decomposition of the complete load flow Jacobian as well
us reduced Jacobian formulations. [ P.A.Lof, T.Smed, G.Andersson, D.J.Hill – Two
IEEE Transaction publications, 1992, 1993]. Further, identification of critical
buses based on left and right singular vectors are also implemented in PowerApps.
Voltage Stability Index L proposed by P.Kessel and H.Glavitsch. [ IEEE Transactions
on Power Delivery, 1986].
Static Voltage Stability Evaluation using relative bus voltage phasors at an operating
point given by load flow solution or static state estimation.. [A
New and Fast Technique for Voltage Stability Analysis of a Grid Network Using System
Voltage Space", Published in International Journal of Electrical Power & Energy
Systems, Elsevier Science Ltd.
Improvements in static voltage stability using a reactive power
optimization tool. [Optimal Static Voltage Stability Improvement Using a Numerically
Stable SLP Algorithm, for Real Time Applications", Published in International Journal
of Electrical Power & Energy Systems, Elsevier Science Ltd.
Description of PowerApps Solution for Voltage Stability Assessment