Voltage stability and reactive power compensation on the T&TEC system

Voltage stability can be defined as the ability of a power system to maintain steady acceptable voltages at all buses in the system under normal operating conditions and after being subjected to a disturbance [P. Kundar (1994)]. We describe the methodology used to study the voltage stability on the T&TEC (Trinidad and Tobago Electricity Commission) system and its propensity to voltage collapse. A post-contingency power flow technique was used to construct the V-P (voltage versus power) curves for different buses in the system. Once susceptibility to voltage collapse was found in any area, the severity was ranked using the V-P curves, and a load margin index. The most severe cases were then analysed for reactive power compensation as a mitigation technique for any voltage instability. Finally, the reactive power compensation was then taken a step further to obtain an "optimal" location of the reactive power sources using V-Q sensitivity techniques.