Method for performing a voltage stability security assessment for a power transmission system

A method of performing a voltage stability assessment for a region of an electric power transmission system having a plurality of buses and a plurality of sources of reactive reserves coupled thereto, the method comprising:

• grouping the plurality of buses into a plurality of voltage control areas such that each of the plurality of buses within each voltage control area has a similar corresponding reactive power versus voltage relationship;
• selecting at least one of the voltage control areas whose buses therewithin have a voltage at the minimum of the corresponding reactive power versus voltage relationship which exceeds a voltage threshold;
• determining a reactive reserve basin for the at least one of the plurality of voltage control areas, the reactive reserve basin comprising at least one of the sources of reactive reserves selected in dependence upon a measure of the depletion of reactive reserves at a predetermined operating point of the electric power transmission system;
• performing a single contingency analysis by computing a corresponding quantity for each reactive reserve basin in response to each of a plurality of single contingencies, wherein the corresponding quantity is representative of a reduction in reactive reserves within the reactive reserve basin, and wherein the plurality of single contingencies includes at least one single generator outage and at least one single line outage;
• selecting the single contingencies whose corresponding quantity exceeds a predetermined threshold;
• and
• assessing the voltage stability for single and multiple contingencies with a plurality of transfer and loading patterns, wherein the single and multiple contingencies are based upon the selected single contingencies.