Online algorithms for the avoidance of voltage collapse: reactive power management and voltage collapse margin assessment

The authors propose two algorithms for online application which would provide advice to the power system control engineer for the avoidance of voltage collapse. The first algorithm is Reactive Power Management (RPM) which recommends targets for despatch to generating plant, targets for the local control systems of compensation plant, and any manual switching of shunt capacitors and reactors. The second algorithm assesses the margin of a power system from voltage collapse under the existing reactive targets. It expresses the voltage collapse margin (VCM) as the additional active power transfer which could be sustained over defined geographical boundaries. Both algorithms take into account the conditions which would result from defined contingencies, as well as the prevailing intact network conditions. VCM advises on limitations which need to be placed on active power despatch to maintain system security, and RPM recommends action which would help avoid these limitations