A.C. security assessment

The analysis of security assessment has evolved from load-flow techniques to evaluate system response for credible outages of transmission and generating plant or loss of loads. The a.c. security assessment described, based on a decoupled load flow, provides a better insight into the state of the system than does the conventional d.c. reactance model. The paper describes a.v.r. and governor representation for evaluation of voltage changes after a loss of generation, pickup of spare generation and analysis of split-network conditions. It also includes a phase-shifter representation which retains network symmetry, the use of sensitivity factors for an adjusted a.c.decoupled-load-flow solution which produces fast and accurate results and automatically maintains voltage and generating limits to specified values. It concludes by giving computation and storage time for a number of practical networks.