Probabilistic techniques in a.c. load-flow analysis

The paper describes how the previously published formulations for an a.c. probabilistic load-flow analysis can be extended to ensure precise computation of expected values, and how these may be used to obtain more precise values of standard deviations and probability-density curves than was possible thereto. Both of the present formulations linearise the problem around the precise expected value, and one of them accounts for the coupling effect between active and reactive powers. It is shown that this coupling effect may have a significant impact on some of the voltages and reactive powers, but little effect on angles and active powers. A typical system is analysed and discussed to illustrate the increased depth of information that can be gained from these improved techniques.