Probabilistic undervoltage load shedding using point estimate method

Undervoltage load shedding (UVLS) is executed as a last resort to avoid voltage instability in critical situations. In this study, a robust UVLS scheme based on the point estimate method (PEM) is developed taking load uncertainties into consideration. The utilised PEM converts the continuous probability distribution functions (PDFs) of load uncertainty to discrete statistical moments. The extracted moments could represent the behaviours of original continuous PDFs. The proposed stochastic UVLS strategy is expressed as a non-linear programming problem, which is optimised using sequential quadratic programming technique. The fulfilment of the suggested scheme is compared with Monte Carlo simulation technique for two IEEE 14-bus and IEEE 118-bus test grids.