Probabilistic Voltage Stability Assessment Considering Load and Wind Uncertainties

The operational uncertainties in the power network are increasing due to the increased integration of intermittent renewable energy sources and system loads variation, which may affect the stability of the future grid. This paper presents the probabilistic assessment of voltage stability considering a wide range of network scenarios, such as (1) different system load models, including constant power, constant impedance, constant current, and composite load models (ZIP), (2) multiple levels of dynamic loads (0%, 25%, 50%, 75% and 100%), (3) different system loading levels (40%, 60%, 80%, and 100%), (4) varying levels of wind penetration (0%, 10%, 15%, and 20 % ), (5) multiple levels of system reactive power capability (0%, +25%, +50%, and +75 % ) and (6) different system topologies. The IEEE 39 bus network is simulated in DIgSILENT PowerFactory software to perform the probabilistic voltage stability simulation by running 2000 Monte Carlo Simulations. The simulation results have identified the influence of different power network uncertainties on the voltage stability (load margin or system loadability) as measured from the P-V curves. It has been observed from the P-V curve analysis that the probabilistic voltage stability is greatly influenced by the type of the system load models, percentages of dynamic load, and the system loading level.