Assessing Static Voltage Stability of Bulk Power Systems with DER Uncertainties: A Scenario Based Approach

An enormous number of studies has been carried out on distributed energy resources (DERs) from the microgrids’ point of view and later as an attachment to the distribution subsystems. However, recent requirements to decarbonize the grid with potential retirement of fossil-fuel based generators necessitate consideration of DERs for participation in bulk power systems. This paper investigates the potential impact of DERs on the voltage stability of bulk power systems. The paper adopts a scenario-based approach to study the allocation and penetration level of DERs and evaluate their effect on the static voltage stability using the continuation power flow method. The uncertainties of DERs and loads are simulated from their statistical model distributions using Monte Carlo simulation technique. The assessment is performed on the simplified 14-generator, 59-bus Australian benchmark system as a test case assembled in MATLAB/Simulink and analyzes the different loading conditions. Results show that DERs have a significant positive influence on the voltage stability of power systems, requiring careful planning for reactive power support for wind farms in order to achieve optimal performance. Moreover, by placing DERs closer to loading centers and increasing solar power penetration, results indicate an improved voltage stability, while wind farms, unless compensated, may have comparably lower impact due to their increased reactive power demand.