Impact of static and dynamic load models on security margin estimation methods
Journal article, 2022

The post-contingency loadability limit (PCLL) and the secure operating limit (SOL) are the two main approaches used when computing the security margins of an electric power system. While the SOL is significantly more computationally demanding than the PCLL, it can account for the dynamic response after a disturbance and generally provides a better measure of the security margin. In this study, the difference between these two methods is compared and analyzed for a range of different contingency and load model scenarios. A methodology to allow a fair comparison between the two security margins is developed and tested on a modified version of the Nordic32 test system. The study shows that the SOL can differ significantly from the PCLL, especially when the system has a high penetration of loads with constant power characteristics or a large share of induction motor loads with fast load restoration. The difference between the methods is also tested for different contingencies, where longer fault clearing times are shown to significantly increase the difference between the two margins.

Dynamic security margins

load modelling

security assessment

security margin estimation

dynamic security limits


Hannes Hagmar

Chalmers, Electrical Engineering, Electric Power Engineering

Anh Tuan Le

Chalmers, Electrical Engineering, Electric Power Engineering

Robert Eriksson

Swedish national grid

Electric Power Systems Research

0378-7796 (ISSN)

Vol. 202 107581

Advanced visualization of voltage stability limit and system protection based on real-time measurement

Swedish national grid, 2016-06-01 -- 2020-12-31.

Swedish Energy Agency (44358-1), 2016-06-01 -- 2020-12-31.

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Sustainable development

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Energy Systems

Control Engineering

Other Electrical Engineering, Electronic Engineering, Information Engineering



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