10 This study is focused on assessing the effect of energy storage system (ESS) presence on security 11 improvement of power systems hosting remarkable renewable energy resources. To this end, ESS 12 presence is suitably included in security-constrained optimal power flow (SCOPF) model; the required 13 technical amendments are hence considered. To launch a realistic model, ramping constraints of thermal 14 units are also taken into account, which, limit the generators from completely responding

more »

... to power 15 shortfalls. Considering a high penetration level of renewable generations, different scenarios of outages in 16 transmission lines and generators are simulated to measure the line outage distribution factor (LODF) and 17 power transfer distribution factor (PTDF). Also, in order to illustrate the economic impact of wind power 18 generation curtailment and load shedding, two penalty parameters value of wind curtailment (VWC) and 19 value of loss of load (VOLL) are considered in the model. Two test systems, including a PJM 5-bus 20 system and an IEEE 24-bus RTS, are put under numerical studies to assess the possible impact of ESS on 21 security improvement of the investigated systems. The obtained results are discussed in depth. 22 Keywords: Renewable, uncertainty, security-constrained optimal power flow (SCOPF), energy storage 23 system (ESS), security analysis. 24 25