Due to the increasing penetration of renewable energy

the power inertia will keep decreasing in the future. To deal with the decreasing of power system inertia and prevent cascading failure

the frequency dynamics constraints are modeled considering frequency nadir and rate of change of frequency. The frequency constraints are added into security-constrained unit commitment(SCUC). The power flow entropy is added into the objective of SCUC. The case studies in IEEE 30-bus system shows that the introduction of power flow entropy and frequency dynamics will improve power flow distribution and lower cascading failure risk at small cost. The frequency security and load demand can be satisfied with the proposed model.