Cascading Outage Simulation Based on Dynamic Fast Decoupled Load Flow Model

—Frequency is an important indicator of balance between active power generation and load. Active power-frequency dynamics analysis is an important task of power system operation. This paper proposes a novel cascading outage simulation model based on dynamic Fast Decoupled Load Flow (FDLF) considering frequency deviation. A distributed slack bus model is considered in such a way that all of the dispatched generating units share the power imbalance according to their power frequency characteristics. It can reflect the frequency dynamics based on steady-state load flow calculation in the simulation of cascading outage. Also the frequency characteristics of the loads in response to the power imbalance are considered. A novel AC-OPF model introducing the system frequency deviation as a new state variable is proposed to search for a new operating condition when dynamic FDLF is not convergent. The case studies on a two-area, 4-machine power system and a Northeastern Power Coordinating Council (NPCC) 48-machine, 140-bus power system validate the proposed model. Frequency deviation obtained from dynamic FDLF model matches very well with that at the steady-state of time-domain simulation. The statistics of cascading outage samples indicates the frequency insecurity has great impacts on the severity of the cascading outage.