Online Verification Method for Power Grid Frequency Security Considering Multi-Time Scales Frequency Modulation Characteristics

With the large-scale integration of renewable energy such as wind power and photovoltaics, the power grid now exhibits characteristics of low inertia and reduced anti-interference ability. Consequently, it presents significant risks to the frequency security of the grid. The traditional online security verification of power grid frequency encompasses two distinct working conditions. Firstly, it involves the transient frequency security verification, which focuses on the primary frequency modulation during grid faults. Secondly, it also encompasses the medium and long-term security verification, specifically targeting the secondary frequency modulation under steady-state conditions of the power grid. This method cannot consider the multi-time scales factors of power grid frequency fluctuations. An online verification method for power grid frequency security considering multi-time scales frequency modulation characteristics is proposed. Based on the sliding filter algorithm, disturbance signals of different time scales are generated for simulation verification. Simulation methods are selected based on the fluctuation levels of disturbance signals at various time scales. By considering the priority of the primary and secondary frequency modulation time sequences of the power generating unit, an online security and stability verification method for grid frequency with consideration of multi-time scale frequency response is developed. The dynamic response process of the primary and the secondary frequency modulation of the system is simulated and verified based on the IEEE-39 system.