Process simulation of Under Frequency Load Shedding (UFLS) based on Matlab with State flow

In today´s electricity market, the power supply enterprises have to face power quality problems. The reducing of power system frequency threaten the safety of power grids. At this time, we have to use the Under Frequency Load Shedding(Hereinafter referred to as the UFLS) device to remove partial load, to restore the system frequency within the level of security. UFLS device, therefore, the correct action or not is directly related to the safe and stable operation of the power grid. Based on Matlab/Simulink, we set up a simulation model to simulate and analyze the process of UFLS of single machine and interconnected system with module (PSB) and State Flow. Using State Flow in power system simulation is not used in the former scientific research. This subject verifies the validity of the logic action of State Flow using on the power system simulation.