Dynamic security analysis of the urban power grid in islanding

Customers is becoming more and more dependent on electric power and the urban power grid is more complicated than before. So it is necessary to study the dynamic security of the urban power grid in islanding for continuing power supply for customers in case of emergency. The models of synchronous generator, asynchronous generator and integrated loads are formed for the urban power grid as algebraic and differential equations, and rotor angle curve, frequency curve and voltage curve of each bus versus time are obtained by implicit trapezoidal integration method and Newton method. For typical urban power grid, simulations and analysis are conducted under different conditions. The results show that there are many hidden dangers of dynamic security in the urban power grid and adequate control measures should be adopted.