Study on the variation of the steady-state frequency of power systems under the rapid growth of renewable energies

The power grid of China is going through a rapid growth of renewable energies, which can change the frequency stability characteristics of the power system. In this paper, we study the variations of the steady-state frequency caused by the load changes in the power system with the penetration of renewable energies. An analytic model is firstly constructed to analyse the steady-state frequency of a simple power system. Two scenarios with/without the participation of new energy power generation in the primary frequency are considered. We find that increased renewable energies deteriorates the frequency stability of the system. A drastic change of the system frequency stability occurs when the renewable energy power generation reaches a specific proportion. This proportion will rise if renewable energy has a certain ability to participate in the system frequency control. We do simulations on power system test cases generated by modifying the IEEE 9 Bus Test Case. Simulation results verified the correctness of the model and the analytical conclusions obtained.