Analysis of the Frequency Influence of LVRT Strategy on Power Grid with High-permeability PV

The low voltage ride through (LVRT) ability of PV inverter is very important to the safety and stability operation of grid. The current LVRT control strategy emphasizes reactive current support during voltage dip, and there is no active power requirement, so in the grid with high PV permeability, it is easy to cause large active power shortage during the voltage dip, then the frequency will decrease. In order to solve this problem, this paper analyzes the output characteristics of PV inverter using LVRT control strategy dominated by national standard, and the influence to frequency stability of grid with high PV penetration. Based on IEEE standard 3-machine 9- bus network frame, the grid frequency performance is simulated with the model of PV power station, The frequency variation during voltage dip using two typical LVRT control strategies were compared. At last, it is suggested to strengthen the active power support of PV power station during the grid dip, the output of reactive power and active power is guaranteed at the same time, the active and reactive power support to grid is realized, the LVRT performance of PV power station is improved to support grid.