II. VOLTAGE CONTROL ARCHITECTURE
Firstly, a detailed power network model in a WF is established for monitoring and control, including WTGs, transformers, SVC/SVGs and all the feeder lines spreading within an area more than fifty square kilometers. External power grid of this WF is modeled as a Thevenin equivalent voltage source and equivalent impedance. Based on the detailed model, online state estimation (SE), power flow (PF) calculation and reactive power and voltage sensitivities (RPVS) calculation [9] are carried out for further voltage control.