During voltage sags, both the Static Var Generator (SVG) and inverter-interfaced renewable generation can provide active support for grid voltage, while the risks of insufficient support capacity and overcurrent still exist. Given an actual renewable generation farm configuration, a new coordinative control method for the SVG and renewable generation is proposed to actively improve the voltage level at the Point of Common Coupling (PCC). First, a coordinative control algorithm is developed to achieve multiple control objectives, in terms of voltage support, voltage imbalance improvement and fault current limitation, during the unbalanced voltage sags. Then, a voltage sag scenario classification algorithm is developed. In each identified scenario, the developed coordinative control algorithm between the SVG and renewable generation is optimized to obtain the promised performance in this scenario. Finally, the proposed method applies Matlab/Simulink to verify the effectiveness and correctness of the method. Compared with the conventional voltage support method which only relies on renewable generation, the proposed method shows a clear improvement on voltage support ability, especially in the circumstance of severe voltage sag. This work is supported by the National Key Research and Development Program of China (No. 2017YFB0903400).