Abstract: Due to the lack of reactive power capacity allocation in the wind farm, the grid-connected point voltage often exceeds the limit under certain operation conditions. The drainage effect of the increased/decreased reactive power of surrounding reactive power compensation substations participating in the reinforcing dispatch and control for the grid-connected point voltage will occur.This effect not only weakens the support for the wind farm voltage, but also may cause new voltage violations at other nodes. For the prevention and control of grid-connected point voltage violations, a system-side reinforcing dispatch and control method for the wind farm considering the drainage effect is proposed. Firstly, the drainage effect of the increment of the reactive power compensation is introduced and the drainage ratio is defined. Secondly, the basic conditions participating in reinforcing dispatch and control of substations to be regulated surrounding the wind farms are discussed and a scheme for selecting candidate substations is given. Finally, a heuristic decision-making method for allocating reinforcing dispatch and control tasks and an optimization decisionmaking method of linear programming model considering the difference of dispatch and control cost are designed. The case study results show that the two proposed decision-making methods for the reactive power compensation of the reinforcing dispatch and control substations can both adjust and stabilize the grid-connected point voltage of the wind farm within the set range.