Method for controlling voltage of wind farm through hierarchical coordination of multiple reactive power sources

The invention provides a method for controlling the voltage of a wind farm through hierarchical coordination of multiple reactive power sources. The method can effectively control the voltage, reduce the regulation frequency of a discrete device and lower the running cost of a system. The method comprises the steps as follows: step 1, data information in the system is collected through SCADA (Supervisory Control and Data Acquisition) and is uploaded to a control center; step 2, tertiary control is performed by the control center; step 3, secondary control is wind farm control, a collected real-time voltage value Ut of a collection point is compared with a voltage reference value Uref according to the formula that Delta U equals to Uref minus U, in order to prevent frequent regulation of the device, a dead zone range of the voltage is set, if Delta U is larger than or equal to -0.01 but less than or equal to 0.01, control is not carried out, however, if Delta U exceeds the dead zone range, the control strategy is calculated according to a two-layer multistage model in step 4 and then implemented, and the control period of the stage is on the order of minutes; step 4, calculation of the control strategy is divided into two layers, and after calculation, primary control is performed by various reactive power voltage regulating devices according to the issued control strategy after the secondary optimized calculation; and step 5, step 2 is carried out again when the next period of the three stages of control comes.