Since the control range of reactive power of substation gateway(RPSG)in traditional nine-zone automatic voltage control(AVC)strategy cannot adapt to output fluctuation of wind farm in a distribution network

the active loss characteristic of distribution network with distributed wind power integration is analyzed. An optimal interval matrix is defined

the physical meaning and calculation method of matrix elements are explained. To obtain the corresponding element value

the intersection of optimal intervals of RPSG under different load levels is set. The intervals are obtained and improved according to the correlation characteristic between the active loss and RPSG and the voltage limits when the wind power output changes. A block interval method is proposed to obtain the control interval which can adapt to the wind farm operation condition. The simulation shows that the setting methods are simple and practical in engineering

which realize the multi-objective of volt/var control such as saving energy

avoiding frequent regulation and improving voltage quality. This work is supported by National Natural Science Foundation of China(No. 51277070).