A method for optimal reactive power planning of radial distribution systems with distributed generation is proposed. The wind power generation units installed in distribution systems may cause reverse power flow and voltage variations due to the randomlike output of wind power generation units. To conquer that disturbance

an optimal reactive power planning model is proposed to combine the reactive power support from SVC and distributed diesel units

and the optimal object is consist of power loss cost

SVC installation cost

reactive power production cost of diesel units. With the genetic algorithm as the optimization method and using Monte-Carlo simulation

the location and the output of SVC and distributed diesel units are determined. The proposed model is applied to a sample system.