INNC Method Applied to Multi-objective Reactive Power Optimization in AC/DC Interconnected Power Grid

In order to minimize both active power loss and square sum of voltage deviation in all key nodes, a multi-objective reactive power optimization model of AC/DC interconnection system was built and an improved normalized normal constraint method was proposed to obtain Pareto optimal solutions of this model. The proposed method, considering the difference of the angle between Utopia line and tangent line of each Pareto frontier point, is an improvement of the normalized normal constraint method. In this improved normalized normal constraint method, the Pareto frontier was divided into four segments according to certain rule, each segment corresponds to a sub-Utopia line, and hence the original multi-objective optimization problem was translated to four sets of multi-objective optimization problems. The four sub-Utopia lines can be divided by equidistant respectively, and each set of multi-objective optimization problem can be converted to solve a series of single objective optimization problems. Results on the 765 nodes equivalent system of China Southern power grid demonstrate that the multi-objective optimization problem in large AC/DC power grid can be solved effectively by the proposed method and the distribution of optimal solutions at Pareto frontier becomes more uniform.