Reactive Power Planning Using a Two-Level Optimizer Based on Multi-Objective Algorithms

Reactive Power Planning (RPP) is proposed here as a three-objective optimization: reactive compensation investment, system loss, and the active power stability margin after critical contingencies. A two-level optimizer with Improved Non-dominated Sorting Genetic Algorithm (NSGAII) and Interior Point Algorithm is proposed to obtain the Pareto front of RPP. NSGAII performs optimization in the planning stage to find the optimal compensation scheme (locations and sizes of VAR devices). According to the compensation scheme, operation-oriented stage adjusts the output of the VAR devices to optimize the economic aspect (system loss) and security (post-contingency stability margin). A simulation was conducted on New England 39-bus system and a three dimensional Pareto front was obtained, showing the decrease of system loss and the increase of stability margin with gradual addition of VAR support. Solutions under different compensation level are given, among which suitable solutions can be selected for RPP.