Optimal Placement of Facts Units for Minimizing the Impact of Voltage Sags in Power Networks with High Wind Energy Penetration

This paper presents a methodology for the optimal placement of wind farms and FACTS units in power networks, in order to guarantee the voltage profile and to maximize the loadability of the system under voltage sags conditions. Results shown in the paper indicate that the proposed formulations can be used to determine which the best buses are where the addition of Var sources can enhance the voltage stability of the whole network. INTRODUCTION In recent years, there has been an increasing interest in the production of electric energy from renewable energy sources. By 2020, it is expected that the total wind power generation will supply around 12% of the total world electricity demands. However, integration of such wind resources into power system grids presents still some major challenges to power system operators and planners. The more critical aspects are the fault ride-through capability of wind farms and the voltage stability of the power network. Electric power planning with the presence of high wind energy requires the definition of several factors, such as: the best technology to be used, the number and capacity, the best location or the grounding connection. The installation of STATCOM, SVC or DVR units at optimal places can result in an improvement of voltage stability and a reduction of system losses. The selection of the best places for installing FACTS in large distribution system is a complex combinatorial problem. Recently, Distributors Operators have successfully applied metaheuristics optimization methods for planning issues. Among the advantages of using it, are the capability to provide a satisfactory solution of the problem, the low computational complexity and the speed to reach the solution. The use of Genetic Algorithms (GA) in power systems planning is gaining popularity, not only due to the robustness of the method, but also to the possibility to find the global optimal solution in complex multi-dimensional search spaces [1]. OBJECTIVE The objective of this analysis is to find the best allocation of different FACTS systems in order to maximize loadability of the system and improve voltage stability after fault situations using heuristic methods. The methodology is based on the application of the two following processes: An automatic method for optimal allocation of wind and FACTS units on distribution network. The aim of this method is to maximize loadability conditions of the system and to provide potential candidates to the problem solution. For this task GA are used to evaluate possible solution of the optimization problem. A method for evaluating the impact of wind farm and FACTS units installation on voltage profile and voltage stability after voltage sags on the distribution network. Fig. 1. Implementation of the optimization algorithm Figure 1 shows a flowchart of the optimization problem.