This paper presents the Benders decomposition technique and Branch and Bound algorithm used in the reactive power planning in electric energy systems. The Benders decomposition separates the planning problem into two subproblems: an investment subproblem (master) and the operation subproblem (slave), which are solved alternately. The operation subproblem is solved using a successive linear programming (SLP) algorithm while the investment subproblem, which is an integer linear programming (ILP) problem with discrete variables, is resolved using a Branch and Bound algorithm especially developed to resolve this type of problem.122131140Belati, E.A., (1998) Planejamento de Sistemas de Transmissão Usando Técnicas de Decomposição Matemática e de Branch-and-Bound, , Dissertação de Mestrado. Universidade Estadual Paulista - UNESP, Ilha Solteira - SP, BrasilBenders, J.F., Partitionning procedures for solving mixed variables programming problems (1972) Numerische Mathematik, 4, pp. 238-259Carpentier, J.L., CRIC. A new active reactive decoupling process in load flows, optimal power flow and systems control (1986) Proc. IFAC Conference on Power Systems and Power Plan Control, pp. 65-70. , Beijing, ChinaDornellas, Otimização do despacho de reativos utilizando algoritmos genéticos (1996) Anais do 11° congresso Brasileiro de Automática, , São Paulo - S.PFreris, L.L., Sasson, A.M., Investigation of the load-flow problem (1968) Proceedings of IEE, 10 (115), pp. 1459-1470Garcia, A.V.E., Mantovani, J.R.S., Planejamento de Reativos em Sistemas de Energia Elétrica Utilizando um Modelo Implicitamente Acoplado (1988) Anais do 7° congresso Brasileiro de Automática, , São José dos Campos - S.PGeoffrion, A.M., Generalized benders decomposition (1972) Journal of Otimization Theory and Applications JOTA, 10 (4), pp. 237-260Gómez, T., A security-constrained decomposition approach to optimal reactive power planning (1991) IEEE Transactions on Power Systems, 6 (3), pp. 1069-1076. , AugustGranville, S., (1988) Mathematical Decomposition Techniques for Power System Expansion Planning. Vol. 3: An Integrated Methodology for VAR Sources Planning, 3. , EL-52299, Research Project 2473-6, Final Report, EPRI, Palo Alto - California, USAGranville, S., An integrated methodology for var - Sources planning (1989) IEEE Transactions on Power Apparatus and Systems, 4 (2), pp. 677-686Granville, S., Lima, M.C.A., Aplication of decomposition techniques to var planning: Methodological & computational aspects (1994) IEEE Transactions on Power Systems, 9 (4), pp. 1780-1787. , NovemberHong, Y., Multi-year, multi-case optimal VAR planning (1990) IEEE Transactions on Power Apparatus and Systems, 5 (4), pp. 1294-1301Hong, Y., Liu, C., A heuristic and algorithmic approach to var planning (1992) IEEE Transactions on Power Systems, 7 (2), pp. 505-512Hsiao, Y., A computer package for optimal multi-objective var planning in large scale power systems (1994) IEEE Transactions on Power Systems, 9 (2), pp. 668-676Iba, K., Reactive power optimization by genetic algorithm (1994) IEEE Transactions on Power Systems, 9 (2), pp. 685-692Lebow, W.M., A hierarchical approach to reactive volt ampere sources (var) optimization in system planning (1985) IEEE Transactions on Power Apparatus and Systems, 104 (8), pp. 2051-2057Lebow, W.M., (1984) Optimization of Reactive Volt-Ampere Sources in System Planning - Vol. 1Solution Techniques Computing Methods and Results, 1 EL-3279. , Final Report - EPRI, USAMantovani, J.R.S., Garcia, A.V., A heuristic method for reactive power planning (1996) IEEE Transactions on Power Systems, 11 (1), pp. 68-74. , FebruaryMantovani, J.R.S., Planejamento de reativos em sistemas de energia elétrica utilizando uma metodologia mista: Programação linear - Algoritmo genético (1998) Anais do 12° congresso Brasileiro de Automática, pp. 2017-2022. , Uberlânia - M.GMonticelli, A., Security - Constrained optimal power flow with post - Contingency corrective rescheduling (1987) IEEE Transactions on Power Systems, 2, pp. 175-182Obadina, O.O., Berg, G.J., Var planning for power systems security (1989) IEEE Transactions on Power Apparatus and Systems, 4 (2), pp. 677-686. , MayPalacios-Gomez, F., Nonlinear optimization by successive linear programming (1982) Management Science, 28 (10), pp. 1106-1120Scucuglia, J.W., (1999) Planejamento de Reativos em Sistemas de Energia Elétrica Usando a Técnica de Decomposição de Benders e Branch-And-Bound, , Dissertação de Mestrado, Universidade Estadual Paulista -UNESP, Ilha Solteira - SP, BrasilStott, B., Alsac, O., (1983) Experience with Linear Programming for Optimal Rescheduling of Active and Reactive Power, , Paper 104-01, CIGRE-IFAC, Florence, Itália