Reactive power planning by optimal allocation of static VAr compensator (SVC) and thyristor controlled series capacitor (TCSC) is presented in this paper. Three objective functions (minimization of the installation cost of SVC or TCSC, minimization of the energy loss cost, and minimization of the total cost defined as the sum of the installation cost and energy loss cost) are considered for comparison purpose. All the objective functions are subject to power flow equations, bus voltage limits, reactive power output of generators at voltage controlled buses, and limits of setting values for SVC and TCSC. An optimization technique based on particle swarm optimization (PSO) algorithm is developed to determine the optimal locations of SVC and TCSC and their corresponding setting values. A case study with a modified IEEE 14-bus system is carried out to demonstrate the effectiveness of the proposed technique. It is found that the obtained optimal solutions meet the requirement of the objective functions while satisfying all the constraints. Numerical results for total real and reactive power losses, energy loss cost, installation cost, and total cost are also discussed.

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This paper presents the optimal dispatch for the under load tap changer (ULTC) of a substation transformer, substation capacitors, and feeder capacitors for volt/VAr control in a distribution system. Three objectives of interest in the problem consist of energy loss, total capacitor kVAr to be switched on, and total number of daily switching operations of the ULTC and all capacitors. The optimization problem is subjected to power flow equations, voltage limits, and maximum switching operations for the ULTC and the capacitors. All the objectives are fuzzified using a trapezoidal membership function and are integrated to represent the fuzzy decision value. Fuzzy multiobjective and particle swarm optimization are employed to determine the optimal dispatch schedule that provides the best compromise among all the objectives. The methodology is demonstrated by a 29-bus distribution system of Provincial Electricity Authority (PEA), Thailand.

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