925 words - 4 pages

Voltage and reactive power control in distribution networks means appropriate operational planning of on-load tap changer and all of switched shunt capacitors on the network to achieve an appropriate voltage profile and reactive power flow due to the constraints and objective functions are considered in the optimization problem.

The growth of distributed generation based on Renewable Energy Sources in distribution networks, an important influence on the voltage and reactive power control as one of the most important duty of distribution network operator. The small X/R ratio of distribution line and radial structure of distribution network, the effect of these resources on the problem of ...view middle of the document...

present a method for volt/var control to dispatch OLTC, substation capacitor and feeder capacitors based forecasts hourly load such that the total feeder loss can be minimized, voltage profile can be improved and reactive power flow into maim transformers can be checked [3]. Besides these, researchers have dealt with this problem in the presence of distributed generation. For example, Niknam et al. proposed a price based approach for volt/var control in distribution system using Distributed Generation (DG) units [4]. Zare et al. present a multiobjective volt/var control in distribution network including renewable energy resources for environmental and economic management. The objective function of this model, including conflicting functions; i.e. the electrical energy losses, the voltages deviations, the total electrical energy costs and the total emissions of RESs and substations [5]. In [6] azimi et al. presented a multiobjective daily volt/var control in distribution system, including distributed generation units. The main purpose is to determine optimum dispatch for OLTC and shunt capacitors based on the day-ahead load forecast. Although most studies have focused on the optimization of distribution network losses and voltage profile but little of these studies is included optimum performance capacitors and transformers [10]. Since many mathematical techniques such as dynamic programming, gradient and sensitivity analysis is proposed to solve the voltage and reactive power control problem [13]. Due to the multi-phase nature of the problem and the non-linearity of the objective functions, mathematical methods are complex and require heavy computational volume. Hence, today an evolutionary algorithm is used to solve this problem [9-12]. For example, ulinuha et al. presented a hybrid genetic-fuzzy algorithm (GA-Fuzzy) for optimal volt/var/total harmonic distortion control in distorted distribution system serving non-linear loads [7]. In ref. [8] niknam...

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