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13 | Hadaeghi & Abdollahi
proposed method is demonstrated. Moreover, this method test feeder. A new algorithm to solve the problem of distribution
achieves stable configurations that remained feasible over long networks reconfiguration using Improved Selective Binary
periods of time without requiring further reconfigurations. These Particle Swarm Optimization (IS-BPSO) has been proposed in
results indicate the need to include load uncertainties when [13]. The proposed method demonstrates a new sigmoid
analyzing under realistic conditions. A feeder reconfiguration function that can improve the control in the rate of change of the
problem in the presence of distributed generators has been particles and improve the convergence of the results. The
presented in [7] to minimize the system power loss while proposed algorithm is used to reduce power losses in distribution
satisfying operating constraints using Hyper Cube-Ant Colony networks, this method is used on two test systems of 33 and 94
Optimization (HC-ACO) algorithm. In this study, loss bus distributions. The simulation results show that the proposed
sensitivity analysis was used to identify the optimal location for method is very efficient and guarantees the achievement of the
the installation of DG units. The simulations have been global optimum. Reference [14] deals with the simultaneous
performed on a 33- bus radial distribution system at four distributed generation (DG) planning and distribution network
different cases to confirm the efficiency of the proposed method reconfiguration issue. The problem is formulized as an
compared to other methods in the articles. The results of this optimization model which includes three types of variables such
method were very fast and effective. In [8] the Cuckoo Search as DGs location as the integer variables, DGs operating point as
Algorithm (CSA) has solved the distribution system the continuous ones and switches open or close state as the
reconfiguration with the goal of reducing losses and improving binary variables. A 3D-GSO method has also been introduced to
the voltage profile. In [9] A Modified Bacterial Foraging cope with this issue. The proposed method is a general
Optimization Algorithm (MBFOA) is presented and the problem optimization scheme applicable to all types of optimization
of distribution network reconfiguration is studied to minimize problems which deal with an integer, continuous, and binary
power loss. In reference [10] with the help of multi-objective variables at the same time. Five different scenarios at three load
distribution network reconfiguration, a method for optimizing levels are also considered to cover all possible conditions. The
unbalanced distribution network to maintain voltage stability proposed method is validated through comprehensive
using the Firefly algorithm is proposed. The objectives that simulation studies on 33-bus and 69-bus test systems.
should be minimized are the total network power losses, the
deviation of bus voltage and load equalizing in the feeders. Each In this paper, a new method based on the combination of the
goal is moved into the fuzzy domain utilizing its membership Teaching-learning-based-optimization (TLBO) and Black-hole
function and fuzzy field independently. The proposed method (BH) algorithm has been proposed to reconfiguration of
for network reconfiguration has been implemented in 25-node distribution networks in order to minimize active power losses
and 19-node UDNs. The results obtained by the suggested and improve voltage profiles in the presence of distributed
method of these two unbalanced networks have been compared generation sources. The proposed model is simulated using 33
with that of obtained by Genetic algorithm (GA), ABC IEEE radial bus networks and the results show the efficiency of
algorithm, PSO algorithm and GA-PSO algorithm using the the proposed method.
same objective function. A Combined method with existing
methods is also presented. In [11] using Ant Colony II. PROBLEM FORMULATION
Optimization (ACO) technique, a novel method is proposed for
simultaneous dynamic scheduling for distribution network As already mentioned, the distribution network
reconfiguration in the presence of DG units with uncertain and reconfiguration problem is actually an optimization problem
variant generations over time. This method is applicable to both and, like any other optimization problem, has objective
smart and classic distribution systems. For the second case, state functions and constraints, which are as follows:
estimation method should be used to estimate the loads at
different buses using a limited number of measurements. The A. Minimizing the Active Power Losses
objective of this method is to minimize the total operational cost
of the grid, the cost of power purchase from the sub transmission Minimizing the active power losses can be an objective
substation, cost of customer interruption penalties, Transformers function for the optimization problem. This index is considered
Loss of Life expenses, and the switching costs. In [12] a as follows [15]:
dynamic reconfiguration method for a three-phase unbalanced
distribution network is presented. The topology is optimized for !!"## = ?')*(+ $$[('$#)% + ('$&)% - 2'$#'$& cos /$] (1)
the predicted time periods and is adaptive to the time-varying
load demand and DG output while minimizing the daily power Where '$# and '$& are the values of the voltage amplitude at
loss costs. To improve the calculation efficiency, several the two ends of sending and receiving line m, respectively. $$
linearization methods have been proposed to formulate the is conductivity of line m, /$ is the phase difference between the
dynamic reconfiguration as a mixed-integer linear programming two ends voltages of line m, and 23 is the number of lines.
problem. The effectiveness of the proposed method has been
verified by the test results obtained on a modified IEEE 33 node B. Voltage Profile Improvement
Voltage is one of the most important indicators of power
quality, which its profile improvement can be considered as one
of the objective functions in the optimization problem. This
objective function can be expressed mathematically as the