## 1 Introduction  
Electrical distribution networks are a critical component of the electrical power system. They are generally denser and more complex than the transportation networks that supply them through transformer stations [1]. Given the ever-increasing complexity of distribution networks, automation of previously manual tasks is becoming increasingly more important. To that end, new tools that aid in the operation of these networks, known as advanced automation functions in the literature, have emerged. The role of these functions is to provide the distribution network operator with the ability to solve network problems as they occur [2]. Furthermore, in order to ensure a secure economically optimal electricity supply, it is important to use distribution network reconfiguration to find the best solutions based on the requirements and constraints defined by the operators. Distribution network reconfiguration can be defined as the process of altering the topological structures of the distribution network by changing the open/close status of the sectionalizing and tie switches. This process can improve the performance of the system according to different particular objectives and constraints [3]. In recent years, applied researchers have become increasingly interested in finding the optimal distribution network reconfiguration taking into account several objectives. A close literature review indicates that reliability enhancement has always been one of the main objectives [4]. Besides, much attention was focused on other criteria such as active power loss minimization, load balancing. and voltage stability security margin [5,6]. The reliability of an electrical network is described as the ability of the power system to supply consumers uninterruptedly with an adequate quality electricity supply. Some of the methods for reliability enhancement are as follows: adding new devices for protection, utilization of more reliable equipment to avoid contingencies, fast switching and reclosing schemes, accurate precise fault allocation techniques, fast crew to speed up the repair process, and system topology reconfiguration [7]. The reliability of distribution networks has become increasingly important in the deregulated power sector [8,9]. To address these issues, distribution network reconfiguration is regarded as a cost-effective and efficient way to increase system reliability. The reliability index considered to measure the reliability of the distribution network in this work is the energy not supplied (ENS). This index forecasts the amount of energy that will be lost due to failures over a given time period. Based on the accurate estimation of the ENS index, appropriate planning and design initiatives in distribution systems can be implemented to provide consumers with cost-effective and reliable power. In addition to reliability improvement, active power loss reduction of a power system enhances the delivery of better power quality [10]. There are many measures to reduce active power losses inthe distribution system such as operating at higher voltage levels, installing a distribution generator or capacitor, and network reconfiguration. specifically, network reconfiguration is an effective measure to reduce active power losses because it does not require any additional cost. The objective functions for the network reconfiguration considered in this work are the active power losses and ENS reliability index. The distribution network topology can be altered by performing the action of opening/closing on the sectionalizing and tie switches. Since the number of switches isrelatively high in a large distribution network, it is almost impossible for the operator to find the best topology without an optimization study. The distribution network reconfiguration problem was first solved by [11]. Since then, many algorithms have been developed for reliability improvement and power loss reduction in distribution networks such as exhaustive search, ant colony optimization, and cuckoo search algorithm [12, 13, 14, 15, 16].