## 1 Introduction  
Medium- and low-voltage distribution networks have undergone important changes in their physical and computational structures that have transformed these passive grids into to active distribution networks [1, 2]. These changes have been provoked by new regulations regarding the integration of renewable energy resources that have focused on the decaborization of the world's energy matrix [3, 4, 5]. The main goal of electricity distribution networks is to transport electricity to end-users with the necessary standards of efficiency, quality, and reliability. This requires minimizing energy losses and improving transport processes in order to achieve more efficient and competitive networks [6]. To improve the efficiency of electrical distribution networks with regard to reducing power losses, reactive power compensation is one of the most widely recognized methods,given its contribution in this regard and other benefits such as power factor correction, increased transport capacity, improved operation of network lines and devices, voltage stability, and improved voltage profiles. All of these depend on different operating constraints [7], as it is of great importance to reduce losses and minimize investment costs for current distribution systems. One of the best options for energy loss reduction is distributed generation (DG). The authors of [8] presented a decision-making analysis aimed at determining the optimal location and sizes for DG in radial distribution networks, considering the improvement of the voltage profiles and the minimization of the total grid's active and reactive power losses. However, DG may have very high initial installation costs, especially when compared to strategies such as grid reconfiguration and shunt reactive power compensation with capacitors [9]. Capacitive compensation can yield the benefits of loss reduction, power factor correction, and voltage profile improvement to the fullest if the location and size are efficiently determined. However, capacitor banks typically inject reactive power in fixed steps [10], which reduces the positive effect of reactive power injection on reducing energy losses, mainly when daily demand profiles with high variations are considered in the grid operation environment. In order to improve the advantages of using reactive power to minimize total grid power losses, it is possible to use distribution static compensators (D-STATCOMs). These are regulation devices based on a power electronics voltage source converter that add flexibility to the power distribution network. In comparison with a variable-step capacitor bank, a D-STATCOM is a more flexible device, as it injects the exact amount of reactive power in accordance with the network requirements. This is by means of efficient control techniques [11]. It is important to mention that D-STATCOMs can inject and absorb reactive power with very fast dynamic responses through the injection of phase-shifted current to the system at the common coupling point, which aids in power factor correction and harmonic filtering, among other benefits [12]. D-STATCOMs can be located in any of the nodes of the distribution system, so it is important to determine their optimal siting and sizing using efficient optimization techniques for the reduction of energy losses and the minimization of operating costs. In the specialized literature, there are multiple reports regarding the optimal location and sizing of D-STATCOMs in distribution networks. Some of these approaches are discussed in this document. The authors of [12] presented a complete way to determine the optimal location and size of D-STATCOMs via analytical and heuristic optimization methods. In addition, they presented the typical objective functions of the specialized literature to improve network performance, i.e., voltage stability and power losses indicators. The work by [13] proposed a multi-objective particle swarm optimizer to place and size D-STATCOMs while considering simultaneous power grid reconfiguration.