## 1 Introduction  
Increases in power losses at the consumer's end necessitates an increase in the generation of energy, and its effects on the power system are manifold. While it increases the operation and maintenance costs, it also increases the stress on the power system, leading to the voltage profile deterioration and several other challenges [1]. Increasing the generation may also require additional time to respond to the problem and incur additional costs for installation of newer generation plants/facilities. It is noteworthy that the losses and voltage profile significantly depend upon the reactive power injection. Therefore, reactive power injection, if done optimally, can be more time- and cost-efficient [2]. Various methods are used for injecting reactive power in distribution system for reducing power losses, including the method of capacitor placement [3], distribution generator (DG) [4], FACT devices [5], and synchronous condenser (SC) [6]. The SC is a conventional and well-established method for power loss compensation. However,nowadays, SCs are rarely used because they require special arrangements to start. They also cannot be adjusted rapidly with changes in load [7]. In recent years, (DGs) have been widely preferred, as they could (i) minimize power losses; (ii) improve the voltage profile; and (iii) due to the green onsite generation. Due to the fact that the conventional power system is designed for unidirectional power flow, additional care must be taken in order to avoid reverse power flow [5]. Using (FACTs) devices, power flow and oscillation damping can be controlled. However, initial and maintenance costs of these devices are very high. They may also not achieve sufficient damping over oscillation [8]. Capacitor placement in the distribution system for minimization of power losses is widely used because they are more economical and reliable than the methods discussed above [9]. Other advantages of capacitor placement are power loss minimization, improvement in voltage profile, power factor improvement and control, and minimization of total system cost. However, improper installation of the capacitor in a distribution system can increase power loss and worsen the voltage profile [10]. In order to achieve optimum benefits, the optimally sized capacitors should be installed at proper locations [3], which is a challenging task [11]. This optimization problem includes finding the total number, location, and optimal size for the capacitors, so that maximum benefits can be achieved while satisfying system constraints. To tackle this complex optimization problem, an effective optimization tool is required because the nature of these problems is non-linear and complex. The available algorithms in the literature for solving optimization problems are classified as analytical, artificial intelligence, numerical programming, and heuristic algorithm [12]. For optimization of the power system, classical methods have been proposed by researchers in [13]. Solving optimization problems with classical approaches has limitations, such as the difficulty to escape local minima and being unable to handle discrete control variables properly [14]. Recently, researchers have paid more attention to the optimal capacitor allocation problem--a combinatorial problem used to determine heuristic approaches [15]. An optimization technique called grasshopper optimization algorithm (GHOA) is used to allocate a capacitor bank in a distribution system optimally [16]. However, the installation and maintenance cost was not considered in this study. A two-loop hybrid method is utilized for placing capacitors optimally with the objective of maximizing the annual profit of the distribution system [17]. [PERSON] et al. used the flower pollination algorithm (FPA) to determine the optimal size and location for the capacitors with the objective of minimizing losses and costs of the capacitors [18]. However this algorithm sometimes converge prematurely, which increases the possibility of inaccurate results.