## 1 Introduction  
Reforming electrical power systems is a challenging task to carry out. National policies, environmental issues, economic developments, and applications of power networks based on restricted conditions are major factors involved in reformation complexity [1]. In general, there is no unique appropriate solution suitable to all countries [2]. Therefore, every country performs its own deregulation process according to its regional needs. Deregulation of electrical power systems means revolution and conversion of old rules and the reformulation of existing electrical infrastructure into a new competitive form [3]. In recent decades, the electrical power system has moved from a vertically integrated and monopolistic model to an independent, competitive, and restructured model [4; 5]. A vertically integrated monopolistic model means a sole entity, i.e., government, has full control of all power system sectors (e.g., generation, transmission, and distribution) [6]. However, an independent restructured competitive model signifies unbundling the generation, transmission, and distribution as a discrete identity [7] which allows the integration of various stakeholders (i.e., private entities, market regulators, and independent power procedures) in terms of developing a competitive, affordable, and efficient power system [8]. In this way, this new competitive restructured power system model changed the operation of traditional control of the power system [9]. The primary objective of deregulation is to create a competitive environment, which leads to lower prices, improved customer services, increased innovation, etc. [10]. In summary, deregulation comprehensively changed the electrical world [11]. At the heart of restructuring is the need for competition in the trading of electrical energy as a commodity. However, it is also necessary to maintain a balance between ever-changing load and generation, keeping voltage and frequency within the defined bounds and coping with various outages [12]. Modernization of electrical networks in terms of upgrading existing networks is affected by several factors such as political influence, high cost, space, efficiency, etc. [13]. Therefore, a flexible alternating current transmission system (FACTS) envisioned by the Electric Power Research Institute (EPRI) is a beneficial option to reconstruct electrical utilities [14]. A major thrust of FACTS technology is the development of power-electronics-based systems that provide dynamic control of the power transfer parameters like transmission voltage (V\({}_{\text{T}}\)), line impedance (Z\({}_{\text{L}}\)), and phase angle [15]. Improving power flow is one of the advantages of FACTS devices. This power improvement allows utilities to operate transmission networks nearer to their thermal limits [16]. Similarly, stability enhancement, reliability, congestion management, integrated power networks, and low-efficiency energy resource utilization are driving factors of deregulation. Generally, power systems are interconnected with various power generating units to ensure power supply particularly in high-demand regions [17]. However, this interconnected power system frequently encounters uncertain and unpredictable load demand which can affect the system frequency [18]. In addition, uneven distribution of load adversely affects the voltage profile which increases the interconnected power system's vulnerability to short circuits [19]. That is why deregulated power systems are faced with a surfeit of various technical issues such as voltage drop, congestion management, power losses, rise in transients, etc. [20; 21]. Therefore, transferring power nearer to thermal limits requires comprehensive coordination to ensure the stability and reliability of transmission networks [22]. To ensure stability and ameliorate various power system problems (particularly associated with voltage and frequency), a FACTS is an effective option [23].