## 3 Minimizing Active Power Losses in Power Transmission Systems Using GWO
### GWO in FACTS Devices  
FACTS, which stands for flexible alternating current transmission system, is an electronic device that can be used to solve problems with the strength of electric power that can be sent. It has been explained in detail how the grey wolf optimization method can be used to reduce overall system losses and voltage variation through the optimal placement of FACTS devices [49]. The GWO method, which is based on wolf social hierarchy and hunting behavior, is used to find the best solution for the whole world. It has been proven to be a good way to find the best global solution while keeping a good balance between exploration and exploitation. According to experts in the field, there is an alternative to traditional devices for flexible control and growth in transmission line power transfer capabilities. This alternative is called the series-shunt FACTS device, which is also called the unified power flow controller (UPFC). As the number of UPF on a network grows, it becomes important to carry out calculations to figure out the right number of FACTS devices that would cause the least amount of loss in both normal and emergency situations. A Nigerian National Grid transmission line with 31 buses and 330 kV of power was used to test the method [50]. The MATLAB programming environment was used to do this. The GWO method is used with AGC and multiple FACTS devices to choose gain settings for the PDF plus (1 + PI) controller, which is based on the PDF plus (1 + PI) controller. In this work, PI and PID controllers, as well as a PDF plus 1 + PI controller and GWO, are used to look at how the system moves. Three-area FACTS devices were compared, and the IPFC's dynamic response was found to be superior to other FACTS devices, such as the SSSC, TCSC, TCPS, and inter-line power flow controller (IPFC). This is because of the PDF plus (1 + PI) controller and GWO technique [51]. The FACTS controls the flow of both active and reactive power through the transmission lines that connect to the GWO. These lines are in series with the GWO [52]. It might be easier to reduce harmonic distortion in a system if an active power filter (APF) is used. A non-linear optimization problem with constraints must be solved to find and size the APF in a radial distribution system (RDS). In this paper, GWO and cost effectiveness are discussed in detail regarding the OPSAPF method. Scientists came up with the GWO, which is based on things that happen in the world. As a result, both exploration and exploitation methods have the same optimization properties. For harmonic voltage distortion (THDV), individual harmonic voltage distortion (IHDV), and the size of the APF to be safe, they must all meet three inequality rules. To obtain a harmonious load flow and simple integration, a 33-bus system should be used [53]. FACTS devices such as the UPQC have shown that the electric power system has become more stable in the last few years. The unified power quality conditioner (UPQC) was able to work well with power systems because of a lot of other changes. Despite this, the system's reliability did not get better, and there was no signal that the system could react to. A hybrid strategy is now being used to improve the quality of electrical power. This is a search engine optimization tool called \"Cuckoo GWO.\" It is made up of the cuckoo search algorithm (CSA) and GWO [54]. This method, as previously stated, considers the cost of UPQC devices as well as the voltage stability index (VSI) and power losses to figure out where UPQC devices should be placed. Grey wolf optimization (GWO) has been used to make a new FACTS allocation method, called the improved grey wolf optimization method (IGWO). For real power losses, voltage changes, and system costs, the improved grey wolf optimization method (IGWO) is used to find the best location and size for the various FACTS controllers. After its first appearance, the UPFC quickly became known as a useful FACTS device. It has since been used a lot.