The most important goal of power system operators is to provide the power required by the consumer at a constant voltage, without harmonics and with a certain frequency. The optimal situation in the production and transmission system is that this system should be able to produce the desired power and the desired consumer. This demand is usually considered in the initial design, but over time due to changes such as: consumption growth, connection of other networks to the previous network, construction of new lines and power plants, etc., upset this balance and put some restrictions. They create power in the operation of the network. In the early days of power systems, they were relatively simple and were designed to be able to operate independently. In addition, transmission system designers have found that AC transmission systems must be controlled by devices to respond to dynamic conditions. Transmission systems were first controlled by classical power control devices under constant conditions or slow load changes and current power control and voltage changes. The dynamics of the system were performed with large stability ranges to cover the critical conditions predicted by faults, line and generator outages, and equipment faults. These factors made transmission systems less efficient and the only solution needed to power them was to build new lines. Therefore, the use of FACTS and D-FACTS devices was proposed, which solved many of the above problems and has a higher efficiency. Manuscript profile