One of the main directions of the development of electric power systems is the introduction of technologies based on high-power semiconductor switches, such as FACTS devices and HVDC technologies. These systems effectively solve a number of urgent tasks of EPS, connected with asynchronous connection of EPS, transmission of electricity, improve local and systemic flexibility and reliability of EPS, increasing the capacity of network elements that contains a “weak” connection. However, the implementation and operation of mentioned technologies in the EPS determines the need for a wide range of analysis and research that can only be done with the help of mathematical modeling.