## 1 Introduction  
Emergency disturbances, such as single-phase or multi-phase short circuits (SCs), frequently occur in electric power systems (EPSs). These scenarios result from damage to generating and/or electric network equipment due to external or internal causes, as well as errors made by maintenance personnel [1; 2]. The emergency shutdowns of individual types of equipment alter the topology and power flows in an EPS, leading to overloads of the generating and/or network equipment that remains in operation and a decrease in voltage at the nodes of the electric network [3; 4; 5]. Short circuits are normally localized by the action of protection devices that operate without time delay or with the minimum possible time delay to ensure selectivity. Nevertheless, failures in the operation of individual units of equipment cause systemic accidents, accompanied by significant losses for industrial and commercial consumers of electricity [6; 7]. Analysis of the causes of system failures reveals that the EPS structure has \"bottlenecks\" and the operation planning does not consider the possibility of cascading failure processes. Their likelihood is especially high during periods of extensive repairs of generating and electric network equipment, when EPS topology may change significantly [8; 9]. Consequently, to ensure the survivability of the EPS in the event of emergency disturbances during repairs, it is essential to provide appropriate topological and operational strategies [10]. The works addressing the topic at issue indicate that despite the implementation of topological and operational measures in EPSs, many countries experience system-wide accidents, including cascading failures, almost every year [11; 12; 13]. Below, consideration is given to some examples:  
* Massive power outages of more than 30,000 MW that lasted for 7 h in the USA in November 1965 [14; 15];
* Massive power outages of more than 1800 MW that lasted for 25 h in the USA (New York) in July 1977 [16];
* Large-scale power outages of approximately 8000 MW that lasted for 4 h in Japan (Tokyo) in July 1987 [17];
* The disconnection of the total capacity of power consumers equal to 11,850 MW that lasted from a few minutes to several hours in July and disconnection of 28,000 MW that lasted from a few minutes to nine hours in the western United States in August, 1996 [18; 19; 20; 21; 22];
* The shutdown of intersystem overhead power transmission lines (PTLs) between the northeastern United States and Canada in August 2003, with an outage size of 61,800 MW, that lasted for 42 h (except for consumers with backup power sources) [23];
* Power outages of 724 MW that lasted for 37 min and affected consumers in the UK (London), on 28 August 2003 [24];
* The disconnection of electricity consumers with a total capacity of 20,000 MW that lasted for 20 h in Italy on 28 September 2003 [25];
* System failure accompanied by the disconnection of electricity consumers with a capacity of 2500 MW, with the duration of outages for individual consumers reaching up to 32 h in Russia (Moscow) in May 2005 [26; 27; 28];
* Power outages of a total capacity of 110,000 MW that lasted for 8 h in India, on 30-31 July 2012 [29];
* Blackout in South America (Argentina, Paraguay, Uruguay) that simultaneously left 48 million people without electricity on 16 June 2019 [30];
* Outages that affected more than 10 million people, lasting for 16 h, in Indonesia (Jakarta) in 2019 [31];Power outages that resulted in disconnection of a 973 MW capacity, affecting 1.15 million people in the UK (London) on 9 August 2019 [32]. The considered examples show that despite the evolution of EPSs and the adoption of modern devices designed to control operating conditions, the number of system failures is practically not decreasing, and their consequences are becoming increasingly more significant for consumers of electric power.