###### Abstract  
The identification of fault locations (FL) on overhead power lines (OHPLs) in the shortest possible time allows for a reduction in the time to shut down OHPLs in case of damage. This helps to improve the reliability of power systems. FL devices on OHPLs according to the emergency mode parameters (EMPs) are widely used, as they have a lower cost. However, they have a larger error than FL devices that record traveling wave processes. Most well-known algorithms for FL on OHPL by EMP assume a uniform distribution of resistivity along the OHPL. In real conditions, this is not the case. The application of these algorithms in FL devices on OHPLs with inhomogeneities leads to significant errors in calculating the distance to the fault location. The use of search algorithms for unconditional one-dimensional optimization is proposed to increase the speed of the implementation of iterative procedures in FL devices on OHPLs by EMPs. Recommendations have been developed for choosing optimization criteria, as well as options for implementing computational procedures. Using the example of a two-sided FL on OHPL, it is shown that the use of search algorithms can significantly (from tens to hundreds of times) reduce the number of steps of the computational iterative procedure. The implementation of search algorithms is possible in the software of typical relay protection and automation terminals, without upgrading their hardware. overhead power line; fault location; emergency mode parameters; search algorithms Article Application of Search Algorithms in Determining Fault Location on Overhead Power Lines According to the Emergency Mode Parameters  
1  
Most FL algorithms for OHPLs, implemented in relay protection and automation (RPA) terminals, neglect the unevenness and inhomogeneity of the distribution of resistivity along the OHPL. Such inhomogeneity of OHPLs occurs for the following reasons:  
* Availability of cable inserts with transition points;
* The use of different types of OHPL towers in certain areas [24];
* Change in the grounding resistance of towers caused by the passage of OHPL through areas with different soils, crossings of rivers, swamps, and reservoirs [25; 26];
* Convergence with other high-voltage power lines in joint corridors;
* The presence or absence of a ground wire in certain sections of OHPL;
* Different span lengths of overhead transmission lines [27];
* Use of different wires types and cross-sections in high-voltage power lines;
* Other factors. There are two main classes of FL on OHPL methods implemented in relay protection and automation terminals: methods based on assessing the parameters of emergency mode currents and voltages (EMP) [28; 29; 30] and traveling wave methods [31; 32; 33]. Moreover, traveling wave methods include the use of active sounding of high-voltage power lines, as well as passive registration of wave processes propagating to the ends of the power line and arising when it is faulted. In practice, FL devices on OHPLs by EMP have a higher error than devices that record traveling wave processes. However, FL devices on OHPLs by EMP have become the most widely used, since they have a lower cost. This is due to a simpler technical implementation, since the components of currents and voltages of industrial frequency are used in FL devices on OHPLs and it does not require the use of analog-to-digital converters with a high sampling rate, as well as high-performance processors [34]. In such devices, algorithms for the FL devices on OHPL by EMP can be implemented, involving single-ended and double-ended (multi-ended) measurements in currents and voltages [35]. Single-ended algorithms do not require the use of communication channels to exchange information about the measured currents and voltages but have a higher error compared to double-ended ones [36]. The inhomogeneity of the OHPL leads to the need to use complex and, as a rule, iterative algorithms with sequential step-by-step organization of calculations.