Improvement of Short-Circuit Calculation Results Reliability for Large Electric Power Systems

The magnitude of the short-circuit currents in the power system has a significant influence on its operation modes and also defines the principles and approaches to prospective designing and development planning. The paper presents the results of the analytical research, within the framework of which the comparison of the calculated values with the actual short-circuit currents fixed in the power system by means of fault location devices was performed. The analysis was carried out for 155 cases of faults in the regional power system under consideration, resulting in significant differences between the actual and calculated values. In this paper, the authors present the analysis of the key topological and operational factors affecting the magnitude of the error in calculating the short-circuit current values as well as classification and ranking of the factors by the effect on the total deviation of the calculated value of the short-circuit current from the actual value. Based on the results of the study, recommendations are formulated that can be used in the designing and operational activities of energy utilities to improve the reliability of short-circuit currents calculation.