Pankiv V. Methods and means for increasing accuracy of current primary measuring channels of power system digital substations

The object of the research: electromagnetic processes in three-phase primary measuring channels of current of digital substation. The dissertation purpose is development of scientific and technical bases for the construction of high-voltage three-phase primary measuring channels (PMC) of current of digital substation in the direction of development of methods and means for increasing their accuracy under transient conditions of electric power systems with saturation of iron core of current transformers (CT). The methods of the research: numerical, analytical and experimental methods in the field of modeling of electromagnetic processes in CT and three-phase PMC of current and digital processing of output currents of PMC. Theoretical and practical results and innovation: based on the theory of the Jiles-Atherton ferromagnetic hysteresis mathematical model of CT was perfected by the description of its anhysteresis magnetization curve by second order rational function instead of the modified Langevin function; a mathematical model of a three-phase PMC of current was developed composed of the model of the group of CTs developed in the Matlab Simulink software environment and developed software, which performs the functions of filtration of secondary currents of CTs, their discretization and digital processing; the method of real-time detection of the saturation of iron cores of phase CT and the periods and duration of distortion of their secondary currents as part of PMC of current was developed; the methods of real-time determination of the parameters of the input currents of PMC under the short-circuit in the electric power systems and the increasing the accuracy of measuring the fault currents of three-phase PMC under the short-circuit in electric power systems and saturation of CTs iron cores were developed. The subject and the degree of implementation: the obtained results in the form of models, methods and software were implemented at Small private enterprise «ANIGER» during the development of new modifications of «Regina» devices, used during the execution of a number of research works carried out at the Institute of Electrodynamics of the National Academy of Sciences of Ukraine, as well as in the educational process of the National Technical University of Ukraine «Igor Sikorsky Kiev Polytechnic Institute». The effectiveness of the implementation: the developed method of increasing the accuracy of PMC allows to reduce the total error of PMC under transient condition of electric power systems and saturation of iron cores of its CTs from 70-90% to 6-15%. The sphere of usage: organizations and enterprises engaged in the design, development, manufacture and operation of electromagnetic CT, PMC with digital output, relay protection devices and monitoring systems of parameters of electric power systems conditions.