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The article reveals relevance of the problem of unbalance of line voltages in closed electrical networks with distributed generation as a source of electromagnetic interference, in particular, the problem of electromagnetic compatibility of coastal and ship technical equipment. There is presented mathematical description of the process of occurrence of conductive low-frequency EMF by the voltage unbalance coefficient in the reverse sequence and an algorithm for finding it; using the equations, parameters of this coefficient are described, such as mathematical expectation, standard deviation, probability of occurrence for the billing period, as a result, a computer program has been developed to calculate these parameters; a method for processing the obtained data of power quality indicators according to the found coefficient has been developed; an algorithm for balancing voltages in an electrical network based on finding the most optimal power supply scheme for end consumers (certificate of state registration of an electronic resource No. 23664).

At present, semiconductor converters have found wide application in the electric power industry [6]. One of the most common semiconductor converters is a frequency converter, as it provides a three-phase voltage with adjustable frequency from a three-phase mains voltage. However, it, like other semiconductor converters, is the cause of the appearance of harmonics and, as a result, the non-sinusoidal shape of the voltage curve [1]. Harmonics are the cause of such negative effects in the electrical network as concomitant heating of the windings of motors, transformers, etc., false alarms in distribution networks, asymmetry in industrial networks with three-phase sources when harmonics occur in one phase, the occurrence of noise in communication networks, the influence on adjacent low-current and power cables due to the induced EMF, and also with the appearance of harmonics, there is a need to increase the cross section of neutral wires due to the summation of harmonics multiple of the 3rd in three-phase networks [3]. Therefore, the study of the harmonic components of the voltage is an urgent task. Subject of research: processes occurring in electrical networks with a frequency converter. Purpose of research: to identify the presence of harmonic voltage components in electrical networks with a frequency converter. Object of research: a research stand that simulates the operation of electrical networks with a frequency converter. Methods of research: in the process of performing research, scientific and technical generalization of literary sources on the initial prerequisites for research, methods of the theoretical foundations of electrical engineering and the theory of electrical networks, the method of analytical research, methods of system analysis were used. Experimental studies were carried out by a complex method using the Resurs-PKE device. Results of research he study: based on the studies carried out, it was shown that the frequency converter is a source of harmonic voltage components, while harmonics appear only in certain sections of the electrical circuit.

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