Calculation of resonant modes in electric networks in case of sources of higher harmonics

Subject of research: resonant modes in electrical networks 35/6/0.4 kV of oil producing enterprises. Purpose of research: calculation of frequencies at which the occurrence of resonant modes is possible, determination of the multiplicity of overvoltages in the nodes of the electrical network. Object of research: distribution electrical networks 35/6 kV, groups of non-linear electrical receivers 0.4 kV, which are sources of harmonic distortion. Main results of research: a method for calculating resonant modes in the presence of sources of higher harmonics is presented. The frequencies at which the occurrence of resonances is possible are determined; for each voltage class, the multiplicity of arising overvoltages is determined. Physical measurements of non-sinusoidality levels were carried out using certified equipment. Based on a comparison of the calculation results and the actual level of higher harmonics in the electrical network, a technically sound decision is made to install filter-compensating devices to suppress higher harmonics and prevent an emergency.