: pp. 64-72
Lviv National Agrarian University
Lviv Polytechnic National University
Krakow University of Technology, Poland

New  technical  developments,  such  as  in  the  field  of  frequency  drives  of  technological  units,  electrified transport, wind, and solar power plants, apply devices built on the basis of powerful transistors. Modern devices designed on these elements  are  powerful  generators  of  higher  harmonics  of  currents  that  penetrate  the  grids  of  power  systems.  It  requires  the development of measures and means to limit the higher harmonics of currents in the electrical grids. 

The method and the means of determining the voltage distortion coefficient by higher harmonics in electric networks are considered in the paper. This factor belongs to the group of main indicators of electricity quality, which are regulated by national standards and international standards for electricity quality. The shortcomings in the existing methods are pointed out and a method is proposed which allows  increasing  the accuracy of  the specified  indicator significantly. Based on  the actual measurement and using certified equipment, it is shown that the error of the measurement results and their calculation by using the proposed method does not exceed 1 % of the nominal voltage, while the existing norms of this factor, depending on the voltage of the power supply system,  regulate value of error  from 2 % to 8 %. Considering  that  the commonly used measuring equipment does not  take into account the interharmonics and exponential components in the supply voltage, the proposed method regarding these components over a predetermined time interval, much larger than one period, provides higher accuracy for determining the distortion factor. By examining  all  harmonics  and  interharmonics,  including  zero  and  exponential  components,  we  provide  substantially  higher accuracy than the existing methods described in the standards and norms for electricity quality. 

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