Abstract:
In this paper, the object of the research is 110 kV power grids of three regions of the Republic of Kazakhstan: Astana city, Turkestan region and Shymkent city, as well as West Kazakhstan region. Operators of the studied power grids have no idea about the real levels of voltage and current sinusoidality distortion coefficients, as well as about their relationship with other regime and system parameters of power grids. Similar problems may be faced by other grid companies that do not have the appropriate information and measurement infrastructure to monitor the modes of power grids in terms of voltage and current sinusoidality distortion. In the course of the present study, using portable three-phase power quantity and quality analyzers, it was possible to make daily measurements of mode parameters in 41 110 kV transmission lines with a length of 5 to 120 km. The results of measurements showed that in Astana city, the voltage quality is at a satisfactory level, but the distortion coefficient of sinusoidality of current reaches 39 % (the average level for 15 studied lines is 13.3 %) due to the high concentration of non-linear load of consumers. In the South of Kazakhstan, the voltage and current sinusoidality distortion coefficients are re- latively moderate, but voltage drops are frequent (sometimes up to 10 % or more) due to the large distance between load centers and relatively high population density. In the power grids of Western Kazakhstan, voltage and current sinusoidality distortion coefficients have high levels (reach 14 % and 70 %, respectively) due to low network load with a large length of transmission lines. The analysis makes it possible to trace the relationship of voltage and current sinusoidality distortion coefficients with such regional characteristics as population density, nature of loads, power losses, voltage and current levels.
