Comparison of national standards requirements established to basic electrical energy quality indices

Modern power industry is advancing towards national and regional electrical power systems intensive consolidation. The systems often use different standards in electrical energy quality field. Main line of modern world power engineering development is to create powerful energy pools, covering enormous areas with energy supplies and productive capacities distributed very unevenly. Synchronous networks operation has to provide appropriate quality of the electrical energy. Electric power quality maintenance is not only the most important condition of power network normal operation, but also the condition of modern electric power market operation. The UES/UPS 13109-97 standard and international EN50160 standard, which is in force within UC´TE and NORDEL systems, have several distinctions. Requirements to frequency and voltage levels in high voltage systems and general-purpose systems differ in different countries. The specified parameters are of a great importance for networks integration. Therefore, calculation methods and extreme intervals for the parameters need to be unified.