Problem of Supraharmonic Diagnostics in Power Networks

The increasing number of power electronic devices in power networks causes a significant increase in supraharmonics in these networks. Supraharmonics are spectral components in the 2–150kHz bandwidth that cause high-frequency signal distortions that can disturb the operation of other supplied loads, including in the field of communication or control. In the case of an increase in the occurrence of supraharmonics, it is necessary to identify the source of the disturbance, taking into account, among others, the indication of its supply point. This article presents the results of observations of supraharmonics in modern power networks. Based on results of long-term research carried out in controlled laboratory conditions and under a real power network in industrial conditions, significant diagnostic problems in the identification of supraharmonic sources related to the influence of typical loads in a low-voltage network are indicated. For the presented cases, the propagation of selected spectral components in a low-voltage network with a branched radial topology is presented. The influence of typical loads in low-voltage networks on the diagnosis of supraharmonics in modern power systems is presented. The possibilities of amplification or supression of supraharmonics by loads that are not their source are demonstrated, depending on their supply point in the power network.