The development of methods to study the propagation of supraharmonics in LV and even MV grids is a current research topic among the power quality community, which has been motivated by the efforts to establish limits for non-intentional supraharmonic emissions and planning levels. The assessment of how much distortion a bulk use of power electronics devices can inject into the grid is necessary before stating emission limits and planning levels for supraharmonics. To address this issue, the development of suitable models that can predict the supraharmonic emission from a low-voltage installation as a whole is required. This article presents a comparison of models for the summation of supraharmonics. An improved model for the summation of supraharmonics is proposed, which is validated experimentally. It is shown that by using the proposed model, predictions of supraharmonic propagation can be accomplished. Furthermore, it is demonstrated experimentally that, with the increasing number of supraharmonic emitting devices, the supraharmonic current distortion injected into a grid by an installation increases up to a maximum value and then decreases due to the capacitive nature of power electronics appliances existing in low-voltage networks.

This paper investigates the characteristics of emission in the frequency range 2-150 kHz (supraharmonics) in time and frequency domain and how it propagates under different scenarios posed by the customer connections and changes in the grid. The analysis is based on measurements performed in a low-voltage installation, considering the simultaneous operation of a set of PV inverters and LED lamps in order to create changes in both impedance and emissions. The results confirm that supraharmonics tend to interact with nearby devices in the customer installation. As the number and constellation of emitting devices change so does the propagation of the supraharmonics. The propagation towards the grid can either increase or decrease with the increasing number of connected devices depending on the ratio between the impedances of the device and the grid impedance. Devices’ technology plays an important role in defining supraharmonic characteristics, emission levels and propagation. Finally, a qualitative analysis of the individual devices’ impedance and discussion of some of the practical aspects is provided.

Supraharmonic (SH) propagation is determined by the impedance of both the grid and the devices connected to it. Few attempts to characterize this combined dependency have been done. The interest of grid operators is in counteracting the propagation of SHs upstream to maintain power quality. Characterizing the impact of impedance on SH propagation gives information to strategically counteract this propagation to the upstream grid. This paper presents an experimental case study for the assessment of the sensitivity of SH propagation to changes in impedance of the grid at the delivery point. The results are then compared to the changes of SH propagation provoked by the connection of low-voltage (LV) equipment.

Supraharmonic (SH) propagation depends on the impedance of both the grid and the devices connected to it. Few attempts to quantify the impact of the customer's load variability have been done. The interest of grid operators is in counteracting the SH propagation upstream to maintain power quality. Quantifying the impact of impedance on supraharmonic propagation gives information to strategically counteract this propagation to the grid. This article presents a method for analysis of SH propagation that uses a stochastic approach to describe the impact of low-voltage (LV) loads. Scenarios of a strong and a weak grid are presented to study the impact of reinforcement grid measures.

Supraharmonics (SH) have proliferated in low-voltage (LV) and medium-voltage (MV) grids due to the increasing use of technologies emitting distortion in the range 2–150 kHz. Currently, no recommended practices to assess the effects of SH on the electrical system exist. The propagation of SH through LV and MV grids leads to interference with the elements for power delivery and end-user equipment, e.g., light flicker, aging of capacitors and cable terminations, audible noise, and interruption of electric vehicle (EV) charging. As such incidents happen more often, the need for guidelines that facilitate the diagnosis of problems related to SH arises. Different features of the SH distortion are responsible for different interferences. This article introduces guidelines for the evaluation of the impact of SH based on the morphology of the interference. The evaluation is performed with easy-to-use methods and formulas directly related to the characteristics of the SH distortion. The adverse effects of SH considered are audible noise, light flicker, tripping of LV residual current devices (RCDs), and MV cable termination failure. This work interests field engineers and researchers facing problems related to SH; it also serves as a guide for further research.