Supraharmonic Emissions in Power Distribution Systems

Supraharmonic emissions are non-sinusoidal distortions in the frequency band between 2 kHz and 150 kHz arising chiefly from the widespread use of power-electronic converters in distribution networks. These converters—employed in electric-vehicle chargers, renewable energy inverters and advanced lighting systems—switch at high frequencies to regulate voltage and current, inadvertently injecting high-frequency components into the grid. Unlike conventional harmonics tied directly to the fundamental mains frequency, supraharmonics propagate through complex networks, interacting with the frequency-dependent impedance of cables, transformers and filter elements. Such emissions can induce resonances, lead to undue heating of network components, accelerate dielectric ageing, trigger maloperation of protective devices and disrupt power-line communication. International standardisation efforts are under way to establish measurement frameworks, emission limits and mitigation strategies. Current research spans the characterisation of supraharmonic sources, the development of high-resolution detection algorithms and the modelling of their propagation and summation. Understanding these phenomena is imperative for ensuring power quality in increasingly electrified and digitally controlled distribution systems, and for harmonising grid-integrated technologies with the broader goal of a reliable and efficient energy transition.

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Supraharmonic Emissions in Power Distribution Systems publication trend

The graph below shows the total number of articles in supraharmonic emissions in power distribution systems across all publications each year (not limited to Nature Index journals).

Technical terms

Supraharmonic emissions: Non-intentional voltage or current distortions in the range 2 kHz to 150 kHz produced by high-frequency switching in power-electronic devices.

Grid impedance: The frequency-dependent opposition to current flow in a distribution network, determined by the inductance, capacitance and resistance of its components.

Resonance: Amplification of voltage or current at specific frequencies when inductive and capacitive reactances within the network balance, potentially leading to elevated distortion levels.

LCL filter: A three-element passive filter (inductor–capacitor–inductor) incorporated into converter interfaces to attenuate switching harmonics and manage current ripple.

Diversity factor: A ratio expressing the relation between summed supraharmonic currents from multiple sources and the arithmetic sum of individual emissions, reflecting mutual interaction and absorption.

References

1. The impact of V2G charging stations (active power electronics) to the higher frequency grid impedance. Sustainable Energy Grids and Networks (2024).
2. Summation of supraharmonic currents (2–150 kHz) from EV fast charging stations. Electric Power Systems Research (2023).
3. The Effects of Supraharmonic Distortion in MV and LV AC Grids. Sensors (2024).
4. Supraharmonics in Power Grid: Identification, Standards, and Measurement Techniques. IEEE Access (2021).