Processing techniques and metrics for the assessment of conducted emissions up to 150 kHz in renewables-based power systems

The work has analyzed the feasibility of some processing techniques and metrics for harmonics and supraharmonics measurements, up to 150 kHz, according to current standards requirements, in renewables-based power systems. The study has been supported by extensive experimental tests, made on both reference test signals and on-field measurements. As regards the low-frequency range (up to 2.5 kHz), the standards accurately define the metrics and accuracy requirements for developing a device compliant with into the highest accuracy class (Class A/I). Thus, the study has been focused on the development and characterization of proper metrics and techniques for implementing such measurements on a low-cost device. Results demonstrated the feasibility of the proposed solutions, which may allow the integration of further metrics, even for covering a wider frequency range. For the higher frequency components (up to 150 kHz), standards only provide indicative information on possible metrics, leaving room for the implementation of different solutions, each having its own advantages and drawbacks in terms of results compatibility and implementation feasibility. In this viewpoint, some modifications of standard metrics could allow reaching a better trade-off between such needs, enabling the possibility of metrics integration on on-field devices. Results obtained from real on-field signals show that the non-univocal definition of the metrics for the evaluation of conducted emissions in generation and storage systems from renewable sources, both for the ac and dc sides of the converters, represents a still open problem, due to the impact that these phenomena can have in terms of both PQ and energy efficiency levels.