The impact of modern devices on high-frequency grid impedance
The integration of power electronic systems such as PV inverters, heat pumps, and EV charging stations is reshaping the demands placed on grid operators. These technologies emit high-frequency signals (often exceeding 500 kHz) that significantly influence grid impedance – posing potential threats to power quality (PQ) and grid stability.
Why is frequency-dependent grid impedance so important?
Frequency-dependent grid impedance describes how an electrical grid responds to high-frequency currents, particularly in the range of 2 kHz to 500 kHz. As the deployment of power electronics increases, this characteristic becomes increasingly critical. A precise understanding of frequency-dependent grid impedance is essential for:
Identifying critical resonance points
In complex distribution networks, resonance phenomena caused by capacitive and inductive components can occur. These can lead to voltage distortions and adversely affect the operation of inverters, frequency converters, and charging infrastructure. Only through accurate impedance measurement can such points be reliably identified and evaluated.
Analysing grid disturbances
Switching operations, harmonics, and high-frequency injections (e.g. from PV inverters) generate disturbances that propagate through the grid via its impedance. Excessive or insufficient impedance at certain frequencies can amplify these effects. Measuring the grid impedance enables targeted analysis and mitigation of such disturbances.
Verifying regulatory compliance
Standard IEC 61000-3-12 (VDE 0838-12) requires the limitation of harmonic currents – depending on the actual grid impedance. A realistic assessment of regulatory compliance is impossible without knowledge of the frequency-dependent grid impedance. Accurate measurement is therefore essential for planning, operational and certification processes in distribution networks.
High-resolution grid impedance measurement with ONIS by morEnergy
morEnergy is the only provider offering a field-proven measurement solution for real-time impedance monitoring up to 500 kHz. The ONIS system detects critical changes in the grid early and provides the data foundation for well-informed corrective actions. Our technology was recognised as early as 2020 in etz, the technical journal of the VDE Publishing House, and has since remained a leading solution in the field of power quality monitoring.
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