On waveform distortion in the frequency range of 2 kHz–150 kHz—Review and research challenges

Power quality issues in the electric power system of the future

Harmonic emissions have been changed in distribution networks, with respect to frequency range and magnitude, due to the penetration of modern power electronics systems. Two new frequency ranges 2–9 and 9–150 kHz have been identified as new disturbing frequency ranges affecting distribution networks. This paper presents the effects of grid-connected three-phase systems with different front-end topologies: conventional, small dc-link capacitor, and electronic inductor. A power converter with a small dc-link capacitor can create a resonant frequency with the line impedance below and above 1 kHz depending on the grid configurations. The resonant effects depend on many factors, such as load power levels, filter types, and the number of parallel drives. These issues can affect the grid current harmonics and power quality of the distribution networks. Analyses and simulations have been carried out for three different topologies and the results have been verified by experimental test at system level. Current harmonic emissions have been considered for 0–2, 2–9, and 9–150 kHz frequency ranges.

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Harmonic Emissions of Three-Phase Diode Rectifiers in Distribution Networks

This paper discusses some of the electromagnetic-compatibility issues concerning the use of power lines for communication. Based on a series of measurements performed in a laboratory environment and in the field, five different types of interactions between communication and end-user equipment are distinguished. Measurement examples are shown for several of these types. It is concluded that the creation of a low-impedance path by end-user equipment is the main cause of interference.

Interaction Between Narrowband Power-Line Communication and End-User Equipment

This book links the challenges to which the electricity network is exposed with the range of new technology, methodologies and market mechanisms known under the name "smart grid." The main challenges will be described by the way in which they impact the electricity network: the introduction of renewable electricity production, energy efficiency, the introduction and further opening of the electricity market, increasing demands for reliability and voltage quality, and the growing need for more transport capacity in the grid. Three fundamentally different types of solutions are distinguished in this book: solutions only involving the electricity network (like HVDC and active distribution networks), solutions including the network users but under the control of the network operator (like requirements on production units and curtailment), and fully market-driven solutions (like demand response). An overview is given of the various solutions to the challenges that are possible with new technology; this includes some that are actively discussed elsewhere and others that are somewhat forgotten. Linking the different solutions with the needs of the electricity network, in the light of the various challenges, is a recurring theme in this book. Table of Contents: Introduction / The Challenges / Solutions in the Grid / Participation of Network Users / Market Incentives / Discussion / Conclusions

The Smart Grid: Adapting the Power System to New Challenges

This paper presents different methods to describe voltage and current distortion in the frequency range 2 to 150 kHz. The time-frequency domain was shown to give additional information next to the time- and frequency-domain representations. Measurements of different devices and at different locations showed remnants of the switching frequency of the power electronics as well as lower frequency oscillations around the current zero crossing to be present in voltage and current. The voltage distortion is shown to vary a lot during the day and between locations.

C Martin Lundmark

Papers

Measurements of High-Frequency (2–150 kHz) Distortion in Low-Voltage Networks