Frequencies above the harmonic range - challenge of the future?

Abstract

During the last two decades, the main topic in respect to power quality (beside voltage dips and outages) was and still is harmonic distortion. However, following the development in power electronics with an increasing use of self-commutated converters, problems are shifting slowly to higher frequencies. Voltages with frequencies above the "classical" harmonic range create new challenges and require new solutions. With the largescale introduction of electric vehicles, solar power, wind turbines or similar applications, the level of voltages with frequencies in the kHz range are most likely to increase in the next years. For the operator of a network, by now there exists no sufficient guidance yet in respect to tolerable disturbance levels. Effects of significant voltage levels of higher frequencies are known only to some extent. Such, there seems to be a lot to do in order to ensure a troublefree operation of electric distribution networks in the future. The paper tries to give an overview on the current status of voltages above the harmonic range and to identify critical points which require some efforts in the future.

Evaluation of functional reliability indices for DC-link capacitors in pulse-width modulation converters

“…The ESR model of an electrolytic capacitor is shown in Figure 5 [8,11], where the resistance 0 R accounts for the sum of resistances of foil, tabs, and terminals, 1 R represents the electrolyte resistance, 1 C represents the terminal capacitance, and the parallel combination of 2 R and 2 C represents the dielectric losses. According to Figure 5, the complex impedance of the capacitor is described as…”

“…The high-frequency harmonic distortion of the current and voltage waveforms in PWM converters is produced by the voltage-source inverter using fast electronic switches which are commutated with very high rate of voltage rise (up to 50 kV/μs) and pulse repetition frequency (about 10-50 kHz) [1,2]. As an example, Figures 1 and 2 present the distorted current and voltage waveforms generated by LS800-42K2-TD frequency converter with dc-link and registered by digital oscilloscope during laboratory measurements [3].…”

“…Mostly variable speed drives in industrial environments were found stopping due to dc-link overvoltage. At least in one case investigated, a match between an internal rectifier resonance frequency with the disturbing network frequency contributed to the failure [1,5].…”

Supraharmonic Interactions between Multiple Devices within Different Local Low Voltage Grid Structures

“…Through this supraharmonic distortion, malfunctions or impairments of household devices (LED lamps, mobile phone chargers, laptop power supplies etc.) increasingly occur [1] [2]. Furthermore, already implemented measurements and simulations have shown that supraharmonic disturbances are basically a local phenomenon because of the interaction between multiple devices and the interaction of the devices with the low voltage grid.…”

Optimization Measures for Increased Immunity against High Frequency Disturbances and Reduced Emission in the Range of 2 kHz to 150 kHz Realized on Different LED Lamps

“…Additionally, more and more power electronic components are used for the efficiency enhancement in electric devices. The increasing amount of these high frequency switching techniques like photovoltaic (PV) inverters or active power factor correction (PFC) circuits in switched-mode power supplies with typical switching frequencies above 2 kHz cause increasing HF emissions in the frequency range of 2 kHz to 150 kHz [1] [2]. Therefore, the influence of these HF disturbances on electronic mass-market products like LED lamps have to be investigated in more detail.…”