On-site Waveform Characterization at Static Meters Loaded with Electrical Vehicle Chargers

Abstract

For assessing the underlying problem behind the static meter misreadings, a measurement technique must be developed for characterizing the currents that static meters are usually exposed to. In previous studies it was shown that misreadings of the static meters occur when impulsive currents are drawn from the net, even with standalone commercial off the shelf equipment. Time domain electromagnetic interference (EMI) measurements create a novel opportunity for analyzing these noisy waveforms and identifying their fundamental parameters. The next step is extending this measurement approach to on-site scenarios in which these kind of waveforms coexist in superposition with other components that are properly measured by the static meter when they occur alone. This especially holds for up and coming technologies like electric vehicle (EV) charging stations. The characterization is intended in the future for describing realistic waveforms that can be used as new standardized type-testing signals, which will be employed to produce novel standards. Time Domain Electromagnetic Interference Measurement and Post-processing System (TEMPS) software is used in conjunction with a low cost baseband digitizer to measure the waveforms of EV chargers on four different lines, that is the three phases (L1, L2, and L3) and the neutral line (N) simultaneously. To distinguish the impulsive nature of the waveforms a statistical approach is performed in the form of an amplitude probability distribution (APD) diagram. Furthermore the multichannel capability of the low cost digitizer is utilized to achieve a frequency range extension by using two probes simultaneously with different frequency ranges.

Estimation of Static Energy Meter Interference in Waveforms Obtained in On-Site Scenarios

“…Site 1 uses a three-phase system, while sites 2 and 3 use a single-phase system. Some preliminary results of sites 1 and 2 were already published in [17] and [18].…”

“…In [15], the existence of current waveforms with fast inclining slopes that occur in low-voltage (LV) customer terminals is shown. Moreover, within the framework of the MeterEMI project [16], surveys are performed in modern LV networks, including networks with electric vehicle (EV) charging stations [17], and PV installations [18]. It was found that the on-site surveyed waveforms are typically a superposition of the fundamental frequency, other frequency components including pulses, and low-amplitude random noise.…”

Reduction of Static Electricity Meter Errors by Broadband Compensation of Voltage and Current Channel Differences

“…Because a time shift is equivalent to a phase angle proportional to frequency, this solution is only suitable for pure sinewaves consisting of a single frequency, such as the mains frequency. However, for waveforms with a rich spectral content in both voltage and current, such as highly-distorted broadband waveforms caused by non-linear loads such as dimmed LED lamps [7,8], other consumer electronics [17,18] or renewable energy sources [19], this solution results in miscalculations and, consequently, reading errors.…”

On-Site Waveform Survey in LV Distribution Network using a Photovoltaic Installation

“…Further examples of such representative situations are LV distribution networks connected to photovoltaic (PV) installations and electric vehicle (EV) charging stations. An EV charging station was already investigated and the results were reported in [11].…”