Statistical Time-Domain Analysis of Equipment in Low-Voltage Networks

Abstract

The increased use of non-linear equipment results in conducted electromagnetic interference problems. As an example, static energy meters, used to measure the energy consumption in households, show misreadings due to pulsed currents from a speed controlled water pump or dimmed lighting equipment. To determine the existence of similar equipment in low-voltage networks, this letter surveys current waveforms drawn by equipment in the low-voltage network. These waveforms are analyzed and compared to critical waveforms from previous research that caused static energy meter interference. In this way the extent of critical situations in a real-world environment is determined. The equipment survey is performed using a multi-channel timedomain measuring method able to capture the voltage and currents synchronously. Then using a time-domain parametric model a statistical overview of parameters such as the charge, crest factor, peak value, pulse duration, and rising slope is given. The survey shows the existence of a large variety of non-linear signals, and 43% contained critical parameters related to static energy meter interference.

Interference on Static Energy Meters Resulting From Droop of the Current Transformer

“…Using two on-site studies it was found that those interfering waveforms are representative for the actual residential grid. First, an extensive study on the waveforms from individual appliances that are typically connected in a residential grid showed that 43% of the surveyed equipment has parameters inside the critical range related to the static energy meter interference [15]. Second, the waveforms that occur at the meter connection point are surveyed in [16] at representative sites including modern sites that include an electric vehicle (EV) charging station and a photovoltaic (PV) installation.…”

From Susceptible Static Energy Meters to Electromagnetic Compatible Energy Measurements

“…To assess the underlying problem of the SM misreadings, this chapter describes a measurement technique for characterizing the currents that SMs are usually exposed to. The work presented incorporates the research published in [34], [77]- [80].…”