Conducted Interference, Challenges and Interference Cases

Abstract

T he chosen theme for this issue is Conducted Interference in Power Electronics. The attention paid to this area has been on the increase over many years due to the use of electron ic switching to condition power, e.g. for rectification, voltage level changes, etc. This causes high rates of change for voltage and current thus contributing significantly to EMC problems.Applications such as Smart Grids have brought electronic switch ing techniques into conventional power networks with the atten dant EMI problems.The first paper by Leferink provides a broad overview of conduct ed interference, including the relevant standards. It is followed by the paper by Luszcz and Smolenski covering harmonics generat ed by PWM converters. Finally, the use of filtering techniques to reduce EMI on power electronic interfaces is addressed in the paper by Smolenski et al. The three papers taken together offer a balanced view of this EMC topic of growing importance. Conducted Interference, Challenges and Interference CasesFrank Leferink is with the University of Twente, Enschede, The Netherlands, and with Thales Nederland B.lI., Hengelo, The Netherlands History Conducted interference is one of the oldest types of interference, but the interest in this topic is rapidly increasing due to the intro duction of new technologies. Already in 1892 a Law on Telegraphy Installations [1] was published in Germany, to prevent interference between power lines and telegraph lines. After a few decades wireless, or radio, became important. URSI was established in the 1920s and CISPR in the 1930, both on radio-communication. The Professional Te chnical Group (PTG) on RFI (Radio Frequency Inter ference) of the lEE, the precursor of the IEEE EMC Society, was created in 1957. These groups were interested in radio interfer ence (only). The military standards published in the 1950's covered also conducted interference but the objective (then) was still to protect the radio spectrum. In 1963 the PTG-RFI was changed to PTG-Electromagnetic Compatibility (EMC)' and conducted effects via power supply networks were included. The MIL-STD 461 (1967) also added conducted emission and susceptibility effects on power supply and interfaces, starting at 30 Hz up to the MHz region [2]. IEC TCn was established in 1973 and tasked for "EMC EMI over more than a century: In the past conducted interference was mains hum, then power supply distortion due to harmonics and flicker, then single (transient) effects causing com puter interference. Now it is rather continuous, non stationary, switching of all kind of non-linear elec tronic devices. between electrical equipment including networks". The energy distribution companies were then strongly involved, as can also be observed from the 555 series of standards on harmonics and flick er. These were changed in the 90's to the IEC 61000-3 series. The energy distribution companies moved their interest to IEC TC8, "Systems aspects for electrical energy supply", and published for instance the EN 50160 [3]. Now TCn, SCnA covers EMC...

Detection Methods for Current Signals Causing Errors in Static Electricity Meters

“…In order to detect current waveforms causing meter errors, four methods are developed and tested on the disturbing current signal depicted in Fig. 1a: 1) Since the rise time of the current waveform might be related to the cause of false static meter readings [1], [3], [4] the most straightforward indicator to detect such wave shapes is the calculation of their derivatives. Thus, the first method is the calculation of the dI/dt.…”

“…However, the use of more power electronics results in the generation of highly distorted currents, entering the distribution grid. In addition to the generated high frequency harmonics (between 2-150 kHz), some of these currents are characterized by sharp transitions with very short rise times which can cause EMI [1], [2]. Such phenomena, mainly observed when non-linear, fast switching loads are connected, can result in large errors in static electricity meters.…”

Misreadings of Static Energy Meters due to Conducted EMI caused by Fast Changing Current

“…In previous research it was shown that conducted EMI can result in faulty static meters readings. In photo voltaic (PV) systems high interference levels were caused by either the power drives of fans [3] or active infeed converters connected to PV systems [4], [5]. These interference levels resulted in lower readings of static meters.…”

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

“…In this regard, it has been shown that significant errors occur when the meters are exposed to interference caused by home appliances. For photo voltaic (PV) systems, errors on the meters were caused by either the active infeed converters [3], [4] or the power drives of fans [5]. In these studies lower readings of the meters were encountered.…”