###### Abstract  
Random Pulse Width Modulation (RPWM) allows controlling the switching signal of power converters in order to reduce the harmonic peaks by spreading the noise spectrum. Currently, many manufacturers of power converters are deploying this modulation scheme in order to comply with Electromagnetic Compatibility (EMC) test requirements. However, when the converters coexist with Power Line Communication (PLC) systems, such as in Smart Grid (SG) applications, resorting to RPWM needs further investigations since it potentially affects the communication channel by increasing the bit error rate. This possible detrimental effect is investigated in this work, by considering a PLC system for automatic meter reading (AMR) implemented in a SG application. To this end, the model of a complete PLC system is implemented in SIMULINK, and Quadrature Phase Shift Keying (QPSK) modulation is used to model the PLC modems in the communication channel. Results show that, even if the deployment of RPWM techniques may lead to an appreciable reduction/spreading of the peaks in the noise spectrum, it may also lead to an increase of the bit error rate on the PLC system. conducted emission (CE); electromagnetic compatibility (EMC); electromagnetic interference (EMI); power electronics; power line communication (PLC); quadrature phase shift key (QPSK); random pulse width modulation (RPWM) +
Footnote †: journal: Electronicspower grid, it is very difficult to achieve the condition of matching with the terminal loads, which is a prerequisite for transmitting high-frequency signals without distortion [12]. Moreover, the presence of power electronics converters in the AC mains represents a source of high-frequency conducted noise, which may cause co-existence issues with the PLC signal. To reduce the Conducted Emission (CE) exiting power converters, alternative modulation strategies, known as Random Pulse Width Modulation (RPWM), are recently gaining an increasing attention, as cost-effective alternatives to the use of traditional EMI filters. Differently from conventional modulation techniques, in RPWM, one or more parameters of the switching pulse, such as pulse position, switching frequency, or duty cycle, are varied randomly to spread the spectral peaks of the noise exiting the converter [13]. Several research studies have been conducted in this framework. For example, in References [14; 15; 16], the reduction of CEs of different power converter typologies by resorting to different RPWM is presented. In contrast, enough research has not been conducted on the effects of power converter modulation schemes on PLC systems. Undoubtedly, random modulation offers the benefit of reducing the CEs by spreading the noise spectrum in the frequency range of interest. However, this may cause an increase in transmission errors and the random modulated EMI can have detrimental effects over a wider bandwidth. In Reference [17], the model of PLC system for SG application is presented. The main objective in Reference [17] is to model a PLC system for smart metering application using SIMULINK. However, a systematic analysis of the interference between the communication system and the noise exiting the power converters with different modulation schemes is not addressed. In fact, in that paper, only PWM modulation is considered for power converters. In Reference [18], it is proven that applying RPWM on a AC/DC converter causes more signal errors or delays in the PLC system compared to conventional Pulse Width Modulation (PWM). Contrary to this, in Reference [19], it is presented that resorting to RPWM modulation allows improving transmission performance. In Reference [20], the effects of power converter modulation scheme on low frequency digital communication systems were studied, and it was proven that RPWM does not have significant effect on digital communication systems.