## 3 Characteristic of the Laboratory Hardware and Software Setup  
The laboratory setup for the analysis of the direct impact of harmonic content in the supply voltage on the emission of supraharmonics consists of three 3-phase programmable power supplies KIKUSUI PCR500 LA [32], which, together with the standardised reference impedances (for the phase wire \(\mathrm{z_{A}}=(0.24+\mathrm{j0.15})\)\(\Omega\) and the neutral wire \(\mathrm{z_{N}}=(0.16+\mathrm{j0.1})\)\(\Omega\)) formed the equivalent of a standard low-voltage grid connection point (Figure 4a). The reference impedances follow the standard IEC 61000-3-3 [33] and are recommended to realize the equivalent of the power grid used in the calculation and measurement of the directly measured parameters of voltage changes, voltage fluctuations, and flicker. The materials used in constructions of the impedances preserve the reference value of the impedances in a 50 Hz system with a nominal current up to 5A. The operation of power supplies in the three-phase source mode was obtained using 3P03-PCR-LA three-phase output driver cards [34]. The programmable power supplies were controlled by the Quick Immunity Sequencer [35] installed on a PC that was used to define power supply voltage waveform and subsequent test series. Communication between PC and the programmable AC supply used general purpose interface bus (GPIB interface IB03-PCR-LA) [36]. Using the authorised software different scenarios were created for the input signal with pre-sets of harmonics contribution in the range 0-2 kHz. This application realized communication with the programmable power supply and configuration sets for the harmonics contribution in the supply voltage. It used a waveform bank and the sequence operation function, which is responsible for transfer, execution, and output control of the waveform. In this paper, some selected pre-sets of harmonic contributions were considered: (a) pure sinusoid, (b) limits of harmonics in the low-voltage public network formulated in EN 50160:2010 [3], (c) low-frequency immunity test levels of the equipment defined in IEC 61000-4-13 [30]. These pre-sets were defined in the waveform bank. Figure 3: Comparison of the emission (E), compatibility (C), mains signalling (S), and immunity (I) levels for conducted disturbances and signalling in the frequency range 2–150 kHz (based on standards [16; 17; 18; 19; 20; 21]. The PLC transmission was provided by a compact model containing three electricity meters equipped with PRIME PLC communication modules (two 3-phase and one 1-phase meter) and a data concentrator working in the same technology. PRIME is a specification for narrowband power line communication. The PRIME physical layer is based on Orthogonal Frequency Division Multiplexing (OFDM). The transmission band is 42-89 kHz. In the course of individual research steps, using functions and reports implemented in the PLC concentrator software, the statistics of PLC transmission between the concentrator and the meters were observed and recorded. The view of the constructed laboratory setup is presented in (Figure 4b). In terms of information and communication technologies, the test stand was separate, both physically and logically, local area network (LAN) computer network connecting computers (in this case, meters, concentrator and the controlling computer). The functional diagram of the test stand as a local area network (LAN) is presented in Figure 5.  
Figure 4: The laboratory setup: (**a**) electrical diagram of the test stand, (**b**) view of the power supply system in the form of programmable AC power supplies and model with power line communication (PLC) meters. The recording of measurement data was carried out by the authorised university hardware setup based on National Instrument cRIO technology (Figure 6). In detail, the voltage measurement acquisition is realized by National Instrument C series \(\pm\)10V voltage input module with 1 MS/s sampling rate and 16-Bit resolution [37].