# Multi-Point Time-Synchronized Waveform Recording for the Analysis of Wide-Area Harmonic Propagation
## 5 Conclusions  
The results of the research project focused on the study of the phenomenon of harmonic distortion propagation through distribution networks were presented. The methodology included processing of synchronized waveforms at both MV and LV levels of the proposed experimental power network. Several MV/LV substations were involved in the experiment. The harmonic impact of PV inverter, EV charger and emulated injection source was the focus of this study. It was shown that utilization of time-synchronized waveform recorders with high accuracy at multiple points of the grid introduces a unique and powerful opportunity to study basic mechanisms governing transfer of harmonic components such as: diversity and harmonic cancellation, harmonic interaction, and attenuation and influence of system and load impedance.  
Based on the performed measurements, the global synchronization of current and voltage samples proved to be effective in evaluating diversity phenomena of harmonic currents emitted by various devices. Results show that, depending on the levels of background distortion, current emissions can exhibit cancellations and final voltage distortion value can deviate from anticipated patterns. This fact was also studied and confirmed with provision of harmonic phasors estimated by means of a specific phasor estimation algorithm taking into account fluctuations of fundamental frequency of supplied voltage. Furthermore, taking into consideration summation of harmonics, synchronized voltage and current spectra allowed for deducing conclusions about dominant sources of the distortion and make some judgment about the path of harmonic propagation. As such, one of the important conclusions based on this work is that, with synchronized measurements, it is possible to recreate the impacts on harmonic distortion by calculation, even with network simplifications-- so the calculation can be tested and validated in this way as well.  
Additionally, based on the executed experiments, system topology changes were considered to be an important factor governing phenomena of harmonic distortion propagation. The effect was also facilitated by the fact that power system components (cables and transformers) exhibit certain frequency-dependence at higher frequencies.  
Conceptualization, S.C.; Data curation, A.D.; Formal analysis, S.B. and V.C.; Funding acquisition, S.B. and V.C.; Methodology, S.B., R.S.S., and S.C.; Project administration, S.C. and A.D.; Resources, A.D.; Software, A.D.; Supervision, S.B.; Writing--original draft, S.B. and R.S.S.; Writing--review and editing, S.B. All authors have read and agreed to the published version of the manuscript.  
This research has been performed using the ERIGrid Research Infrastructure and is part of a project that has received funding from the European Union's Horizon 2020 Research and Innovation Programme under Grant Agreement No. 654113. The support of the European Research Infrastructure ERIGrid and its partner PNDC (University of Stratchlyde), Cumbernault, UK is very much appreciated.  
The authors would like to thank the staff of Power Networks Demonstration Center, Cumbernault, UK for the technical and administrative support provided during the execution of reported experiment.  
The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.