# Grid Nodes Selection Strategies for Power Quality Monitoring
## 4 Problems and Future Prospects
### PQ--Part of Smart Grid and Its Communication Network
To conclude, in order to enable massive remote monitoring and increase the number of ICT alternatives, all possible measures must be taken in order to lower data transmission requirements (including the most important, the data rate). \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Data Characteristic 1** & \multicolumn{4}{c}{**Classification/Value Range 2**} \\ \hline \multicolumn{4}{c}{**(1) Data use category:**} \\ \multicolumn{4}{c}{**(2) Reach:**} \\ \multicolumn{4}{c}{**(3) Information transfer time:**} \\ \multicolumn{4}{c}{Data occurrence interval} \\ \multicolumn{4}{c}{Data aggregation Method of broadcast Priority} \\ \multicolumn{4}{c}{**Unicast**} \\ \multicolumn{4}{c}{Priority} \\ \multicolumn{4}{c}{**Low**} \\ \multicolumn{4}{c}{Low-low (\(<\)3 ms)} \\ \multicolumn{4}{c}{**(5) Synchronicity:**} \\ \multicolumn{4}{c}{**(6) Information reliability:**} \\ \multicolumn{4}{c}{Availability Level of assurance HEMP, IEMI} \\ \multicolumn{4}{c}{**(7) Data volume:**} \\ \multicolumn{4}{c}{**(8) Security:**} \\ \multicolumn{4}{c}{Confidentiality Integrity Availability Level of assurance HEMP, IEMI} \\ \multicolumn{4}{c}{**(8) Security:**} \\ \multicolumn{4}{c}{Confidentiality Integrity Availability Level of assurance HEMP, IEMI} \\ \multicolumn{4}{c}{**(9) Security:**} \\ \multicolumn{4}{c}{**(10) Security:**} \\ \multicolumn{4}{c}{Confidentiality Integrity Availability Level of assurance HEMP, IEMI} \\ \multicolumn{4}{c}{**(11) IEEE Std 2030 table is extended with addition of “Data aggregation” row. 2 Legend: bold text—either final or current feature; normal text (black)—perspective feature (in many cases—to ensure smooth integration and compatibility with other Smart Grid applications), invisible text (grey)—rejected option. 3 From single end-node. Depends on data processing and feature extraction strategies. \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Proposed definitions of PQ data flow: current situation and perspective. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Group** & **Technology** & **Bandwidth** & **Coverage** \\ \hline \multirow{8}{*}{Wireless HAN} & ZigBee & 250 kbps at 2.4 GHz; 40 kbps at 915 MHz; & 10–75 m (30 m indoor) \\  & & 20 kbps at 868 MHz & & \\  & Wi-Fi & 802.11b: 11 Mbps at 2.4 GHz; 802.11a and & Max 250 m (100 m indoor) \\  & & 802.11g: 54 Mbps; 802.11n: 600 Mbps & & \\  & Bluetooth & Max 1 Mbps & & \\  & Z-Wave & 40 kbps at 868 MHz (Europe); & & \\  & Z50 kbps at 2.4 GHz & & & \\  & 6 LoWPAN & 250 kbps at 2.4 GHz; 40 kbps at 915 MHz; & 200 m \\  & & 20 kbps at 868 MHz & & \\ \hline \hline \end{tabular}
\end{table} 
Table 8: The list of main ICTs and their features for Smart Grid applications [27; 29; 31; 32; 33; 34; 35]. On the one hand, the ICT layer will bring new challenges, for example: grid network designing and planning issues, data transfer errors, cybersecurity, reliability reduction (since monitoring system will become more complicated), etc. On the other hand, the ICT layer will be beneficial. Firstly, it will simplify and accelerate data collection from a vast amount of PQ monitors--time, human, and transport resources will be saved. Secondly, less memory will be required in end-nodes (due to central data storage), but legislation defining minimum history storage time must be introduced. Thirdly, a great leap forward will be achieved in data loss avoidance and decrease in required DRF (which means a lower number of monitors). Therefore, optimal PQ monitors' allocation strategy is important not only for primary resources saving (such as monitor cost) but also for economy in ICT layer--CAPEX and OPEX saving, bandwidth reduction, and channel jamming prevention, data flow optimization in order to simplify data processing. In Figure 10, an example of measurements of data loss is given: three phase-to-ground voltage arrays have been lost (from 3 March 2020 to 6 March 2020) during PQ measurement campaign in a 35 kV grid belonging to Lithuanian DSO (\"Energijos skirstymo operatorius\", AB).