Big Data Analysis with Key Performance Indicators for Reactive Power Balance and Associated Voltage Quality Visual Mapping in the North-Western Part of the Danish Grid

This paper will explain how steady state voltage quality in a power system (in terms of voltage limits) is affected when overhead transmission lines are converted to underground cables. Furthermore, it will be showed how the voltage quality can be analysed from Big Data (SCADA) measurements using Key Performance Indicators (KPIs).

Overhead lines and underground cables act very differently due to the difference in their reactive properties. The reason behind this will be briefly explained. A PowerFactory simulation showing the issues of reactive power transport with, and without, the necessary compensation equipment, will also be shown. Operation of synchronous machines and transformers are severely affected by over-voltages and this will compromise the security of supply if voltages are not maintained within limits. To highlight the consequences, Key Performance Indicators (KPIs) are used to score the quality based on voltage magnitude and the operation of local compensation units. The developed KPIs are then applied to real-world data from the northwest part of Denmark to prove the negative impact on voltage quality.