The voltage quality of electricity is important for grid stability, but is currently not systematically measured or regulated in Germany. Voltage fluctuations, flicker and voltage dips are summarised as quality. If the voltage quality is too low, this can lead to problems or damage to devices or machines. The increasing integration of renewable energies and the coal phase-out could lead to an increase in voltage quality problems, particularly in medium and low-voltage grids where many industrial customers are connected.
A joint study ‘Measurement and regulation of power quality – status quo in Germany and experiences of other European countries’ by the Energy Economics Institute (EWI) at the University of Cologne and the Fraunhofer IEG as part of the QUIRINUS Control research project funded by the Ministry of Economic Affairs, Industry, Climate Protection and Energy is investigating ways of regulating and improving power quality in Germany. Possible regulatory measures under discussion include the introduction of mandatory measurements and the integration of power quality into existing quality regulation.
“Reports of declining voltage quality in the electricity grids have recently increased. Voltage quality regulation should therefore be considered now as part of the energy transition,” says Philipp Artur Kienscherf, project manager at the EWI, who prepared the short study together with Merit Dressler, Dr Lisa Just, Antonie Reinecke, Amelie Sitzmann, Stephan Terhorst and Amelie Wöstmann. Voltage quality is currently not regulated in Germany, which is why measurements of voltage quality in the lower grid levels are not carried out across the board.
In other European countries, power quality is currently monitored systematically in 23 countries. In countries such as Austria, this monitoring is carried out continuously. The data on selected power quality parameters is reported to the regulatory authority and published in an annual report. Non-compliance with national or European power quality standards is also regulated.
In order for grid operators to be incentivised to systematically record and improve voltage quality, this would have to be integrated into incentive regulation, which is the regulatory basis for the activities of grid operators in Germany. This would require a reliable data basis on the condition of the electricity grid. A first step would be to make measurements of relevant power quality parameters mandatory for grid operators. Spot measurements at critical grid points could create transparency about the voltage quality. The widespread introduction of smart metering systems could offer a cost-effective way of continuously recording power quality data at the low-voltage level.
In a second step, power quality could be included in the existing quality element of incentive regulation. This follows a bonus-malus system: grid operators with particularly high supply quality receive surcharges on their revenue cap (bonus), while a discount is applied (malus) if they fall short. When linking voltage quality with financial incentives, the regulator would have to carefully weigh up which voltage quality aspects are economically relevant and where the benefits of an improvement exceed the costs incurred.
Power quality can be regarded as a public good, the maintenance of which is crucial for security of supply and grid stability. Different customer groups, such as industrial and household customers, are affected by power quality problems to varying degrees. Accordingly, the benefits that these customer groups could derive from higher voltage quality also differ. In contrast, the introduction of mandatory power quality measurements incurs costs that are passed on to the end consumer via grid charges. It is therefore crucial that the costs and benefits of the measures are weighed up against each other during regulation.
There is currently a lack of reliable information on the costs and benefits of area-wide power quality measurements. An accompanying survey of the economic damage caused by power quality problems would be useful for evaluation purposes. “Comprehensive regulation of power quality would be associated with many implementation challenges. A step-by-step approach could help to identify a good measure for regulation,” says Kienscherf.
