EV Charging for Grid Services Creates Hidden Power Quality Problem
When electric vehicles charge to help balance the electrical grid, they introduce electrical distortion that degrades power quality for nearby customers, a new study warns. The finding matters to utilities and regulators planning to rely on EV charging as a flexible resource—they'll need to account for these hidden costs or risk customer complaints and equipment damage.
Originaltitel: Flexibility Provision Induced Harmonic Distortion Increment in LV Networks: A Stochastic Assessment
<p>Harnessing demand-side flexibility for system-wide flexibility services is becoming increasingly popular. The effect of such services on distribution grid parameters, such as harmonic distortion, has remained underexplored. This paper describes a Monte Carlo simulation-based stochastic harmonic distortion assessment with segmented Gaussian mixture model (GMM) based harmonic injection models. The proposed method is capable of capturing uncertainties and temporal changes of the load behavior and operation when providing flexibility services. The study is carried out considering aggregated electric vehicle (EV) charging for manual frequency restoration reserve (mFRR) activation market-based balancing flexibility provision. Two real low-voltage (LV) networks, representing residential and mixed customer loads were used for the analysis. The analysis focused on the hourly variation of harmonic voltage distortion at the LV side of the transformer and customer connection points. The variation of transformer loss factors for non-sinusoidal currents introduced in IEEE std C57.110-2018 is also analyzed. Results show a significant increment in considered LV grid parameters between highly available flexible hours and non-flexible hours in flexible charging. The daily maximum and 95<sup>th</sup> percentile values were seen to be increased in flexibility provision-based charging compared to the baseline. The total harmonic distortion (THD) voltage increment during the day, for an average residential supply in the charging baseline was 11.25%, which was increased to 40.12% in the flexibility provision. In conclusion, distribution system operators should be aware of the possible risk of flexibility-induced harmonic distortion increment when the distributed energy resources are allocated for system-wide flexibility services.</p>