Battery Energy Storage System Impact to Transmission Network Operation

Main objective

To evaluate connected Battery Energy Storage System (further on, BESS) influence on network operation modes.

Performed calculations

Long-time voltage level, voltage fluctuation, harmonics, short circuits. Analyzed various network operation modes: minimal and maximum.

Voltage level and fluctuations

BESS impact to minimal and maximum network operation voltage levels was calculated. Based on EA-PSM calculation results, BESS impact to 330 kV network is up from
-0,009% to + 0,006%. BESS impact to 110 kV network is up from -0,031% to +0,021%, to 10 kV network is up from -0,127% to + 0,084%. According to calculations, BESS should be installed with 11/0,4 transformer that tap changer is at 3^rd position. BESS should be able operate at ≤-12% U_n voltage level.

Higher harmonics

Performed higher harmonics calculations for the network without and with connected BESS. In the modeled network without a connected BESS system, harmonic voltages calculation results match with performed measurements and are in the range of IEC61000-2-2 and EN50160 defined limits. Total harmonic distortion THD is up to around 0,625 %.

Harmonic voltages at the network with connected BESS were analyzed with the assumption that the inverter generates current harmonics as presented by the manufacturer.  As calculation results show, BESS’s impact on voltage harmonics is minimal. THD increase from 0,679% to 0,685% whereas long-term harmonic voltage limit is >6%.

Short circuit calculations

Performed short circuit calculations show that to protect BESS from short circuits, under-voltage protection should be installed. BESS overcurrent protection time setting should not be shorter than 250 milliseconds.