Experimental assessment of active power control of distributed generation units

To secure balanced operation of electric networks and mitigate costly grid reinforcements, distributed generation (DG) units play a role in providing flexibility activation services. This paper analyses high-resolution measurements and reports lessons learnt from experimental active power control (APC) of installed DG units – two PV plants, a wind farm, and a biogas plant – in operation on the Danish island of Bornholm. The paper evaluates how quickly these units can respond to flexibility requests and how accurate and precise their output is when following specific active power setpoints. This assessment helps exploring the potential of DG units in providing grid services, either standalone or as part of a virtual power plant, within existing technology standards. The experiments demonstrate satisfactory performance of DG units when receiving APC requests, with PV inverters and biogas generators exhibiting high accuracy (mean deviation from setpoints of ± 0.1% and ± 0.15%, respectively). Furthermore, when subject to power limitation requests, PV inverters and wind turbines show less variation in their responses (± 0.05% and ± 0.6%, respectively) compared to biogas generators (± 0.1%). The results further highlight the significance of appropriately tuning internal control settings within DG units to ensure continuous flexible operation and avoid undesirable dynamics.