Potential of small hydro power plants for delivering ancillary services in Germany

A high penetration of renewable energy sources leads to a higher demand on ancillary services. To ensure the stability of the network, new approaches need to be developed. Small run-of-the-river hydro power plants offer the opportunity to control the network voltage by reactive and active power. Furthermore, the units can participate on the power balancing market to ensure the operation of the transmission system. For this purpose, the main aspects of ancillary services are presented. Especially, the fundamental regulatory requirements for control reserve and for voltage control are descripted. The efficiency of voltage control in medium and low voltage networks by reactive power variation is investigated in a case study. Thereby, the reachable deviation by this control measure is determined considering high feed-in and high load scenarios, respectively. The deliverable control energy of small hydro power plants is estimated and evaluated concerning the fundamental technical aspects. Especially, the potential for the control reserve capacity for each TSO will be analysed.