Ancillary Services from DERs for Transmission and Distribution System Operators

The adverse impacts of transforming into decentralized power system network, due to penetration of substantial quantum of Renewable Energy Sources (RES) based generations like solar and wind, has to be managed by the Transmission System Operator (TSO) with the local support or coordination from the Distribution System Operators (DSO). The increasing share of Distributed Energy Resources (DER) in the network facilitates flexibility provisions from the distribution side to the transmission network and also to manage the local network problems like voltage limit violations, power losses and congestion in lines. Apart from these traditional issues, the flexibility support from DERs can be optimally utilized through appropriate activations and management for dealing with more complex and deeper power quality issues like harmonic mitigation and ensuring continuity of supply through Ancillary Services (AS) support for system protection in adverse conditions. For this, dynamic reactive power support, active power ramping capability etc. from the DERs are critical. This manuscript gives a review of the traditional and new ASs available from the DERs that can be exploited by the system operators for balancing, network management, power quality and supply reliability. The implications of decentralized system operation with specific emphasis on its ASs and their applicability for traditional and evolving challenges of power system is discussed in detail.