Investigations on Procurement of Ancillary Services in Renewable Integrated Deregulated Power System

Abstract

The electric utilities are changing their way of operation and business from vertically integrated arrangements to deregulated one. Earlier, the vertically integrated utilities performed all the functions involving generation, transmission, distribution, and were responsible for supplying the energy and service quality. Under deregulation, these electric utilities are segregated into three companies namely GENCOs, TRANSCOs, and DISCOMs that are specifically responsible for generation, transmission, and distribution, respectively. Such segregation is directed to enhance the competition and offer new choices and economic benefits to the consumers. Electricity is therefore being treated as a tradable commodity. The deregulation is confronted with two key challenges i.e. maintaining real-time supply-demand balance and transfer of bulk electricity through the desired path. The variability and intermittency of renewable wind and solar integration further complicate the power system operation in the deregulated environment. Such issues to an extent can be handled through congestion management and ancillary service procurement. Tackling network congestion is a vital concern for the System Operator (SO) in the deregulated market because it entails additional cost and poses a threat to power system security. The transmission network is also subjected to physical and operating constraints such as line limits and bus voltage magnitude, etc. in facilitating transactions. The network operation beyond these limits leads to a blackout. Therefore congestion management under deregulation is to relieve congestion by prioritizing the transactions and committing to such a schedule that would not overload the network. The Ancillary Services (AS) are the support services that are essential for supporting transactions while maintaining reliable operation and ensuring the required degree of quality and safety. The provision of ancillary services is another challenging task to be performed by the SO in the deregulated market environment.