Comparative study of hybrid synchronous condenser incorporating battery energy storage system for ancillary service provision

In the face of the increasing penetration of renewable energy sources, the synchronous machine-based power plants are slowly being phased out. This fact is potentially creating severe system issues in the transmission network. Key among the problems faced are the reduction of short circuit levels, inertia, as well as steady-state and dynamic reactive power support. To enhance the transmission system power transfer capability, complementary technological solutions, including synchronous machines, energy Storage Systems, and reactive power compensation devices can be combined to provide more services than a single device. Phoenix project, funded by Ofgem through Network Innovation Programme, is deploying a hybrid synchronous condenser (H-SC), which is a hybrid system of synchronous condenser (SC) and static synchronous compensator (STATCOM), and at the same time looking at the option of combining SC and battery energy storage system (BESS). In order to maximize the benefits of the hybridization of SC and BESS, there remains a need to assess and quantify the grid support functionalities provided by the SC and BESS individually, as well as a part of a hybrid solution. Furthermore, the control of the BESS converter solution to mimic the synchronous machine termed as grid-forming control is also drawing significant interest from the recent years owing to the potential of improved grid response characteristic compared to the grid supporting controls using phase-locked loop (PLL) and DQ current control. In this paper, we analyse the grid support functionalities provided by the SC, BESS with gridforming and grid-following control, separately as well as a part of a hybrid system with synchronous condenser.