Feasibility Study of BESS-Integrated MMC Integration into a Hybrid High Voltage AC-DC System

This paper investigates the implications and the potential of a Battery Energy Storage System (BESS) integrated Modular Multilevel Converter (MMC). It introduces an allocation problem highlighting the various options to place this battery system into a relevant hybrid AC-DC grid with the objective of delivering ancillary services to the HVDC grid and the Point of Common Coupling (PCC) with the HVAC grid. This work addresses the crucial need for flexibility in the future power system to ensure secure and stable operation amidst increasing renewable integration. By using BESS-integrated MMCs, this work demonstrates how low-voltage battery storage solutions can be effectively incorporated into HV-grids without requiring extensive conversion stages or bulky low-frequency transformers. The findings indicate that the allocation problem is a multi-objective optimisation challenge, where the optimal solution depends on trade-offs regarding performance, cost-effectiveness, operation constraints, and wind power integration.