Modeling and design of a transmission ultracapacitor (TUCAP) integrating modular voltage source converter with ultracapacitor energy storage

Energy storage systems (ESSs) are considered an 'enabling' infrastructure technology that can provide ride-through electricity during outages, enhance power quality, and improve utility reliability. Transmission ultracapacitor (TUCAP), integrating modular voltage source converters (VSCs) with ultracapacitor (UCAP) energy storage unit, are state-of-the-art power electronics-based EESs for utility high power application. In this paper, modeling and design of a TUCAP is presented. Firstly, the testing results of UCAP are described. The model and parameters of UCAP are extracted from the experimental results of both low-voltage cell and high-voltage string. Secondly, a cascade multilevel converter (CMC) utilizing modular VSCs is proposed for TUCAP's Power Conditioning System (PCS). The potential issues of UCAP for high power operation are discussed. The interface and control technology of a TUCAP combining CMC and UCAP are presented. And the simulation results are given for controller verification. Finally, the experimental results on a scaled-down transient network analyzer (TNA) system are given and validate the model and design of the TUCAP system.