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.