Experimental evaluation of an energy storage system for medium voltage distribution grids enabling solid?state substation functionality

Klumpner, Christian; Rashed, Mohamed; De, Dipankar; Patel, Chintan; Asher, Greg

Abstract

"Smart grids" is a new concept of managing the power transfer in modern grids that will rely not only on the on-line processing of a variety of consumption and generation power data but will also need new hardware to facilitate a flexible and efficient conversion and storage of electrical power to maintain grid stability under fast changing operating conditions. This paper will present the results of the experimental evaluation of a 1.5MJ/25kW energy storage system that is connected directly to a medium voltage grid in order to provide fast and flexible grid control capabilities. The demonstrator consists of a cascaded modular multilevel converter able to interface directly to the medium voltage grid, fed by dual active bridge converters with isolation provided by medium frequency transformers whilst in the low voltage side DC bus, a low voltage inverter and a supercapacitor stack are connected via interleaved converters. The experimental performance showcased in the paper consists of fast power peak levelling, reactive current injection, grid fault ride through, nonlinear load harmonic current compensation whilst maintaining a high round trip efficiency over a wide range of power levels. The concept on which the demonstrator was designed can also facilitate the implementation of a solid-state substation with integrated energy storage concept that can further increase flexibility and reliability of future grids.

• Journal Article Type: Article
• Acceptance Date: Jan 25, 2021
• Online Publication Date: Mar 30, 2021
• Publication Date: Apr 1, 2021
• Deposit Date: Mar 11, 2021
• Publicly Available Date: Mar 30, 2021
• Journal: IET Smart Grid
• Electronic ISSN: 2515-2947
• Publisher: Institution of Engineering and Technology (IET)
• Peer Reviewed: Peer Reviewed
• Volume: 4
• Issue: 2
• Pages: 190-201
• DOI: https://doi.org/10.1049/stg2.12019
• Public URL: https://nottingham-repository.worktribe.com/output/5319773
• Publisher URL: https://ietresearch.onlinelibrary.wiley.com/doi/full/10.1049/stg2.12019
• Additional Information: Special Issue: 5th UK Energy Storage (UKES 2019) conference