The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 08, 2026
Filed:
Jul. 15, 2025
Hitachi Energy Ltd, Zürich, CH;
Mohapatra Bikash Kumar Sahoo, Bhadrak, IN;
Kent Wikstrom, Västerås, SE;
Ann Palesjo, Västerås, SE;
Hongyang Zhang, Stockholm, SE;
Saran Teja Malladi, Chennai, IN;
HITACHI ENERGY LTD, Zurich, CH;
Abstract
There is disclosed herein a method for detecting a ground fault in an energy storage system comprising at least one string having a plurality of energy storage modules. The string is connected between a first direct current (DC) pole and a second DC pole. The first DC pole and the second DC pole are connected to an AC side through a respective converter. The method comprises determining a first co-phasal harmonic component based on at least one phase-to-ground voltage measured at the AC side, determining a second co-phasal harmonic component based on at least one pole-to-ground voltage measured at the DC side, and determining presence of a ground fault if the first co-phasal harmonic component increases and/or the second co-phasal harmonic component decreases. There is also disclosed herein a control unit and an energy storage system.