Battery String Ground Fault Location by Candidate Bypass
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Solution Overview
Problem
Locating ground faults in large energy storage systems is challenging, leading to prolonged maintenance times and safety risks due to the difficulty in identifying the exact fault location, especially in systems with multiple energy storage units.
Innovation Solution
A method and control unit that utilize pole unbalance voltage, energy storage system voltage, and the number of energy storage units to determine a potential ground fault location, followed by successive bypassing of energy storage unit candidates to pinpoint the exact fault, reducing the need for on-site personnel and minimizing maintenance time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual searching method is used to locate ground fault, then personnel can find the fault location, but maintenance time becomes excessively long
Solution Approach 1:
The patent segments the ground fault detection process into two distinct phases: (1) identifying potential ground fault locations using pole unbalance voltage measurements, and (2) systematically verifying each candidate location by bypassing energy storage units. This segmentation transforms a single time-consuming manual search into a structured multi-step process that reduces overall maintenance time while maintaining accurate fault location identification.
Solution Approach 2:
The patent performs preliminary identification of potential ground fault locations before actual fault verification. By calculating pole unbalance voltages and identifying candidate energy storage units in advance, the system prepares a targeted list of potential fault locations, eliminating the need for comprehensive manual searching and significantly reducing maintenance time.
2Measurement precision
If comprehensive ground fault detection is performed in large energy storage systems, then detection accuracy improves, but system complexity increases
Solution Approach 1:
The patent extracts and focuses measurement efforts on the critical parameter of pole unbalance voltage, which directly indicates ground fault conditions. By concentrating on this specific measurement rather than monitoring all possible parameters in the complex system, the patent achieves accurate ground fault detection without requiring comprehensive monitoring of the entire energy storage system, thus managing system complexity.
Solution Approach 2:
The patent introduces pole unbalance voltage as an intermediary parameter that mediates between the complex internal states of multiple energy storage units and the ground fault condition. This intermediary measurement simplifies the detection process by providing a direct indicator of ground faults without requiring direct analysis of each individual energy storage unit's complex internal parameters.
3Loss of information
If manual ground fault searching is performed, then fault location can be identified, but system downtime increases
Solution Approach 1:
The patent implements a feedback mechanism where pole unbalance voltage measurements provide continuous information about ground fault conditions. The system uses this feedback to identify potential fault locations and guide the bypass verification process, enabling rapid iteration and quick identification of the actual fault location, thereby minimizing system downtime while ensuring accurate fault location information is obtained.
Solution Approach 2:
The patent performs preliminary analysis of pole unbalance voltages to identify candidate fault locations before initiating the bypass verification process. This preliminary action provides advance information about where faults are most likely located, allowing the maintenance team to focus their efforts on specific candidates rather than searching the entire system, thus reducing the time the system remains down.
Data Source
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AI summary
There is disclosed herein a method (100) for locating a ground fault in an energy storage system (20) comprising a plurality of parallel strings (21). A string comprises a plurality of energy storage units (22) connected in series and an energy storage unit includes one or more energy storage modules (24) and a bypass circuit (26). The method comprises for each string of said energy storage system, identifying (110) an energy storage unit candidate (122) as a potential ground fault location based on a number of energy storage units (116) in the string, a pole unbalance voltage (112) and an energy storage system voltage (114), and determining (120) in which string the ground fault is located by successively bypassing, one string at a time, at least some of the identified energy storage unit candidates and identifying the string for which a deviation from an expected behaviour is measured.