Battery Fault Current Limiter for Fast Transient Interruption
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Solution Overview
Problem
Energy storage systems face issues with large transient fault currents during battery stack switching, leading to false trips in over-current protection circuitry of the electrical grid, which can cause delays and interruptions in energy distribution.
Innovation Solution
A fault current limiting device (FCLD) is introduced, utilizing insulated gate bipolar transistors (IGBTs) controlled by current sensors to quickly interrupt the connection between energy sources and loads, detecting and limiting transient fault currents within microseconds to prevent unnecessary trips.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional over-current protection circuitry is used in the electrical grid, then fault currents can be detected, but large transient currents during battery stack switching cause false trips and interruptions
Solution Approach 1:
The system segments the energy storage system into multiple battery stacks, each equipped with its own local fault current limiter. This distributed architecture allows each stack to independently manage its transient currents, preventing false trips in the central grid protection circuitry while maintaining continuous energy distribution.
Solution Approach 2:
The fault current limiter is activated before transient fault currents can propagate to the grid. Current sensors continuously monitor battery terminal voltages and detect switching transients in advance, triggering the IGBT switches to interrupt fault currents at their source before they reach the grid's over-current protection circuitry.
2Adaptability or versatility
If battery stacks are switched in and out to meet demand, then energy distribution flexibility is improved, but large transient fault currents are generated
Solution Approach 1:
The fault current limiter acts as an intermediary device between the battery stack and the grid. It uses IGBT switches controlled by current sensors to intercept and limit transient fault currents generated during switching operations, allowing flexible demand response while preventing harmful current propagation to the grid.
Solution Approach 2:
The system converts the potentially harmful transient fault currents into a controllable signal. Current sensors detect the transient switching currents, and the control system uses this information to activate the IGBT switches, transforming the harmful fault condition into a controlled switching event that maintains grid stability.
3Reliability
If fast-acting fault current interruption is implemented at the battery stack level, then false trips are prevented, but device complexity increases
Solution Approach 1:
Each battery stack is equipped with self-contained fault current limiting capability using IGBT switches and current sensors. The system performs self-diagnosis and self-protection by detecting transient currents locally and interrupting them without requiring complex external protection circuitry, simplifying the overall grid protection architecture.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The FCLD effectively limits high transient currents, preventing false fault detections and ensuring efficient energy distribution by interrupting fault currents faster than traditional solutions, thus reducing downtime and maintaining grid stability.
Implementation Method 1
Each IGBT may be further controlled by a circuit using a current sensor to detect excessive currents, such as a Hall effect sensor.
Data Source
AI summary
A fault-current limiting device having an input voltage node configured to receive a first voltage signal from an energy source, such as a battery, and an input reference node configured to receive a reference signal from the energy source. The device further includes a first switch coupled between the input voltage node and an output voltage node and a second switch coupled between the input reference node and an output reference node. The device further includes a current sensor circuit coupled to the output voltage node and coupled respectively to the first switch and the second switch wherein the current sensor circuit is configured to open the first and second switches in response to sensing a current signal at the output voltage node that exceeds a threshold current (e.g., a transient fault current).