Microgrid Fault Isolating Device with Time Window Control
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Solution Overview
Problem
Existing methods for locating and isolating electrical faults in microgrids with inverter-based sources, especially when disconnected from the main power grid, are complex, unreliable, and interfere with conventional fuses, as they fail to function effectively at low currents.
Innovation Solution
A distributed apparatus with voltage meters, timers, and microcontrollers at each branch of the microgrid, which sets unique time windows to isolate faults by opening switches in response to voltage anomalies, allowing for fault detection and isolation without interfering with conventional fuses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fault isolating devices are distributed throughout the microgrid, then fault location precision is improved, but device complexity increases
Solution Approach 1:
The microgrid is segmented into multiple zones with fault isolating devices distributed at strategic locations. Each device independently monitors its local section and can isolate faults in its segment, improving fault location precision while the modular segmented architecture prevents the need for complete system-wide complexity.
Solution Approach 2:
Each fault isolating device is self-contained with its own voltage meter, timer, switch, and microcontroller, enabling autonomous operation. The devices independently detect voltage anomalies, determine fault presence, and actuate switches without requiring complex centralized control, reducing overall system complexity while maintaining distributed precision.
2Reliability
If voltage meters and microcontrollers are used at each branch, then fault detection reliability is improved, but cost and device complexity increase
Solution Approach 1:
The microcontroller serves multiple functions: monitoring voltage, detecting faults, determining fault presence, controlling switch actuation, and managing the time window operation. This multi-functionality consolidates what could be separate complex components into a single integrated controller, improving reliability while managing complexity through functional integration.
Solution Approach 2:
Each branch's fault isolating device is self-sufficient with its own voltage meter and microcontroller that autonomously perform detection and control functions. This self-service capability eliminates the need for complex inter-branch communication and centralized control systems, achieving high detection reliability with relatively simple distributed units.
3Measurement precision
If time windows are set for each device, then fault isolation accuracy is improved, but coordination complexity increases
Solution Approach 1:
The system uses periodic time windows at predetermined intervals after voltage anomaly detection to actuate switches. This periodic action provides a structured, predictable timing pattern that simplifies coordination between distributed devices, as each device follows the same time-based protocol rather than requiring complex real-time negotiation, thereby improving isolation accuracy while managing coordination complexity.
Data Source
AI summary
A fault isolating device for use in a microgrid disconnected from a main power grid includes a voltage meter for detecting a voltage anomaly indicative of an electrical fault, a timer for establishing a time window that begins and ends a predetermined time after a voltage anomaly is detected, a switch that is opened at the start of the time window, and a microcontroller that determines whether to leave the switch open to isolate a faulted portion of the microgrid or to close the switch. A plurality of fault isolating devices can be distributed throughout a microgrid to isolate a faulted branch or faulted branches of an islanded microgrid without interfering with normal fuse operation when the microgrid is connected to the main power grid.