Microgrid Isolation Switch Sequencing for Inverter Backup Transfer
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Solution Overview
Problem
Existing automatic transfer switches (ATS) are sub-optimal for switching between primary and secondary power systems, particularly when the secondary power source is an inverter-based system like a battery or fuel cell, as they require power to operate and cannot isolate without it, leading to a 'chicken and egg' problem during power outages.
Innovation Solution
An automatic isolation switch (AIS) system and method that detects adverse power conditions, isolates the primary power system from the load, and activates an inverter-based secondary power system to supply power, with configurable operational modes and energy storage to ensure seamless power transfer and conservation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an automatic transfer switch (ATS) is used to switch between primary and secondary power systems, then power supply reliability is improved, but the system cannot operate without power to activate the secondary source, creating a 'chicken and egg' problem
Solution Approach 1:
The system performs preliminary isolation of the primary power system before activating the secondary power source. The isolation switch disconnects the load from the primary power system in advance, ensuring that the secondary system can be activated without risk of back-feeding or electrical conflict, thus resolving the activation dilemma
Solution Approach 2:
The patent inverts the conventional ATS sequence by first isolating the primary power system and then activating the secondary power source, rather than attempting to activate the secondary source while maintaining connection to the primary system. This reversed sequence eliminates the 'chicken and egg' problem
2Device complexity
If the primary power system remains connected during outages, then system complexity is reduced, but false power condition detections cause unnecessary switching and energy waste
Solution Approach 1:
The system implements a time delay mechanism that waits for a predetermined period after detecting an adverse power condition before executing isolation and switching operations. This preliminary waiting period allows transient fluctuations to settle, preventing false positives from triggering unnecessary switching and energy consumption
Solution Approach 2:
The system applies a counter-measure by introducing a time delay threshold that opposes premature switching actions. This delay acts as a protective barrier against false detections, ensuring that only sustained adverse power conditions trigger the isolation and power switching sequence
Data Source
AI summary
An automatic isolation switch (AIS) system is provided for controlling a supply of electrical power to a load. The system includes a switch and a controller. The switch is connected between a first power system and the load and between the first power system and a second power system. The first power system includes a grid, and the second power system includes a power source and an inverter coupled to the power source. The controller is configured to detect an adverse power condition on the first power system for supplying electrical power to the load; to isolate, via at least one switch, the first power system from the load and the second power system, in response to the detecting of the adverse power condition; and to activate the inverter of the second power system to supply electrical power from the second power system to the load.