Microgrid Power Source Switching for Low State-of-Charge Events
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Solution Overview
Problem
In power systems, when abnormality occurs in the utility power system, the microgrid is disconnected, and energy storage systems switch to support voltage and frequency, but if renewable energy is insufficient, the state of charge decreases, necessitating load shedding, which is inefficient and disruptive.
Innovation Solution
A power system incorporating a remote transfer switch and controller that manages switches to maintain power supply by switching between energy sources, including energy storage, renewable energy, and power generators, with load shedding only when necessary to ensure stable voltage and frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the energy storage system switches to voltage source mode to support voltage and frequency when utility power fails, then system stability is maintained, but the state of charge decreases rapidly when renewable energy is insufficient
Solution Approach 1:
The patent implements dynamic switching between different operating modes (islanding mode with voltage support, grid-connected mode, and generator-based mode) based on real-time system conditions. The controller dynamically adjusts the energy storage system's function from pure voltage support to power supply when renewable energy is insufficient, optimizing the balance between maintaining system stability and preserving state of charge.
Solution Approach 2:
The system changes operational parameters by switching between different control modes: when renewable energy is sufficient, the energy storage operates in voltage support mode; when renewable energy is insufficient, it transitions to power supply mode. This parameter change allows the system to adapt to varying conditions and prevent excessive state of charge depletion while maintaining stability.
2Quantity of substance
If renewable energy generation is insufficient to meet load requirements, then the state of charge decreases, but continuous power supply to all loads cannot be maintained
Solution Approach 1:
The patent segments the load into multiple priority levels and implements selective load management. When renewable energy is insufficient and state of charge is decreasing, the system selectively sheds non-critical loads while maintaining power to critical loads. This segmentation allows the system to preserve state of charge while ensuring continuous power supply to essential functions.
Solution Approach 2:
The controller acts as an intermediary that mediates between renewable energy generation, energy storage, and load requirements. It monitors the balance between generation and consumption, and when imbalance is detected, it activates the generator or implements load shedding to maintain both state of charge and continuous power supply to critical loads.
3Quantity of substance
If load shedding is implemented when renewable energy is insufficient, then state of charge is preserved, but power supply continuity is disrupted
Solution Approach 1:
The system performs preliminary actions by proactively starting the generator when renewable energy becomes insufficient and before state of charge depletion occurs. The controller monitors the balance between generation and consumption, and when renewable energy falls short, it activates the generator in advance to prevent the need for load shedding, thereby preserving both state of charge and power supply continuity.
Solution Approach 2:
The system implements self-service by using the generator as a backup power source that automatically activates when renewable energy is insufficient. This eliminates the need for external intervention or manual load shedding, allowing the system to maintain continuous power supply while preserving state of charge through automated generator activation.
Data Source
AI summary
A Method of controlling a power system, comprising: determining whether a state of charge of an energy storage system lower than a first threshold value. When the state of charge is lower than the first threshold value, a power generator is activated and determining whether the power generator is abnormal. When the power generator is abnormal, supplying the power to loads by the energy storage system. When the power generator is normal, supplying the power to loads by the power generator. Determine whether the state of charge of the energy storage system is lower than the second threshold value, and reduce a part of loads when the state of charge is lower than the second threshold value.