Triple-Function BESS Control for Hybrid Microgrid Stability
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Solution Overview
Problem
Hybrid AC/DC microgrid systems face challenges in maintaining transient stability during faults, power quality during sudden load changes, and mitigating power and frequency fluctuations due to variations in wind speed and solar irradiance, often requiring costly auxiliary control devices.
Innovation Solution
A three-in-one battery energy storage system (BESS) that uses a unified control and structural design to improve transient stability, power quality, and mitigate power and frequency fluctuations, eliminating the need for additional higher-cost auxiliary control devices by employing a droop-based control method and dual loop decoupled control structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If auxiliary control devices are used to improve transient stability and power quality, then system reliability is improved, but device complexity and cost increase
Solution Approach 1:
The BESS is designed to perform multiple functions simultaneously: improving transient stability during faults, enhancing power quality during load changes, and mitigating power fluctuations from renewable sources. This multi-functional approach eliminates the need for separate auxiliary control devices for each function, reducing overall system complexity while maintaining high reliability
Solution Approach 2:
The patent combines three distinct control functions into a single unified BESS control system. By merging the transient stability control, power quality control, and power fluctuation mitigation into one integrated system with a dual-loop decoupled control structure, the patent reduces device complexity and eliminates the need for multiple separate auxiliary control devices
2Adaptability or versatility
If multiple auxiliary control devices are deployed to handle different operating situations, then adaptability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The BESS employs a universal control structure that adapts to different operating situations including faults, load changes, and renewable source variations. This single adaptable system replaces multiple specialized devices, reducing manufacturing complexity and cost while maintaining high adaptability to changing conditions
Solution Approach 2:
The control system is designed to dynamically adapt to changing operating conditions through its dual-loop decoupled control structure. The system automatically adjusts its control parameters and responses based on the current operating situation, providing versatility without requiring multiple fixed-function devices
3Reliability
If a complex control structure is used to achieve all three functions, then system reliability is improved, but ease of operation and implementation difficulty increase
Solution Approach 1:
The control system is segmented into two independent loops: an outer control loop for power regulation and an inner control loop for current control. This segmentation allows each loop to be optimized independently while working together to achieve all three functions, improving reliability while maintaining ease of operation through modular design
Solution Approach 2:
The dual-loop decoupled control structure dynamically coordinates between power and current control loops, allowing the system to achieve complex control objectives through simple, well-defined loop interactions. This dynamic coordination improves system performance while keeping the control structure manageable and easier to implement
Data Source
AI summary
An improved “3-in-1” BESS that performs three functions: (1) improving the transient stability in a hybrid AC/DC microgrid (HMG) system during any fault; (2) improving power quality in the HMG during any sudden load change; and (3) mitigating power and frequency fluctuations due to variations in wind speed and solar irradiance in the HMG. The same control and structural design is used for all three functions, and the improved BESS thus is adaptive to the changing operating situations within the HMG, and eliminates the requirement for a number of higher cost auxiliary control devices. The control structure of the improved BESS is simple, so it is easier and cheaper to manufacture, and can be easily implemented in practice, and retro-fit into existing HMGs.