Decentralized VSG Controller for Microgrid Frequency Stabilization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional control strategies for microgrids with low inertia fail to consider the real-time dynamics of battery energy storage systems, leading to improper utilization and potential imbalance in state of charge, which can destabilize the grid during disruptions.
Innovation Solution
A decentralized consensus-based virtual synchronous generator (VSG) system that emulates the inertial response of synchronous generators, using a multi-agent system to synchronize power and state of charge (SOC) of battery energy storage systems (BESSs) through a ROCOF control loop, ensuring balanced frequency regulation and stabilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional control strategies are used for microgrids with low inertia, then the system structure is simple, but the state of charge balance among battery energy storage systems deteriorates and grid stability worsens during disruptions
Solution Approach 1:
The patent creates a virtual copy of synchronous generator inertia behavior through software control. The virtual synchronous generator emulates the inertial response characteristics of physical synchronous generators by calculating and injecting virtual inertial power based on frequency deviation, without requiring actual rotating mass. This copying approach provides the stability benefits of high-inertia systems in low-inertia microgrids while maintaining the simplicity of power electronic-based energy storage systems.
Solution Approach 2:
The patent introduces a consensus-based distributed control mechanism as an intermediary between individual battery energy storage systems and the overall microgrid. This intermediary layer coordinates the operations of multiple BESSs, enabling them to share information about their state of charge and power output, and to adjust their operations collectively to maintain both charge balance and frequency stability without requiring a centralized controller.
2Adaptability or versatility
If battery energy storage systems operate independently without consensus control, then the control system is simple, but the state of charge balance among BESSs deteriorates leading to improper utilization
Solution Approach 1:
The patent implements feedback mechanisms where each battery energy storage system continuously monitors its own state of charge and power output, exchanges this information with neighboring BESSs through the communication network, and adjusts its operation based on the consensus algorithm's guidance. The consensus controller provides feedback signals that guide each BESS to adjust its charge/discharge rate to maintain overall charge balance while responding to grid frequency deviations.
3Reliability
If centralized control is used to coordinate BESSs, then frequency regulation can be achieved, but the system becomes prone to single-point failure and communication costs increase
Solution Approach 1:
The patent segments the centralized control function into distributed control units located at each battery energy storage system. Instead of one central controller making all decisions, each BESS has its own consensus controller that makes local control decisions based on locally available information and consensus algorithms. This segmentation eliminates the single-point failure vulnerability of centralized control while reducing communication requirements to only neighboring units.
Data Source
AI summary
A device, method, and non-transitory computer readable medium for controlling a power distribution system includes an islanded microgrid and a control system. The islanded microgrid includes battery energy storage systems (BESSs) that operate as a primary energy source, and a decentralized consensus-based virtual synchronous generator (VSG). The control system simultaneously, emulates inertial response of a synchronous generator by the virtual synchronous generator during grid disruptions to regulate and stabilizes frequency of the islanded microgrid, and maintain consensus among the plurality of battery energy storage systems (BESSs).