Hybrid Virtual Power Plant Control for Primary Frequency Response
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Solution Overview
Problem
Current management methods for virtual power plants, either centralized or decentralized, face limitations in coordinating battery and hydroelectric power plants to provide effective primary frequency control, particularly in terms of communication delays and flexibility in reserve distribution.
Innovation Solution
A hybrid control method implemented by a centralized controller that coordinates battery and hydroelectric power plants, adjusting power setpoints to compensate for frequency variations, allowing for optimized sizing and reduced stress on batteries by leveraging the flexibility of hydroelectric power plants to provide additional frequency reserves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If decentralized management is used where each production means adjusts its power independently according to a static law P(f), then the system is simpler to implement and more autonomous, but the coordination between battery and hydroelectric power plants is insufficient and cannot optimize the aggregate response to frequency variations
Solution Approach 1:
The system divides control into two levels: local controllers at each production means (battery and hydroelectric plants) that independently execute control actions, and a centralized controller that coordinates the aggregate response. This segmentation maintains operational autonomy while enabling coordinated frequency control through the centralized controller's ability to distribute frequency control setpoints to individual production means based on their dynamic characteristics.
2Adaptability or versatility
If centralized management is used with a single controller coordinating all production means, then the coordination and optimization of aggregate response is improved, but communication delays increase and system complexity increases
Solution Approach 1:
The control architecture is segmented into a centralized controller for high-level coordination and local controllers for execution. The centralized controller determines the total frequency control setpoint based on aggregate characteristics and distributes it to individual production means, while local controllers execute the control actions independently. This reduces communication requirements compared to fully centralized control while maintaining coordination capabilities.
Solution Approach 2:
Local controllers at each production means independently execute frequency control actions based on their own dynamic characteristics and the distributed setpoints. Each production means serves itself by autonomously adjusting its power output according to the coordinated strategy, reducing the need for continuous centralized monitoring and control signals.
3Productivity
If the entire frequency control reserve is provided by batteries, then conventional generators can be operated at rated power optimizing efficiency, but the battery sizing must be large and the stress on batteries increases reducing their lifespan
Solution Approach 1:
The system merges battery storage systems with hydroelectric power plants to create a hybrid frequency control aggregate. The battery provides fast frequency response due to its rapid dynamic characteristics, while the hydroelectric plants provide additional frequency control capacity. This combination allows conventional generators to operate at rated power while distributing the frequency control burden between battery and hydroelectric plants, reducing stress on the battery and extending its lifespan.
Solution Approach 2:
The system changes the parameter distribution of frequency control capacity across different production means. Instead of concentrating all frequency control reserve in the battery, the aggregate's total frequency control capacity is distributed between the battery and hydroelectric plants based on their respective dynamic characteristics and available capacity. This parameter distribution optimizes both battery utilization and overall system efficiency.
4Ease of operation
If battery and hydroelectric power plants are managed independently without coordination, then each can operate autonomously, but the aggregate cannot provide optimized frequency control service and the battery must be oversized to compensate for lack of coordination
Solution Approach 1:
The control system is segmented into independent local controllers at each production means and a centralized coordinator. Local controllers maintain operational independence by executing control actions autonomously based on their dynamic characteristics, while the centralized coordinator optimizes the aggregate frequency control service by distributing frequency control setpoints. This segmentation enables coordinated frequency control without requiring oversized battery capacity.
Solution Approach 2:
The system changes the operational parameters of the battery and hydroelectric plants through coordinated frequency control setpoints. The centralized controller adjusts the frequency control contribution of each production means based on real-time conditions and their dynamic characteristics, optimizing the aggregate response. This parameter coordination allows the battery to be properly sized rather than oversized, while maintaining operational independence at the local level.
Data Source
AI summary
A method, implemented by a centralized controller, for controlling a virtual power plant connected to the power grid. The virtual power plant includes a battery controlled by a local controller configured to perform primary frequency control of the power grid. The virtual power plant also includes a set of hydroelectric power plants each controlled by a corresponding local controller. The centralized controller provides a power adjustment setpoint to the local controller of the battery so as to compensate for a variation in the total power relative to an overall target power for the set of hydroelectric power plants, and the centralized controller supplies, to at least one local controller of a hydroelectric power plant, at least one power adjustment setpoint, calculated on the basis of a frequency measurement, in accordance with a management strategy for the battery. Figure for abstract: FIG. 4