Hybrid Virtual Power Plant Control for Primary Frequency Reserve
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Solution Overview
Problem
Current control methods for virtual power plants, either centralized or decentralized, face limitations in managing a combination of battery and hydroelectric power stations to provide primary frequency reserve effectively, particularly due to communication delays and inflexible power distribution, which can lead to suboptimal operation and increased costs.
Innovation Solution
A hybrid control strategy that combines centralized and decentralized approaches, where a centralized controller coordinates the power adjustments of both batteries and hydroelectric power stations based on real-time frequency measurements and total power production, allowing for optimized sizing and reduced stress on batteries by leveraging the flexibility of hydroelectric power plants during frequency deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If decentralized control is used for each means of production, then each unit can autonomously adjust its power according to frequency measurements, but the coordination between battery and hydroelectric plants is insufficient leading to suboptimal aggregate performance
Solution Approach 1:
The patent merges decentralized autonomous control capabilities with centralized coordination functions. Each means of production retains its own controller for autonomous frequency measurement and adjustment, while a centralized controller aggregates frequency measurements from all units and distributes optimized power adjustment instructions back to each unit, creating a hybrid control architecture that combines the advantages of both approaches
Solution Approach 2:
The system implements feedback loops where each local controller measures frequency at its location and reports to the centralized controller, which then processes this feedback information and sends back coordinated power adjustment instructions. This multi-level feedback mechanism enables both autonomous response and centralized optimization
2Productivity
If centralized control is used to coordinate power adjustments, then aggregate performance is optimized, but communication delays and rigid power distribution reduce system flexibility and responsiveness
Solution Approach 1:
The control system is segmented into autonomous local control units that each independently measure frequency and can autonomously adjust their power output based on local conditions. This segmentation allows each unit to respond flexibly and rapidly to frequency deviations without waiting for centralized instructions, while still contributing to coordinated aggregate control
Solution Approach 2:
The control architecture dynamically adapts between centralized and decentralized modes. During normal operation, units operate autonomously with high flexibility. When significant frequency deviations occur or coordination is needed, the centralized controller activates to provide optimized power distribution instructions, creating a dynamic control strategy that adjusts to system needs
3Power
If battery alone provides primary frequency reserve, then conventional generation can operate at nominal power, but battery sizing must be large and cycling causes aging and increased costs
Solution Approach 1:
The patent merges battery storage systems with conventional hydroelectric generation to provide combined frequency reserve. The battery and hydroelectric plants are controlled as an integrated aggregate, where each unit contributes to frequency regulation based on its characteristics and availability, reducing the burden on the battery alone
Solution Approach 2:
The system dynamically changes the operating parameters of both battery and hydroelectric plants based on frequency conditions, state of charge, and availability. This allows optimal allocation of frequency reserve provision between the two technologies, reducing battery cycling by utilizing hydroelectric flexibility when available
4Reliability
If hydroelectric plants operate below rated power to provide frequency reserve, then frequency adjustment is ensured, but production cost increases due to reduced energy generation
Solution Approach 1:
Instead of requiring all hydroelectric plants to operate below rated power continuously, the system applies partial frequency reserve activation only when needed. The centralized controller assesses frequency deviations and activates frequency regulation actions selectively, allowing plants to operate at nominal power during normal conditions and only reduce output when frequency correction is required
Data Source
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AI summary
The invention relates to a method for controlling, via a centralized controller (10), a virtual power plant connected to the electrical grid. The virtual power plant comprises a battery (30) controlled by a local controller (20) configured to perform primary frequency adjustment of the electrical grid. The virtual power plant includes a set of hydroelectric power plants (50, 51, 52), each controlled by a corresponding local controller (40, 41, 42).The centralized controller (10) provides the local battery controller (20) with a battery power adjustment setpoint (P0_bat, K) to compensate for a variation in total power relative to an overall setpoint power of the entire hydroelectric power plant, and the centralized controller (10) provides at least one local controller (40, 41, 42) of a hydroelectric power plant (50, 51, 52) with at least one power adjustment setpoint (Pflex_1, Pflex_2, Pflex_3), calculated on the basis of a frequency measurement, in accordance with a battery management strategy.