Power Conditioner Black-Start Control via Touch-Safe AC Generation
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Solution Overview
Problem
Distributed resource island systems face challenges in efficiently controlling power conditioner activation and de-activation during black-start processes, relying on costly energy storage or generation sources that impact system reliability.
Innovation Solution
The system employs bi-directional power conditioners with integrated black-start modules and a microgrid interconnect device to generate a touch-safe low-voltage AC, allowing self-initiated start-up and shut-down without external communication, and utilizing energy storage and renewable sources to maintain system control and safety during islanded operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If energy storage sources (super-capacitor, battery) or generation sources (generator) are used to power the central controller during black-start, then the central controller can remain powered during power outages, but system cost increases and system reliability is adversely impacted
Solution Approach 1:
The power conditioner is designed to autonomously generate a black-start signal and initiate start-up operations without requiring external energy storage sources or central controller intervention. The power conditioner itself serves as both the controlled device and the control source, eliminating the need for separate battery or generator systems to power the controller during black-start events.
Solution Approach 2:
The black-start functionality is extracted from the central controller and embedded directly into the power conditioner. This removes the dependency on the central controller for initiating black-start operations, allowing the power conditioner to operate independently during grid outages without requiring external energy storage or generation sources.
2Reliability
If distributed energy resources receive central commands for activation, then unwanted energization is prevented, but system complexity and communication requirements increase
Solution Approach 1:
The power conditioner autonomously determines when to activate by monitoring its own operational state and generating black-start signals internally. This self-service capability eliminates the need for complex communication protocols between the central controller and distributed energy resources, while still preventing unwanted energization through built-in safety logic.
Solution Approach 2:
The power conditioner performs preliminary safety checks and generates activation signals before actual start-up occurs. This preliminary action ensures that unwanted energization is prevented through internal safety mechanisms, removing the need for continuous external communication and control commands.
3Object-affected harmful factors
If the microgrid interconnect device disconnects the system from the main grid during black-start, then line-worker safety is ensured, but the system loses access to AC power for the central controller
Solution Approach 1:
The power conditioner autonomously generates the black-start signal and initiates start-up operations without requiring the central controller to remain powered. This self-service capability allows the system to safely disconnect from the main grid for line-worker protection while the power conditioner independently manages the black-start process without external power assistance.
Solution Approach 2:
The black-start initiation function is extracted from the central controller and placed in the power conditioner. This extraction allows the system to disconnect from the main grid safely while the power conditioner independently performs black-start operations without requiring the central controller to remain powered during the disconnection event.
Data Source
AI summary
Method and apparatus for controlling power conditioners in a distributed resource island. In one embodiment, the method comprises comparing, at a power conditioner operating in a de-energized state, an input of the power conditioner to an input threshold, wherein the power conditioner is coupled to an islanded grid; operating the power conditioner, when the input exceeds the input threshold, in a soft-grid mode to generate a touch-safe AC voltage that is coupled to the islanded grid; and activating the power conditioner, based on an impedance of the islanded grid and load demand for the power conditioner, to operate proximate its nominal output voltage.