Generator Synchronization Using a Virtual AC Bus Reference
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Solution Overview
Problem
Synchronous electric machines often require sequential synchronization with AC bus systems, leading to prolonged power loss events and potential damage from unsynchronized current surges when bringing additional generators online, which is inefficient and can exceed the capacity of short-term backup power solutions.
Innovation Solution
Implementing a system for synthetic synchronization, where generators synchronize their output to a common external source, allowing parallel synchronization independent of bus voltage and frequency, using high-speed communication networks and precise voltage and speed control to match output waveforms, enabling simultaneous connection to the bus and reducing the need for sequential breaker operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sequential synchronization is used to bring generators online, then equipment damage from unsynchronized current surges is prevented, but power loss duration increases and productivity decreases
Solution Approach 1:
The system performs preliminary synchronization of multiple generators to a virtual generator before the actual power failure occurs. The synchronization controller receives a loss-of-power indication and begins synchronizing generators in advance, so that when the power failure actually occurs, the generators are already ready to immediately energize the bus without sequential delays.
Solution Approach 2:
The patent introduces a virtual generator as an intermediary reference for synchronization. Instead of synchronizing directly to the physical bus (which may be de-energized), all generators synchronize to the virtual generator's nominal output waveform. This intermediary allows parallel synchronization without requiring the bus to be energized, enabling simultaneous connection of multiple generators.
2Reliability
If sequential synchronization is used, then equipment damage from unsynchronized current surges is prevented, but the physical size and cost of backup energy sources must increase
Solution Approach 1:
The system enables continuous power delivery by synchronizing multiple generators in parallel and connecting them simultaneously to the bus. This continuity eliminates the sequential gaps in power delivery, allowing the backup system to maintain uninterrupted power supply with smaller, more efficient generator capacity rather than requiring oversized generators to compensate for sequential operation delays.
3Reliability
If sequential synchronization is used, then equipment damage from unsynchronized current surges is prevented, but productivity and response speed decrease
Solution Approach 1:
The synchronization controller receives a loss-of-power indication from the utility power system and begins synchronizing generators to the virtual generator in advance, before the actual power failure occurs. This preliminary synchronization ensures that when the power failure actually occurs, multiple generators are already ready and can connect to the bus simultaneously, dramatically accelerating power restoration while maintaining synchronization safety.
Solution Approach 2:
The patent segments the synchronization process into independent parallel operations. Each generator synchronizes independently to the virtual generator rather than sequentially to the physical bus. This segmentation allows multiple generators to complete synchronization simultaneously, enabling parallel connection to the bus and thus improving overall productivity without compromising equipment protection.
Data Source
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AI summary
The present disclosure contemplates a method for synchronizing a large number of generators on an AC bus by synchronizing each generator's output to a nominal output that is generated from a common external source. For example, each generator, using a high speed communication signal, can synchronize to a nominal output provided by a master generator, or centralized command module. In another example, each generator can generate its own nominal output referenced to a common external time signal, such as a global positioning system (GPS) signal, or other reference. By synchronizing independently of bus voltage and frequency, the generators are able to synchronize in parallel, instead of serially.