Synchronized Power Converter Startup via Voltage Ramp Profile
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Solution Overview
Problem
Starting multiple power converters in grid forming mode with a black grid poses challenges such as inrush current issues and synchronization problems, particularly when transitioning from a powered-down state, which can lead to tripping of power converters and inefficient power distribution.
Innovation Solution
Implementing a voltage and frequency ramp profile across power converters without the need for communication, where each converter follows the same startup parameters to synchronize with others based on voltage readings at the point of common coupling, allowing for synchronized startup without a master controller or communication infrastructure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple power converters are started simultaneously in grid forming mode, then the microgrid can be restored quickly, but inrush currents occur causing converters to trip
Solution Approach 1:
The patent applies preliminary action by implementing a voltage ramp profile before full power operation. Each power converter gradually increases its output voltage from zero to nominal level following a predetermined ramp profile, which prevents inrush currents from causing converter tripping while still enabling quick microgrid restoration.
2Device complexity
If multiple power converters are started without communication, then the system complexity is reduced, but synchronization between converters becomes difficult
Solution Approach 1:
The patent applies equipotentiality by ensuring all power converters operate at the same voltage level during the blackstart process. Each converter follows an identical voltage ramp profile, creating equivalent operating conditions that enable automatic synchronization without requiring communication between converters or a master controller.
Solution Approach 2:
The patent applies parameter changes by using a predetermined voltage ramp profile that all converters follow. By changing the voltage parameter in a controlled, time-dependent manner according to the ramp profile, converters automatically synchronize their operation without needing to communicate with each other.
3Ease of operation
If power converters start at different voltage levels, then individual converter control is simplified, but power distribution efficiency decreases
Solution Approach 1:
The patent applies parameter changes by implementing a predetermined voltage ramp profile that all power converters follow during blackstart. Each converter independently adjusts its output voltage according to this profile, simplifying individual control while ensuring all converters reach the same voltage level simultaneously, thereby maintaining efficient power distribution.
Data Source
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AI summary
A power system and method for performing a blackstart on a microgrid. The power system includes at least a first power converter (130) and a second power converter (140). The first power converter comprises a first controller (230) having a plurality of startup sequences for performing the blackstart. The second power converter is electrically coupled to the first power converter at a point of common coupling (180). During the blackstart, the first controller is configured to select and perform one of the plurality of startup sequences according to a point at which the second power converter is within the second power converter's startup sequence during the blackstart. The first controller selects the one of the plurality of startup sequences according to a microgrid voltage at the point of common coupling.