Current Source Threshold Control for Fast Off-Grid Inverter Response
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Solution Overview
Problem
Off-grid inverters in a master-slave system are slow to respond, causing excessive pressure on the master inverter and potential damage.
Innovation Solution
Establish parallel control between a current source and a voltage source, controlling the current source to output current when the voltage is below a first threshold, stopping output when it exceeds a second threshold, and distributing power after synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the slave inverter performs power regulation through loop power control or loop current control in a conventional master-slave system, then the power can be evenly distributed, but the response speed is slow and exerts great pressure on the master inverter
Solution Approach 1:
The patent inverts the conventional control approach by having the slave inverter directly detect voltage and output current based on voltage thresholds, rather than receiving power commands from the master inverter. This reversal of control hierarchy enables the slave inverter to respond autonomously and rapidly to voltage changes, dramatically improving response speed while maintaining system reliability through voltage-based protection mechanisms
Solution Approach 2:
The slave inverter performs self-service by autonomously detecting voltage across the AC bus and independently deciding when to output current based on predetermined voltage thresholds. This self-service capability eliminates the need for slow communication with the master inverter, enabling rapid response while the voltage threshold mechanism ensures system stability through automatic protection
2Reliability
If the slave inverter responds slowly in a conventional master-slave system, then the master inverter can maintain control, but the excessive pressure may damage the master inverter
Solution Approach 1:
The patent introduces voltage threshold detection as an intermediary mechanism that mediates between the slave inverter and the AC bus. The voltage thresholds act as a protective intermediary, automatically limiting the slave inverter's current output when voltage exceeds safe levels, thereby protecting the master inverter from excessive pressure while enabling the slave inverter to contribute fully to system capacity
Solution Approach 2:
The system performs preliminary action by pre-setting voltage thresholds before operation. These predetermined thresholds enable the slave inverter to immediately respond to voltage conditions without waiting for master inverter commands, allowing the slave inverter to rapidly adjust its output to protect the master inverter while maximizing system capacity utilization
Data Source
AI summary
A method and a device for a current source to respond, and a computer-readable storage medium are provided. Parallel control for the current source and a voltage source is established, and a voltage across an alternating-current bus is acquired. When the voltage is lower than a first threshold, the current source outputs a current to increase the voltage across the alternating-current bus. Then, it is determined whether the voltage exceeds a second threshold. When the voltage exceeds the second threshold, the current source stops outputting the current. When the voltage does not exceed the second threshold, power is distributed between the current source and the voltage source after power synchronization. The current source directly outputs the current, and therefore unnecessarily wait for the power from the voltage source.