Generator Synchronization Reducing Shaft Torque Impact
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Solution Overview
Problem
Existing methods for synchronizing electric machines with an electric grid can result in high torque impacts on the machine's shaft during faulty synchronization, leading to potential damage and the need for over-engineering of the shaft to withstand such forces.
Innovation Solution
A method that involves synchronizing the frequency and voltage of the generator with the grid in stages, where the generator's voltage is increased to a lower value (5-20% less than the grid voltage) before connection, allowing for phase synchronization, thereby reducing the torque impact during potential phase shifts of 120°.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional synchronizing methods are used where the generator voltage is matched to the grid voltage before connection, then the synchronization accuracy is improved, but the torque impact on the shaft during faulty synchronization increases significantly
Solution Approach 1:
The patent applies preliminary action by performing frequency synchronization before voltage synchronization. The generator frequency is adjusted to match the grid frequency in advance, and only after this preliminary step is complete does the system proceed to voltage matching and phase synchronization. This staged approach ensures that if conductor interchange occurs, the frequency-matched condition limits the severity of torque impacts during faulty synchronization events.
Solution Approach 2:
The synchronization process is segmented into distinct stages: frequency synchronization first, then voltage synchronization, and finally phase synchronization. This segmentation allows each parameter to be optimized independently and ensures that the system reaches a stable state progressively, reducing the risk of severe torque impacts during the connection process.
2Power
If the generator voltage is increased to match the grid voltage before connection, then the power transfer capability is improved, but the torque impact during faulty synchronization increases
Solution Approach 1:
Frequency synchronization is performed as a preliminary action before voltage synchronization. The generator frequency is adjusted to match the grid frequency in advance, establishing a stable foundation that limits torque impacts during subsequent voltage matching and connection operations.
Solution Approach 2:
The synchronization process is made dynamic and adaptive through staged voltage increase. Rather than immediately matching full grid voltage, the generator voltage is increased progressively through controlled stages, allowing the system to adapt to actual grid conditions and reducing the risk of severe torque impacts during faulty synchronization.
3Reliability
If the shaft is designed to withstand large torque impacts, then the reliability during faulty synchronization is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
Frequency synchronization is performed in advance as a preliminary action, ensuring that when connection occurs, the frequency-matched condition is already established. This preliminary preparation significantly reduces the magnitude of torque impacts during faulty synchronization, allowing the shaft to be designed with lower safety factors and reduced complexity.
Solution Approach 2:
The staged synchronization approach acts as a cushioning mechanism against torque impacts. By progressively matching parameters (frequency first, then voltage, then phase) rather than attempting all simultaneous matching, the system cushions against the full force of potential synchronization errors, reducing the structural demands on the shaft.
Data Source
Figure 1~2
Figure 3~4
AI summary
The method for synchronising an electric machine (1) with an electric grid (2) comprises the steps of synchronising the frequency of the generator (1) with that of the grid (2) and regulating the voltage of the generator (1) towards the voltage of the grid (2), thus connecting the generator (1) to the grid (2) when the voltage of the generator (1) reaches a first value (V1) lower than the grid voltage (Vg). The present invention also refers to arrangements of electric generator (1) and electric grid (2).