Resonance Suppression in Grid-Connected Inverters
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Solution Overview
Problem
Conventional resonance suppression methods in grid-connected generation systems are ineffective for large-scale systems, leading to unstable operation due to unsuitable control and increased resonance, especially with multiple inverters, which complicates the suppression of resonance and affects the reliability and safety of the system.
Innovation Solution
A method and device that monitor current sample voltages in real-time, adjust inverter parameters using current corrections and a preset resonance suppressing algorithm, dynamically shifting the resonance point to suppress resonance, involving adjustments to bandwidths, active damping coefficients, and inactive damping resistors, ensuring reliable and stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional active damping resonance suppressing method is used, then resonance can be suppressed in small-scale systems, but the method has poor feasibility and stability for large-scale grid-connected generation systems with multiple inverters
Solution Approach 1:
The patent segments the resonance suppression problem by treating each inverter independently. Each inverter is assigned a specific resonance frequency band to suppress, rather than attempting to suppress all resonances centrally. This segmentation allows the system to handle large-scale multi-inverter configurations effectively, as each inverter only needs to manage its designated frequency range, reducing overall control complexity while maintaining system-wide resonance suppression.
Solution Approach 2:
The patent implements dynamic resonance frequency identification and assignment. The resonance frequency bands are dynamically determined based on the actual system configuration and operating conditions. This dynamic approach allows the control algorithm to adapt to different system scales and configurations, improving feasibility for large-scale systems while maintaining stability through real-time frequency band optimization.
2Object-affected harmful factors
If resonance suppression control is applied, then resonance can be reduced, but unsuitable control may increase resonance and affect system reliability
Solution Approach 1:
The patent implements a feedback mechanism where the actual resonance frequencies are continuously monitored and measured. Based on this feedback, the resonance frequency bands are dynamically identified and assigned to appropriate inverters. This closed-loop feedback ensures that the control action is based on actual system conditions rather than fixed assumptions, preventing unsuitable control that could increase resonance and thereby maintaining system reliability and safety.
Solution Approach 2:
The patent changes the control parameters dynamically by adjusting the resonance frequency bands assigned to different inverters based on measured system conditions. Instead of using fixed control parameters, the system adapts the frequency band parameters according to actual resonance characteristics, ensuring that suppression control is always suitable for the current operating state and preventing resonance amplification.
3Power
If multiple inverters are added to increase generation capacity, then system power output increases, but resonance occurs due to mutual influence among impedances
Solution Approach 1:
The patent applies segmentation by dividing the frequency spectrum into multiple bands and assigning each band to a specific inverter. This frequency domain segmentation eliminates the mutual interference among inverters, as each inverter operates on its designated frequency band without affecting others. This allows multiple inverters to be added to increase generation capacity while preventing resonance through systematic frequency allocation.
Solution Approach 2:
The patent transitions from time-domain control to frequency-domain control by introducing frequency band assignment as an additional dimension of control. Instead of managing multiple inverters in the time domain where their interactions cause resonance, the system uses frequency domain segmentation to orthogonalize the inverter operations. This dimensional change in control space allows scalable system expansion without resonance issues.
Data Source
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AI summary
A method and device for monitoring and suppressing a resonance are provided, which are applied to a grid-connected generation system. A current sample voltage of a preset sample point of the grid-connected generation system is monitored in a real time manner; amplitudes of harmonics of the current sample voltage are acquired using a preset algorithm; it is verified whether a resonance occurs in the grid-connected generation system currently based on the acquired amplitudes of the harmonics; in a case that the resonance occurs in the grid-connected generation system, current corrections of parameters of inverters in the grid-connected generation system are acquired according to a preset rule and the parameters of the inverters are adjusted using the current corrections and a selected resonance suppressing algorithm, until the resonance disappears in the grid-connected generation system. It follows that, with the method and device, a resonance point of the grid-connected generation system is adjusted dynamically to suppress the resonance occurred in the grid-connected generation system, thereby ensuring a reliable and stable operation of the grid-connected generation system.