Grid-Connected Inverter Vector Synchronization for Small-Signal Stability
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Solution Overview
Problem
Existing methods for enhancing small interference stability in grid-connected inverters require substantial modifications to mature commercial inverters or additional equipment, and are often limited to suppressing instability at specific frequencies under certain control strategies, hindering the safe and stable operation of power systems.
Innovation Solution
A vector synchronization method and system that converts power grid voltage into d-axis and q-axis voltage vector components, performs gain and integral operations to calculate current compensation signals, and injects these signals into the current control loop of the grid-connected inverter to enhance stability, without the need for additional equipment or large-scale modifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If synchronous condensers or power system stabilizer solutions are added to enhance small interference stability, then the stability of the power system is improved, but the device complexity and investment cost increase
Solution Approach 1:
The grid-connected inverter performs self-diagnosis and self-regulation by monitoring its own output current and grid voltage, automatically adjusting control parameters to suppress small interference instability without requiring external stabilizing equipment
Solution Approach 2:
The patent replaces mechanical stabilizing devices (synchronous condensers, power system stabilizers) with a control algorithm that uses mathematical modeling and real-time computation to achieve the same stability enhancement function
2Reliability
If grid-connected inverter control strategy network transformation is implemented, then small interference stability is improved, but the ease of operation and modification requirements increase
Solution Approach 1:
The patent pre-establishes a mathematical model of the grid-connected inverter system and pre-calculates the relationships between control parameters and stability characteristics, enabling rapid parameter adjustment without complex real-time analysis
Solution Approach 2:
The patent achieves stability enhancement by adjusting control parameters (such as current control loop parameters, synchronization parameters) within the existing inverter system, avoiding the need for hardware modifications or network transformation
3Reliability
If existing stability enhancement methods are applied, then small interference stability at certain frequency is improved, but the adaptability to different frequencies and control strategies is reduced
Solution Approach 1:
The patent develops a universal stability enhancement method based on mathematical modeling that can analyze and suppress small interference instability across different frequency ranges and control strategies by adjusting the model parameters rather than requiring different solutions for different cases
Solution Approach 2:
The patent implements dynamic parameter adjustment where the control parameters are continuously optimized based on real-time operating conditions, frequency characteristics, and grid state, enabling the system to adapt to varying frequencies and control strategies
Data Source
AI summary
Disclosed are a vector synchronization method and system, the method includes: converting a three-phase instantaneous value of a power grid voltage into a two-phase voltage vector component through employing a power grid voltage vector phase angle at a previous moment; subtracting the d-axis voltage vector component from the power grid vector amplitude to obtain a d-axis voltage component deviation; performing gain and integral operations on the d-axis voltage component deviation to obtain a power grid vector amplitude; performing gain, integral and proportional-integral operations on the q-axis voltage component deviation to obtain a power grid voltage vector phase angle; respectively converting the d-axis voltage component deviation and the q-axis voltage component deviation into a q-axis current compensation signal and a d-axis current compensation signal of the grid-connected inverter; and the small interference stability of the grid-connected inverter is enhanced by adopting d-axis and q-axis current compensation signals of the grid-connected inverter.