VSG Inverter Control for Grid Stability and Harmonic Reduction
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Solution Overview
Problem
The stability of photovoltaic power generation systems connected to the grid is compromised due to the lack of rotational inertia and frequency/voltage regulation capabilities, leading to reduced grid stability and adaptability.
Innovation Solution
An inverter control method that simulates the frequency regulation characteristics of a virtual synchronous generator (VSG) to determine relational expressions for active power-frequency droop and rotor angular velocity, adjusting virtual damping and inertia through fuzzy control to maintain system stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a grid-connected inverter is used for photovoltaic power generation, then the response speed is fast, but the system lacks rotational inertia and frequency/voltage regulation capability, resulting in reduced system stability
Solution Approach 1:
The patent copies the frequency-voltage regulation characteristics of synchronous generators by implementing virtual synchronous generator control in the inverter. The control system simulates the mechanical torque equation and electromagnetic torque equation of synchronous generators, creating virtual rotational inertia and damping coefficients that replicate the stabilizing effects of physical rotating mass, thereby enabling the inverter to provide frequency and voltage support without actual rotational components
Solution Approach 2:
The patent dynamically adjusts control parameters including virtual rotational inertia, virtual damping coefficient, active power-frequency droop coefficient, and reactive power-voltage droop coefficient based on grid conditions and photovoltaic output characteristics. These parameter changes enable the inverter to adapt its frequency-voltage regulation behavior to different operating scenarios, maintaining system stability while preserving fast response capabilities
2Productivity
If photovoltaic power generation is connected to the grid, then energy transmission is achieved, but the randomness and volatility of photovoltaic output reduce grid stability and adaptability
Solution Approach 1:
The patent implements closed-loop feedback control where the inverter continuously monitors grid frequency and voltage deviations, and adjusts its active and reactive power output accordingly. The active power-frequency droop control and reactive power-voltage droop control create automatic feedback mechanisms that enable the inverter to respond to grid conditions and photovoltaic output variations, maintaining grid stability despite the randomness of solar generation
Solution Approach 2:
The patent introduces dynamic virtual rotational inertia and damping coefficients that adapt to changing grid conditions and photovoltaic output characteristics. This dynamic behavior allows the inverter to provide frequency support during sudden photovoltaic output changes and voltage support during load variations, significantly improving grid adaptability while maintaining continuous energy transmission
Data Source
AI summary
The present invention provides an inverter control method, device, computer equipment and storage medium, belonging to the field of power electronics. The method comprises: determining a frequency control equation of the inverter under a grid-connected condition when the inverter is in a VSG control mode; determining a relationship between a virtual electromotive force of a virtual synchronous generator in a reactive state and an output voltage of the inverter; constructing a voltage-current double closed-loop control structure of the inverter under the VSG control mode, and determining a current reference value and a voltage reference value of the virtual synchronous generator under dq axes through the frequency control equation and the relationship; constructing a fuzzy control rule of a virtual damping coefficient and a virtual inertia according to the current reference value and the voltage reference value; and controlling the virtual damping coefficient and the virtual inertia through the fuzzy control rule, thereby improving the stability and performance of the inverter during the grid-connected process, reducing the harmonic disturbance of the power system, and helping to improve the adaptability and reliability of the entire photovoltaic power generation system.