Virtual Synchronous Impedance Control for Fast Load Response
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Solution Overview
Problem
Existing power conversion systems struggle to quickly respond to load fluctuations while maintaining the amplitude of the output voltage and reproducing synchronizing power using virtual synchronous impedance models.
Innovation Solution
A control system for power conversion devices that includes a virtual synchronous impedance compensation block to simulate voltage drops and calculate output voltage commands, combined with a virtual synchronous generator model to determine angular frequency, ensuring the output voltage coincides with the desired amplitude and phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voltage control is performed by subtracting output voltage drop from internal induced voltage, then synchronizing power is reproduced, but output voltage amplitude cannot quickly respond to load fluctuations
Solution Approach 1:
The control system pre-calculates the voltage drop across the virtual synchronous impedance based on the output current, and uses this information to proactively adjust the internal induced voltage before load fluctuations cause voltage amplitude deviations. This preliminary calculation and adjustment mechanism enables the system to maintain both synchronizing power reproduction and quick response to load changes.
2Reliability
If virtual synchronous impedance model is used, then synchronizing power is reproduced, but output voltage amplitude deviates from command value during load fluctuation
Solution Approach 1:
The control system continuously monitors the output voltage amplitude and compares it with the command value. When load fluctuations cause deviations, the feedback mechanism adjusts the internal induced voltage based on the detected voltage drop across the virtual synchronous impedance, ensuring the output voltage amplitude accurately follows the command value while maintaining synchronizing power reproduction.
3Reliability
If voltage drop simulation is performed, then synchronizing power is reproduced, but control complexity increases
Solution Approach 1:
The control system introduces a virtual synchronous impedance element as an intermediary that mathematically models the voltage drop characteristics. This virtual impedance serves as a mediator between the output current and the internal induced voltage, enabling synchronizing power reproduction through standardized control algorithms without requiring complex physical modifications or multi-variable control strategies.
Data Source
AI summary
A control system is provided for a power conversion system having a power converter that controls a virtual synchronous generator simulating a synchronous generator and interconnected to a power grid. The control system has a virtual synchronous impedance compensation block inputting an output current detection value of the power converter and a set voltage amplitude command value, simulating a voltage drop due to a virtual synchronous impedance, and calculating an output voltage command value and an internal induced voltage according to the simulated voltage drop; a virtual synchronous generator model determining an angular frequency simulating the synchronous generator; and a PCS output voltage control unit performing control so that an output voltage of the power conversion system coincides with the output voltage command value calculated by the virtual synchronous impedance compensation block.