Grid-Forming Inverter Feed-Forward Control for Faster Inertia Response
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Solution Overview
Problem
Grid-following inverters lack the inertia provided by traditional synchronous generators, leading to instability in grids with increasing renewable energy sources, which can destabilize voltage and frequency due to variability and reduce the overall grid stability.
Innovation Solution
A grid-forming inverter with a control circuit that integrates an inertia model and performs feed-forward control using pulse width modulation (PWM) to mimic the inertia of synchronous generators, enhancing frequency stability and response speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a grid-following inverter is used to convert renewable energy to grid-compatible power, then the inverter configuration is simple and easy to operate, but the inverter cannot provide inertia to the grid and may deteriorate grid stability
Solution Approach 1:
The patent inverts the traditional grid-following approach by implementing a grid-forming inverter that actively establishes voltage and frequency references instead of passively following them. The control circuit generates a voltage reference signal and adjusts it based on frequency deviation, thereby providing inertia-like support to the grid while maintaining operational simplicity through automated control algorithms.
Solution Approach 2:
The patent changes the operational parameters of the inverter by dynamically adjusting the voltage reference signal based on grid frequency deviations. The control circuit modifies voltage magnitude and phase angle in response to frequency changes, enabling the inverter to provide synthetic inertia without requiring complex mechanical structures, thus resolving the contradiction between operational simplicity and grid stability.
2Productivity
If multiple grid-following inverters are connected to the grid to increase renewable energy proportion, then energy generation capacity increases, but the lack of inertia from synchronous generators emerges as a serious problem for grid management
Solution Approach 1:
The patent copies the inertia-providing function of synchronous generators by implementing a control algorithm that simulates inertial response. The grid-forming inverter calculates frequency deviations and generates corrective voltage signals that mimic the physical inertia behavior of traditional generators, enabling multiple inverters to be connected without compromising grid stability while maximizing renewable energy generation.
3Reliability
If a grid-forming inverter is used to provide inertia to the grid, then frequency stability is improved, but the response speed of the inverter is slow
Solution Approach 1:
The patent implements preliminary action by pre-calculating and storing voltage reference adjustments for various frequency deviation scenarios. When frequency deviations occur, the control circuit immediately retrieves and applies the appropriate corrective signals, eliminating computational delays and achieving rapid response while maintaining frequency stability through pre-optimized control parameters.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The grid-forming inverter provides virtual inertia, improving frequency stability and response speed, ensuring rapid adjustments to power commands and maintaining grid stability even with reduced synchronous generators.
Implementation Method 1
control the switching devices using pulse width modulation (PWM) according to the second phase control value
Data Source
AI summary
A grid-forming inverter comprises: a power stage configured to convert electric power according to on/off controls of switching devices and to output converted electric power to a grid; and a control circuit configured to calculate a first phase control value using an inertia model that integrates a difference between a power command value and an active output power value of the power stage, to calculate a second phase control value through feed-forward control that additionally reflects the power command value in the first phase control value, and to control the switching devices using pulse width modulation (PWM) according to the second phase control value.