Grid-Forming Inverter Control with Virtual Inertia and Droop Sync

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Solution Overview

Problem

Renewable energy-based power supplies, such as inverter-based systems, lack the ability to automatically synchronize droop, phase, inertia, voltage magnitude, and frequency with the power grid when disconnected and connected, posing challenges in seamless integration.

Innovation Solution

An apparatus and method for controlling inverters using controllers with droop control, voltage magnitude control, phase control, and inertia control, incorporating voltage, virtual inertia, and droop control loops to synchronize inverter-based power supplies with the grid.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If inverter-based power supplies are disconnected from the power grid, then independence and flexibility are improved, but the ability to automatically synchronize droop, phase, inertia, voltage magnitude, and frequency upon reconnection deteriorates

Engineering Contradiction:

Improveindependence of power supplyVSAvoidsynchronization capability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent replaces traditional rotating machine-based synchronization systems with inverter-based electronic control systems. The controller uses software algorithms to simulate inertial response and synchronize electrical parameters (frequency, voltage, phase) without mechanical components, enabling grid-forming capability in inverter-based power supplies.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a controller as an intermediary between the inverter-based power supply and the power grid. This controller mediates the synchronization process by continuously monitoring grid parameters and adjusting inverter output to match grid conditions, enabling seamless connection and disconnection.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If rotating machine-based systems are used for synchronization, then reliable grid connection is achieved, but system complexity and maintenance requirements increase

Engineering Contradiction:

Improvegrid connection stabilityVSAvoidsystem structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent eliminates rotating machines and their associated mechanical complexity by using purely electronic inverter systems with software-based control algorithms. The controller implements virtual inertia and synchronization functions through digital signal processing, removing the need for physical rotating components.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The inverter-based system performs multiple functions (power conversion, synchronization, inertia simulation, voltage regulation) that traditionally required separate rotating machine systems. This multi-functionality reduces overall system complexity while maintaining reliability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Device complexity

If inverter-based power supplies are used, then system simplicity and reduced maintenance are achieved, but the ability to synchronize with the power grid deteriorates

Engineering Contradiction:

Improvesystem structureVSAvoidsynchronization capability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent implements feedback control loops in the controller that continuously monitor grid frequency, voltage, and phase, and adjust inverter output accordingly. This closed-loop control enables inverter-based systems to automatically synchronize with the grid by comparing reference signals with actual measurements and correcting deviations.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent dynamically changes control parameters (droop coefficients, virtual inertia constants, voltage magnitude) based on operating conditions to optimize synchronization performance. The controller adjusts these parameters in real-time to maintain stable grid connection while preserving system simplicity.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS12587019B2Apparatus and method for controlling one or more inverters

Publication Date: 2026.03.24 THE UNIV OF NORTH CAROLINA AT CHAPEL HILL

AI summary

An example apparatus for controlling one or more inverters is provided herein. In some embodiments, the apparatus for controlling one or more inverters may include one or more controllers. In some embodiments, each of the one or more inverters is associated with at least one power source. In some embodiments, each of the one or more controllers may configured to provide droop control, voltage magnitude control, phase control, frequency control and inertia control for an associated inverter of the one or more inverters. In some embodiments, each of the one or more controllers comprises a voltage control loop, a virtual inertia control loop, and a droop control loop enabling the power supplies to sync with a power grid and/or other power supplies when the power supply is disconnected from the power grid and/or other power supplies and/or connected to a power supply to the power grid and/or other power supplies.