Adaptive Inverter Voltage Control for Renewable Grid Stability

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Solution Overview

Problem

The integration of renewable energy sources through inverters in power systems poses challenges to transient stability due to the lack of inherent synchronization mechanisms found in synchronous generator-dominated systems, necessitating a control strategy to ensure synchronized operation and enhance stability.

Innovation Solution

A method and system are developed to enhance transient stability by constructing an external subsystem and matrices based on voltage control, generating a Lyapunov function, and using adaptive voltage control signals to regulate inverter behavior.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If inverter-based renewable energy sources are integrated into the power system, then the proportion of renewable energy increases, but transient stability deteriorates due to lack of inherent synchronization mechanisms

Engineering Contradiction:

Improverenewable energy integrationVSAvoidtransient stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent implements a synchronous signal generation module that receives voltage signals from the power system and generates synchronous signals through phase-locked loop technology. This feedback mechanism continuously tracks the grid voltage phase and frequency, enabling inverters to synchronize with the grid dynamically, thereby maintaining transient stability while allowing high renewable energy penetration.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent introduces a synchronous signal generation module as an intermediary component between the inverter control system and the grid. This module generates reference synchronous signals that mediate the synchronization process, allowing inverters to coordinate their operation with the grid without requiring direct physical coupling like traditional synchronous generators, thus maintaining stability while enabling renewable integration.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-generated harmful factors

If inverter-based generators replace synchronous generators, then carbon emission is reduced, but synchronization control complexity increases

Engineering Contradiction:

Improvecarbon emissionVSAvoidsynchronization control

Core Design Contradiction:

Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The patent implements a self-synchronization mechanism where each inverter-equipped renewable energy source autonomously generates its own synchronous signals using phase-locked loop technology. The system automatically tracks grid voltage characteristics and adjusts its output phase and frequency without requiring complex external synchronization control, thereby reducing control complexity while enabling carbon-free operation.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent replaces the mechanical synchronization inherent in synchronous generators with an electronic synchronization system based on phase-locked loop technology. This substitution eliminates the need for mechanical coupling and rotor inertia while achieving synchronization through electronic signal processing, thereby reducing carbon emissions while managing control complexity through software-based solutions.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If bus voltage is maintained constant during fault conditions, then transient stability is improved, but inverter switches to constant current control mode

Engineering Contradiction:

Improvetransient stabilityVSAvoidcontrol mode flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent implements a dynamic control strategy where the inverter transitions between voltage control mode and current control mode based on system conditions. During normal operation and post-fault conditions, the inverter operates in voltage control mode to maintain bus voltage and enhance transient stability. During severe fault conditions, it automatically switches to current control mode to provide fault current limitation, thereby adapting to different operational requirements while maintaining overall system stability.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS12438379B2Method and system for enhancing transient stability of power system with renewable energy

Publication Date: 2025.10.07 CHINA SOUTHERN POWER GRID COMPANY

AI summary

A method for enhancing transient stability of a renewable energy power system is performed as follows. An external subsystem corresponding to the renewable energy power system is constructed. A first matrix corresponding to the external subsystem based on voltage control is constructed. A second matrix corresponding to the renewable energy power system is generated. A transient stability Lyapunov function corresponding to the renewable energy power system is constructed in real time based on the first matrix and the second matrix. A first control signal corresponding to the renewable energy power system is generated based on Lyapunov's second method. The transient stability of the renewable energy power system is controlled and enhanced in real time based on the first control signal. The first control signal is an adaptive voltage control signal of the renewable energy power system.