Virtual Oscillator Control for Inverter Synchronization

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Solution Overview

Problem

Existing power inverter systems in microgrids face challenges in synchronization without communication, particularly in nonlinear and dynamic load conditions, where load impedance and number of inverters complicate synchronization processes.

Innovation Solution

The implementation of a control paradigm that utilizes local measurements only, allowing individual inverters to synchronize through a virtual oscillator system, independent of load impedance and number of inverters, by formulating a sufficient condition for global asymptotic synchronization using L2 input-output stability methods and linear time-invariant network analysis.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If communication-based synchronization methods are used, then synchronization accuracy is improved, but system complexity and communication requirements increase

Engineering Contradiction:

Improvesynchronization accuracyVSAvoidsystem complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

Each inverter is equipped with a virtual oscillator that autonomously generates synchronization signals based on local measurements of voltage and current. The oscillators naturally synchronize through their coupling to the common electrical network, eliminating the need for external communication infrastructure or centralized control while achieving accurate synchronization.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The virtual oscillator acts as an intermediary mechanism that translates local electrical measurements into synchronization signals. Instead of direct communication between inverters, the electrical network itself serves as the medium through which oscillators exchange information and achieve synchronization.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If traditional synchronization methods are used, then synchronization is achieved under ideal conditions, but performance deteriorates under nonlinear and dynamic load conditions

Engineering Contradiction:

Improvesynchronization reliabilityVSAvoidadaptability to load conditions

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The virtual oscillator control paradigm employs dynamic models that continuously adapt to changing load conditions. The oscillators respond to variations in voltage and current waveforms in real-time, automatically adjusting their frequency and phase to maintain synchronization under nonlinear and dynamic loads, whereas traditional methods assume idealized steady-state conditions.

Inventive Principle:

Principle #15Dynamics

3Stability of the object's composition

If centralized control is used, then system coordination is improved, but loss of information and communication requirements increase

Engineering Contradiction:

Improvesystem coordinationVSAvoidinformation exchange requirements

Core Design Contradiction:

Stability of the object's compositionVSLoss of information

Solution Approach 1:

The centralized control function is segmented and distributed to individual inverters, each equipped with its own virtual oscillator. This segmentation eliminates the need for a central control entity and the associated information exchange, while maintaining system coordination through the natural coupling of oscillators to the common electrical network.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS9484745B2Virtual oscillator control of power electronics inverters

Publication Date: 2016.11.01 THE BOARD OF TRUSTEES OF THE UNIV OF ILLINOIS

AI summary

A system includes power electronics inverters connected in a network. The power electronics inverters can utilize measurements at local terminals, without a need to exchange information between other power electronics inverters.