Grid-Tied Converter Reactive Power Prediction

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Solution Overview

Problem

Conventional grid-tied converters lack the ability to accurately predict their reactive power capability, which is essential for effective grid management and reactive power compensation, as this capability is influenced by the grid's impedance, voltage, frequency, and the converter's internal states, leading to inefficiencies and potential malfunctions.

Innovation Solution

A system that dynamically predicts the maximum reactive power capability of grid-tied converters in real-time using internal status information and external connection point feedback, specifically considering direct current link maximum voltage, instantaneous grid network voltage, and line current, allowing for optimized energy regulation and compensation strategies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional simple estimation methods are used to predict reactive power capability, then the prediction process is simple and fast, but the prediction accuracy is poor because it ignores grid impedance, voltage, frequency, and converter internal states

Engineering Contradiction:
Improvereactive power capability prediction accuracyVSAvoidprediction system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent implements a feedback mechanism where the converter continuously monitors its internal states (active power output, DC bus voltage) and external grid conditions (voltage, frequency, impedance) and uses this feedback information to dynamically adjust and predict its reactive power capability. This closed-loop feedback approach enables accurate real-time prediction without requiring complex manual calculations or external intervention.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The converter performs self-assessment of its reactive power capability by utilizing its own internal status information and external connection point feedback. The system independently predicts its maximum reactive power capability without requiring external grid management system calculations, thereby achieving accurate prediction while maintaining system simplicity.

Inventive Principle:
Principle #25Self-service

2Adaptability or versatility

If the converter continuously adapts to different grid codes and external conditions, then the adaptability is improved, but the computational burden and system complexity increase

Engineering Contradiction:
Improveadaptability to different grid codesVSAvoidsystem complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements a dynamic prediction approach where the converter's reactive power capability is continuously updated based on real-time operating conditions and grid codes. The system adapts to varying grid requirements by dynamically adjusting its prediction model parameters according to the applicable grid code, enabling versatility without requiring multiple static prediction systems.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system achieves adaptability to different grid codes by changing key parameters such as maximum DC bus voltage limits, voltage thresholds, and frequency ranges based on the specific grid code requirements. This parameter-based adaptation allows the same prediction system to serve multiple grid environments without increasing structural complexity.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If the converter uses accurate real-time prediction of maximum reactive power capability, then the grid management efficiency is improved, but the measurement and calculation requirements increase

Engineering Contradiction:
Improvegrid management efficiencyVSAvoidmeasurement and calculation complexity
Core Design Contradiction:
ProductivityVSDifficulty of detecting and measuring

Solution Approach 1:

The converter independently performs the complex measurements and calculations required for accurate reactive power capability prediction using its own internal sensors and processors. By offloading this computational burden to the converter itself rather than requiring centralized grid management system calculations, the system achieves high prediction accuracy while maintaining grid management efficiency.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP3149825B1Reactive power prediction capability
Publication Date: 2020.07.01 GE ENERGY POWER CONVERSION TECHNOLOGY LTD(GB)
  • EP3149825B1 patent drawingFigure 1
  • EP3149825B1 patent drawingFigure 2
  • EP3149825B1 patent drawingFigure 3

AI summary

Provided is a system for regulating energy provided to an electricity grid (102) from an energy source, the system includes a converter (106) configured to receive the energy from the source. The converter (106) is configured to dynamically predict real-time maximum reactive power capability as a function of at least one from the group including (i) a direct current link maximum voltage, (ii) an instantaneous grid network voltage, and (iii) a line current. The predicted maximum reactive power capability is configured for optimizing regulation of the energy.