Modular Power Converter Cold Start-Up via Virtual Grid Simulation

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Solution Overview

Problem

Power converters cannot perform essential validation tests without an AC grid voltage, leading to high commissioning costs due to the need for grid connection during testing.

Innovation Solution

A modular power converter system with a control module, DC and AC switches, an auxiliary AC power supply, and a transformer allows for grid synchronization and full-power operation testing without connecting to the AC grid, using an AC source or DC source with transformation to simulate grid conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the power converter is connected to the AC grid to perform essential validation tests, then the testing capability is improved, but the commissioning costs increase

Engineering Contradiction:

Improvetesting capabilityVSAvoidcommissioning costs

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent creates a virtual copy of the AC grid environment through software simulation. The virtual grid model replicates grid characteristics, synchronization requirements, and operational conditions, allowing comprehensive validation testing without physical grid connection. This copying approach enables full functional verification while eliminating the need for expensive grid commissioning services.

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The patent introduces a virtual grid as an intermediary layer between the power converter and the physical AC grid. This virtual intermediary provides all necessary grid characteristics and testing scenarios without requiring actual grid connection, thereby maintaining testing capability while avoiding commissioning costs.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If the power converter is tested without AC grid connection, then the commissioning costs are reduced, but the availability of AC voltage source for testing becomes problematic

Engineering Contradiction:

Improvecommissioning costsVSAvoidavailability of AC voltage source

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

Instead of relying on physical AC grid connection, the patent creates a complete virtual copy of the grid environment including voltage sources, frequency references, and synchronization signals. This virtual copying provides all necessary AC voltage characteristics without external grid dependency, enabling testing in isolated locations.

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The power converter system generates its own virtual grid environment and testing conditions without requiring external AC grid infrastructure. The system serves itself by creating the necessary voltage sources and synchronization references internally through software simulation, making the testing process independent of external utilities.

Inventive Principle:

Principle #25Self-service

3Reliability

If grid connection is required for validation tests, then the synchronization testing is possible, but the deployment flexibility is reduced

Engineering Contradiction:

Improvesynchronization testingVSAvoiddeployment flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent creates a virtual grid that replicates all synchronization characteristics, phase angles, and frequency variations of a real grid. This virtual copying enables comprehensive synchronization testing including phase lock, frequency tracking, and reactive power control without requiring actual grid connection, thereby maintaining deployment flexibility.

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The patent performs all synchronization testing and validation in advance through virtual grid simulation before actual grid connection. By completing synchronization verification preliminarily in the virtual environment, the system ensures readiness for grid connection while maintaining full deployment flexibility and eliminating the need for post-installation grid testing.

Inventive Principle:

Principle #10Preliminary action

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

Enables testing of power converters before installation, reducing commissioning costs by simulating grid conditions internally, ensuring proper synchronization and operation without external AC grid dependency.

Implementation Method 1

an auxiliary transformer connected with the AC bus and with the auxiliary AC power supply via a switch

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS11336171B2Power converter with cold start-up and cold start-up method for power converter

Publication Date: 2022.05.17 POWER ELECTRONICS ESPANA SL

AI summary

The present invention discloses a converter with cold start-up and a cold start-up method for modular power converters that allows converter operation tests to be carried out without a connection to the AC grid. For that purpose, the control module powers the power converter modules, disconnects the power converter from the AC grid, selects a power converter module as the AC-source module and configures a voltage and a frequency for the AC-source module, selects the power for the other power converter modules and sets starting conditions. Previously, the control module is powered by an AC source that can be internal or external, such as an uninterruptible power supply (UPS) or a DC source (photovoltaic field), via a DC-AC transformer.