Dual-Converter Furnace Power Supply With STATCOM Backup

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Solution Overview

Problem

Existing converter systems for electric metal heating furnaces often fail to completely compensate for voltage flicker and may experience downtime due to maintenance or outages, which can be costly and disrupt power supply.

Innovation Solution

A converter system comprising two power converters and an energy storage system, connected to an electric metal heating furnace and the power grid, allowing for flexible operational modes including STATCOM, power supply, and combined power compensation, ensuring continuous operation even if one converter is unavailable.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single STATCOM is used to compensate voltage flicker, then power quality is improved, but the system lacks reliability during maintenance or outages

Engineering Contradiction:
Improvesystem availabilityVSAvoidconverter configuration
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system divides the single STATCOM function into two separate power converters (first and second converters), each capable of independently providing STATCOM functionality. This segmentation allows one converter to be maintained while the other continues operation, ensuring system availability without requiring a completely redundant dual-converter setup.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Each power converter is designed with multi-functionality, capable of operating in multiple modes including STATCOM mode, power supply mode, and combined power compensation mode. The control unit enables each converter to adapt its function based on operational requirements, allowing a single converter to perform various roles and reducing the need for specialized equipment for each function.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If AC/DC/AC converter configuration is used, then power quality is improved, but system availability decreases due to maintenance downtime

Engineering Contradiction:
Improvecontinuous operation capabilityVSAvoidmaintenance complexity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The system segments the power conversion function into two independent converters, allowing maintenance to be performed on one converter while the other remains operational. This eliminates the complete system downtime that would occur with a single AC/DC/AC converter during maintenance.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system provides beforehand cushioning by having a second converter ready to take over the load if the first converter requires maintenance or fails. This redundant capability ensures continuous operation and protects against unexpected outages, allowing maintenance to be scheduled without disrupting production.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Adaptability or versatility

If multiple converters are used for flexible operation, then operational versatility is improved, but system complexity increases

Engineering Contradiction:
Improveoperational mode flexibilityVSAvoidconverter and switching unit configuration
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

Each power converter is designed with universal multi-functionality, capable of operating in STATCOM mode, power supply mode, and combined power compensation mode. The control unit enables dynamic switching between these modes for each converter, providing operational versatility without requiring separate specialized equipment for each function.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system employs dynamic operational modes where the function of each converter can be changed in real-time based on system requirements. The control unit dynamically adjusts the operating mode of each converter, allowing flexible adaptation to different operational conditions without physical reconfiguration or additional equipment.

Inventive Principle:
Principle #15Dynamics

4Reliability

If redundant equipment is added for continuous operation, then reliability is improved, but investment and footprint increase

Engineering Contradiction:
Improvecontinuous operation capabilityVSAvoidequipment quantity
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The system achieves redundancy with minimal equipment by designing each converter to perform multiple functions. Instead of requiring separate dedicated STATCOM units and power supply units, each converter can adapt to perform either function as needed, reducing the total equipment quantity while maintaining continuous operation capability.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system implements partial redundancy where two converters provide both STATCOM and power supply capabilities, rather than requiring full redundancy with separate dedicated units for each function. This partial action approach achieves the necessary reliability for continuous operation while minimizing the quantity of equipment required.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP4503364A1A converter system for an electric metal heating furnace system
Publication Date: 2025.02.05 HITACHI ENERGY LTD
  • EP4503364A1 patent drawingFigure 1
  • EP4503364A1 patent drawingFigure 2~3
  • EP4503364A1 patent drawingFigure 4~5

AI summary

A converter system (1) connectable to an electrical power grid (4) via a load bus (5), and to an electric metal heating furnace system (7). The converter system comprises a first power converter (2), and a second power converter (3). Each one of the power converters comprises AC and DC terminals (12, 15, 13, 16). The first power converter is connectable to the load bus, and, at its DC terminals, to the second power converter and to an energy storage system. The second power converter is connectable, at its DC terminals, to the first power converter and to the energy storage system, and, at its AC terminals, to the electrical metal heating furnace system and to the load bus. The converter system further has a control unit to set the converter system in any of several operational modes. One operational mode is a STATCOM mode where at least one of the power converters is connected to the load bus and acts as a STATCOM for the electric metal heating furnace system. The electric metal heating furnace system is connected to the load bus. Another operational mode is a power supply mode where the first power converter is connected to the load bus, the second power converter is connected to the first converter and to the electric metal heating furnace system, and the electric metal heating furnace system is disconnected from the load bus.