Switchable Longitudinal Voltage Source for Bidirectional DC Power Flow

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Solution Overview

Problem

Existing switchable longitudinal voltage sources require a large number of components, leading to inefficiencies and increased complexity.

Innovation Solution

A switchable longitudinal voltage source with a polarity reversal device connected between output terminals, utilizing a minimal number of switches and switches with external control, allowing for efficient current distribution to high-voltage DC transmission lines.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a longitudinal voltage source with switchable polarity is implemented, then the direction of active power flow can be reversed en masse, but the device complexity increases due to additional switching components

Engineering Contradiction:
Improvepower flow direction controlVSAvoidswitching component complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The longitudinal voltage source is segmented into two independent voltage sources (first and second voltage sources) that can be independently controlled. Each voltage source connects to one polarity terminal, allowing independent control of each half-circuit. This segmentation enables polarity reversal without requiring complex switching arrangements, as each segment can be activated or deactivated independently through simple switching elements.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements dynamic polarity switching by providing switching elements that can dynamically change the connection state of each voltage source to the common connection point. The switching elements enable the longitudinal voltage source to transition between different polarity states (first polarity, second polarity, or floating) in real-time, allowing adaptive control of power flow direction based on system requirements.

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If polarity reversal is achieved through conventional switching methods, then the direction of active power flow can be changed, but power loss increases due to additional switching operations

Engineering Contradiction:
Improvepower flow direction controlVSAvoidpower loss during switching
Core Design Contradiction:
Adaptability or versatilityVSLoss of energy

Solution Approach 1:

By segmenting the voltage source into two independent halves, each with its own switching element, the patent enables selective activation. When polarity reversal is needed, only the necessary switching operations are performed on the relevant segment, rather than requiring full-system switching. This reduces the number of simultaneous switching operations and associated power losses.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The common connection point serves as an intermediary that facilitates polarity reversal without requiring direct switching of the entire voltage source. The switching elements connect or disconnect voltage sources to this common point, enabling polarity change through controlled connection reconfiguration rather than direct polarity switching, which minimizes switching losses.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Adaptability or versatility

If a longitudinal voltage source with switchable polarity is implemented, then bidirectional active power flow control is enabled, but the control system complexity increases

Engineering Contradiction:
Improvebidirectional power flow controlVSAvoidcontrol system complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The control system manages complexity by controlling each voltage source segment independently. The control unit can selectively activate or deactivate the first or second voltage source based on power flow requirements, simplifying the control logic compared to managing a single complex switching network. Each segment's control is independent, allowing straightforward implementation of bidirectional power flow control.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The control system achieves dynamic polarity reversal control through independent switching elements that can be actuated based on real-time power flow requirements. The control unit monitors system conditions and dynamically switches between different polarity configurations by controlling the switching elements, enabling adaptive bidirectional power flow control with relatively simple control logic.

Inventive Principle:
Principle #15Dynamics

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

The solution reduces the number of components required while maintaining effective current distribution, minimizing electrical losses, and enabling bidirectional load flow control.

Implementation Method 1

a first voltage source (131) and a second voltage source (132) are arranged in a longitudinal voltage source (130)

Methodology Applied
Scientific EffectBattery (electricity): Battery (electricity)

Data Source

PatentEP3830944B1Switchable longitudinal voltage source, DC transmission system with longitudinal voltage source, and method for operating a longitudinal voltage source
Publication Date: 2026.05.06 SIEMENS ENERGY GLOBAL GMBH & CO KG
  • EP3830944B1 patent drawingFigure 1
  • EP3830944B1 patent drawingFigure 2
  • EP3830944B1 patent drawingFigure 3

AI summary

The invention relates, inter alia, to a switchable longitudinal voltage source (10, 10'). According to the invention, a center terminal (M1) of a first series circuit (R1) directly forms a first output terminal (A1) and a center terminal (M2) of a second series circuit (R2) directly forms a second output terminal (A2).