HVDC Converter H-Bridge Submodules for Arc Extinguishing
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Solution Overview
Problem
Existing methods for eliminating faults on high-voltage direct current lines connected to alternating current networks via self-commutated converters are inefficient and costly, often requiring additional circuit elements that increase losses during fault-free operation.
Innovation Solution
A method utilizing a modular converter design with a small number of H-bridge submodules and a larger number of half-bridge submodules, where H-bridge submodules generate a reverse voltage to extinguish arcs and reduce short-circuit currents upon fault detection, eliminating the need for additional circuit elements and minimizing losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional circuit elements are used to interrupt current during faults, then fault elimination capability is improved, but losses during fault-free operation increase
Solution Approach 1:
The converter itself performs the fault elimination function by generating reverse voltage through its existing H-bridge submodules, eliminating the need for separate current interruption devices. The converter serves both its primary power conversion function and the secondary function of fault clearance, thereby avoiding additional energy losses from extra circuit elements during normal operation.
Solution Approach 2:
The H-bridge submodules in the converter are designed to perform multiple functions: normal power conversion and fault current interruption. By programming the converter control to generate reverse voltage during faults, the same hardware components serve dual purposes, improving reliability without adding dedicated fault protection circuitry that would cause energy losses during normal operation.
2Reliability
If traditional fault elimination methods are used, then current interruption is achieved, but production costs increase
Solution Approach 1:
The converter system clears faults using its own built-in H-bridge submodules and control programming, eliminating the need for separate expensive fault protection devices. This self-service approach reduces manufacturing costs while maintaining current interruption capability.
Solution Approach 2:
The fault elimination function is extracted from separate dedicated devices and integrated into the converter's existing H-bridge submodule structure. By removing the need for additional standalone fault protection equipment, production costs are reduced while the converter retains full current interruption capability through its modified control strategy.
3Power
If more H-bridge submodules are used, then reverse voltage generation capability is improved, but manufacturing costs increase
Solution Approach 1:
Instead of equipping all submodules with expensive H-bridge configurations, the invention uses only a small number of H-bridge submodules (partial action) strategically positioned within the converter. This provides sufficient reverse voltage generation capability for fault elimination while significantly reducing manufacturing costs compared to using H-bridge submodules throughout the entire converter structure.
Solution Approach 2:
The H-bridge submodules are deployed locally and selectively at specific positions within the converter where they are most effective for generating reverse voltage during faults. This localized quality approach concentrates the expensive H-bridge technology only where needed rather than uniformly across all submodules, optimizing the balance between power capability and manufacturing cost.
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
This approach allows for rapid fault elimination with minimal effort and low losses, reducing production costs and maintaining efficient operation during normal conditions by using fewer and less expensive H-bridge submodules compared to traditional designs.
Implementation Method 1
H-bridge submodules are controlled in such a way that a reverse voltage to the voltage at the arc occurs; the short-circuit current is reduced relatively quickly
Data Source
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AI summary
In order to be able to eliminate a fault on a high-voltage DC line (19) with an AC voltage supply system (17) which is connected via a self-commutated converter (1) in a reliable manner with a comparatively low level of expenditure, the short-circuiting current flowing in the event of the fault is reduced by means of driving in each case at least one H-bridge submodule (36, 37, 38; 39, 40, 41) in phase branches (4, 5, 6; 7, 8, 9) of the converter (1), which is of modular design, so as to generate a countervoltage to the voltage across the arc. The invention also relates to a system for transmitting an electric current via a high-voltage DC line, and to a converter.