Segmented Capacitor Converter for High Power Transmission
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Solution Overview
Problem
Existing power transmission systems using self-commutated converters with capacitors for energy storage are limited by the size of the capacitor, leading to restricted transmission power and vulnerability to high short-circuit currents, which can result in installation destruction.
Innovation Solution
The system employs multiple individually switchable energy storage means and closed-loop control to manage zero phase angle, amplitude, and instantaneous AC voltage values, allowing for improved power transmission characteristics and stability by distributing energy storage across multiple smaller units, reducing complexity and enhancing operational reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a single large capacitor is used as energy storage means, then transmission power can be increased, but the system becomes vulnerable to destruction from high short-circuit currents and requires complex magnetic coupling
Solution Approach 1:
The patent divides the single large capacitor into multiple smaller capacitors connected in series, forming a string of capacitor units. Each unit has its own switching element with power semiconductor and freewheeling diode. This segmentation allows the system to handle high transmission power while protecting individual units from destructive short-circuit currents, as each unit can be independently protected and replaced if needed.
2Power
If a single large capacitor is used as energy storage means, then transmission power can be increased, but the device complexity increases due to required magnetic coupling
Solution Approach 1:
The patent extracts and eliminates the complex magnetic coupling components from the system by using a purely electronic switching architecture. Each capacitor unit is equipped with its own power semiconductor switch and freewheeling diode, allowing direct electronic control of current flow without requiring external magnetic coupling devices, thus reducing overall device complexity while maintaining high transmission power capability.
Solution Approach 2:
The patent implements dynamic control of each capacitor unit through individually controllable power semiconductor switches. This allows real-time adjustment of switching states to optimize power transmission and protect against faults, replacing static magnetic coupling with dynamic electronic control that adapts to system conditions.
3Power
If distributed capacitors are used in individual switching elements, then transmission power limitation is overcome, but the control complexity of multiple converters increases
Solution Approach 1:
The patent incorporates control means that monitor the state of each converter and capacitor unit, using feedback signals to coordinate switching operations. This feedback mechanism enables synchronized control of multiple converters connected in series, managing the increased complexity through real-time status monitoring and coordinated switching decisions based on system conditions.
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 enables finer voltage graduation, increased transmission power, and improved system stability, reducing the risk of destruction from short-circuit currents and eliminating the need for complex magnetic coupling, while maintaining system reliability even in fault conditions.
Implementation Method 1
So-called voltage sourced converters (VSC) with power semiconductors which can be switched off require a temporary energy store, generally a capacitor.
Data Source
AI summary
A device for the transmission of electrical energy includes at least one current converter. Each current converter has phase elements with respective arrangements of circuit elements that comprise at least two switchable power semiconductors each and at least two free-wheeling diodes, each connected in parallel thereto, and energy storing means. The transfer properties in or between power distribution networks are improved with the novel device. The device is provided with means for controlling the current converter in such a manner that the zero crossing, the amplitude and/or the instantaneous values of an alternating current of a transfer network that can be connected to the device and/or the direct current of a direct current line that connects at least one current converter to a direct current source, and/or the direct voltage and the direct current of at least three interconnected current converters can be controlled.