Capacitive DC-to-DC Transformer for Substation Area Reduction
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Solution Overview
Problem
Existing high voltage electric power transmission systems face challenges in efficiently transforming power between DC nodes of differing voltages without the use of magnetically based transformers, requiring expensive and large substation areas, and involving double DC/AC conversion for power transfer between DC lines.
Innovation Solution
The use of capacitive column-based DC-to-DC transformers, where capacitive modules alternately accept and deliver electric charge between DC nodes, allowing self-redundant power exchange between multiple DC transmission lines and an AC system without double conversion, utilizing power electronic switches and a controller to manage the sequence of charge exchanges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional AC-to-DC converters and magnetic transformers are used to connect DC lines to AC system, then self-redundancy requirement is satisfied, but system cost and substation area increase significantly
Solution Approach 1:
The patent replaces magnetic transformers with a capacitive voltage transformer (CVT) system that uses capacitive columns and power electronic switches to achieve voltage transformation. This substitution eliminates the need for large magnetic cores and associated cooling systems, significantly reducing substation area and equipment cost while maintaining the voltage transformation function needed for self-redundant operation.
Solution Approach 2:
The patent divides the voltage transformation function into multiple capacitive modules arranged in columns. These modular capacitive columns can be independently controlled and reconfigured through power electronic switches, allowing flexible voltage transformation ratios and enabling self-redundant operation without requiring complete duplicate systems.
2Power
If triple transformation (DC-to-AC-to-DC) is used to transform power between DC voltage levels, then voltage transformation is achieved, but system complexity and energy losses increase
Solution Approach 1:
The patent creates a universal capacitive voltage transformer system that can perform multiple functions: transforming power between different DC voltage levels, connecting DC lines to AC systems, and enabling self-redundant operation. This single CVT platform replaces the need for separate converter stations and transformers, simplifying the overall system architecture.
Solution Approach 2:
The patent introduces an AC node as an intermediary that allows direct DC-to-DC power transfer through the capacitive voltage transformer. The AC node serves as a common coupling point where multiple DC lines can exchange power without requiring double conversion, reducing system complexity and energy losses.
3Reliability
If double DC/AC conversion is used for power transfer between DC lines, then self-redundancy is achieved, but energy efficiency and economic viability deteriorate
Solution Approach 1:
The patent enables continuous and direct power transfer between DC lines through the capacitive voltage transformer and AC node, eliminating the need for complete DC-to-AC-to-DC conversion cycles. This continuous action reduces conversion losses while maintaining self-redundant capability through the flexible reconfiguration of capacitive columns.
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 efficient and economic transformation of power between DC nodes, maintaining power exchange continuity even if one DC line is lost, reducing the need for large substation areas and eliminating double conversion, while allowing direct transfer between DC lines.
Implementation Method 1
capacitive column-based DC-to-DC transformers, in which capacitive columns, made up of individual capacitive modules alternately accept electric charge from one DC node and then deliver it to one or more others
Data Source
AI summary
A power transformation system that is constructed and arranged to transform power from one or more primary voltage nodes to a separate secondary voltage node using one or more columns comprised of a plurality of capacitive modules each of which is capable of being either electrically inserted into the column or electrically isolated and electrically bypassed. There is a secondary voltage node, at a non-ground potential, to which a first end of the column is electrically connected. In the two-primary node example there are two high voltage switches, each in series with a reactor; one high-voltage switch adapted to electrically connect a second end of the column to the first primary voltage node and the other high-voltage switch adapted to electrically connect the second end of the column to a second primary node. A controller is adapted to control high voltage switches to connect the capacitances comprising the column sequentially to each primary node so as to transform power, by resonant exchange of energy, between those primary nodes and the secondary node.