Flexible AC Loop Closing with Modular Converter-Transformer Chains
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Solution Overview
Problem
Existing high-voltage power systems face challenges in closed-loop operation due to phase and magnitude differences between power sources, leading to excessive currents and high costs and space requirements for conventional solutions like back-to-back converters and series-type configurations, which are economically inefficient and difficult to integrate with auxiliary equipment.
Innovation Solution
A high-voltage direct-mounted flexible AC closed-loop device utilizing a three-phase converter chain with multi-winding transformers and high-voltage isolation transformers, supported by insulators and a high-potential platform, to manage phase and magnitude differences, reducing equipment voltage and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If back-to-back full-power converters are used to connect AC buses of two power sources, then flexible interconnection and voltage regulation are achieved, but cost and space requirements increase significantly
Solution Approach 1:
The patent divides the converter into modular submodules (active submodules and reactive submodules) connected in series, where each submodule handles a portion of the voltage regulation task. This segmentation allows for compact arrangement and reduces overall equipment space while maintaining flexible interconnection capability.
Solution Approach 2:
The patent employs a hierarchical structure where multiple submodules are nested within a unified converter framework. The active submodules and reactive submodules are integrated in a nested configuration, with each submodule containing its own bridge circuit and capacitor, achieving space-efficient design while preserving adaptability.
2Adaptability or versatility
If back-to-back full-power converters are used to connect AC buses of two power sources, then flexible interconnection and voltage regulation are achieved, but device cost increases significantly
Solution Approach 1:
By segmenting the converter into standardized submodules, the patent enables modular manufacturing and assembly. Each submodule uses common components (bridge circuits, capacitors) that can be mass-produced, reducing per-unit cost while maintaining flexible interconnection through modular configuration.
Solution Approach 2:
The patent changes the operational parameters by using series-connected submodules with individual voltage ratings, allowing the system to achieve high voltage capability without requiring a single large expensive converter. The distributed parameter approach reduces overall device cost while preserving adaptability.
3Area of stationary object
If series-type configuration is used, then cost and space occupancy are reduced, but regulation capability is constrained by system impedance
Solution Approach 1:
The patent implements dynamic control of the series-connected submodules, where each submodule can independently adjust its output based on real-time system conditions. This dynamic operation compensates for the series configuration's impedance constraints, maintaining regulation capability while achieving compact design.
Solution Approach 2:
The patent dynamically changes operational parameters (voltage, current, phase angle) of individual submodules to adapt to system impedance variations. This parameter flexibility restores regulation capability that would otherwise be constrained by the series configuration, while maintaining reduced equipment space.
4Area of stationary object
If series-connected configuration is used, then cost and space occupancy are reduced, but auxiliary equipment integration becomes difficult due to floating high potential
Solution Approach 1:
The patent introduces an intermediary grounding structure that provides a reference potential for auxiliary equipment. The grounding system acts as a mediator between the floating high-potential series configuration and ground-referenced auxiliary equipment, enabling easy integration of cooling systems and other auxiliaries while maintaining the compact series design.
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 provides stable energy supply with reduced operational losses, equipment footprint, and costs, while enabling efficient integration with cooling systems and other electrical loads.
Implementation Method 1
each of the multi-winding transformers comprises a primary winding and N first secondary windings
Implementation Method 2
The AC side can regulate the AC voltage magnitude and phase separately, allowing for flexible interconnection
Implementation Method 3
each phase of the converter chain comprises N active submodules connected in series and a series reactor
Implementation Method 4
any one of the N active submodules comprises a first bridge circuit, a first DC capacitor, and a first full-bridge circuit
Data Source
Figure 1~2
Figure 3~5
Figure 6~7
AI summary
The application provides a high-voltage direct-mounted flexible AC closed-loop device. The high-voltage direct-mounted flexible AC closed-loop device comprises a three-phase converter chain and three multi-winding transformers, wherein the three-phase converter chain connects a first AC system and a second AC system, each phase of the converter chain comprises N active submodules connected in series and a series reactor, and N is an integer greater than or equal to 1; each of the multi-winding transformers comprises a primary winding and N first secondary windings, with the N first secondary windings being connected to the N active submodules in a one-to-one correspondence mode; and the primary winding of each multi-winding transformer is connected to the first AC system or the second AC system.