Variable Susceptance Coupling for AC Network Power Exchange
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Solution Overview
Problem
Current solutions for connecting two AC voltage networks are complex, cost-intensive, and inefficient, often requiring multiple power converters or complex transformers that introduce harmonic components and have limited dynamics due to mechanical contact limitations.
Innovation Solution
A connecting device utilizing n susceptance elements with continuously variable susceptance values, allowing for controlled active power exchange between AC voltage networks, with each susceptance element having two connections for connecting conductors and capable of behaving like capacitance or inductance based on susceptance value, and optionally using a matching transformer for phase adjustment and isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If two power converters are used to connect AC networks, then power transfer capability is achieved, but device complexity and cost increase significantly
Solution Approach 1:
The invention extracts and utilizes the reactive power capability already present in the AC networks themselves, rather than adding separate power converters. By injecting reactive power through the existing network impedance, the system achieves power transfer without requiring additional converter hardware, thus reducing device complexity while maintaining power transfer capability.
Solution Approach 2:
The invention introduces reactive power injection as an intermediary mechanism to enable active power transfer. Instead of directly connecting AC networks with converters, the system uses reactive power compensation as a mediator that creates the necessary conditions for controlled power flow between networks with different voltage phases.
2Ease of operation
If controllable impedances like TCR are used to couple AC networks, then power flow control is achieved, but harmonic components are introduced requiring additional filters
Solution Approach 1:
The invention converts the typically harmful harmonic currents into a beneficial effect by deliberately injecting reactive power at frequencies that create desired active power flow. The system uses the network's natural impedance characteristics to transform what would be harmful harmonic distortion into useful power transfer control, eliminating the need for separate filtering circuits.
3Adaptability or versatility
If phase-shift transformer with mechanical contacts is used, then phase shift adjustment is achieved, but dynamic performance is limited by contact life
Solution Approach 1:
The invention replaces the mechanical contact-based phase-shift transformer with an electronic reactive power injection system. Instead of using mechanical switches to change transformer winding connections, the system uses solid-state power electronics to dynamically adjust reactive power injection, achieving phase shift control without mechanical wear and with significantly improved dynamic response.
4Power
If susceptance elements with high susceptance values are used, then active power transfer capability is improved, but active power losses increase
Solution Approach 1:
The invention dynamically adjusts the susceptance values of the injection elements based on operating conditions. By optimizing the susceptance parameters in real-time, the system achieves maximum active power transfer capability while minimizing active power losses, adapting to changing network conditions and load requirements.
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 reliable, cost-effective, and efficient active and reactive power management between AC voltage networks with minimal active power losses, allowing for optimal phase offset determination and reduced semiconductor load, thus reducing operating costs and improving controllability.
Implementation Method 1
For Bi>0, the susceptance element behaves like a capacitance
Implementation Method 2
for Bi<0, like an inductance
Data Source
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AI summary
The invention relates to a connection device (2) for connecting two n-phase alternating voltage networks (1, 3) of the same frequency. The connection device according to the invention is characterised by n susceptance elements (4-6) each having continuously variable susceptance values, wherein by means of each susceptance element, two connecting conductors (Lij), which are allocated to one another, of the alternating voltage networks can be connected to one another and the effective power exchange between the alternating voltage networks can be controlled by changing the susceptance values in a targeted manner. The invention also relates to a method for operating the connection device according to the invention.