Magnetic Switching Device for Transformer DC Flux Compensation
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Solution Overview
Problem
Existing electrical transformers in energy transmission and distribution networks face issues with direct current (DC) feed, leading to increased losses, heating problems, noise emission, and limited reliability due to semiconductor switching devices, which are temperature-dependent and costly, especially at high voltages.
Innovation Solution
A magnetic switching device based on a magnetic core and winding arrangement replaces semiconductor power electronics, allowing for magnetic saturation control to generate compensation currents without external energy sources, enabling reliable and cost-effective DC compensation at higher voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If semiconductor switching devices (thyristors) are used for DC compensation, then DC compensation can be achieved, but reliability decreases and service life is limited due to temperature dependence and cooling requirements
Solution Approach 1:
The patent replaces semiconductor switching devices with a magnetic switching device that uses magnetic saturation control. The magnetic core and winding arrangement create switching action through magnetic field saturation rather than electronic semiconductor switching, eliminating temperature-dependent failure modes and cooling requirements while achieving the same DC compensation function.
Solution Approach 2:
The invention changes the operating parameters by using magnetic saturation states (saturated vs. unsaturated) to control switching action. By controlling the magnetic flux density in the core through the windings, the device transitions between conducting and blocking states without relying on semiconductor junction characteristics that degrade with temperature.
2Reliability
If thyristors are used for high voltage DC compensation (5kV, 8kV and above), then DC compensation is possible, but cost increases significantly
Solution Approach 1:
The magnetic switching device replaces expensive high-voltage thyristors with a construction using standard magnetic core materials and windings. The magnetic core provides inherent high-voltage insulation capabilities without requiring costly semiconductor devices rated for 5kV, 8kV or higher voltages.
3Power
If semiconductor switching devices are used for DC compensation, then DC compensation can be achieved, but cooling devices are required which increase device complexity
Solution Approach 1:
The magnetic switching device eliminates the need for cooling devices entirely. By replacing semiconductor-based switching with magnetic field-based switching, the invention removes the primary heat-generating component (the semiconductor switches) and their associated cooling systems, thereby reducing overall device complexity.
4Reliability
If the voltage induced in the compensation winding is limited to 690V for thyristor use, then reliability is maintained, but adaptability to high voltage transformers is reduced
Solution Approach 1:
The magnetic switching device changes the voltage handling capability by using magnetic core materials and winding configurations that can naturally withstand high voltages. The device can operate with compensation winding voltages far exceeding 690V, adapting to various voltage levels in power transformers without compromising reliability.
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 solution enhances the reliability and service life of DC compensation systems, allows for higher voltage applications, and eliminates the need for cooling devices, making it suitable for high-power transformers like HVDC systems.
Implementation Method 1
A control current is fed into the control winding so that the magnetic saturation state of the core can be changed by this control variable
Implementation Method 2
a winding arrangement which is magnetically coupled to this core
Implementation Method 3
an undesired direct current can be fed into the primary winding or secondary winding... A DC component or a GIC results in a magnetic direct flux component in the core of the transformer
Data Source
Figure 1~3
Figure 4~5
Figure 6~7
AI summary
Arrangement for reducing a DC magnetic flux component (ΦDC) in the core (1) of a transformer, comprising: - a measuring device (7) which provides a measurement signal (8) corresponding to the DC magnetic flux component (ΦDC), - a compensation winding (K) which is magnetically coupled to the core (1) of the transformer, wherein the magnetic flux flowing in the core (1) induces a voltage (UK) in the compensation winding, - a switching device (5) which is electrically arranged in a current path (6) in series with the compensation winding (K), - a control device which controls the switching device (5) by means of a control variable (11) such that the switching device (5) can be switched to a conducting state at a switch-on time, wherein the switch-on time depends on the measurement signal (8) and is grid-synchronous, i.e., phase-synchronous with the voltage in the compensation winding (K).a current is fed into the compensation winding (K) whose effect opposes the DC component (ΦDC), - wherein - the switching unit (5) is formed by a magnetic core (10) and a winding arrangement (3, 20) magnetically coupled to this core (10), - the control variable (11) is supplied to the winding arrangement (3, 20) so that the magnetic saturation state of the core (10) can be changed, thereby making the conducting state of the switching unit (5) producible.