DC Component Suppression in High-Voltage Transformers
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Solution Overview
Problem
Existing devices for suppressing direct current components in electrical transformers, such as those used in high-voltage networks, are expensive, complex, and require frequent maintenance due to the need for sophisticated electronics and phase control systems.
Innovation Solution
A device with a compensation winding and a circuit that includes a power converter unit and multiple choke sections, where switching units can be controlled to bypass sections and rectify current flow, allowing for simple digital control to minimize direct current components, reducing the need for complex electronics and phase control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If phase-angle control with thyristors and complex electronics is used for DC compensation, then the controllable current range is increased, but the device complexity and maintenance requirements increase significantly
Solution Approach 1:
The inductor is divided into multiple series-connected sections with switching branches. Each section can be independently switched in or out of the circuit, providing discrete steps of DC compensation. This segmentation achieves a wide controllable current range while using simple switching elements instead of complex phase-angle control electronics.
Solution Approach 2:
The patent replaces expensive, maintenance-prone electronic control systems (thyristors with phase-angle control) with inexpensive mechanical or simple electronic switches. The switching elements are designed to be simple and reliable, reducing both initial cost and maintenance requirements while maintaining the ability to provide the full range of DC compensation.
2Measurement precision
If voltage-synchronous triggering of thyristors is implemented for DC compensation, then current control precision is improved, but the cost and maintenance issues increase
Solution Approach 1:
The patent uses periodic switching of the inductor sections synchronized with the AC cycle, but employs simple on/off switching rather than complex voltage-synchronous triggering. The periodic nature of the AC system provides natural timing references, allowing precise current control through straightforward switching strategies without requiring elaborate synchronization electronics.
Solution Approach 2:
The control system utilizes the inherent characteristics of the AC power system (voltage zero-crossings, frequency) to automatically time the switching operations. This self-synchronization approach eliminates the need for external triggering signals and complex control electronics, achieving precise current control through the system's own operational characteristics.
3Object-affected harmful factors
If a compensation winding with high magnetomotive force is used to counteract large DC components, then the DC suppression capability is improved, but the device complexity and cost increase
Solution Approach 1:
The patent employs a dynamically adjustable compensation circuit where the inductance value can be changed in discrete steps by switching different sections in or out of the circuit. This dynamic adjustment allows the system to adapt to varying DC component magnitudes, providing effective suppression across a wide range of conditions without requiring an overly complex fixed-design compensation winding.
Solution Approach 2:
The same inductor sections serve multiple functions: they provide both the compensating magnetomotive force and the necessary reactance for current limiting. The switching branches serve dual purposes of both controlling the compensation current and protecting the circuit. This multi-functionality reduces the need for separate dedicated components, simplifying the overall device while maintaining strong DC suppression capability.
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 effectively minimizes direct current components with reduced maintenance and operational costs, avoiding high harmonic current components and eddy current losses, while providing precise control over direct current levels.
Implementation Method 1
a compensation winding (3) for generating a magnetic flux in the core (20), the effect of which opposes the DC flux component
Implementation Method 2
at least one converter unit (4) arranged in the circuit and in series with the compensation winding (3), which allows current flow through it in only one direction
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a device (1) for suppressing a magnetic DC component in the magnetizable core of an electrical device, comprising: - a compensation winding (3) for generating a magnetic flux in the core, the effect of which opposes the DC flux component, - a circuit (2) in which the compensation winding (3) is arranged, - at least one converter unit (4) arranged in the circuit (2) and in series with the compensation winding (3), which allows current flow through it in only one direction, - a coarse stage branch (5) arranged in the circuit (2) and in series with the compensation winding (3), comprising at least two main choke sections (71, 72, ... 7n) connected in series, wherein at least one main choke section (72, ... 7n) has a low-impedance bypass path (82, ...8n) is connected in parallel, in which a switching unit (9) is arranged which can be switched from a forward position, in which a current flow through the switching unit (9) is allowed, to an interrupted position, in which a current flow through the switching unit (9) is prevented, or vice versa, -a sensor (11) for detecting the DC component and a control unit (10) connected to each switching unit (9) and the sensor (11), which is configured to actuate each switching unit (9) so that a current flow through so many main choke sections (71, 72, ... 7n) can be adjusted to minimize the DC component detected by the sensor (11).