External DC Component Compensation Circuit for Transformers
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Solution Overview
Problem
Existing transformer designs face challenges in effectively compensating for direct current (DC) components, which cause undesirable magnetic shifts and increased losses, leading to noise emission and insulation degradation, especially in high-voltage applications, and retrofitting with compensation windings is complex and costly.
Innovation Solution
A circuit arrangement outside the transformer housing uses a transducer circuit with passive components to dissipate DC components to ground, eliminating the need for a separate compensation winding and utilizing a magnetic switch controlled by a detection device to counteract DC currents, allowing for efficient compensation of high GICs without active semiconductor components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a compensation winding is installed inside the transformer tank, then DC component compensation is achieved, but the transformer must be disconnected from the grid and retrofitting is complex and costly
Solution Approach 1:
The invention extracts the DC compensation function from the transformer interior to the exterior by connecting the compensation winding to the neutral point through external connecting conductors. This allows the compensation winding to be installed outside the transformer tank, eliminating the need for disconnection and complex retrofitting while maintaining effective DC component compensation.
Solution Approach 2:
The invention introduces connecting conductors as an intermediary element between the neutral point and the compensation winding. This mediator allows the compensation winding to be positioned externally while maintaining electrical connection, thus avoiding the need to install the winding inside the transformer tank and eliminating the associated retrofitting complexities.
2Reliability
If a compensation winding is provided in the transformer core, then DC compensation is effective, but the installation space required increases the transformer dimensions
Solution Approach 1:
The invention extracts the compensation winding from the transformer core interior and positions it externally, connected to the neutral point through connecting conductors. This extraction eliminates the need to allocate installation space within the transformer core, maintaining compact transformer dimensions while preserving DC compensation functionality.
3Ease of operation
If semiconductor switching devices are used for compensation current, then DC component control is precise, but the service life is limited and reliability decreases
Solution Approach 1:
The invention replaces limited-life semiconductor components with robust passive components (resistors, capacitors, and inductors) that have significantly longer service lives. The passive compensation circuit achieves sufficient DC component control without relying on semiconductor switching devices, thereby improving reliability and service life.
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 provides a cost-effective, reliable, and simple method for compensating DC components in operational transformers, reducing noise and losses, and extending the service life of transformer components, while allowing for retrofitting without the need for additional installation space or complex semiconductor components.
Implementation Method 1
a transducer circuit (1), which is arranged in a current path (20) that connects a connection point (12) lying on a node-free section of the connecting conductors (3) to ground
Implementation Method 2
the input side of which is provided by a detection device with a signal about the size and direction of the direct current component to be compensated is supplied
Implementation Method 3
utilizing a magnetic switch controlled by a detection device to counteract DC currents
Data Source
Figure 1~2
AI summary
Circuit arrangement for compensating an inductive direct current (IDC) component in a transformer (4), wherein the transformer (4) has a winding arrangement (8) which is connected to a network (15) for the transport of electrical energy by means of connecting conductors (3) and has a neutral point connected to earth (11), comprising: - a transducer circuit (1) which is arranged in a current path (20) which connects a connection point (12) located on a node-free section (31) of the connecting conductors (3) to earth (11), - a control and regulating device (6) which controls the transducer circuit (1) by means of a control signal (16) and which receives on the input side a signal (17) provided by a detection device (5) about the magnitude and direction of the inductive direct current (IDC) component to be compensated.