MV/LV Transformer with Air-Operated Adjustment for Voltage Stability
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Solution Overview
Problem
Existing MV/LV transformers face challenges in dynamically adjusting transformation ratios to maintain circulating voltage within acceptable limits, especially with load fluctuations, due to complex and costly mechanical or semiconductor-based solutions that are inefficient and prone to high maintenance costs.
Innovation Solution
An oil-filled MV/LV transformer system with a secondary adjustment transformer and air-operating switching means, allowing for precise adjustment of the transformation ratio under load without de-loading, using a control system powered via the secondary circuit to manage socket switching and ensure continuous operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If mechanical switching systems are used to adjust transformation ratio, then the transformation ratio can be modified, but the device complexity and manufacturing cost increase due to oil pollution from electric arcs
Solution Approach 1:
The patent extracts the switching operation from the oil-filled environment by introducing a separate adjustment transformer with air-operated switching means. The main transformer remains oil-filled while the adjustment transformer handles all switching operations in air, eliminating electric arc pollution to the oil and simplifying the overall system.
Solution Approach 2:
The adjustment transformer serves as an intermediary device that enables transformation ratio modification without directly switching the main transformer. By inserting this intermediate transformer with adjustable taps into the circuit, the system achieves adaptability while keeping the main transformer simple and maintenance-free.
2Reliability
If vacuum interrupters are used to eliminate electric arc problems, then switching reliability improves, but the device complexity and initial cost increase
Solution Approach 1:
The patent removes the switching operation entirely from the oil-filled main transformer environment. By placing all switching means in the air-operated adjustment transformer, vacuum interrupters or complex arc-quenching mechanisms become unnecessary, simplifying the overall design while maintaining reliability.
3Device complexity
If semiconductors are used for switching on the LV side, then mechanical switching complexity is reduced, but precision is lost due to fewer voltage adjustment turns
Solution Approach 1:
The patent replaces mechanical switching in the main transformer with air-operated switching means in the adjustment transformer. This substitution maintains mechanical simplicity while preserving precision through the transformer's tap configuration, avoiding the limitations of semiconductor-based solutions on the LV side.
4Volume of moving object
If adjustment is made on the LV side with semiconductors, then device size is reduced, but regulation precision decreases due to high current and low voltage
Solution Approach 1:
Instead of making adjustments on the LV side where precision is compromised by high current conditions, the patent inverts the approach by performing all adjustment operations on the MV side through the adjustment transformer. This inversion maintains precision while keeping the system compact.
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 a reliable, cost-effective, and precise method to adjust transformation ratios, reducing voltage fluctuations and maintaining voltage stability with minimal additional components and maintenance, while avoiding the complexities and costs associated with existing solutions.
Implementation Method 1
The primary winding of the adjustment transformer comprises for its part at least two taps, in particular at the ends, and preferably three. The transformation ratio of the adjustment transformer is advantageously chosen to correspond to a predetermined percentage N, conventionally between 0.5% and 5%, in particular 2.5%, of that of the main transformer
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
In order to allow adjustments in the voltage on the basis of the charge fluctuations, an MV/LV transformer (10) is combined with a second booster transformer (20), comprising a plurality of sockets (22, 24, 26) on the primary winding of same, the connection of said sockets with the LV network being controlled by low voltage contactor switching means (32, 34, 36). The modification in the voltage thus produced by the second transformer (20) modifies the transformation ratio of the assembly (10, 20) and allows voltage variations. The invention is particularly suitable for three-phase oil immersed transformers.