Single-Phase Auxiliary Transformer Premagnetization for Power Transformers
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Solution Overview
Problem
Existing converter systems require complex and costly devices for premagnetization of power transformers, involving three-phase auxiliary transformers and extensive measurement equipment, leading to high circuitry-related and procedural efforts, which are not efficient for remote power plants like wind turbines and photovoltaic systems.
Innovation Solution
A premagnetization device using a single-phase auxiliary transformer connected to the grid, providing a reference voltage synchronized with the grid voltage, allowing for efficient premagnetization of the power transformer without the need for three-phase auxiliary power connections, reducing costs and effort by eliminating the need for extensive measurement equipment on the grid side.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a three-phase auxiliary transformer and extensive measurement equipment are used for premagnetization, then the premagnetization function is achieved, but the device complexity and cost increase significantly
Solution Approach 1:
The patent extracts the essential function of obtaining reference voltage from the complex three-phase auxiliary transformer system and implements it using a simple single-phase auxiliary transformer. This extraction principle removes unnecessary complexity while preserving the core premagnetization functionality by using only the minimal required components.
Solution Approach 2:
The patent replaces expensive three-phase auxiliary transformers and extensive measurement equipment with a simple single-phase auxiliary transformer and basic voltage detection circuitry. This substitution uses cheaper, simpler components that achieve the same functional result without requiring complex or expensive equipment.
2Device complexity
If a single-phase auxiliary transformer is used for premagnetization, then the device complexity and cost are reduced, but the synchronization with grid voltage must be achieved with simpler means
Solution Approach 1:
The patent enables the single-phase auxiliary transformer to provide its own secondary voltage as a reference for premagnetization. The system uses the auxiliary transformer's inherent electrical characteristics and its connection to the grid to automatically establish the reference voltage, eliminating the need for separate measurement equipment or complex synchronization systems.
Solution Approach 2:
The patent uses the single-phase auxiliary transformer as an intermediary device that bridges the grid connection and the power transformer premagnetization process. The auxiliary transformer's secondary voltage serves as an intermediate reference that simplifies the synchronization task by providing a readily available voltage signal with known relationship to the grid.
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 enables simple and cost-effective premagnetization of power transformers, minimizing inrush currents and reducing operational costs, while maintaining synchronization with grid voltage parameters, thus extending the service life of circuit-breakers and reducing the overall complexity of the converter system.
Implementation Method 1
A premagnetization device for a converter system connectable to a three-phase electrical grid is disclosed, which has a three-phase power transformer and a converter. The premagnetization device is configured to premagnetize the power transformer when the primary side of the power transformer is isolated from the grid, such that a voltage on the primary side of the power transformer is substantially synchronous with a grid voltage of the grid.
Data Source
AI summary
Provided is a premagnetization device for a converter system that is connectable to a three-phase electrical grid that has a three-phase power transformer, a converter connected to the power transformer and a circuit-breaker on the grid side of the power transformer. The premagnetization device is premagnetizes the power transformer in a state isolated from the grid. The premagnetization device uses a single-phase reference voltage (Uref) that has a fixed relationship to the grid voltage (Ugrid) with regard to the voltage parameters, in order to generate, based on the measured instantaneous reference voltage (Uref) and the known fixed parameter relationships, by actuating the converter, a three-phase alternating voltage synchronous to the grid voltage (Ugrid) on the grid side of the power transformer.