A Novel Test Method for Real-time Magnetic Flux Measurement of Power Transformers

Abstract

Optimizing magnetic flux distribution in iron cores is very important in the transformer design. It can affect whether the iron cores of transformers are saturated or not in severe conditions. If saturated, the transformer will overheat and generate harmful harmonics to the grid. The measurement of the dynamic magnetic flux is an effective method to observe the behavior of transformers and ensure their safety. However, there are limited methods to measure the magnetic flux in real-time. In this paper, a novel test method based on a special transformer design is proposed. The new design integrates an additional bypass iron core which shares a partial magnetic path with the main core. By injecting high-frequency signals into the attached coil of the bypass core, the measured signals reflect the trend of the magnetic flux variation in the main core over time. To improve the accuracy of the derived measured data, the Empirical Mode Decomposition algorithm is also used to diminish the noise without additional designs in the signal acquisition circuit. The proposed method is modeled and tested, and the results show that this method can dynamically measure the magnetic flux in the transformer.

Keywords

• magnetic circuits
• power transformers
• empirical mode decomposition
• test equipment
• finite element analysis