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Power transformer modelling for optimal performance

Alabdrbalreda, Mohammed (2015) Power transformer modelling for optimal performance. Honours thesis, Murdoch University.

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Power transformer efficiency is dependent on various losses. Efficiency is simply a ratio of the power output to power input. Due to losses the efficiency of a power transformer is always less than 100 per cent. Moreover, the transformer’s performance slightly varies under different loads because of load-dependent losses (winding losses). The main objective of this thesis is to find the optimum load which maximises the efficiency and minimises the voltage regulation on a power transformer operated at its rated voltage. The complete equivalent circuit of a power transformer is developed with various losses taken into account such as winding losses, leakage fluxes, core losses, and magnetisation currents. The model parameters are found by carrying out laboratory measurements. Once the complete equivalent circuit is developed, it is used to calculate the efficiency and the voltage regulation under different loading cases. A simulated model on ICAP is also used to validate the experimental results. A sensitivity analysis is also conducted in this project to see the effect of variations in the parameters on the transformer’s performance.

Finally, the design parameters of a power transformer that can be optimized to reduce losses are considered in this project. The design parameters are related to the electrical parameters of the transformer by mathematical models. The effect of those design parameters on the transformer’s performance is supported by some papers related to design optimisation. This involves the evolution of power transformers design throughout history and the research being carried out for loss reduction. Other factors such as cost and operation environment are not taken into account in this project as it is only focused on efficiency optimization.

The key findings of this project can be summarized as follows; the resistive load has the poorest voltage regulation. The capacitive load has the lowest voltage regulation and it is always negative. The transformer’s maximum efficiency is observed at 60 per cent of the rated load. This is proved by laboratory based experiments and ICAPS simulations. The key design parameters that can be optimized to improve the efficiency are the core lamination thickness, material electrical resistivity, and maximum flux density.

Item Type: Thesis (Honours)
Murdoch Affiliation(s): School of Engineering and Information Technology
Supervisor(s): Hettiwatte, Sujeewa
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