Abstract
Amorphous alloy is increasingly widely used in the iron core of power transformer due to its excellent low loss performance. However, its potential harm to the power system is not fully studied during the electromagnetic transients of the transformer. This study develops a simulation model to analyze the effect of transformer iron core materials on ferroresonance. The model is based on the transformer π equivalent circuit. The flux linkage–current (ψ–i) Jiles–Atherton reactor is developed in an Electromagnetic Transients Program-Alternative Transients Program and is used to represent the magnetizing branches of the transformer model. Two ferroresonance cases are studied to compare the performance of grain-oriented Si-steel and amorphous alloy cores. The ferroresonance overvoltage and overcurrent are discussed under different system parameters. Results show that amorphous alloy transformer generates higher voltage and current than those of grain-oriented Si-steel transformer and significantly harms the power system safety.
Highlights
The advantages of using amorphous ferromagnetic alloys as a replacement for grain-oriented Si-steel in power transformers are widely reported owing to their low no-load core losses.[1]
This study investigates ferroresonance using grain-oriented Si-steel core and Fe-based amorphous alloy core transformers based on the ψ–i Jiles–Atherton (JA) hysteresis model in the Electromagnetic Transients Program-Alternative Transients Program (EMTP-ATP)
The transient overvoltage and steady overvoltage obtained from Fe-based amorphous alloy core are 1.53 and 1.24 p.u., respectively, which are higher than those obtained with the grain-oriented Si-steel core (1.34 and 1.14 p.u., respectively)
Summary
The advantages of using amorphous ferromagnetic alloys as a replacement for grain-oriented Si-steel in power transformers are widely reported owing to their low no-load core losses.[1] The development of the industrial manufacturing level in soft magnetic materials has facilitated the wide use of Fe-based amorphous alloy (Fe79.2Si8.6B12.2, called 1K101 in China) in distribution transformer cores.[2] Great economic benefits can be obtained using Fe-based amorphous alloy transformers under sinusoidal magnetization condition.[3]. The nonlinear inductance originates from the saturable iron core of a potential or power transformer. The use of a Fe-based amorphous alloy transformer with low iron loss becomes a potentially serious problem to power system safety as a result of its effect on ferroresonance. This study investigates ferroresonance using grain-oriented Si-steel core and Fe-based amorphous alloy core transformers based on the ψ–i Jiles–Atherton (JA) hysteresis model in the Electromagnetic Transients Program-Alternative Transients Program (EMTP-ATP). The ferroresonance overvoltage and overcurrent obtained from different transformer core materials are investigated and compared. The 3D bifurcation diagram is used to compare the safe zones of ferroresonance using different iron cores
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