Application of Probabilistic Neural Networks Using High-Frequency Components’ Differential Current for Transformer Protection Schemes to Discriminate between External Faults and Internal Winding Faults in Power Transformers

Internal and external faults in a power transformer are discriminated in this paper using an algorithm based on a combination of a discrete wavelet transform (DWT) and a probabilistic neural network (PNN). DWT decomposes high-frequency fault components using the maximum coefficients of a ¼ cycle DWT as input patterns for the training process in a decision algorithm. A division algorithm between a zero sequence of post-fault differential current waveforms and the differential current coefficient in the ¼ cycle DWT is used to detect the maximum ratio and faults. The simulation system uses various study cases based on Thailand’s electricity transmission and distribution systems. The simulation results demonstrated that the PNN and BPNN are effectively implemented and perform fault detection with satisfactory accuracy. However, the PNN method is most suitable for detecting internal and external faults, and the maximum coefficient algorithm is the most effective in detecting the fault. This study will be useful in differential protection for power transformers.

Controllable potential barrier for multiple negative-differential-transconductance and its application to multi-valued logic computing

Various studies on multi-valued-logic (MVL) computing, which utilizes more than two logic states, have recently been resumed owing to the demand for greater power saving in the current logic technologies. In particular, unlike old-fashioned researches, extensive efforts have been focused on implementing single devices with multiple threshold voltages via a negative-differential current change phenomenon. In this work, we report a multiple negative-differential-transconductance (NDT) phenomenon, which is achieved through the control of partial gate potential and light power/wavelength in a van-der-Waals (vdW) multi-channel phototransistor. The partial gating formed a controllable potential barrier/well in the vdW channel, enabling control over the collection of carriers and eventually inducing the NDT phenomenon. Especially, the strategy shining lights with different powers/wavelengths facilitated the precise NDT control and the realization of the multiple NDT phenomenon. Finally, the usability of this multiple NDT device as a core device of MVL arithmetic circuits such as MVL inverters/NAND/NOR gates is demonstrated.