Takenori Kobayashi

An adaptive neuro-control system of synchronous generator for power system stabilization

This paper proposes a nonlinear adaptive generator control system using neural networks, called an adaptive neuro-control system (ANCS). This system generates supplementary control signals to conventional controllers and works adaptively in response to changes in operating conditions and network configuration. Through digital time simulations for a one-machine infinite bus test power system, the control performance of the ANCS and advanced controllers such as a linear optimal regulator and a self-tuning regulator is evaluated from the viewpoint of stability enhancement. As a result, the proposed ANCS using neural networks with nonlinear characteristics improves system damping more effectively and more adaptively than the other two controllers designed for the linearized model of the power system.

Power electronics technology in smart grid projects -Applications and experiences-

For the sustainable development of our highly electrified societies, power electronics technology is playing an important role. Especially in the field of electric power systems, it is considered as one of the essential technologies which make power grids more efficient, more reliable and more environment-friendly. Those are the goals of so-called smart grids. In this paper, expected roles and applications of power electronics in smart grids are first introduced. Then recent technological achievements in actual smart grid projects are presented.

Short circuit current estimation using PMU measurements during normal load variation

This paper purposes a short circuit current estimation method using phasor measurement unit (PMU) measurements (synhcrophasors, hereafter called as phasors) of voltages and currents obtained during normal load variation. The method follows the basic concept of representing the source side of power system by an equivalent circuit with a voltage behind back impedance and employs a set of voltage and current phasors measured at substations over a certain period. In order to improve an accuracy of the proposed estimation method, the concept of using a difference between the two consecutive phasors is introduced. Furthermore, to make the method applicable to a real world system, the estimation process is augmented by implementing a reference phasor concept to remove the effects of system wide frequency variations and a filtering process to filter out the outlier phasors. Finally, the validity and effectiveness of the purposed methods were checked and confirmed using field tests.