Junya Matsuki

Slot ripples in the damper windings of a salient-pole synchronous generator

This paper summarizes the results of an experimental and analytical investigation of the slot ripples in the damper windings of a salient-pole synchronous machine under steady state operation. A new method of measuring damper winding currents and voltages directly has been established and used to examine the ripples due to the stator slot openings, which appear in the damper bar currents and voltages, air gap flux density distributions and terminal voltages. By examining the physical relationship between air gap fluxes and damper winding currents and voltages both at no load and on load, slot ripples phenomena have been made clearer than before. >

Damper windings phenomena of synchronous machines during system oscillations

The performances of the damper windings of a synchronous machine (generator) under the oscillatory conditions of the power system to which it is connected, are investigated both experimentally and analytically in this paper. Air-gap fluxes and induced voltages and currents of the damper windings under the oscillatory system conditions, when the machine is equipped both with and without damper windings, are measured and analyzed. Fourier analyses are used to examine the harmonic components appearing in the air-gap flux density distributions and the damper induced voltages and currents to clarify the phenomena caused by the damper as well as the effect of the damper upon power system performances. >

Monitoring of magnetic saturation level of a synchronous generator under load

This paper presents a new method to monitor magnetic saturation level of a synchronous generator operating in an electric power system. The proposed method makes use of air-gap permeance distributions, which can be derived from air-gap flux distributions measured by a search coil wound around a stator tooth of a generator. Tests were conducted on a laboratory-model power system to verify the validity of the proposed monitoring method. Test results under various operating conditions are presented to show a wide range of change in saturation level inside the generator. Its effects on generator performance in the power system and the benefits of the monitoring method are also discussed. >

Loss of synchronism process of a synchronous generator described by its internal flux and force distributions

The authors report on the loss of synchronism process of a synchronous generator in an electric power system. The process is described in terms of the magnetic flux and force distributions inside the machine. Data on the field and armature currents used as input to the flux and force calculation by the finite element method were obtained from experiments on a machine connected to an infinite-bus system. By examining the transition of flux and force distributions during the loss of synchronism process, a physical picture of the process is given. >

Investigations of a thyristor-controlled series capacitor

Thyristor-controlled series capacitors (TCSC) are expected to provide many benefits for electric power systems including the increase of power transfer capability and transient stability as well as the mitigation of subsynchronous resonance (SSR). However, there has been little operating experience and thus further understanding of the characteristics of TCSC is still sought. A laboratory-scale TCSC has been designed, produced and installed on a laboratory power system at Kyoto University to investigate the performances of TCSC experimentally. The paper provides the fundamental impedance characteristics and the dynamic responses of the laboratory-scale TCSC, the effects of inductor and resistor size on these performances and a detailed analysis of loop current dynamics based on a developed mathematical model.

Effect of slot ripples on damper windings of synchronous machines

The authors summarize the experimental results of the effect of slot ripples on damper windings of a synchronous machine under the steady state operation in a one-machine connected to an infinite-bus system. A new method of directly measuring damper winding currents inside a synchronous generator has been established. In particular, the physical relationship between airgap fluxes and damper winding currents both at no load and on-load has been made clear. The effect of saturation on damper currents are also examined.<<ETX>>