Chikasa Uenosono

Development and Testing of an Automatic Stability Prediction and Control (ASPAC) for a Synchronous Generator by Air Gap Flux

This paper presents the basic principles and test results of a newly developed equipment. It is concerned with automatic prediction and control of stability, for a synchronous generator by using its air gap flux directly.

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. >

An analysis on the characteristics of a synchronous machine connected to a d.c.-link

ContentsThe synchronous machine connected to a d.c.-link is used for either a generator or a motor by connecting a bridge rectifier to the terminals of armature windings. —Since the synchronous machine repeats line-to-line short circuiting six times in one cycle due to commutation, it is different from ordinary synchronous machine in respect of operational characteristics and design consideration. — In the present paper, for the synchronous machine connected to a d.c.-link, basic equations are obtained and with this equations the study is made on commutation reactance, phasor diagram, equivalent circuit, basic characteristics and method of calculating field current.ÜbersichtDie Synchronmaschine mit nachgeschaltetem Gleichrichter wird als Generator oder Motor betrieben, indem der nachgeschaltete Gleichrichter an die Klemmen der Ankerwicklung angeschlossen wird. — Da die Synchronmaschine mit nachgeschaltetem Gleichrichter wegen der Kommutierung 6mal in einer Periode zweiphasige Kurzschlüsse entstehen läßt, unterscheidet sie sich in der Charakteristik und in der Konstruktion von normalen Synchronmaschinen. — Im vorliegenden Aufsatz wurden zuerst Grundgleichungen abgeleitet und mit diesen Gleichungen Untersuchungen über Kommutierungsreaktanz, Zeigerdiagramm, Ersatzschaltbild und Bestimmung des Erregerstromes durchgeführt.

Studies on Coroaa in Transformer Oil by Measurement of Space Charge

Studies were carried out in needle-plane gaps with a comparatively long separation (50 to 150 mm) in transformer oil. Relations between needle voltages and space charge quantities due to coronas by lightning impulse and ac voltages were obtained. The charge quantities for ac voltage are 2 times larger than those for positive impulse voltage, and 7 times larger than those for negative impulse voltage. The polarity effect on the charge is not observed in case of ac voltages. Back-discharge phenomena take place, accompanied by sudden space charge reductions, at the wave tail of the impulse voltage. The space charge due to initial coronas at the wave front are reduced to 57 to 85% by the phenomena.

Location of Corona and Measurement of Space Charge in Transformer Oil

An investigation was made in order to develop a location technique of corona discharge in insulating oil, in view of the development of the UHV transformer. This paper describes the principle of analyzing the corona location by making use of electrostatic probes. The corona produces a space charge in the oil, and induces charges on the probes electrostatically. Thus, the location as well as the space charge of the corona can be analyzed.