Analysis of the partial discharge pulse propagation in the stator winding of a synchronous machine (original) (raw)
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Characteristics of Noise and Interphasal PD Pulses in Operating Stator Windings
Online partial discharge measurement in machines requires effective electrical noise suppression to reduce the risk of false indications of stator winding insulation problems. Many noise suppression techniques have been proposed and implemented over the years. This paper examines the method of suppressing noise using 3 phase synchronous (i.e. simultaneous) detection. Known noise pulses were recorded on three phases and they were contrasted with pulses from phase-to-ground PD in the stator slot or phase-to-phase PD between coils in the stator endwinding. Experiments indicated that interphasal PD produces strong pulses on 2 of the 3 phases. In contrast, phase-to-ground PD and noise caused by sparking in one phase of a generator output bus create a dominant pulse in one phase only. With all three types of situations, there may be significant cross-coupling to the other phase(s).
Transformer modelling for studying the propagation of partial discharge pulses
2001
A computer model developed for studying the propagation of partial discharge (PD) pulses in a continuous disc type 6.6 kV transformer winding is described in the paper. The winding model takes the turn as the basis for the analysis and uses multi-conductor transmission line theory to obtain a system of equations to calculate the voltage and current along the winding. Capacitance, inductance, resistance and conductance are calculated as distributed parameters for the winding model. Transfer functions that can be used to study the effect on the PD current as the monitoring point moves from the location of the PD to the line-end and the neutral-end are calculated. The transfer functions represent the frequency response of the signals measured at the line and neutral-end terminals for a PD pulse represented by a Dirac delta function at the point of discharge. The zeros of the transfer functions convey information about the position of the discharge and hence can be used for its location.
Sensors (Basel, Switzerland), 2018
Ideally, an insulation system must be capable of electrically insulating the active components of a machine or device subjected to high voltages. However, due to the presence of polluting agents or imperfections inside or on the surface of the insulation, small current pulses called partial discharges (PDs) are common, which partially short-circuit the insulation and cause it to lose its insulating properties, and thus its insulation capacity, over time. In some cases, measurements of this phenomenon are limited by the type of sensor used; if it is not adequate, it can distort the obtained results, which can lead to a misdiagnosis of the state of the device. The inductive loop sensor has experimentally been demonstrated to be capable of properly measuring different types of PDs. However, because of its current design, there are several practical limitations on its use in real devices or environments. An example is the presence of a primary conductor located at a fixed distance from ...
Simulation of a transformer winding for partial discharge propagation studies
Power Engineering Society, IEEE Winter Meeting, 2002
A simulation model of a continuous disc type 6.6 kV transformer winding was used to study the propagation behaviour of partial discharge (PD) pulses. The model based on multi-conductor transmission line theory uses a single turn as a circuit element with the capacitance, inductance, and losses calculated as distributed parameters. Transfer functions that describe how the location of the PD
Journal of Electrical Engineering
On-line partial discharge (PD) measurement in electrical insulation of the turbine generator (TG) is an essential approach to control the quality of insulation and to avoid any undesired shutdowns of TG. Although in the last few decades the number of research in PD on-line monitoring methods in the stator winding of TG has increased significantly, it is still not clear yet why PD only appears at certain phase angles of the AC cycle in the phase resolved partial discharge (PRPD) pattern. Moreover, there is not yet any clarification on how the winding configuration of stator may affect PD phase angle pattern. For this reason, this work examines detailed study of the impact of the winding diagram on PD occurrence in the stator winding of real turbine generator class TVF-60-2 (60 MW, 10.5 KV). In addition, a computer simulation of various sizes of ellipsoidal cavities from 0.1 to 2.5 mm between conductor bar and stator core were carried out by using Laplaces equation in Finite Element A...