Abstract
Failures in power transformers are one of the most serious occurrences in a power system. Thus, the monitoring of transformers and their ancillary equipment, such as bushings, is of great importance to improving the operational efficiency of these assets. In this context, this paper presents the development of a monitoring system for the measurement of partial discharges (PDs), which are a key parameter in the analysis of insulation condition. PD measurements were performed using the electrical method. For this purpose, a capacitive coupling device was developed for bushings that works as a sensor for high-frequency signals and also as a protection apparatus to guarantee the integrity of the bushings in cases of extreme events, such as lightning surges. In addition, a computational routine is presented that applies a digital filtering process followed by a proposed step for differentiating PDs from noises. For validation, the proposed system was subjected to laboratory tests and field applications, from which the viability of the project and the efficiency in detecting PDs were verified.
Highlights
Power transformers constitute one of the main devices in a Transmission and Distribution (T&D)infrastructure, since they demand high financial investment and represent a link between different voltage classes [1,2]
Weaken dielectric property of the bushing under high voltage stress; and (iii) check whether interference can impair the bushing under(ii) high voltage stress; and (iii)the check whether interference canthe impair the acquisition of the bushing under high voltage stress; and (iii) interference can impair the acquisition of signals collected from the test tap
A monitoring system for detecting partial discharges poweristransformers designed and and uses a capacitive coupling on the test tap of transformer bushings to perform a reading of partial validated in practical situations
Summary
Power transformers constitute one of the main devices in a Transmission and Distribution (T&D)infrastructure, since they demand high financial investment and represent a link between different voltage classes [1,2]. Faults in power transformers are generally catastrophic and lead to internal damage, which may be irreversible, since they occur mainly in the insulation systems of the equipment and may interrupt the power flow [4]. In this context, a crucial issue for ensuring the reliability of a power transformer and, its safe operation, is the monitoring of the insulation of this asset and its ancillary equipment such as bushings or load tap changers, which may involve, for example, dissolved gas analysis (DGA), partial discharge (PD) detection, and thermal analysis [5,6]. Typical monitoring systems perform the integration and data collection of sensors to detect evidence of failures, issue warnings of abnormal level quantities, design trend
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