Liang Lu

Bio: Liang Lu is an academic researcher. The author has contributed to research in topics: Partial discharge & Electrical equipment. The author has an hindex of 1, co-authored 1 publications receiving 10 citations.

The study of Archimedean spiral antenna for partial discharge measurement

Abstract: Partial discharge (PD) is an important indicator for electrical equipment's insulation property in power industry. Through the measurement of partial discharge we can have a good understanding of the equipment's performance. Ultra High Frequency (UHF) detection techniques are being recently a more and more important method to detect partial discharges. In this paper, a wide bandwidth Archimedean spiral antenna was designed. Its main parameters were analyzed by computer simulation software. A partial discharge test platform was built and three typical partial discharge models were designed. We used the designed Archimedean spiral antenna to detect the three models. The experiment results show that the designed Archimedean spiral antenna has good performance to measure electrical equipment partial discharge signals.

Optimisation of a sensor for onsite detection of partial discharges in power transformers by the UHF method

Abstract: Among the different solutions which allow onsite partial discharge measurement in energized power transformers, the UHF technique is gaining general interest. In order to apply this method in existing transformers, it is considered advantageous to design a UHF sensor to be fitted inside the transformer tank. This paper describes the constraints affecting the development of such sensor and the process followed to optimize its design. During this process, different solutions for broadband UHF antennas were analysed. The selection was based on computer simulation and experimental results. Computer simulation was used to evaluate differences in radiation pattern, antenna impedance, gain and effective area. Measurements of the antenna response to different partial discharge sources in oil were performed using an oil dielectric breakdown test set in an electromagnetic shielded laboratory. A group of selected antennas were then tested in a power transformer simulating the broadband signals generated by partial discharges by injecting controlled voltage pulses in the transformer. Finally, a sensor based on a conical monopole antenna structure was built and attached to a specially designed housing to be fitted inside the transformer tank through the drain valve. This final prototype was benchmarked during a high voltage factory test of a power transformer which showed a significant partial discharge activity.

On-Line Partial Discharge Monitoring System for Power Transformers Based on the Simultaneous Detection of High Frequency, Ultra-High Frequency, and Acoustic Emission Signals

Abstract: The article presents a novel on-line partial discharge (PD) monitoring system for power transformers, whose functioning is based on the simultaneous use of three unconventional methods of PD detection: high-frequency (HF), ultra-high frequency (UHF), and acoustic emission (AE) It is the first monitoring system equipped in an active dielectric window (ADW), which is a combined ultrasonic and electromagnetic PD sensor The article discusses in detail the process of designing and building individual modules of hardware and software layers of the system, wherein the most attention was paid to the PD sensors, ie, meandered planar inverted-F antenna (MPIFA), high-frequency current transformer (HFCT), and active dielectric window with ultrasonic transducer, which were optimized for detection of PDs occurring in oil-paper insulation The prototype of the hybrid monitoring system was first checked on a 330 MVA large power transformer during the induced voltage test with partial discharge measurement (IVPD) Next, it was installed on a 315 MVA substation power transformer and integrated according to the standard IEC 61850 with SCADA (Supervisory Control and Data Acquisition) system registering voltage, active power, and oil temperature of the monitored unit The obtained results showed high sensitivity of the manufactured PD sensors as well as the advantages of the simultaneous use of three techniques of PD detection and the possibility of discharge parameter correlation with other power transformer parameters

Two planar antennas for detection of partial discharge in gas-insulated switchgear (GIS)

Abstract: The detection of partial discharge in GIS plays a pivotal role in preventing and mitigating severe operational failure and damage in insulation elements. Partial discharge progressively degrades the insulating medium and, as a result electrical breakdown can occur in GIS. Despite various techniques used for PD detection, the RF analysis is extensively used because it is highly reliable, has good sensitivity and the largest bandwidth. The objective of this study is to examine two applicable planar antennas for detecting the RF energy of partial discharge in GIS infrastructure. Namely, a planar complex spiral antenna and a fractal tree log-periodic dipole antenna which are located on the GIS junction of segments.