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Spiral antenna sensors are commonly used in partial discharge (PD) ultra-high frequency (UHF) detection in gas-insulated switchgears (GISs). However, most of the existing UHF spiral antenna sensors are based on a rigid base and balun, such as FR-4. The safe built-in installation of antenna sensors requires the complex structural transformation of G...
Citations
... In addition to monitoring humidity, antenna sensors also play an important role in other wireless detection of IoT, such as harmful gases [47], [48], food quality [49], human health [50], [51], [52], [53], partial discharge [54], and bacteria detection [55], [56]. ...
Some special environments, such as closed or harsh spaces, require contactless and real-time humidity monitoring. A flexible 920 MHz antenna sensor with vertical graphene (VG) as a sensitive film is proposed, which can measure humidity and transmit data wirelessly in real time. When the humidity changes, the number of H2O molecules absorbed by the graphene film will vary, which affects the permittivity of the antenna patch, and results in shifts in the resonant frequency. Remote humidity monitoring can be realized by analyzing the frequency response at the receiver. By depositing vertical graphene film on the antenna patch, the sensitivity can be improved from 16.3 to 32.6 kHz/% RH (linear range: 0. 57% RH) and from 145 to 290.5 kHz/% RH (57.90% RH). During humidity change, the radiation direction of the VG-based antenna sensor remains stable, and the maximum wireless transmission distance reaches 100 m. For the first time, the model of the antenna sensor is established. Furthermore, the flexible sensor can conform to various installation shapes. The experimental results show that the wireless VG-based antenna sensor is a good candidate for remote humidity monitoring and the Internet of Things.
... However, the UHF signals arising from PD events are subject to some loss when propagating through an inhomogeneous medium because electromagnetic waves are subject to reflection at the interfaces of different media, resulting in what is denoted as standing wave losses. These losses are commonly quantified based on the voltage standing wave ratio (VSWR), where the sensitivity and noise immunity of an antenna increase as the VSWR approaches 1. Antennas utilized for PD detection in power equipment must have VSWR values less than 2 within their operating frequency band [10,11]. In this paper, we denote the frequency band with VSWR < 2 as the detection frequency band of PD. ...
Efforts to protect electric power systems from faults have commonly relied on the use of ultra-high frequency (UHF) antennas for detecting partial discharge (PD) as a common precursor to faults. However, the effectiveness of existing UHF antennas suffers from a number of challenges such as limited bandwidth, relatively large physical size, and low detection sensitivity. The present study addresses these issues by proposing a compact microstrip patch antenna with fixed dimensions of 100 mm × 100 mm × 1.6 mm. The results of computations yield an optimized antenna design consisting of 2nd-order Hilbert fractal units positioned within a four-layer serpentine arrangement with a fractal unit connection distance of 3.0 mm. Specifically, the optimized antenna design achieves a detection bandwidth for which the voltage standing wave ratio is less than 2 that is approximately 97.3% of the UHF frequency range (0.3–3 GHz). Finally, a prototype antenna is fabricated using standard printed circuit board technology, and the results of experiments demonstrate that the proposed antenna is capable of detecting PD signals at a distance of 8 m from the discharge source.
... Therefore, a lower VSWR value is critical for the quality and stability of the transmission circuit in this case, so a lower VSWR is a fundamental requirement for the design and use of high-performance UHF antenna sensors. When VSWR ≤ 2 the antenna sensor receives the best electromagnetic energy, but in fact VSWR ≤ 5 can meet the engineering needs, so this paper will use VSWR ≤ 5 as the PD detection bandwidth of power equipment [28][29][30][31][32][33][34]. ...
... Therefore, a lower VSWR value is critical for the quality and stability of the transmission circuit in this case, so a lower VSWR is a fundamental requirement for the design and use of highperformance UHF antenna sensors. When VSWR ≤ 2 the antenna sensor receives the best electromagnetic energy, but in fact VSWR ≤ 5 can meet the engineering needs, so this paper will use VSWR ≤ 5 as the PD detection bandwidth of power equipment [28][29][30][31][32][33][34]. ...
To meet the real demand for broadband full-band high-gain antenna sensors in the process of partial discharge (PD) Ultra-High frequency (UHF) detection test and online monitoring of power equipment, this paper builds a resonant cavity monopole UHF antenna sensor based on Fabry–Perot resonant cavity antenna technology, conducts the sensor Voltage Standing Wave Ratio (VSWR) optimization study using curved flow technology, conducts the sensor gain optimization study using slot dual resonant structure, and, finally, tests the sensor performance using the built PD detection test platform. The resonant cavity monopole antenna exhibits outstanding VSWR performance in the frequency range of 0.37 GHz–3 GHz, according to simulation and test data: the average gain in the frequency range of 0.3 GHz–3 GHz is 4.92 dBi, and the highest gain at the primary resonant frequency of 1.0 GHz is 7.16 dBi, with good radiation performance over the whole frequency spectrum. The electromagnetic pulse signal sensed by the UHF sensor developed in this paper can demonstrate the energy spectrum distribution characteristics of PD radiation electromagnetic wave signal more comprehensively, laying a firm technical foundation for thoroughly understanding the electromagnetic wave radiation characteristics of various types of PD insulation defects of various power equipment and the selection of a specific direction for its supporting optimization.
... Although there are still challenges to overcome for the improvement of off-line and on-line PD measurements in HVDC grids, PD measurements have proven to be very useful for detecting insulation defects in HVAC installations [1][2][3][4][5][6][7]. The most critical insulation defects that generate PD activity in electrical grids are internal or void-type defects and internal surface defects. ...
On-site partial discharge (PD) measurements have turned out to be a very efficient technique for determining the insulation condition in high-voltage electrical grids (AIS, cable systems, GIS, HVDC converters, etc.); however, there is not any standardised procedure for determining the performances of PD measuring systems. In on-line and on-site PD measurements, high-frequency current transformers (HFCTs) are commonly used as sensors as they allow for monitoring over long distances in high-voltage installations. To ensure the required performances, a metrological qualification of the PD analysers by applying an evaluation procedure is necessary. A novel evaluation procedure was established to specify the quantities to be measured (electrical charge and PD repetition rate) and to describe the evaluation tests considering the measured influence parameters: noise, charge amplitude, pulse width and time interval between consecutive pulses. This procedure was applied to different types of PD analysers used for off-line measurements, sporadic on-line measurements and continuous PD monitoring. The procedure was validated in a round-robin test involving two metrological institutes (RISE from Sweden and FFII from Spain) and three universities (TUDelft from the Netherlands, TAU from Finland and UPM from Spain). With this round-robin test, the effectiveness of the proposed qualification procedure for discriminating between efficient and inappropriate PD analysers was demonstrated. Furthermore, it was shown that the PD charge quantity can be properly determined for on-line measurements and continuous monitoring by integrating the pulse signals acquired with HFCT sensors. In this case, these sensors must have a flat frequency spectrum in the range between several tens of kHz and at least two tens of MHz, where the frequency pulse content is more significant. The proposed qualification procedure can be useful for improving the future versions of the technical specification TS IEC 62478 and the standard IEC 60270.
