Umar Khan

Radiometer monitoring system for partial discharge detection in substation

Progress on the development of an insulation defect detection and location system using a partial discharge (PD) wireless sensor network (WSN) will be presented. Such a PD WSN based on intensity-only measurements has cost and scalability advantages over existing detection and location technologies based on time-difference-of-arrival measurements such as described in (I. E. Portugues, P. J. Moore, I. A. Glover, IEEE Trans. on Power Delivery, 1, 2009, pp. 20–29). Figure 1 shows a hypothetical deployment of the PD WSN in an electricity substation. The (red) pentagram denotes a PD source, yellow circles and triangles denote sensor nodes, and the yellow St Georges cross denotes the data collection/processing node. Each node of the WSN is a broadband radiometer with a measurement band of 50–800 MHz, Figure 2. Three measurement sub-bands allow the radiometer to distinguish different forms of PD; in particular internal PD and corona discharge. WirelessHart has been selected as the network communications technology since this offers improved reliability over other standards (e.g. Zigbee) in harsh industrial environments.

Comparison of contact measurement and free-space radiation measurement of partial discharge signals

Two partial discharge (PD) measurement techniques, a contact measurement technique (similar to the IEC 60270 standard measurement) and a free-space radiation (FSR) measurement technique, are compared for the case of a floating electrode PD source. The discharge pulse shapes and PD characteristics under high voltage DC conditions are obtained. A comparison shows greater similarity between the two measurements than was expected. It is inferred that the dominant mechanism in shaping the spectrum is the band-limiting effect of the radiating structure rather than band limiting by the receiving antenna. The cumulative energies of PD pulses in both frequency and time domains are also considered.

Assessment of absolute partial discharge intensity from a free-space radiometric measurement

Partial discharge (PD) is measured simultaneously using free-space radiometric (FSR) and a galvanic contact measurement technique based on the IEC 60270 standard. The PD source is an emulator of the floating-electrode type. The radiated signal is captured using a biconical antenna. A method of estimating absolute partial discharge (PD) activity level from a radiometric measurement by relating effective radiated power to PD intensity using a PD calibration device is presented.

Comparative study of Partial Discharge emulators for the calibration of Free-Space radiometric measurements

Partial discharge is measured simultaneously using free-space radiometry (FSR) and a galvanic contact measurement technique based on the IEC 60270 standard. Several types of PD (Partial Discharge) sources are specially constructed: two internal PD emulators and an emulator of the floating-electrode type. The excitation applied to the source is AC and the radiated signal is captured using a wideband biconical antenna. The calibration of PD sources is demonstrated. Effective radiated power of the PD source using a PD calibration device is determined.

Wireless sensor network for radiometric detection and assessment of partial discharge in HV equipment

Monitoring of partial discharge (PD) activity within high voltage electrical environments is frequently used for the assessment of insulation condition. Traditional measurement techniques employ technologies that require either offline installation or high power consumption and cost. A wireless sensor network is proposed that utilizes only received signal strength to locate partial discharge within a high-voltage electricity substation. The network comprises low-power and low-cost radiometric sensor nodes which receive the radiation propagated from a source of partial discharge. Results are reported from a test performed within a large indoor environment with a network of nine sensor nodes. An emulated PD source was placed at multiple locations within the network. Signal strength measured by the nodes is reported via WirelessHART to a data collection hub where it is processed using a location algorithm. The results obtained place the measured location within 2 m of the actual source location.

Partial discharge detection using low cost RTL-SDR model for wideband spectrum sensing

Partial discharge (PD) is one of the predominant factors to be controlled to ensure reliability and undisrupted functions of power generators, motors, Gas Insulated Switchgear (GIS) and grid connected power distribution equipment, especially in the future smart grid. The emergence of wireless technology has provided numerous opportunities to optimise remote monitoring and control facilities that can play a significant role in ensuring swift control and restoration of HV plant equipment. In order to monitor PD, several approaches have been employed, however, the existing schemes do not provide an optimal approach for PD signal analysis, and are very costly. In this paper an RTL-SDR (Software Defined Radio) based spectrum analyser has been proposed in order to provide a potentially low cost solution for PD detection and monitoring. Initially, a portable spectrum analyser has been used for PD detection that was later replaced by an RTL-SDR device. The proposed schemes exhibit promising results for spectral detection within the VHF and UHF band.

Validation of partial discharge emulator simulations using free-space radiometric measurements

A useful technique to estimate the degradation of insulation in high voltage (HV) installations is the measurement of partial discharge (PD). Free-space radiometric (FSR) detection of PD is a relatively new technique. Several types of PD emulator sources have been constructed: two internal PD emulators and a floating electrode emulator. The emulators have been simulated using the CST Microwave Studio software package. The intention is to use the simulated emulators to establish a relationship between radiated PD signals and PD intensity as defined by apparent charge transfer. To this end the radiated fields predicted in the simulations are compared with measurements. There is sufficient agreement between simulations and measurements to suggest the simulations could be used to investigate the relationship between PD intensity and the field strength of radiated signals.

An ultrawideband patch antenna for UHF detection of partial discharge

The location of partial discharge (PD) sources by free-space UHF detection is an attractive approach for condition monitoring of high voltage equipment in substations. A low-cost, radiometric, PD wireless sensor network (WSN) has been proposed to provide continuous real-time coverage for an entire substation (J.M. Neto, Y. Zhang, A. Jaber, M. Zhu, M. Judd, R. Atkinson, J. Soraghan, J.S. Neto, M.F. Vieira, I.A. Glover, 2014 XXXIth URSI General Assembly and Scientific Symposium (URSI GASS), Beijing, 16 – 23 Aug. 2014, pp.1–4). A suggested band for UHF PD detection is 0.3 – 1.5 GHz (Z. Tang, C. Li, X. Cheng, W. Wang, J. Li, IEEE Trans. Dielectr. Electr. Insul., 6, 2006, pp. 1193–1199). A novel ultrawideband (UWB) printed monopole antenna is presented here for PD WSN applications.

Partial discharge detection using software defined radio

Partial discharge (PD) is an electrical discharge that occurs within part of the dielectric separating two HV (High Voltage) conductors. PD causes damage to the dielectric which typically deteriorates with time. If left untreated, PD may result in catastrophic insulation failure, destruction of HV equipment, and disruption of power supply. The emergence of wireless network technology and software defined radio has opened new opportunities in PD monitoring and early detection of failures. This paper proposes the use of Universal Software Radio Peripheral (USRP) technology for PD detection.

Multiple source localization for partial discharge monitoring in electrical substation

This paper studies novel localization methods of multiple partial discharge sources in electrical substations. The three compressive sensing algorithms of Orthogonal Matching Pursuit (OMP), Homotopy technique, and Dichotomous coordinate descent (DCD) are presented. The simulation results demonstrate excellent performance with the compressive sensing methods.