Peter Mather

Radiometric wireless sensor network monitoring of partial discharge sources in electrical substations

A wireless sensor network (WSN) with the potential to monitor and locate partial discharge (PD) in high-voltage electricity substations using only received signal strength (RSS) is proposed. The advantages of an RSS-based operating principle over more traditional methods (e.g., time-of-arrival and time-difference-of-arrival) are described. Laboratory measurements of PD that emulate the operation of a PD WSN are presented. The hardware architecture of a prototype PD WSN is described and the particular challenges of an RSS-based location approach in an environment with an unknown, and spatially varying, path-loss index are discussed. It is concluded that an RSS-based PD WSN is a plausible solution for the monitoring of insulation integrity in electricity substations.

Using a sigma-delta modulator as a test vehicle for embedded mixed-signal test

Abstract An embedded mixed-signal test system that utilises a sigma–delta modulator as a vehicle to test analogue and digital embedded circuits is presented. A self-characterisation routine and simulation results relating to a behavioural sigma–delta model of the system will show how correlation analysis techniques can be used to evaluate the impulse response of a linear module under test (MUT) and how frequency and amplitude signal faults can be detected and accurately measured.

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.

Investigation of Doppler Effects on high mobility OFDM-MIMO systems with the support of High Altitude Platforms (HAPs)

The merging of Orthogonal Frequency Division Multiplexing (OFDM) with Multiple-Input Multiple- Output (MIMO) systems is a promising mobile air interface solution for the next generation wireless local area networks (WLANs) and 4G mobile cellular wireless systems. The main aim of this research is to design a highly robust and efficient OFDM-MIMO system to support permanent accessibility and high data rates to users moving at high mobility and speeds up to 300km/h. The paper discusses a comprehensive literature review focused in both technologies and the contributions that have been anticipated during the last years, followed by a research project planning with discussions and what experiments will be carried out using the simulation programs. Furthermore, building the hybrid architecture involves merging the novel model with High Altitude Platform system (HAPs) technology, to analyze the overall performance of the network in delivering IP-broadband services and high load application to users.

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.

Open-area concealed-weapon detection system

Concealed Weapon Detection (CWD) has become a significant challenge to present day security needs; individuals carrying weapons into airplanes, schools, and secured establishments are threat to public security. Although controlled screening, of people for concealed weapons, has been employed in many establishments, procedures and equipment are designed to work in restricted environments like airport passport control, military checkpoints, hospitals, school and university entrance. Furthermore, screening systems do not effectively decipher between threat and non-threat metal objects, thus leading to high rate of false alarms which can become a liability to daily operational needs of establishments. Therefore, the design and development of a new CWD system to operate in a large open area environment with large numbers of people reduced incidences of false alarms and increased location accuracy is essential.

Fault detection algorithm for multiple GCPV array configurations

In this paper, a fault detection algorithm for multiple grid-connected photovoltaic (GCPV) array configurations is introduced. For a given set of conditions such as solar irradiance and photovoltaic module temperature, a number of attributes such as power, voltage and current are calculated using a mathematical simulation model. Virtual instrumentation (VI) LabVIEW software is used to monitor the performance of the GCPV system and to simulate the theoretical I-V and P-V curves of the examined system. The fault detection algorithm is evaluated on multiple GCPV array configurations such as series, parallel and series-parallel array configuration. The fault detection algorithm has been validated using 1.98 kWp GCPV system installed at the University of Huddersfield. The results indicates that the algorithm is capable to detect multiple faults in the examined GCPV plant and can therefore be used in large GCPV installations.

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.