A novel approach for non-invasive radiometric Partial Discharge (PD) detection and localization of faulty power apparatuses in switchyards using Chipless Radio Frequency Identification (RFID) based sensor is presented. The sensor integrates temperature sensing together with PD detection to assist on-line automated condition monitoring of high voltage equipment. The sensor is a multi-resonator based passive circuit with two antennas for reception of PD signal from the source and transmission of the captured PD to the base station. The sensor captures PD signal, processes it with designated spectral signatures as identification data bits, incorporates temperature information, and retransmits the data with PD signals to the base station. Analyzing the PD signal in the base station, both the PD levels and temperature of a particular faulty source can be retrieved. The prototype sensor was designed, fabricated, and tested for performance analysis. Results verify that the sensor is capable of identifying different sources at the events of PD. The proposed low cost passive RFID based PD sensor has a major advantage over existing condition monitoring techniques due to its scalability to large substations for mass deployment.
Top1. Introduction
RFID (Radio Frequency Identification) is emerging as a successful alternative to the traditional barcodes due to its embedded security, larger reading distance irrespective of line of sight, greater storage capacity and elevated reliability (Finkenzeller, 2010).The RFID tags are made robust so that they can be used in any harsh environments and temperatures. Each tag has a unique ID which is used to track or localize goods. The tag uses modulated backscattering of RF signals to communicate with the reader.
Apart from the tracking an object, RFID tags can monitor the surrounding environmental conditions and act as a sensor. Thus a sensor enabled tag monitors some of the physical parameters (temperature, pressure, humidity etc.) in addition to its identification function (Xia, 2009). This offers an accurate and relatively simple implement solution also. An object providing its own condition and identification simultaneously simplifies the infrastructure and enhances the quality of the information. RFID sensors create a link between the digital networked world and the physical world. Its role is to deliver a unique ID to the networked data related to the product. In addition, RFID acts as the virtual connection between the object and composite decision processes that are based on sensory data inputs from the users. RFID sensor technology has revolutionized the field of healthcare, structural damage detection environmental monitoring, transporting pharmaceuticals, storing goods, promoting security etc. (Want, 2004).
The power industry has introduced RFID for asset management, inventory control and equipment monitoring. In Sen et al (2009), five categories of problems in power system management which can be overcome through RFID and wireless technology is presented. These are 1) Locating asset. 2) Identification and status of asset; 3) Tool tracking; 4) Fleet management; and 5) Access management and infrastructure security. Power facility management using RFID integrated with Wireless Sensor Network (WSN) is proposed in (Kim et al., 2006). The combination of RFID and sensors such as (thermal, wind speed and direction, battery life etc.) provides real time condition monitoring facility and improves transmission reliability. Moreover, active RFID is a key ingredient for the Smart Grid where power distribution system automates generation, delivery and consumption of electrical energy using communication and information technologies. Figure 1 is an illustration of power distribution monitoring system using RFID tag and WSN. This provides real time power system surveillance with minimum cost.
Figure 1. A power distribution monitoring system using RFID sensor network
However, chipless RFID is a new dimension in the regime of RFID technology which has not been employed in power management system. Chipless RFID tag circuitry does not have any semiconductor chip or IC in it thus the cost is significantly lower than the chipped tags (S. Preradovic & Karmakar, 2010). It is completely passive having a specific EM structure and operates when the tag is illuminated by a reader antenna. The chipless RFID tag can also incorporate sensing mechanism without utilizing an external sensor within the tag (Bhattacharyya et al., 2010). Chipless RFID sensor can revolutionize the automated condition monitoring of High Voltage (HV) equipment in a power substation by cutting down cost, enhanced dynamic range and longevity. In this chapter a novel application of chipless RFID sensor is proposed for real time condition supervision. Our proposed sensor addresses two aspects of health monitoring for HV equipment which are 1) Partial Discharge (PD) due to insulation deterioration and 2) temperature measurement. We introduce a new era in condition monitoring of electricity substations by integrating these two sensing paradigm on the platform of microstrip based chipless RFID sensor (Figure 2).
Figure 2. Schemetic block diagram of the functionality and scope of our proposed chipless RFID based PD sensor