SBIR-STTR Award

The growth in renewable energy and the inherent distributed nature of these sources is challenging the electric grid, calling for modernization to a more intelligent, reconfigurable distribution system. It is well understood that with greater use of distributed energy sources, which can result in significant- even reverse power flows, smart protective relaying technologies become essential for safe and reliable grid operation. The proposed project will demonstrate a bi-modal fiber optic distributed temperature and acoustic sensor for monitoring both parameters in high voltage distribution cables. This will allow fast detection and location of ground faults, and real-time monitoring of cable conductor temperature to assess dynamic cable rating- critical information for smart protective relaying to enhance grid resiliency and power restoration in the event of a supply interruption. When incorporated within power cable sheathing, the all di-electric construction of optical fibers has no impact on performance of these cables while allowing direct measurement of the conductor with no interference. This project will demonstrate a bimodal distributed temperature and acoustic sensor capable of complete monitoring of these parameters over the entire length of cable. An optical test cable incorporating a pair of conventional telecommunications-grade fibers will be used for the project demonstration, and available for any “live” high-voltage cable tests. A commercial Raman-scatter type distributed temperature instrument will be used to monitor cable/conductor temperature. Such fiber optic sensors have been demonstrated in this application with good results, however the measurement time is not adequate to quickly detect rapid thermal events or mechanical disturbances associated with ground faults. The main development of this project will be a distributed acoustic/vibration sensor capable of almost instantaneous detection and location of disturbances acting on the cable due to ground faults. This sensor detects sudden changes in light propagation in the sensor fiber and applies a fast auto-correlation method to determine its location. The proposed bimodal sensor will deliver critical information for advanced protective relaying control systems, providing real-time intelligence at the physical layer of the grid. The high-speed disturbance sensor innovation has other commercial applications in physical security, pipeline monitoring, and transportation infrastructure safety and integrity.

There is significant transformation underway in electric power supply and demand that presents significant operational and resiliency challenges to today’s electric power grid.Of note is growth in renewable power sources, mainly wind and solar, which are distributed within the power grid rather than fixed as in the traditional network.The emergence of such distributed energy sources leads to alteration and even reverse power flows which are particularly problematic to conventional protective relaying systems.Grid modernization to accommodate dynamic power flows requires advances in protective relaying solutions to ensure grid safety and reliability.This will be accomplished through smart relaying systems that combine advanced relaying components, and sensors and software to detect defective lines and adverse power system conditions to initiate appropriate control circuit action.The proposed program will develop a bimodal fiber optic sensor that monitors temperature and acoustics all along a sensing optical fiber embedded in high voltage power transmission and distribution cables.Sensor data provides critical circuit condition, line rating, and hazard information.Specifically, the proposed bimodal sensor provides real-time thermal rating measurement of the cable to calculate circuit ampacity- the power load capability of the circuits before exceeding its rating, with acoustic monitoring able to instantaneously detect and locate ground faults.This sensor will be important in smart relaying systems for improved demand response, power loading, power restoration, and grid efficiency and management of decentralized power generation.In Phase I, feasibility of the bimodal sensor was demonstrated by integrating distributed temperature and acoustic sensors operated on a test cable over a range of thermal conditions and acoustic events.The system integrated a commercial Raman type distributed temperature sensor with a commercial coherent Raleigh type distributed acoustic sensor, and a LuxPoint proprietary distributed acoustic sensor that has potential cost and operational advantages.Phase I feasibility test results were conclusive, and set a strong foundation to continue development and commercialization of the bimodal sensor.The proposed Phase II project will complete bimodal sensor product development for a final integrated distributed temperature and acoustic sensor in a black box instrument package with common electronic processor, power supply, and interfaces.The development program will further investigate performance and cost of both acoustic sensors to down-select the most promising for commercial release at the conclusion of the project.Commercialization of the bimodal sensor product will establish sales channels through high voltage cable and electrical grid equipment manufacturers, and grid systems and grid management software suppliers.This strategy will foster rapid uptake of the sensor in grid modernization.In addition to the smart relaying application, such bimodal distributed fiber optic sensor product can address commercial opportunities in security, pipeline, transportation and fire detection markets that can benefit from the reach, stability and distributed sensor architecture of the fiber optic sensor.