Ana Goulart

Implementing a real-time cyber-physical system test bed in RTDS and OPNET

Numerous innovative smart grid technologies are deployed in modern power systems, making a power system a typical cyber-physical system (CPS). The increasing coupling between a physical power system and its communication network requires a smart grid simulator to run in a cyber-physical environment for cyber security research. In addition, smart grid technologies introduce numerous access points to the communication network, making cyber security a big concern in smart grid planning and operation. In this paper, a simple real time CPS test bed, implemented in RTDS and OPNET, is discussed. The setup of the test bed is introduced. Results of a case study simulated in the test bed to study the impact of cyber attacks on system transient stability are presented. The simple test bed was capable of accurately modelling a smart grid while providing user-friendly modeling experience.

Development of a Low-Cost Self-Diagnostic Module for Oil-Immerse Forced-Air Cooling Transformers

Fault detection, fault prognosis, and life expectancy estimation of transformers are important issues in improving the reliability of smart grids. Regular maintenance checks can detect the transformers faulty conditions; however, such checks can only be performed limited times annually due to high cost and disruption of service. Therefore, faults that occur between such checks take a long time to be detected. This paper proposes a simple online monitoring algorithm that uses a minimum set of sensor feedback to estimate oil-immersed forced-air cooling transformers life expectancy parameters. Abrupt changes or sufficient deviations of these estimations from their nominal values can be used as an indicator of transformer fault. The algorithm can also estimate the transformer-life expectancy during normal operation. A transformer-monitoring prototype has been developed based on the proposed algorithm. The transformer-monitoring prototype that uses wireless communication capability to transmit transformer life expectancy parameters to the substation has been tested, verified with lab experiments, and deployed to a utility substation.

Implementing attacks for modbus/TCP protocol in a real-time cyber physical system test bed

To understand security vulnerabilities of communication protocols used in power systems, a real-time framework can be developed to conduct vulnerability studies. The framework should implement protection mechanisms against vulnerabilities and study their effectiveness. In this paper, a realtime cyber-physical framework or test bed is presented. It integrates a real-time power system simulator and a communication system simulator to study the cyber and physical system vulnerabilities in smart power grids. The power system simulation is implemented using the Real-Time Digital Simulator (RTDS®) power grid simulator, with LabVIEW and PXI modules that simulate the supervisory control and data acquisition (SCADA) system and intelligent electronic devices (IEDs). The communication system simulation is implemented using Opnets System-in-the-Loop (SITL) simulator and open source Linux tools and servers. Results of two cyber-attacks on the Modbus/TCP protocol are discussed and improvements to the test bed for protocol attack detection and mitigation are proposed.

Optimal selection of wireless channels for real-time communication in ambulances

The design and implementation of ambulances that exchange high quality video, vital signs, voice and text communications, and patient information in real-time with the emergency room are becoming a reality. For instance, the Disaster Relief and Emergency Medical Service (DREAMStrade) project has developed such ambulances. Through wireless Internet access, the ambulances take advantage of the widespread cellular coverage in rural and urban areas to transfer audio, video and vital signs. In this paper, our goal is to improve the intelligence of the channel selection mechanism of the ambulance based on metrics such as data transfer efficiency and reliability. Using a simple optimization algorithm, we propose a strategy to assign the next designated channel for the high priority data.

A Design of Experiment (DOE) Analysis of the Performance of Uplink Real-Time Traffic over a 3G Network

The bandwidth and reliability of the reverse link (or uplink) as the performance metrics of real-time traffic are studied in this paper. A two-level full factorial design of experiment (DOE) was conducted to identify the impact on the bandwidth and reliability of four factors: packet size, data streaming rate, time of the day, and buffer size in a real network environment. Two extreme cases for each factor were tested and statistical analysis is performed to characterize how different factors and their interactions may affect the bandwidth and reliability. The importance of this study is illustrated in the optimal channel selection mechanism where appropriate packet size, data streaming rate and buffer size can be chosen to achieve the best result.

In-Vehicle Emergency Call Services: eCall and Beyond

What is the status of in-vehicle emergency call services? Which standards are being adopted? Does the NG-911/112 architecture support such services? The objective of this article is to address these questions. To do so we review the evolution of eCall, compare approaches developed in different parts of the world, and discuss interoperability between selected systems. This study shows that it is challenging to compare and classify in-vehicle emergency call systems because of different standards, terminologies, and proprietary specifications. We conclude that the NG-911/112 framework provides the building blocks to support next generation eCall, and can contribute to a common standard for the interface between private service centers and public safety answering points.

A regression algorithm for transformer fault detection

A transformers failure can lead to disruption in power, decrease in system reliability and monetary loss to the utility and distribution companies. Fault detection of transformers is a critical step for improving the reliability of distribution systems. Regular maintenance checks can detect most of faulty conditions, but due to high cost and difficulty, the maintenance checked can only be performed annually. This paper proposes a simple on-line monitoring algorithm that uses a minimum set of sensor information, including ambient temperature, hot spot temperature, and load, to estimate several system parameters such as oil and thermal properties of the transformer and detect abnormal behavior. Fault can be detected when these parameter estimations experience sudden changes or the estimated values have sufficient deviation from their nominal values.

Testbed Experiments on the Location to Service Translation (LoST) Protocol for Mobile Users

The Location to Service Translation (LoST) protocol is a service discovery protocol, which uses location information to map service Uniform Resource Identifiers (URI). The LoST protocol was developed to support the routing process of IP-based emergency calls, known as Next Generation 9-1-1 (NG-911). In this paper, we describe testbed experiments and a new algorithm to improve the performance of the LoST protocol for mobile users. The proposed algorithm is based on the minimum distance approach to detect service boundary crossings. After comparing the minimum distance algorithm with the Ray-Tracing method, our results showed that the new algorithm considerably reduces the processing time at the mobile LoST client.

Statistical Analysis of Broadband Wireless Links in Rural Areas

Third-generation (3G) cellular systems are often considered as a promising strategy for high-speed internet deployment in rural areas. However, bandwidth in 3G systems is a limited resource and can be quite different from the advertised bandwidth. In addition, in wireless applications such as voice over IP, video-conference, remote monitoring and telemetry (e.g., for healthcare applications) the Quality of Service (QoS) is critical. It is therefore important to understand how different factors affect the QoS requirements of real-time applications. Focusing on the reverse link (or uplink), we performed an assessment of the bandwidth and packet loss rate in a real network environment, using test data collected with two wireless data cards from different providers, in both rural and urban locations. The main contribution of this paper is the presentation of a formal statistical method – a Design of Experiments (DOE) analysis - that can be used to analyze the interactions between different variables, such as packet size, location, buffer size, and wireless provider. With a better understanding of the impact of such factors and their interactions, the end-user may be able to make the best selection of certain controllable parameters, in an effort to improve the QoS of the 3G connection. This is especially important for users located in rural areas, where cellular coverage is limited.

Performance of secure SIP and LoST signaling in a Next Generation 9–1–1 testbed

Security is an important concern in Voice over IP (VoIP) applications. An approach to securing the signaling, such as the Session Initiation Protocol (SIP) and Location to Service Translation (LoST) messages, is to use Transport Layer Security (TLS). Several studies have measured the impact of using TLS on SIP. However, there have not been any tests on the impact of TLS or Internet Protocol Security (IPSec) on IP-based emergency calls or Next Generation 9-1-1 (NG-9-1-1). In this paper, we address the practical issues in establishing a secure framework for NG-9-1-1 with performance metrics such as call setup and server processing delays.