Dhananjay Anand

A Hierarchical Incentive Arbitration Scheme for Coordinated PEV Charging Stations

Distribution utilities are becoming increasingly aware that their networks may struggle to accommodate a large number of plug-in electric vehicles (PEVs), especially at times of peak loading. In this paper, a centralized scheduling scheme is formulated to coordinate charging of a heterogeneous PEV fleet, which is then divided into load groups, each with a set of local objectives, constraints, and a decentralized control algorithm. Realistic energy tariffs are used to formulate probable “real-world” objectives for each load group, and a distributed dynamic program is used to regulate the net load of each load group. It is shown that charging coordination not only reduces peak network loads, but can also significantly reduce the customers PEV charging cost. Potential improvements from the perspective of communication and modeling are also highlighted by adopting a systematic approach to divide the PEV fleet into load groups.

An efficient timestamp-based monitoring approach to test timing constraints of cyber-physical systems

Formal specifications on temporal behavior of Cyber-Physical Systems (CPS) is essential for verification of performance and safety. Existing solutions for verifying the satisfaction of temporal constraints on a CPS are compute and resource intensive since they require buffering signals from the CPS prior to constraint checking. We present an online approach, based on Timestamp Temporal Logic (TTL), for monitoring the timing constraints in CPS. The approach reduces the computation and memory requirements by processing the timestamps of pertinent events reducing the need to capture the full data set from the signal sampling. The signal buffer size bears a geometric relationship to the dimension of the signal vector, the time interval being considered, and the sampling resolution. Since monitoring logic is typically implemented on Field Programmable Gate Arrays (FPGAs) for efficient monitoring of multiple signals simultaneously, the space required to store the buffered data becomes the limiting resource. The monitoring logic, for the timing constraints on the Flying Paster (a printing application requiring synchronization between two motors), is illustrated in this paper to demonstrate a geometric reduction in memory and computational resources in the realization of an online monitor.

A Low-Cost GPS Spoofing Detector Design for Internet of Things (IoT) Applications

The civilian Global Positioning System (GPS) is widely used for precise positioning, timekeeping, and synchronization in embedded systems. As a result, emerging digital infrastructure such as the Internet of Things (IoT) are dependent on GPS to locate and synchronize \textit{Things} in the network. From a security perspective, civilian GPS signals are vulnerable to malintent because they are not encrypted and can easily be spoofed. Several countermeasures have been proposed to detect GPS spoofing attacks, but most of them require extensive signal processing capabilities and additional electronic components to capture and analyze RF signals. These add-ons may not be available to IoT devices, and if present, they will affect the device\textquoteright s power budget significantly. Therefore, new techniques for spoofing detection and survival are required before integrating GPS receivers with IoT devices and other critical infrastructures where energy and computation power are limited. In this work, we propose a novel GPS spoofing detection scheme based on hardware oscillators. Our design depends on measuring the frequency drift and offset of a free-running crystal oscillator with respect to the GPS signals. In our secure GPS spoofing detector design the trust is intrinsic, \textit{i.e.}, the receiver only trusts the on-board free running local oscillator. Intrinsic properties of these oscillators exhibit a strong correlation with the authentic GPS signals and any anomaly in this measurement will indicate potential attacks on the received GPS signals. This proposed design is cost-effective, secure, backward compatible with existing receivers, and does not require additional RF circuitry or network connection with other clocks for detecting attacks.

Multicast Delayed Authentication for Streaming Synchrophasor Data in the Smart Grid

Multicast authentication of synchrophasor data is challenging due to the design requirements of Smart Grid monitoring systems such as low security overhead, tolerance of lossy networks, time-criticality and high data rates. In this work, we propose inf -TESLA, Infinite Timed Efficient Stream Loss-tolerant Authentication, a multicast delayed authentication protocol for communication links used to stream synchrophasor data for wide area control of electric power networks. Our approach is based on the authentication protocol TESLA but is augmented to accommodate high frequency transmissions of unbounded length. inf TESLA protocol utilizes the Dual Offset Key Chains mechanism to reduce authentication delay and computational cost associated with key chain commitment. We provide a description of the mechanism using two different modes for disclosing keys and demonstrate its security against a man-in-the-middle attack attempt. We compare our approach against the TESLA protocol in a 2-day simulation scenario, showing a reduction of 15.82% and 47.29% in computational cost, sender and receiver respectively, and a cumulative reduction in the communication overhead.