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Title:Attack resilient GPS based timing for phasor measurement units using multi-receiver direct time estimation
Author(s):Bhamidipati, Sri Ramya
Advisor(s):Gao, Grace Xingxin
Department / Program:Aerospace Engineering
Discipline:Aerospace Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Global positioning systems
Phasor measurement units
Timing attacks
Abstract:Modern power distribution systems are incorporating Phasor Measurement Units (PMUs) to measure the instantaneous voltage and current phasors at different nodes in the power grid. These PMUs depend on Global Positioning Systems (GPS) for precise time and synchronization. However, GPS civil signals are vulnerable to external attacks because of its low power and unencrypted signal structure. Therefore, there is a need for the development of attack resilient GPS time transfer techniques to ensure power grid stability. To counteract these adverse effects, we propose an innovative Multi-Receiver Direct Time Estimation (MR-DTE) algorithm by utilizing the measurements from multiple GPS receivers driven by a common clock. The raw GPS signals from each receiver are processed using a robust signal processing technique known as Direct Time Estimation (DTE). DTE directly correlates the received GPS signal with the corresponding signal replica for each of the pre-generated set of clock states. The optimal set of clock candidates is then determined by maximum likelihood estimation. We further leverage the known geographical diversity of multiple receivers and apply Kalman Filter to obtain robust GPS timing. We evaluate the improved robustness of our MR-DTE algorithm against external timing attacks based on GPS field experiments. In addition, we design a verification and validation power grid testbed using Real-Time Digital Simulator (RTDS) to demonstrate the impact of jamming, meaconing (i.e., record-andreplay attack) and satellite data-level anomalies on PMUs. Later, we utilize our power grid testbed to validate the attack-resilience of our proposed MR-DTE algorithm in comparison to the existing techniques such as traditional scalar tracking and Position-Information-Aided Vector Tracking.
Issue Date:2017-04-28
Rights Information:Copyright 2017 Sriramya Bhamidipati
Date Available in IDEALS:2017-08-10
Date Deposited:2017-05

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