4 research outputs found
A Unifying Framework for the Electrical Structure-Based Approach to PMU Placement in Electric Power Systems
The electrical structure of the power grid is utilized to address the phasor
measurement unit (PMU) placement problem. First, we derive the connectivity
matrix of the network using the resistance distance metric and employ it in the
linear program formulation to obtain the optimal number of PMUs, for complete
network observability without zero injection measurements. This approach was
developed by the author in an earlier work, but the solution methodology to
address the location problem did not fully utilize the electrical properties of
the network, resulting in an ambiguity. In this paper, we settle this issue by
exploiting the coupling structure of the grid derived using the singular value
decomposition (SVD)-based analysis of the resistance distance matrix to solve
the location problem. Our study, which is based on recent advances in complex
networks that promote the electrical structure of the grid over its topological
structure and the SVD analysis which throws light on the electrical coupling of
the network, results in a unified framework for the electrical structure-based
PMU placement. The proposed method is tested on IEEE bus systems, and the
results uncover intriguing connections between the singular vectors and average
resistance distance between buses in the network.Comment: Submitted to IEEE Transactions on Smart Grid. arXiv admin note: text
overlap with arXiv:1309.130
Hidden Attacks on Power Grid: Optimal Attack Strategies and Mitigation
Real time operation of the power grid and synchronism of its different
elements require accurate estimation of its state variables. Errors in state
estimation will lead to sub-optimal Optimal Power Flow (OPF) solutions and
subsequent increase in the price of electricity in the market or, potentially
overload and create line outages. This paper studies hidden data attacks on
power systems by an adversary trying to manipulate state estimators. The
adversary gains control of a few meters, and is able to introduce spurious
measurements in them. The paper presents a polynomial time algorithm using
min-cut calculations to determine the minimum number of measurements an
adversary needs to manipulate in order to perform a hidden attack. Greedy
techniques are presented to aid the system operator in identifying critical
measurements for protection to prevent such hidden data attacks. Secure PMU
placement against data attacks is also discussed and an algorithm for placing
PMUs for this purpose is developed. The performances of the proposed algorithms
are shown through simulations on IEEE test cases
Real-time Faulted Line Localization and PMU Placement in Power Systems through Convolutional Neural Networks
Diverse fault types, fast re-closures, and complicated transient states after
a fault event make real-time fault location in power grids challenging.
Existing localization techniques in this area rely on simplistic assumptions,
such as static loads, or require much higher sampling rates or total
measurement availability. This paper proposes a faulted line localization
method based on a Convolutional Neural Network (CNN) classifier using bus
voltages. Unlike prior data-driven methods, the proposed classifier is based on
features with physical interpretations that improve the robustness of the
location performance. The accuracy of our CNN based localization tool is
demonstrably superior to other machine learning classifiers in the literature.
To further improve the location performance, a joint phasor measurement units
(PMU) placement strategy is proposed and validated against other methods. A
significant aspect of our methodology is that under very low observability (7%
of buses), the algorithm is still able to localize the faulted line to a small
neighborhood with high probability. The performance of our scheme is validated
through simulations of faults of various types in the IEEE 39-bus and 68-bus
power systems under varying uncertain conditions, system observability, and
measurement quality.Comment: 11 pages, 8 figure
Physics-Informed Learning for High Impedance Faults Detection
High impedance faults (HIFs) in distribution grids may cause wildfires and
threaten human lives. Conventional protection relays at substations fail to
detect more than 10\% HIFs since over-currents are low and the signatures of
HIFs are local. With more PMU being installed in the distribution system,
high-resolution PMU datasets provide the opportunity of detecting HIFs
from multiple points. Still, the main obstacle in applying the PMU
datasets is the lack of labels. To address this issue, we construct a
physics-informed convolutional auto-encoder (PICAE) to detect HIFs without
labeled HIFs for training. The significance of our PICAE is a physical
regularization, derived from the elliptical trajectory of voltages-current
characteristics, to distinguish HIFs from other abnormal events even in highly
noisy situations. We formulate a system-wide detection framework that merges
multiple nodes' local detection results to improve the detection accuracy and
reliability. The proposed approaches are validated in the IEEE 34-node test
feeder simulated through PSCAD/EMTDC. Our PICAE outperforms the existing works
in various scenarios and is robust to different observability and noise.Comment: 7 pages, 6 figure