4,248 research outputs found
Enhancement of Distribution System State Estimation Using Pruned Physics-Aware Neural Networks
Realizing complete observability in the three-phase distribution system
remains a challenge that hinders the implementation of classic state estimation
algorithms. In this paper, a new method, called the pruned physics-aware neural
network (P2N2), is developed to improve the voltage estimation accuracy in the
distribution system. The method relies on the physical grid topology, which is
used to design the connections between different hidden layers of a neural
network model. To verify the proposed method, a numerical simulation based on
one-year smart meter data of load consumptions for three-phase power flow is
developed to generate the measurement and voltage state data. The IEEE 123-node
system is selected as the test network to benchmark the proposed algorithm
against the classic weighted least squares (WLS). Numerical results show that
P2N2 outperforms WLS in terms of data redundancy and estimation accuracy
Solving Optimal Power Flow for Distribution Networks with State Estimation Feedback
Conventional optimal power flow (OPF) solvers assume full observability of
the involved system states. However, in practice, there is a lack of reliable
system monitoring devices in the distribution networks. To close the gap
between the theoretic algorithm design and practical implementation, this work
proposes to solve the OPF problems based on the state estimation (SE) feedback
for the distribution networks where only a part of the involved system states
are physically measured. The SE feedback increases the observability of the
under-measured system and provides more accurate system states monitoring when
the measurements are noisy. We analytically investigate the convergence of the
proposed algorithm. The numerical results demonstrate that the proposed
approach is more robust to large pseudo measurement variability and inherent
sensor noise in comparison to the other frameworks without SE feedback
Data based identification and prediction of nonlinear and complex dynamical systems
We thank Dr. R. Yang (formerly at ASU), Dr. R.-Q. Su (formerly at ASU), and Mr. Zhesi Shen for their contributions to a number of original papers on which this Review is partly based. This work was supported by ARO under Grant No. W911NF-14-1-0504. W.-X. Wang was also supported by NSFC under Grants No. 61573064 and No. 61074116, as well as by the Fundamental Research Funds for the Central Universities, Beijing Nova Programme.Peer reviewedPostprin
A Survey on Wireless Security: Technical Challenges, Recent Advances and Future Trends
This paper examines the security vulnerabilities and threats imposed by the
inherent open nature of wireless communications and to devise efficient defense
mechanisms for improving the wireless network security. We first summarize the
security requirements of wireless networks, including their authenticity,
confidentiality, integrity and availability issues. Next, a comprehensive
overview of security attacks encountered in wireless networks is presented in
view of the network protocol architecture, where the potential security threats
are discussed at each protocol layer. We also provide a survey of the existing
security protocols and algorithms that are adopted in the existing wireless
network standards, such as the Bluetooth, Wi-Fi, WiMAX, and the long-term
evolution (LTE) systems. Then, we discuss the state-of-the-art in
physical-layer security, which is an emerging technique of securing the open
communications environment against eavesdropping attacks at the physical layer.
We also introduce the family of various jamming attacks and their
counter-measures, including the constant jammer, intermittent jammer, reactive
jammer, adaptive jammer and intelligent jammer. Additionally, we discuss the
integration of physical-layer security into existing authentication and
cryptography mechanisms for further securing wireless networks. Finally, some
technical challenges which remain unresolved at the time of writing are
summarized and the future trends in wireless security are discussed.Comment: 36 pages. Accepted to Appear in Proceedings of the IEEE, 201
Tutorial on Congestion Control in Multi-Area Transmission Grids via Online Feedback Equilibrium Seeking
Online feedback optimization (OFO) is an emerging control methodology for
real-time optimal steady-state control of complex dynamical systems. This
tutorial focuses on the application of OFO for the autonomous operation of
large-scale transmission grids, with a specific goal of minimizing renewable
generation curtailment and losses while satisfying voltage and current limits.
When this control methodology is applied to multi-area transmission grids,
where each area independently manages its congestion while being dynamically
interconnected with the rest of the grid, a non-cooperative game arises. In
this context, OFO must be interpreted as an online feedback equilibrium seeking
(FES) scheme. Our analysis incorporates technical tools from game theory and
monotone operator theory to evaluate the stability and performance of
multi-area grid operation. Through numerical simulations, we illustrate the key
challenge of this non-cooperative setting: on the one hand, independent
multi-area decisions are suboptimal compared to a centralized control scheme;
on the other hand, some areas are heavily penalized by the centralized
decision, which may discourage participation in the coordination mechanism
- …