False Analog Data Injection Attack Towards Topology Errors: Formulation and Feasibility Analysis

In this paper, we propose a class of false analog data injection attack that can misguide the system as if topology errors had occurred. By utilizing the measurement redundancy with respect to the state variables, the adversary who knows the system configuration is shown to be capable of computing the corresponding measurement value with the intentionally misguided topology. The attack is designed such that the state as well as residue distribution after state estimation will converge to those in the system with a topology error. It is shown that the attack can be launched even if the attacker is constrained to some specific meters. The attack is detrimental to the system since manipulation of analog data will lead to a forged digital topology status, and the state after the error is identified and modified will be significantly biased with the intended wrong topology. The feasibility of the proposed attack is demonstrated with an IEEE 14-bus system.Comment: 5 pages, 7 figures, Proc. of 2018 IEEE Power and Energy Society General Meetin

Network-based Optimization Techniques for Wind Farm Location Decisions

This thesis develops network-based approaches to analysis and optimization of wind energy systems. The wind energy system is a complex system that produces a massive amount of wind speed data over time, characterized by high level of variability. We study this system using the powerful tools of graph theory and network analysis, which provide a valuable tool for extracting important information from systems generating large amounts of data. The main contribution of this thesis is a network-based method for finding appropriate locations for wind farms that maximize the overall energy, while controlling the effects of wind speed variability. For this purpose, we constructed networks that model potential wind farm locations as vertices and represent the pairwise correlations of the corresponding wind speed measurements using edges. More specifically, two vertices are connected by an edge if the correlation of their wind speeds considered over the given time period is below zero. If the weights of vertices are given by the average wind speed at the corresponding locations, then the problem of finding appropriate locations for wind farms is formulated as the problem of finding a tightly knit cluster of vertices with high weights. More specifically, we model clusters using the graph-theoretic concept of a clique and its relaxations, 2-plex and 3-plex. To test the proposed approaches, we used real data from Bolivian studies of wind velocities conducted over a 10-year period at 201 locations spanning the entire Bolivian territory. The solutions obtained using the proposed approaches provide sets of diverse locations with high possible wind energy outputs. In particular, using clique relaxations results in larger number of diversified locations compared to that given by the maximum clique solutions. Another studied problem deals with determining a small number of locations that would be representative of the overall behavior of wind speeds in the whole system. This problem was addressed searching for small dominating sets in graphs where edges correspond to pairs of locations with positively correlated wind speeds. Finally, we proposed a methodology for evaluating costs of setting up wind farms in certain locations in Bolivia. The cost of setting up wind farms involves many variables, wind speeds being an important factor in determining the profitability of the system. We observe that for sites with higher wind speeds the net present value (NPV) of setting up and operating wind farms is positive and the internal rate of return (IRR) is higher than the discount rate, which ensures some profit to the investor. More specifically, the study has shown that with wind speeds around 6.9 m/s, the 2MW and 3MW wind turbine installments yield IRR of 13% and 15%, respectively. On the other hand, we concluded that lower wind speeds would result in projects that would not be able to recover the investment in the first 25 years. However, these projects could be profitable if the government develops policies for some green credits, or carbon bonus as income for generating and selling clean energy produced from wind power plants. The results obtained in this study could help the governments and investors interested in developing wind energy farms in Bolivia and other countries with similar geographical characteristic

On Communication-Assisted Line Protection for Multi-Inverter Microgrids

Protection is critical in maintaining grid stability and reliability. Microgrids, which are small-scale power systems that can operate autonomously or while connected to the main grid, pose unique challenges for protection schemes. Traditional protection methods, such as time-delayed overcurrent relays, reclosers, and fuse-based protection may not be sufficient to detect faults in microgrids. This paper discusses the differences in protection requirements between autonomous and grid-connected microgrids, a comparison of overcurrent and differential protection schemes, and the advancements in microgrid communication, cybersecurity, standards, and test beds. A benchmark 4-bus microgrid system is implemented in distribution voltage ratings, with simulation results demonstrating the effectiveness of synchrophasor-based relays in detecting faults. Showing the feasibility of differential protection over overcurrent protection. Paper is concluding with future work needed to enhance the novel protection concepts

Enhancing Microgrid Protection: Wavelet Response Analysis for Islanded and Grid-Connected Modes

Research Conference Paper.Copyright ©2023 by IEEE.Microgrid systems have emerged as a viable solution to address the challenges associated with conventional power grids, such as reliability, resiliency, and sustainability. The protection of microgrids plays a crucial role in ensuring their safe and efficient operation. This paper presents a novel approach to enhance microgrid protection by applying wavelet response analysis for current measurements. The proposed technique utilizes a differential technique for fault identification in both islanded and grid-connected modes. The proposed enhanced microgrid protection scheme provides an innovative and robust solution for ensuring the reliable fault detection of microgrids in both islanded and grid-connected modes of operation. Simulation results highlight the application of wavelet response analysis offering a comprehensive and efficient approach to detect and mitigate power system abnormalities, contributing to microgrid systems’ overall stability and resilience. The proposed technique can effectively identify abnormal conditions by implementing wavelet transform to analyze current waveforms through differential relaying techniques distinguishing between short circuit faults, external disturbances, and tap loads. Simulation studies were conducted on a representative 4-Bus benchmark microgrid model to evaluate the performance of the protection scheme. Results demonstrate the effectiveness and superiority of the proposed scheme in accurately identifying symmetrical and asymmetrical faults, effectively segregating tap loads, and contributing to the reliability and resilience of microgrid systems.This collaborative work was supported jointly by the Department of Energy under Award Number DE-IA0000025 and the Indo-US Science and Technology Foundation in partnership with the Department of Science and Technology, Government of India, under grant no. IUSSTF/JCERDC-Smart Grids and Energy Storage/2017

Voltage-Based Frequency Synchronization for Phasor Measurements in Microgrid Protection

Accepted Conference Paper, will be presented in November 2023 in Power Africa, Marrakesh, Morocco.Copyright ©2023 by IEEE.The accurate measurement of current phasors is crucial for the reliable and effective protection of microgrids. However, the presence of harmonics and variations in the fundamental frequency due to the integration of inverter-based resources (IBRs), can lead to errors in current phasor measurements in islanded microgrids. In this work, we propose a novel approach to current phasor measurement in microgrid protection that utilizes voltage-based fundamental frequency stabilization. The proposed method is based on the use of voltage measurements to synchronize a set of variable frequencies, and three-phase signals to track changes in the fundamental frequency and adjust the current phasor measurements accordingly. Simulation results demonstrate that the proposed method is effective in reducing errors in current phasor measurements caused by variations in the fundamental frequency, at the same time it can segregate between a fault and a tap load. The proposed method has the potential to enhance the performance of microgrid protection systems and ensure the reliable operation of microgrids.This collaborative work was supported jointly by the Department of Energy under Award Number DE-IA0000025 and the Indo-US Science and Technology Foundation in partnership with Department of Science and Technology, Government of India, under grant no. IUSSTF/JCERDC-Smart Grids and Energy Storage/2017

Network-based optimization techniques for wind farm location decisions

2018 The Author(s) 2018. Published by Higher Education Press. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0)This study aims to find appropriate locations for wind farms that can maximize the overall energy output while controlling the effects of wind speed variability. High wind speeds are required to obtain the maximum possible power output of a wind farm. However, balancing the wind energy supplies over time by selecting diverse locations is necessary. These issues are addressed using network-based models. Hence, actual wind speed data are utilized to demonstrate the advantages of the proposed approach.We would like to thank the anonymous reviewers for their insightful comments. The partial support of the Ministny of Education of Bolivia Texas A&M Energy Institute is also gratefully acknowledged

On Fault Mitigation Schemes for Grid Forming Inverters in AC-Microgrids: Studying Instantaneous Current Limiters

In AC microgrid systems, maintaining stability and reliability is paramount, especially during fault conditions. This paper presents a novel fault mitigation technique for grid-forming inverters, focusing on instantaneous current limiter schemes. The primary objective of this approach is to protect inverter’s internal semiconductor components under short-circuit faults conditions by implementing advanced reference frame techniques that limit current and voltage outputs. At the same time, providing fault protection/mitigation during symmetrical and asymmetrical disturbances, the investigated control scheme allows inverters not to disconnect during faults, thus maintaining grid stability and reliability, allowing time for grid protection to react and operate normally. Simulation results demonstrate the efficacy of the proposed scheme in enhancing the resilience of AC microgrid systems, facilitating seamless integration of renewable energy sources. This paper addresses a critical need in modern power systems by providing a robust solution for inverter fault tolerance, protection and short circuit fault management for AC microgrids

Relative group homology theories with coefficients and the comparison homomorphism

Let G be a group, let H be a subgroup of G and let Or(G) be the orbit category. In this paper we extend the denition of the relative  group homology theories of the pair (G;H) dened by Adamson and Takasu to have coecients in an Or(G)-module. There is a canonical comparison homomorphism dened by Cisneros- Molina and Arciniega-Nevrez from Takasu's theory to Adamson's theory. We give a  necessary and sucient condition on the subgroup H for which the comparison homomorphism is an isomorphism for all coecients. We also use the Luck-Wiermann construction to introduce a long exact sequence for Adamson homology. Finally, we provide some examples of explicit computations for the comparison homomorphism

Microgrid Protection with Penetration of DERs - A Comprehensive Review

Conference Paper, Pre PrintCopyright ©2023 by IEEE.Distributed Energy Resources (DER) early uses as a backup generation has been progressing toward permanent Distributed Generation (DG), along with the development and enhancement of new technologies over small-scale generation. Over last few years, increasing penetration of renewables in the distribution networks at consumer level raises concerns on protection, control, stability and reliability. Considering the DG integration and wide variations in operating conditions of the microgrid, relays experience protection issues at fault current level violating important tripping decision rules. This study reviews the impact of DG penetration as integration means on traditional overcurrent (OC) protection schemes, being the most common and widely used relaying scheme in radial distribution networks. This paper reviews the most representative methods with respect to various challenges uncovered by exhaustive studies and validations and reported in the literature. Further, potential adaptive and intelligent schemes are also discussed for enhancing the performance over traditional protection schemes in microgrids."This material is based upon work (partially) supported by the Department of Energy under Award Number DEIA0000025 and the Indo-US Science and Technology Foundation in partnership with Department of Science and Technology, Government of India, under grant no. IUSSTF/JCERDC-Smart Grids and Energy Storage/2017. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.