@article{du_lu_wang_chen_tu_lukic_2021, title={Dynamic Microgrids in Resilient Distribution Systems With Reconfigurable Cyber-Physical Networks}, volume={9}, ISSN={["2168-6785"]}, DOI={10.1109/JESTPE.2020.2981921}, abstractNote={Modern distribution systems energized by inverter-interfaced distributed generators (DGs) operate as coupled cyber-physical networks (C/P-networks), where the controllable components in the P-network are coordinated through the C-network. The concept of dynamic microgrids (MGs) operation has been adopted to enable distribution system autonomous operation with varying electric boundaries. To further enhance the system operation resiliency and flexibility, dynamic MGs operation with reconfigurable C/P-networks is discussed in this article. An evaluation framework is proposed to assess the operational feasibility of distribution feeders with multiple inverter-based dynamic MGs and come out with possible restoration solutions in the context of cross-layer C/P-network reconfiguration. Furthermore, distributed controllers are developed for components with different operating characteristics to realize seamless system topology variations and provide coordinated secondary regulation in various operation modes. The proposed evaluation framework, along with the developed distributed controller, has been validated using a hardware-in-the-loop (HIL) real-time CPS testbed.}, number={5}, journal={IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS}, author={Du, Yuhua and Lu, Xiaonan and Wang, Jianhui and Chen, Bo and Tu, Hao and Lukic, Srdjan}, year={2021}, month={Oct}, pages={5192–5205} }
 @article{du_tu_lu_lukic_2021, title={Privacy-Preserving Distributed Average Observers in Distribution Systems With Grid-Forming Inverters}, volume={12}, ISSN={["1949-3061"]}, DOI={10.1109/TSG.2021.3105651}, abstractNote={Information security is critical for the safe and secure operation of distribution systems. Distributed averaging has been frequently utilized to coordinate multiple inverter-interfaced distributed generators (DGs) within the distribution grid. Unfortunately, state-of-the-art dynamic consensus-based average observers lead to loss of privacy due to neighboring information exchange, i.e., the local states of each DG that contain private information could be inferred by the neighboring DGs. In this paper, to avoid privacy disclosure and guarantee the effectiveness of distributed averaging, a privacy-preserving distributed average observer is proposed. The proposed observer adopts an algorithm-based approach in privacy preservation. Compared to the existing distributed privacy-preserving algorithms in the literature, the proposed observer achieves accurate averaging and does not introduce additional restrictions on the communication network topology. Two-fold obfuscation is implemented to mask the true values of one agent’s local states from its neighbors during the average seeking. Particularly, the true values are randomly deviated at each agent locally before publishing, and the true values of the deviations are further masked using dynamic weights that vary randomly. Additionally, the proposed observer supports “plug-and-play” functionality and is robust against communication delays. The proposed observer is implemented on hardware controllers, and its observation and privacy-preserving performance are validated in a controller hardware-in-the-loop (HIL) testbed.}, number={6}, journal={IEEE TRANSACTIONS ON SMART GRID}, author={Du, Yuhua and Tu, Hao and Lu, Xiaonan and Lukic, Srdjan}, year={2021}, month={Nov}, pages={5000–5010} }
 @article{du_lu_tu_wang_lukic_2020, title={Dynamic Microgrids With Self-Organized Grid-Forming Inverters in Unbalanced Distribution Feeders}, volume={8}, ISSN={["2168-6785"]}, DOI={10.1109/JESTPE.2019.2936741}, abstractNote={In contrast to conventional static microgrids (MGs), MGs with dynamic and adjustable territories (i.e., dynamic MGs) are proposed and implemented in this article. Dynamic MGs are commonly dominated by grid-forming inverters and nested in unbalanced distribution feeders. Unlike balanced systems where only positive-sequence components exist, proper operation of unbalanced dynamic MGs presents additional challenges. A distributed secondary control strategy is developed in this article for distributed generators (DGs) interfaced with grid-forming inverters in unbalanced dynamic MGs by providing coordinated regulations on both positive- and negative-sequence system models. System frequency and voltage are under constant regulation, along with voltage unbalance (VU) management for multiple critical load buses (CLBs). The proposed control strategy enables seamless system transition during unbalanced dynamic MGs reconfiguration and guarantees proportional positive- and negative-sequence power-sharing among connected DGs with respect to system topology variation. Detailed controller designs are provided and stability analyses are derived. The proposed control strategy is fully implemented in hardware controllers and validated on a hardware-in-the-loop (HIL) MG testbed.}, number={2}, journal={IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS}, author={Du, Yuhua and Lu, Xiaonan and Tu, Hao and Wang, Jianhui and Lukic, Srdjan}, year={2020}, month={Jun}, pages={1097–1107} }
 @article{dubey_karsai_volgyesi_metelko_madari_tu_du_lukic_2019, title={Device Access Abstractions for Resilient Information Architecture Platform for Smart Grid}, volume={11}, ISBN={1943-0663}, DOI={10.1109/LES.2018.2845854}, abstractNote={This letter presents an overview of design mechanisms to abstract device access protocols in the resilient information architecture platform for smart grid, a middleware for developing distributed smart grid applications. These mechanisms are required to decouple the application functionality from the specifics of the device mechanisms built by the device vendors.}, number={2}, journal={IEEE EMBEDDED SYSTEMS LETTERS}, author={Dubey, Abhishek and Karsai, Gabor and Volgyesi, Peter and Metelko, Mary and Madari, Istvan and Tu, Hao and Du, Yuhua and Lukic, Srdjan}, year={2019}, month={Jun}, pages={34–37} }
 @article{du_tu_lukic_2019, title={Distributed Control Strategy to Achieve Synchronized Operation of an Islanded MG}, volume={10}, ISBN={1949-3061}, DOI={10.1109/TSG.2018.2861679}, abstractNote={To seamlessly transition a microgrid (MG) from islanded to grid-connected mode, it is necessary to synchronize the magnitude, frequency, and phase of the MG voltage to the voltage of the main grid. In this paper, we propose a distributed control strategy to achieve synchronized operation of an islanded MG supported by multiple controllable distributed generators (DGs). The proposed method utilizes a pinning-based consensus algorithm to ensure explicit coordination between magnitude, frequency, and phase angle regulation while ensuring proportional power sharing. System frequency is regulated by all the DGs in proportion to their capacity, while a selected DG eliminates the phase and magnitude regulation errors. Controller design criteria is based on small-signal stability analysis. The proposed control strategy is implemented in hardware controllers and its effectiveness is demonstrated using a real-time hardware-in-the-loop MG testbed.}, number={4}, journal={IEEE TRANSACTIONS ON SMART GRID}, author={Du, Yuhua and Tu, Hao and Lukic, Srdjan}, year={2019}, month={Jul}, pages={4487–4496} }
 @article{du_lu_wang_lukic_2019, title={Distributed Secondary Control Strategy for Microgrid Operation with Dynamic Boundaries}, volume={10}, ISSN={["1949-3061"]}, DOI={10.1109/TSG.2018.2879793}, abstractNote={Microgrids (MGs) with dynamic boundaries, also known as dynamic MGs, are able to support critical loads without energization from utility and allow system topology variation upon request. Utilization of dynamic MGs can provide more flexible solutions toward distribution system restoration from natural disasters. This paper proposes a distributed secondary control strategy for dynamic MG operation under both static topology and topology variation. The proposed control strategy aims to guarantee seamless transitions during dynamic MG reconfiguration and proper power management among distributed generators (DGs) that are grouped dynamically. Smart switches (SSWs) are utilized to identify, process, and implement the reconfiguration request. The proposed control strategy provides a framework to coordinate the operation of multiple DGs in neighboring autonomous MGs and determine the operation status of SSWs, so that no transient over-shoots are introduced as SSWs operate and DGs are able to support the system power demand proportionally. Detailed controller designs are provided. Sufficient conditions under which the proposed controllers are exponentially stable are derived and the dynamic performance of the proposed controller are validated by comprehensive case studies in MATLAB/Simulink.}, number={5}, journal={IEEE TRANSACTIONS ON SMART GRID}, author={Du, Yuhua and Lu, Xiaonan and Wang, Jianhui and Lukic, Srdjan}, year={2019}, month={Sep}, pages={5269–5282} }
 @inproceedings{du_jain_lukic_2016, title={A novel approach towards energy storage system sizing considering battery degradation}, DOI={10.1109/ecce.2016.7854726}, abstractNote={Energy Storage System (ESS), with its fast ramping and bi-direction power flow capabilities, is playing a more vital role in the electric market. However, it still stands on the farther end of economic viability. As a result, a good estimate of battery service life, and therefore revenue, is necessary before the investment is made in any given application. In this paper, a set of improved degradation models are propose to estimate the useful life of an ESS when subjected to daily duty cycles (4-sec resolution). The models are validated and tuned for the target Li-Nickel Cobalt Aluminum Oxide (NCA) batteries. Time to End of Life (EOL) is estimated for batteries of different sizes to provide ancillary services and/or energy services in electric market, given different end-of-cycle state of charge. Finally, the strategies which can be used to size the battery for maximizing time to EOL are discussed.}, booktitle={2016 ieee energy conversion congress and exposition (ecce)}, author={Du, Y. H. and Jain, R. and Lukic, S. M.}, year={2016} }