More Like this

1. Asynchronous Periodic Distributed Event-Triggered Voltage and Frequency Control of Microgrids

   https://doi.org/10.1109/tpwrs.2021.3059158  

   Mohammadi, Keywan; Azizi, Elnaz; Choi, Jeewon; Hamidi Beheshti, Mohammad Taghi; Bidram, Ali; Bolouki, Sadegh (February 2021, IEEE Transactions on Power Systems)

   null (Ed.)

   In this paper, we introduce a distributed secondary voltage and frequency control scheme for an islanded ac microgrid under event-triggered communication. An integral type event-triggered mechanism is proposed by which each distributed generator (DG) periodically checks its triggering condition and determines whether to update its control inputs and broadcast its states to neighboring DGs. In contrast to existing event-triggered strategies on secondary control of microgrids, the proposed event-triggered mechanism is able to handle the consensus problem in case of asynchronous communication. Under the proposed sampled-data based event-triggered mechanism, DGs do not need to be synchronized to a common clock and each individual DG checks its triggering condition periodically, relying on its own clock. Furthermore, the proposed method efficiently reduces communication rate. We provide sufficient conditions under which microgrid's frequency and a critical bus voltage asymptotically converge to the nominal frequency and voltage, respectively. Finally, effectiveness of our proposed method is verified by testing different scenarios on an islanded ac microgrid benchmark in the MATLAB/Simulink environment as well as a hardware-in-the-loop (HIL) platform, where the physical system is modeled in the Opal-RT and the cyber system is realized in Raspberry Pis. 

   more » « less
2. Unified Distributed Control of Grid-Forming and Grid-Feeding Converters in DC Microgrids with Average Voltage Regulation and Current Sharing

   https://doi.org/10.1109/ISGTAsia49270.2021.9715610  

   Mohiuddin, Sheik M.; Qi, Junjian (December 2021, 2021 IEEE PES Innovative Smart Grid Technologies - Asia (ISGT Asia))

   This paper proposes a unified distributed secondary control for the grid-forming (GFM) and grid-feeding (GFE) converters in DC microgrids. An optimization problem is formulated for the secondary control and the objective function considers regulating the global average of the GFM and GFE converter output voltages and proportional current sharing among all GFM and GFE converters. A unified distributed control is then designed to generate voltage and current references respectively for GFM and GFE converters based on the formulated optimization problem. The dynamic model of the DC microgrid under the proposed control is also developed, and steady-state analysis is performed to show that the proposed distributed control can achieve the control objectives in steady state. The performance of the proposed control is validated through real-time simulations in OPAL-RT on an 8-DG DC microgrid system. 

   more » « less
3. Data Integrity and Cyberattack Detection using Dynamic Watermarking for Resilient Microgrids

   https://doi.org/10.1109/ISGT59692.2024.10454158  

   Mallaiah, Pradeep Kumar; Yadav, Ankit; Ravikumar, Gelli (February 2024, IEEE)

   Cyber-attacks on microgrid systems, especially data manipulation attacks such as replay attack and Denial-of-Service (DoS), causes communication delay and unstable responses. Even though control strategies such as Consensus Control (CC) are able to coordinate electric current and voltage flow, they are at risk of malicious attacks. Communication delay leads to undetected changes in line current, and voltage leads to incorrect responses from the consensus controller, which overloads the microgrid in milliseconds. To address these challenges, this paper presents an Observer System (OS) based Dynamic Watermark (DW) detection model that detects delay-induced cyber-attacks during steady states and load fluctuations. We have developed a Grid-Specific Dynamic Watermarking (GSDW) signal that enhances real-time detection capabilities, resulting in a real-time non-zero residual showing cyber attack dynamics in the proposed observer system. Our detailed case study demonstrates real-time attack detection and prevention, ensuring the stability and integrity of Microgrid (MG) systems under challenging cyber threat conditions. Comprehensive simulations and validation demonstrate the practicality and efficacy of our approach in mitigating risks posed by delay-induced cyber attacks in MG systems. 

   more » « less
4. Droop-Free Distributed Control of DC Microgrids with Voltage Profile Guarantees and Relaxed Current Sharing

   https://doi.org/10.1109/ISGTEurope52324.2021.9640069  

   Mohiuddin, Sheik M.; Qi, Junjian (October 2021, 2021 IEEE PES Innovative Smart Grid Technologies Europe (ISGT Europe))

   This paper presents a droop-free distributed secondary control for DC microgrids with admissible voltage profile guarantees. The control objectives are achieved through an average voltage regulator, voltage variance regulator, and a relaxed current sharing regulator. Regulations of the global average voltage to the microgrid rated voltage is ensured by the average voltage regulator and regulations of the global voltage variance to a predetermined reference is enabled by the voltage variance regulator. In order to achieve the objectives of voltage regulation, the current sharing from one of the DGs which may be owned by the microgrid community is relaxed. The global dynamic model of the DC microgrid with the proposed control is derived. Besides, steady-state analysis is performed to show that all objectives can be achieved. Finally, simulations on a 4-DG DC microgrid test system are performed to validate the efficacy of the proposed control. 

   more » « less
5. A microgrid control scheme for islanded operation and re-synchronization utilizing Model Predictive Control

   https://doi.org/10.1016/j.segan.2024.101464  

   Fachini, Fernando; Bogodorova, Tetiana; Vanfretti, Luigi; Boersma, Sjoerd (September 2024, Sustainable Energy, Grids and Networks)

   Enhancing grid resilience is proposed through the integration of distributed energy resources (DERs) with microgrids. Due to the diverse nature of DERs, there is a need to explore the optimal combined operation of these energy sources within the framework of microgrids. As such, this paper presents the design, implementation and validation of a Model Predictive Control (MPC)-based secondary control scheme to tackle two challenges: optimal islanded operation, and optimal re-synchronization of a microgrid. The MPC optimization algorithm dynamically adjusts input signals, termed manipulated variables, for each DER within the microgrid, including a gas turbine, an aggregate photovoltaic (PV) unit, and an electrical battery energy storage (BESS) unit. To attain optimal islanded operation, the secondary-level controller based on Model Predictive Control (MPC) was configured to uphold microgrid functionality promptly following the islanding event. Subsequently, it assumed the task of power balancing within the microgrid and ensuring the reliability of the overall system. For optimal re-synchronization, the MPC-based controller was set to adjust the manipulated variables to synchronize voltage and angle with the point of common coupling of the system. All stages within the microgrid operation were optimally achieved through one MPC-driven control system, where the controller can effectively guide the system to different goals by updating the MPC’s target reference. More importantly, the results show that the MPC-based control scheme is capable of controlling different DERs simultaneously, mitigating potentially harmful transient rotor torques from the re-synchronization as well as maintaining the microgrid within system performance requirements. 

   more » « less