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This paper formulates sufficiency-type linear-output feedback decentralized closed-loop stabilization conditions if the continuous-time linear dynamic system can be stabilized under linear output-feedback centralized stabilization. The provided tests are simple to evaluate, while they are based on the quantification of the sufficiently smallness of the parametrical error norms between the control, output, interconnection and open-loop system dynamics matrices and the corresponding control gains in the decentralized case related to the centralized counterpart. The tolerance amounts of the various parametrical matrix errors are described by the maximum allowed tolerance upper-bound of a small positive real parameter that upper-bounds the various parametrical error norms. Such a tolerance is quantified by considering the first or second powers of such a small parameter. The results are seen to be directly extendable to quantify the allowed parametrical errors that guarantee the closed-loop linear output-feedback stabilization of a current system related to its nominal counterpart. Furthermore, several simulated examples are also discussed. [ABSTRACT FROM AUTHOR]

This paper provides a review of the research conducted on complex network analysis (CAN) in electric power systems. Moreover, a new approach is presented to find optimal locations for microgrids (MGs) in electric distribution systems (EDS) utilizing complex network analysis. The optimal placement in this paper points to the location that will result in enhanced grid resilience, reduced power losses and line loading, better voltage stability, and a supply to critical loads during a blackout. The criteria used to point out the optimal placement of the MGs were predicated on the centrality analysis selected from the complex network theory, the center of mass (COM) concept from physics, and the recently developed controlled delivery grid (CDG) model. An IEEE 30 bus network was utilized as a case study. Results using MATLAB (MathWorks, Inc., Nattick, MA, USA) and PowerWorld (PowerWorld Corporation, Champaign, IL, USA) demonstrate the usefulness of the proposed approach for MGs placement. [ABSTRACT FROM AUTHOR]

This paper presents load frequency control of the 2021 Egyptian power system, which consists of multi-source electrical power generation, namely, a gas and steam combined cycle, and hydro, wind and photovoltaic power stations. The simulation model includes five generating units considering physical constraints such as generation rate constraints (GRC) and the speed governor dead band. It is assumed that a centralized controller is located at the national control center to regulate the frequency of the grid. Four controllers are applied in this research: PID, fractional-order PID (FOPID), non-linear PID (NPID) and non-linear fractional-order PID (NFOPID), to control the system frequency. The design of each controller is conducted based on the novel tunicate swarm algorithm at each operating condition. The novel method is compared to other widely used optimization techniques. The results show that the tunicate swarm NFOPID controller leads the Egyptian power system to a better performance than the other control schemes. This research also presents a comparison between four methods to self-tune the NFOPID controller at each operating condition. [ABSTRACT FROM AUTHOR]

This paper proposes an energy management system (EMS) of direct current (DC) microgrid. In order to implement the proposed EMS, the control and operation method of EMS is presented in this work. While most of the studies have individually examined the grid-connected mode used in building and the stand-alone operation mode applicable to the island, the proposed EMS allows it to be used in both grid-connected mode and stand-alone mode with 10 modes. In order to determine each mode in EMS, not only the amount of generated power, load power, and the state of charge (SOC) of the battery, but also the rated power of the energy storage system (ESS) converter that performs charging and discharging operations is additionally considered. Thus, various uncertainties that may occur in the actual DC microgrid environment can be improved. A laboratory-scale DC microgrid is fabricated to conduct experimental validation of proposed EMS. Experiments of DC microgrid with proposed EMS were performed for each mode, and the experiment waveforms of each power conversion device are included in detail. [ABSTRACT FROM AUTHOR]

The conventional scroll compressor cannot run oil-free because of wear and tear and lubrication problems during operation due to some parts, such as anti-rotation devices. The magnetic drive oil-free scroll compressor (MDOFSC) uses a contactless drive method to avoid this drawback. In order to solve the swing problem of the orbiting scroll during the operation of the MDOFSC, decentralized control and centralized control are used to study the trajectory tracking characteristics. Firstly, the structure and working principle of the MDOFSC are introduced, and the system's magnetic circuit and differential control principle are analyzed. Then, the dynamic model of the MDOFSC under the condition of non-compressed gas is established, and the coordinate matrix decoupling method is used to analyze the relationship between the degree of freedom of the system and the measurement distance of the displacement sensor. Finally, the system is simulated and experimentally studied under centralized PID control, and the experimental comparison study between decentralized control and centralized control is conducted. The results show that centralized control dramatically improves the trajectory control ability of the system. [ABSTRACT FROM AUTHOR]