Journal articles: 'Virtual GRID-system'

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Lee, H., and D. Park. "A Grid Service-Based Virtual Screening System." Computer Journal 57, no. 2 (February 18, 2013): 302–7. http://dx.doi.org/10.1093/comjnl/bxt015.

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Zhang, Guanfeng, Junyou Yang, Haixin Wang, and Jia Cui. "Presynchronous Grid-Connection Strategy of Virtual Synchronous Generator Based on Virtual Impedance." Mathematical Problems in Engineering 2020 (November 9, 2020): 1–9. http://dx.doi.org/10.1155/2020/3690564.

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The virtual synchronous generator (VSG) technology of inverter is widely used to provide the inertia and damping support for power system. However, an additional measurement device PLL (phase-locked loop) is required in the virtual synchronous generator grid connection to track the voltage phase, amplitude, and frequency, which restricts the flexible output of the distributed power generation system. To tackle this challenge, a method for grid-connected control of virtual synchronous generator based on virtual impedance is proposed. It is assumed that there is a virtual power exchange between the synchronous machine and the power grid when the virtual synchronous generator is off-grid, the virtual impedance is developed to calculate the virtual current, and when the virtual current is zero, the output voltage of the VSG can be synchronized with the voltage of the power grid, thereby seamlessly switching between off-grid and grid-connected VSG. A semiphysical simulation platform is built based on RT-LAB; simulation and experimental results show that the proposed grid synchronization control strategy of the VSG can achieve seamless transform between different VSG modes, which is simpler than the conventional synchronization control, while having a good active and reactive power tracing performance.

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Zhang, D. P., L. S. He, and H. Yang. "Grid Based Integration Technologies of Virtual Measurement System." Journal of Physics: Conference Series 48 (October 1, 2006): 1258–63. http://dx.doi.org/10.1088/1742-6596/48/1/234.

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Ben Belgacem, Mohamed, Nabil Abdennadher, and Marko Niinimaki. "Virtual EZ Grid." International Journal of Handheld Computing Research 3, no. 1 (January 2012): 74–85. http://dx.doi.org/10.4018/jhcr.2012010105.

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This paper presents the Virtual EZ Grid project, based on the XtremWeb-CH (XWCH) volunteer computing platform. The goal of the project is to introduce a flexible distributed computing system, with (i) an infrastructure with a non-trivial amount of computing resources from various institutes, (ii) a stable platform that manages these computing resources and provides advanced interfaces for applications, and (iii) a set of applications that take benefit of the platform. This paper concentrates on the application support of the new version of XWCH, and describes how two medical applications, MedGIFT and NeuroWeb, utilise it.

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Hao, Xiaohong, Huimin Wang, Bei Peng, Zhi Yao, Yixiong Wang, and Mingfei Gu. "Research on the virtual synchronous generator control strategy of grid-connected permanent-magnet direct-driven wind power system." Thermal Science 22, Suppl. 2 (2018): 401–8. http://dx.doi.org/10.2298/tsci171012252h.

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Renewable energy, distributed generation, and micro-grid technology have been widely concerned for a long time. The traditional grid-connected inverter control strategy does not take into account the problem of inertia which is short and fast to cause the frequency change. The virtual synchronous generator control strategy is adopted to simulate the synchronous generator characteristics, which enhanced the inertia and damp of the system. For the micro-grid of wind power grid-connected, the storage battery is arranged on the AC side of the permanent magnet direct-drive wind turbine, and the model of the virtual synchronous generator is established. Thus the grid-connected performance of large-scale wind farm is improved. Here, the effect of moment of inertia in the virtual synchronous generator and the grid-connected regulation of virtual synchronous generator are verified by using PSCAD/EMTDC. The simulation results show that the grid-connected inverter controlled by the virtual synchronous generator is approximately equivalent to the synchronous generator in external characteristic. The grid-connected inverter based virtual synchronous generator control has a beneficial to adjust frequency and voltage, and can enhance the standby inertia of new energy and grid power generation

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Guan, Ya Yun, Yu Xin Sun, Kai Shi, Huang Qiu Zhu, and Xian Xing Liu. "Research on Grid-Connected Photovoltaic Power System Based on Virtual Synchronous Generator." Applied Mechanics and Materials 703 (December 2014): 343–47. http://dx.doi.org/10.4028/www.scientific.net/amm.703.343.

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In order to realize the solar photovoltaic (PV) system connecting with grid friendly, a PV system with voltage-controlled inverter based on virtual synchronous generator (SG) is presented. This kind of system has features of SG, which supply the virtual moment of inertia to grid. The mathematical model of PV and virtual SG is built, and the control strategy of the maximum power point tracking (MPPT) is also studied in the paper. Simulation model of the grid-connected PV power system is built on Matlab/Simulink. Finally, correctness and feasibility of this system are verified by simulation results.

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Ma, Yun Long, Li Jun Tian, Ying Lin Qin, and Tao Jiang. "Grid-Connected Photovoltaic Monitoring System Based on Virtual Instrument." Applied Mechanics and Materials 521 (February 2014): 233–40. http://dx.doi.org/10.4028/www.scientific.net/amm.521.233.

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Combined with the theories of distributed monitoring, the technologies of virtual instrumentation and database management,a grid-connected photovoltaic monitoring system is developed based on virtual instrumentation technology. The hardware architecture and software programming are expounded, by hardware and software ways, various parameters of the grid-connected photovoltaic system are collected and analyzed real-timely with CompactRIO system and PXI measuring system, it realizes the functions of monitoring the performance of the PV at the real-time, detecting the power quality of the common coupling point (PCC) and historic data management. Compared with traditional monitoring system, not only it meets the requirements of grid research for sampling speed, precision and recording capacity, but also the friendly interactive interface and the flexible expansibility are more comfortable for operators.

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Wang, Lizhe, Marcel Kunze, and Jie Tao. "Performance evaluation of virtual machine-based Grid workflow system." Concurrency and Computation: Practice and Experience 20, no. 15 (October 2008): 1759–71. http://dx.doi.org/10.1002/cpe.1328.

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Coppola, Massimo, Yvon Jégou, Brian Matthews, Christine Morin, Luis Pablo Prieto, Óscar David Sánchez, Erica Y. Yang, and Haiyan Yu. "Virtual Organization Support within a Grid-Wide Operating System." IEEE Internet Computing 12, no. 2 (March 2008): 20–28. http://dx.doi.org/10.1109/mic.2008.47.

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Zhou, Yan, and Deng Ming Hu. "Research of Virtual Cutting Based on Hap Tic Feedback." Applied Mechanics and Materials 214 (November 2012): 944–48. http://dx.doi.org/10.4028/www.scientific.net/amm.214.944.

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As product design has entered the stage of green design, virtual design becomes increasingly important, and cutting research is the core of it. This paper established a basic virtual cutting system and the grid models of virtual objects based on PHANTOM Omni hap tic feedback device and its system development toolkit and built up oriented bounding box and operated bounding box collision detection. On the base of these, the paper also presented a new method of cutting force condition judgment of cutting tool, and gave the cutting path planning and grid model reconstruction on the basis of virtual cutting methods of triangular grid unit model. At last, the paper researched the virtual cutting of grid model using computer programming language, providing design methods for product design. The relative methods may advance the effect of product design drastically.

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Xia, Yao Wen, Ji Li Xie, Sai Dong Lv, and Guo Hua Tang. "The Research and Design of Intelligent Tutoring System in Intelligent Turtoring System Based on Campus Grid." Applied Mechanics and Materials 347-350 (August 2013): 3677–80. http://dx.doi.org/10.4028/www.scientific.net/amm.347-350.3677.

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Grid technology has become the computer and network technologys research hotspot and frontier, Grid technology development and the consummation will promote the development of educational information. The intelligent has shortcoming which are resource isolated, update difficulty etc, Based on the grid technology research and application, using OGSA (Open Grid Services Architecture) grid system structure, Taking GLOBUS as the grid middleware to build grid platform. This paper discuss the educational grid minimum implementation unit - - teaching system of campus grid and put forward the network teaching system model based on the grid technology. Then establish a distributed, heterogeneous sharing information resources of the library, it provides an efficient, fully shared virtual teaching space for network tutoring system. Finally, intelligent network teaching system and the grid binding laid certain foundation.

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Ma, You Jie, Shuai Wang, and Xue Song Zhou. "The Summary of the Inverter Used in PV System." Applied Mechanics and Materials 727-728 (January 2015): 616–19. http://dx.doi.org/10.4028/www.scientific.net/amm.727-728.616.

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the inverter is one of the key technologies in PV system. It transforms the DC power output by the PV panel to AC power that the grid needs. The main technologies of the inverter are the circuit topology and the control tactic. The circuit topologies of inverter including the frequency isolated PV grid-connected inverters, the high-frequency isolated PV grid-connected inverter, the single-stage non-isolated PV grid-connect inverter and the multi-level non-isolated PV grid-connected inverter. The control tactics including the voltage oriented control (VOC), the voltage-based direct power control (V-DPC), the virtual-flux oriented control (VFOC) and the virtual-flux based direct power control (VF-DPC).

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Satymbekov, M. N., I. T. Pak, L. Naizabayeva, and Ch A. Nurzhanov. "Multi-agent grid system Agent-GRID with dynamic load balancing of cluster nodes." Open Engineering 7, no. 1 (December 29, 2017): 485–90. http://dx.doi.org/10.1515/eng-2017-0054.

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AbstractIn this study the work presents the system designed for automated load balancing of the contributor by analysing the load of compute nodes and the subsequent migration of virtual machines from loaded nodes to less loaded ones. This system increases the performance of cluster nodes and helps in the timely processing of data. A grid system balances the work of cluster nodes the relevance of the system is the award of multi-agent balancing for the solution of such problems.

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Jaysawal, Anoop. "Cyber Security in Smart Grid System." International Journal of Advanced Research in Computer Science and Software Engineering 7, no. 8 (August 30, 2017): 341. http://dx.doi.org/10.23956/ijarcsse.v7i8.85.

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Abstract: The smart grid is an evolution of the electrical grid to respond to these challenges. A smart grid is an energy transmission and distribution network enhanced through digital control, monitoring, and telecommunications capabilities. It provides a real-time, two-way flow of energy and information to all stakeholders in the electricity chain, from the generation plant to the commercial, industrial, and residential end user. This evolution is crucial for integrating both renewable and distributed energy resources and to improve the efficiency and sustainability of the electrical grid and associated services. It will also help in other ways, such as enabling:• Smart and positive energy infrastructures• Increased energy density management during peaks• Real-time pricing to customers• Integrated mobility services• New virtual power plants• Micro grid

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Ji, Zhi Xiang, Li Xin Li, Rong Chang Yuan, Yan Huang, Fang Chun Di, and Ling Chen. "The Design and Implementation of Virtualization Technology Application on Power Grid Dispatching Automation System." Advanced Materials Research 816-817 (September 2013): 915–19. http://dx.doi.org/10.4028/www.scientific.net/amr.816-817.915.

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The power grid dispatching automation system is the nerve center of the strong smart grid, and its safe and stable operation is the strong guarantee of power supply. To make efficiently use of computing resources, improve the availability and flexibility of power grid dispatching automation system, this paper proposes to apply the virtualization technology to the power grid dispatching automation system to make it provide the required resources such as computing, storage and network. Through in-depth analysis of the current situation of power grid dispatching automation system and virtualization technology, this paper indicates that the virtualization technology is suitable for application in power grid dispatching automation system. Using the virtualization technology, the virtual resource pool is built; Base on the pool the grid dispatching automation system architecture is given. Then through the deployment of system hardware design, program implementation and advantage analysis, the power grid dispatching automation system based on virtual technology is built. Results show that the power grid dispatching automation system based on virtualization technology has the advantages of high availability, high resource utilization rate, load balancing and easy to scale.

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Petrosyan, Artem. "COMPASS Production System Overview." EPJ Web of Conferences 214 (2019): 03039. http://dx.doi.org/10.1051/epjconf/201921403039.

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Migration of COMPASS data processing to Grid environment has started in 2015 from a small prototype, deployed on a single virtual machine. Since summer of 2017, the system works in production mode, distributing jobs to two traditional Grid sites: CERN and JINR. Now the infrastructure of COMPASS Grid Production System includes 6 virtual machines, each is reserved for one production service: database, PanDA, Auto Pilot Factory, Monitoring, CRIC information system and, finally, production system (ProdSys) management instance, which provides a user interface for production manager and hosts services of automatic processing. Support of COMPASS virtual organization is provided by CERN IT. CRIC is also deployed at CERN Cloud Service. Other ProdSys services are deployed at JINR Cloud Service. There are two storage elements at CERN: EOS for short-term storage and Castor for long-term storage. During last year, along with providing a 24/7 service, the system was instrumented by many features, which allow automating data processing as much as possible. Recently, Blue Waters HPC has become a member of the computing infrastructure of the experiment. Details of implementation, workflow management, and infrastructure overview are presented in this article.

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Bu, Wen Shao, and Lei Lei Xu. "Improved Virtual-Flux-Linkage Observation Method of PWM Rectifier." Applied Mechanics and Materials 678 (October 2014): 528–32. http://dx.doi.org/10.4028/www.scientific.net/amm.678.528.

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In order to improve the virtual flux oriented vector control performance of PWM rectifier, an improved observation method of virtual flux-linkage is proposed. To avoid the relevant problems of pure integrator, and to achieve the accurate observation of the grid voltage’s phase, three first order low-pass filters are cascaded to displace the pure integrator. Based on the SVPWM modulation module and the presented algorithm, grid voltage sensorless control system of three-phase PWM rectifier is given. Simulation results have shown that: either in rectifying or inverting status, the amplitude and phase of virtual flux-linkage can be observed accurately, i.e. the control system of PWM rectifier can operate reliably without the grid voltage sensors; the presented estimation method of virtual flux-linkage is effective.

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Ji, Zhendong, Zhihong Zhao, Jianhua Wang, and Zhipeng Lv. "A Flexible Control Strategy for Shore-to-Ship Power System in Terms of Grid-Connected and Off-Grid Switch." Polish Maritime Research 25, s2 (August 1, 2018): 139–48. http://dx.doi.org/10.2478/pomr-2018-0085.

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Abstract There are promising application prospects for applying the shore power technology to the ships in the port for the purpose of pollution prevention. However, the grid-connection of the shore power supply to the ship power grid leads to current surges, damages the ship power consumption equipment, and results in the instability of the ship power grid system, which will seriously affect the reliability of the operation of the ship power grid system. In order to address this problem, the mathematical model of virtual synchronous generator is introduced in this paper. Then, a control method for the flexible grid-connection of the shore power supply to the ship power grid based on the virtual synchronous generator is proposed. Next, the output characteristics of the shore power supply are optimized to match the characteristics of the ship generator, which contributes to the flexible grid-connection of the shore power supply to the ship power grid system. The effectiveness and the feasibility of this method are verified by simulation and experiments.

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McGough, A. Stephen, Asif Akram, Li Guo, Marko Krznaric, Luke Dickens, David Colling, Janusz Martyniak, et al. "GRIDCC: A Real-Time Grid Workflow System with QoS." Scientific Programming 15, no. 4 (2007): 213–34. http://dx.doi.org/10.1155/2007/516174.

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The over-arching aim of Grid computing is to move computational resources from individual institutions where they can only be used for in-house work, to a more open vision of vast online ubiquitous `virtual computational' resources which support individuals and collaborative projects. A major step towards realizing this vision is the provision of instrumentation – such as telescopes, accelerators or electrical power stations – as Grid resources, and the tools to manage these resources online. The GRIDCC project attempts to satisfy these requirements by providing the following four co-dependent components; a flexible wrapper for publishing instruments as Grid resources; workflow support for the orchestration of multiple Grid resources in a timely manner; the machinery to make reservation agreements on Grid resources; and the facility to satisfy quality of service (QoS) requirements on elements within workflows. In this paper we detail the set of services developed as part of the GRIDCC project to provide the last three of these components. We provide a detailed architecture for these services along with experimental results from load testing experiments. These services are currently deployed as a test-bed at a number of institutions across Europe, and are poised to provide a 'virtual lab' to production level applications.

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Kim, Yang-Woo, Seung-Ha Lee, and Hyuk-Ho Kim. "Dynamic Virtual Organization Management System for Grid Based Information Retrieval Service." KIPS Transactions:PartD 13D, no. 7 (December 31, 2006): 1009–16. http://dx.doi.org/10.3745/kipstd.2006.13d.7.1009.

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Yammani, Chandrasekhar, and Pankaj Prabhat. "Collaborative demand response in smart electric grid with virtual system operator." IET Smart Grid 1, no. 3 (August 21, 2018): 76–84. http://dx.doi.org/10.1049/iet-stg.2018.0023.

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Salnikov, A. O., I. A. Sliusar, M. I. Anisimov, R. I. Levchenko, V. A. Maryanovskiy, N. P. Desiatnik, A. I. Cheredarchuk, and O. O. Sudakov. "Architecture of WEB-oriented system of virtual laboratories in grid-infrastructure." Information Technologies in Education, no. 4 (September 26, 2009): 31–39. http://dx.doi.org/10.14308/ite000089.

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Xinchen, Zhao, Wang Hui, and Wang Ke. "Research on Virtual Synchronous Generator Control for Vehicle-to-Grid System." IOP Conference Series: Materials Science and Engineering 486 (July 10, 2019): 012048. http://dx.doi.org/10.1088/1757-899x/486/1/012048.

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Fang, Jingyang, Hongchang Li, Yi Tang, and Frede Blaabjerg. "Distributed Power System Virtual Inertia Implemented by Grid-Connected Power Converters." IEEE Transactions on Power Electronics 33, no. 10 (October 2018): 8488–99. http://dx.doi.org/10.1109/tpel.2017.2785218.

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Siva Reddy, K. V., SK Moulali, K. Harinadha Reddy, Ch Rami Reddy, B. V. RajannaRajanna, G. Venkateswarlu, and Ch Amarendra. "Resonance Propagation and Elimination in Integrated and Islanded Microgrids." International Journal of Power Electronics and Drive Systems (IJPEDS) 9, no. 3 (September 1, 2018): 1445. http://dx.doi.org/10.11591/ijpeds.v9.i3.pp1445-1456.

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In this paper, a micro grid resonance propagation model is investigated. To actively mitigate the resonance using DG units, an enhanced DG unit control scheme that uses the concept of virtual impedance is proposed. It can be seen that a conventional voltage-controlled DG unit with an LC filter has a short-circuit feature at the chosen harmonic frequencies, whereas a current-controlled DG unit presents an open-circuit characteristic. The application of underground cables and shunt capacitor banks may introduce power distribution system resonances. This paper additionally focuses on developing a voltage-controlled DG unit-based active harmonic damping technique for grid-connected and islanding micro grid systems. An improved virtual impedance control method with a virtual damping resistor and a nonlinear virtual capacitor is proposed. The nonlinear virtual capacitor is used to compensate the harmonic dip on the grid-side inductor of a DG unit LCL filter. The virtual resistance is principally answerable for micro grid resonance damping. The effectiveness of the proposed damping method is examined using each a single DG unit and multiple parallel DG units<strong>.</strong>

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Sultana, Rima, Md Rifat Hazari, Mohammad Abdul Mannan, and Junji Tamura. "A Robust Virtual Inertia Control of Battery Storage System to Enhance Transient Stability of Grid System including Wind Farms." AIUB Journal of Science and Engineering (AJSE) 19, no. 3 (December 31, 2020): 126–33. http://dx.doi.org/10.53799/ajse.v19i3.113.

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With the rising penetration of modern converter-based wind farm (WF) into the existing grid system deteriorates system inertia due to reduction of the capacity of conventional power stations which may lead to the frequency instability as well as power system transient instability. In order to solve this concern, this paper presents a robust virtual inertia control approach for battery storage system (BSS) to enhance the frequency stability of the grid system after the generation failure owing to severe grid disruption. The control approach integrated inertial controller based on the rate of change of frequency (ROCOF) and droop controller according to frequency deviation. The impacts of the proposed virtual inertia controller (VIC) is confirmed through simulation analysis on a multi-machine power system with conventional power stations, permanent magnet synchronous generator (PMSG) with full converter based WF and squirrel cage induction generator (SCIG) based WF. Simulation study clearly demonstrates that by adopting both strategies, the BSS can effectively minimize the frequency nadir and steady-state error.

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Wang, Huan, and Lei Pan. "DFIG Virtual Inertia Frequency Control Strategy." Advanced Materials Research 680 (April 2013): 505–8. http://dx.doi.org/10.4028/www.scientific.net/amr.680.505.

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During the DFIG maximum power tracking control process, the rotor side converter is only based on the wind turbine speed to regulate the active power output; it almost no provides effective inertia. DFIG could add auxiliary virtual inertia control system, when the system frequency is reduced, releasing the rotor "hidden" kinetic energy to support the grid dynamic frequency.

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Prila, Olga, Volodymyr Kazymyr, Volodymyr Bazylevych, and Oleksandr Sysa. "The development of the system for arc nordugrid based grid-computing organization using virtual environments of the docker platform." Eastern-European Journal of Enterprise Technologies 6, no. 2 (114) (December 29, 2021): 117–24. http://dx.doi.org/10.15587/1729-4061.2021.249462.

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The study of modern frameworks and means of using virtualization in a grid environment confirmed the relevance of the task of automated configuration of the environment for performing tasks in a grid environment. Setting up a task execution environment using virtualization requires the implementation of appropriate algorithms for scheduling tasks and distributed storage of images of virtual environments in a grid environment. Existing cloud infrastructure solutions to optimize the process of deploying virtual machines on computing resources do not have integration with the Arc Nordugrid middleware, which is widely used in grid infrastructures. An urgent task is to develop tools for scheduling tasks and placing images of virtual machines on the resources of the grid environment, taking into account the use of virtualization tools. The results of the implementation of services of the framework are presented that allow to design and perform computational tasks in a grid environment based on ARC Nordugrid using the virtual environment of the Docker platform. The presented results of the implementation of services for scheduling tasks in a grid environment using a virtual computing environment are based on the use of a scheduling algorithm based on the dynamic programming method. Evaluations of the effectiveness of the solutions developed on the basis of a complex of simulation models showed that the use of the proposed algorithm for scheduling and replicating virtual images in a grid environment can reduce the execution time of a computational task by 88 %. Such estimates need further refinement; it is predicted that planning efficiency will increase over time with an increase in the number of running tasks due to the redistribution of the storage of virtual images

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Sun, Yusheng, Yaqian Zhao, Zhifeng Dou, Yanyan Li, and Leilei Guo. "Model Predictive Virtual Synchronous Control of Permanent Magnet Synchronous Generator-Based Wind Power System." Energies 13, no. 19 (September 24, 2020): 5022. http://dx.doi.org/10.3390/en13195022.

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As much wind power is integrated into the power grid through power electronic equipment, the use of wind power is increased rapidly. Wind power system makes the power grid lack inertia and damping, thereby reducing power grid stability; in severe cases, it may even be disconnected. virtual synchronous generator (VSG) has been put forward to enhance the anti-disturbance performance of power grid. However, conventional VSG adopts an outer power loop and inner-current loop control. The inner-current loop control needs a pulse width modulation (PWM) module and proportion integration (PI) parameter settings. In order to reduce the parameter settings and simplify control structures, in this study, model predictive control (MPC) is used instead of inner-current loop control. At the same time—for the overall stability and control flexibility of the back-to-back system—we further propose to use outer-voltage loop control (OVLC) and MPC to stabilize direct current (DC) voltage on the machine-side and to employ model predictive virtual synchronous controls to provide inertia and damping for the power grid. The proposed control method was simulated in Matlab/Simulink (MathWorks, Massachusetts, MA, 2016) and verified by experimental results.

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Yang, Chengshun, Fan Yang, Dezhi Xu, Xiaoning Huang, and Dongdong Zhang. "Adaptive Command-Filtered Backstepping Control for Virtual Synchronous Generators." Energies 12, no. 14 (July 12, 2019): 2681. http://dx.doi.org/10.3390/en12142681.

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Distributed energy sources are usually interfaced to the grid using power electronic converters, and lack of inertia in inverter dominated microgrids can affect the system stability. This paper presents a new method for virtual synchronous generator (VSG) control in order to solve the low system inertia and support the grid frequency problem. In this paper, the VSG based on electromagnetic transient characteristics is improved and an adaptive command filter back-stepping controller is designed. Firstly, the rotor swing equation and power part are modeled to complete the controller design for achieving system stability in the islanded, grid-connected and transition modes. In addition, a limited-amplitude command filter is used to deal with computational complexity and nonlinear saturation problems in the design process. Secondly, projection operator, and adaptive inertia and damping control are introduced to reduce the modeling error and disturbance caused by changing parameters. This ensures the boundedness of the estimated value and further improves the frequency response, especially in the transition mode. Finally, simulation results show that the proposed controller is more effective than the traditional control method for achieving power stability and frequency improvement.

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Maidenbaum, Shachar, Jonathan Miller, Joel M. Stein, and Joshua Jacobs. "Grid-like hexadirectional modulation of human entorhinal theta oscillations." Proceedings of the National Academy of Sciences 115, no. 42 (October 3, 2018): 10798–803. http://dx.doi.org/10.1073/pnas.1805007115.

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The entorhinal cortex contains a network of grid cells that play a fundamental part in the brain’s spatial system, supporting tasks such as path integration and spatial memory. In rodents, grid cells are thought to rely on network theta oscillations, but such signals are not evident in all species, challenging our understanding of the physiological basis of the grid network. We analyzed intracranial recordings from neurosurgical patients during virtual navigation to identify oscillatory characteristics of the human entorhinal grid network. The power of entorhinal theta oscillations showed six-fold modulation according to the virtual heading during navigation, which is a hypothesized signature of grid representations. Furthermore, modulation strength correlated with spatial memory performance. These results demonstrate the connection between theta oscillations and the human entorhinal grid network and show that features of grid-like neuronal representations can be identified from population electrophysiological recordings.

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Bilbao, Stefan. "Immersed boundary methods in wave-based virtual acoustics." Journal of the Acoustical Society of America 151, no. 3 (March 2022): 1627–38. http://dx.doi.org/10.1121/10.0009768.

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Volumetric wave-based simulation methods for room and virtual acoustics, such as the finite difference time domain method, are computationally intensive; for large volumes, operation over a regular grid is desirable for the sake of efficiency. In coping with realistic irregular geometries (such as enclosures or scattering objects), form-fitting meshing can disturb grid regularity and introduce new difficulties in terms of maintaining numerical stability. An alternative is the immersed boundary method, allowing for the representation of an irregular boundary over a regular grid through additional forcing terms in the dynamical system. While heavily used in fluid-structure interaction problems, such methods have seen less application in virtual acoustics. In this article, a simplified form of the immersed boundary method tailored to virtual acoustics is presented. Under appropriate passivity-preserving discretisation techniques, simple numerical stability conditions can be proved, and in particular, impedance boundaries may be incorporated easily without any risk of numerical instability. In addition, the method retains a largely explicit character with a small linear system solution required over the immersed boundary surface. Numerical results in two and three dimensions, illustrating various interior and exterior problem scenarios, are presented.

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Liao, Hong Fei, and Qi Feng Liang. "Analysis on Single Photovoltaic Grid-Connected Inverter Control System." Applied Mechanics and Materials 416-417 (September 2013): 461–67. http://dx.doi.org/10.4028/www.scientific.net/amm.416-417.461.

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nverter can operate with power grid in parallel and can return the electricity generated by photovoltaic array with high power factor to power grid. The paper analyzes and compares several grid-connected current control methods, determines that the current control mode used in the design is improved SPWM current virtual value tracking control technology. And the paper analyzes and studies the transfer functions of key links of the inverter, and gives the derivation process of transfer functions. The control system uses dual-loop structure of inner current loop and outer voltage loop, and proposes the design methods of voltage loop and current loop PI regulator.

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Hong, Deng, Chen Li, Wang Chentao, and Deng Qianni. "A grid-based scheduling system of manufacturing resources for a virtual enterprise." International Journal of Advanced Manufacturing Technology 28, no. 1-2 (March 2, 2005): 137–41. http://dx.doi.org/10.1007/s00170-004-2335-9.

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Prado, R. P., S. García-Galán, A. J. Yuste, and J. E. Muñoz Expósito. "Genetic fuzzy rule-based scheduling system for grid computing in virtual organizations." Soft Computing 15, no. 7 (October 12, 2010): 1255–71. http://dx.doi.org/10.1007/s00500-010-0660-5.

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Li, Te, Yongqing Wang, Kuo Liu, Haibo Liu, Jiali Zhang, Xianjun Sheng, and Dongming Guo. "Virtual grid and BPNN based collision avoidance control of automatic fixture system." International Journal of Advanced Manufacturing Technology 95, no. 5-8 (November 30, 2017): 2843–53. http://dx.doi.org/10.1007/s00170-017-1432-5.

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Zhang, Jiangfeng, Ye Su, Keke Zheng, and Liyun Hua. "Frequency Modulation Method and System of Photovoltaic Virtual Synchronous Generator Based on Computer Technology." Journal of Physics: Conference Series 2143, no. 1 (December 1, 2021): 012028. http://dx.doi.org/10.1088/1742-6596/2143/1/012028.

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Abstract With people’s attention to environmental protection, clean energy has become an important research and development direction. Among them, photovoltaic power generation has many advantages, such as simple process, no fuel consumption, no noise, no pollution and so on. The power grid capacity is becoming larger and larger, and has a great impact on the environment. Therefore, the grid connection of photovoltaic power generation will cause major problems for the planning, operation and dispatching of power grid. Virtual synchronous generator (hereinafter referred to as VSG) technology can simulate the inertia, primary frequency regulation and voltage regulation characteristics of synchronous generator, which has become an important way to improve the dynamic frequency response ability of the system. Therefore, VSG technology has become an important research technology of photovoltaic grid connected system, among which FM method will also become an important research direction. Firstly, this paper analyzes the VSG algorithm and its basic characteristics. Finally, this paper analyzes the control scheme of overall primary frequency regulation of photovoltaic power station (hereinafter referred to as PPS).

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BU, Wenshao, and Leilei Xu. "Direct Power Control Strategy of PWM Rectifier Based on Improved Virtual Flux-Linkage Observer." Journal of Control Science and Engineering 2017 (2017): 1–9. http://dx.doi.org/10.1155/2017/9376735.

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In order to achieve the low cost and high performance control of three-phase PWM rectifier, a direct power control (DPC) strategy based on a new-style virtual flux-linkage observer is proposed. The model of three-phase PWM rectifier and the principle of virtual flux-linkage vector control are introduced firstly. Then, in order to avoid the effect of integral initial value and cumulative deviation, three first-order low-pass filters are cascaded to replace the pure integral link; an improved virtual flux-linkage observer of three-phase power grid is presented. From the observed virtual flux-linkage, the voltage and instantaneous power of three-phase power grid are online estimated. On this basis, the power grid voltage sensorless direct power control system of three-phase PWM rectifier is designed. Simulation results have shown that, both in the rectifying state and in the inverting state, the power grid side current and the DC side voltage of three-phase PWM rectifier all can be effectively controlled; the high power factor operation of three-phase PWM rectifier is realized.

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Yan, Xiangwu, Jiajia Li, Ling Wang, Shuaishuai Zhao, Tie Li, Zhipeng Lv, and Ming Wu. "Adaptive-MPPT-Based Control of Improved Photovoltaic Virtual Synchronous Generators." Energies 11, no. 7 (July 12, 2018): 1834. http://dx.doi.org/10.3390/en11071834.

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The lack of inertia and damping mechanism of photovoltaic (PV) grid-connected systems controlled by maximum power point tracking (MPPT) poses a challenge for the safety and stability of the grid. Virtual synchronous generator (VSG) technology has attracted wide attention, since it can make PV grid-connected inverter present the external characteristics of a synchronous generator (SG). Nevertheless, traditional PV-VSG is generally equipped with an energy storage device, which leads to many problems, such as increased costs, space occupation, and post-maintenance. Thus, this paper proposes a two-stage improved PV-VSG control method based on an adaptive-MPPT algorithm. When PV power is adequate, the adaptive-MPPT allows the PV to change the operating point within a stable operation area to actualize system supply-demand, matching in accordance to the load or dispatching power demand; when PV power is insufficient, PV achieves traditional MPPT control to reduce power shortage; simultaneously, improved VSG control prevents the DC bus voltage from falling continuously to ensure its stability. The proposed control approach enables the two-stage PV-VSG to supply power to loads or connect to the grid without adding additional energy storage devices, the effectiveness of which in off-grid and grid-connected modes is demonstrated by typical simulation conditions.

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Dong, Lihu, Danqing Song, and Zhuo Chen. "Small-signal modeling and stability analysis of grid-connected offshore wind power based on virtual synchronous generator control." Journal of Physics: Conference Series 2087, no. 1 (November 1, 2021): 012055. http://dx.doi.org/10.1088/1742-6596/2087/1/012055.

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Abstract With the increasing installed capacity of offshore wind power, the grid-connected of offshore wind power technology based on virtual synchronous generators (VSG) control can simulate the inertia and damping characteristics of synchronous generator, which is helpful to improve the networking ability and inertial supportability of grid-connected inverter. However, VSG control also inevitably causes system oscillation, endangers the safe and stable operation of the power grid. Hence, the main circuit and control circuit of offshore wind power grid connection are firstly modeled, and the small-signal model of offshore wind power grid-connected inverter based on VSG control is obtained. Then the correctness of the model is verified by Matlab/Simulink software. Finally, the root trajectory method is used to identify the effects of VSG control parameters and line parameters on the system stability. The results show that VSG control has a significant influence on the stability of the grid-connected system, and reasonable design parameters are needed to ensure the safe and stable operation of the power grid.

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Al-Badi, Abdullah Hamed, Razzaqul Ahshan, Nasser Hosseinzadeh, Reza Ghorbani, and Eklas Hossain. "Survey of Smart Grid Concepts and Technological Demonstrations Worldwide Emphasizing on the Oman Perspective." Applied System Innovation 3, no. 1 (January 12, 2020): 5. http://dx.doi.org/10.3390/asi3010005.

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The Smart Grid (SG) is considered as an imminent future power network because of its fault identification and self-healing capabilities. Energy sustainability, renewable energy integration and an efficient control system are the key factors to be considered in developing SG system. Among various SG concepts, the term virtual power plant (VPP) integrates renewable energy to the grid and provides higher operational flexibility, but it requires extra capital costs for control system and software. The operational activities of a smart grid largely depend on the active customer demands. This paper defines and discusses various SG system concepts such as virtual power plant, and active demand in consumer networks, and also presents drivers and roadmaps for development of smart grids worldwide. Furthermore, this work provides an insight into present research and development on smart grids around the world, and sheds light on developing and establishing SG for the Sultanate of Oman.

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Wei, Ling, Hong-Xuan Luo, Shao-Lei Zhai, Bo-Yang Huang, and Ye Chen. "GCN based virtual resource allocation scheme for power internet of things." Journal of Computational Methods in Sciences and Engineering 22, no. 2 (March 28, 2022): 635–48. http://dx.doi.org/10.3233/jcm-215864.

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With the construction of smart grid, increasing number of smart devices will be connected to the power communication network. Therefore, how to allocate the resources of access devices has become an urgent problem to be solved in smart grid. However, due to the diversity and time-variability of access devices at the edge of the power grid, such dynamic changes may lead to untimely and unbalanced resource allocation of the power grid and additional system overhead, resulting in reducing the efficiency of power grid operation, unbalanced workload and other problems. In this paper, a grid resource allocation scheme based on Gauss optimization is proposed. The grid virtualization application resources are managed through three main steps: decomposition, combination and exchange, so as to realize the reasonable allocation of grid resources. Considering the time-variability of the grid topology and the diversity of the access device, the computational complexity of the traditional data analysis model is too high to be suitable for time-sensitive power network structure. This paper proposes an MPNN framework combined with the Graph Convolutional Network (GCN) to enhance the calculation efficiency and realize the rapid allocation of network resources. Since the smart gateway connected by the grid terminal has certain computation ability, the cloud computing used in distribution model in deep learning to find the optimal solution can be distributed in the cloud and edge computing gateway. In this way, The entire electricity network can efficiently manage and orchestrate virtual services to maximize the utility of grid virtual resources. Furthermore, this paper also adopt the GG-NN (Gated Graph Neural Network) which is based on the MPNN framework in the training. Finally, we carry out simulation for the Gauss optimization scheme and the MPNN-based scheme to verify that the convolutional diagram neural network is suitable for virtual resource allocating in multi-access power Internet-of –Things (IoTs).

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Islam, Md Kamrul, Mohammad Abdul Mannan, and Md Rifat Hazari. "FRT and Transient Stability Augmentation of Grid-Connected PV Station Using Virtual Synchronous Generator." AIUB Journal of Science and Engineering (AJSE) 20, no. 4 (December 30, 2021): 118–26. http://dx.doi.org/10.53799/ajse.v20i4.171.

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Due to the extensive integration of renewable energy sources (RESs), i.e., photovoltaic (PV) system, the future power system is developing into an inverter-based system from a dominated alternator-based power system. This massive penetration of inverter-based PV system reduced the system inertia and damping characteristics of the power grid, impacting the fault ride-through (FRT) capability and causes frequency instability. Modern grid codes require that PV systems should work in the same way as conventional power plants and assist the system during transient state. However, most of the conventional inverter control mechanisms failed to fulfill the requirements of grid codes, especially when the penetration ratio of the PV system is close to the conventional unit. Therefore, this paper proposes a virtual synchronous generator (VSG) control mechanism of PV system inverter to augment FRT competency and frequency stability. The proposed VSG control system mimics the behavior of conventional power plants. To observe and evaluate the proposed controller behavior, simulation analyses were executed in the PSCAD/EMTDC software for both proposed and conventional controllers. The simulation results clearly indicate that the proposed VSG control system has sufficient damping characteristics to ensure FRT capability and frequency stability.

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Palandurkar, Manjusha, and Mohan M. Renge. "Development of Grid Tied Inverter for Indian Grid and Operating Environmental Condition." ECS Transactions 107, no. 1 (April 24, 2022): 10519–28. http://dx.doi.org/10.1149/10701.10519ecst.

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Solar Photovoltaic (PV) technology is one of the renewable energy source technologies to realize the shift to decarbonize energy supply because of availability of safe, limitless, free and reliable long-term sources of power. PV modules/cells are instruments to convert this solar energy to DC energy. Grid interconnection with solar power system is comparatively easier to install as the same do not require storage system. This paper presents injection of 3 kW power generated from solar PV array to 230V grid distribution network. Technique uses phase angle difference between grid voltage and voltage source inverter. The grid acts like a virtual energy storage system with an unlimited storage capacity. Hence, the proposed system is designed without a battery backup. This system is simulated in MATLAB/Simulink to confirm the desire output. In the second step, hardware circuit is designed and implemented based on the simulation results.

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Buraimoh, Elutunji, and Innocent Ewaen Davidson. "Investigation of the Low Voltage Ride-Through of Inverter Using Virtual Inertia Methods in Microgrid." International Journal of Engineering Research in Africa 44 (August 2019): 200–212. http://dx.doi.org/10.4028/www.scientific.net/jera.44.200.

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Inverter based Distributed Energy Resources lack the inertia and damping features of synchronous generators dominated traditional power system. The growing penetration of renewable energy technologies coupled with their inherent intermittency also constitute grid instability challenge due to insignificant inertia and damping. The virtual inertia machine methods for the control of inverter based Distributed Energy Resources present the required inertia support that mimics the dynamic performance of a typical synchronous generator. These control methods provide excellent improvement in the stability of the grid. Several studies and implementations have been carried out on providing virtual inertia support for inverters in steady-state and under balanced grid voltage, however there is a need to investigate the dynamic performances during voltage sags occasioned by faults and other grid transients. Due to the low overvoltage and overcurrent tolerance capabilities of inverters, this investigation is important to observe the inverter transient behavior while ensuring the protection of constituent power electronic switches. Consequently, this work carried out an investigation to assess the two methods of Virtual Inertia Machine in ensuring the inverter sustained grid connection in compliance with grid codes, fault current limitation and fault recovery.

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Meng, Shao Xin, Hao Bai, and Yu Li Wang. "Optimal Energy Management for Smart Distribution Grid Based on Virtual Power Plant." Advanced Materials Research 986-987 (July 2014): 388–93. http://dx.doi.org/10.4028/www.scientific.net/amr.986-987.388.

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Virtual Power Plant (VPP) technology can take advantage of interactive communication and energy management system to optimize and coordinate the control of distributed generation, controllable load, energy storage device, so as to integrate them and participate in the energy exchange of the grid and the quote trading of power market. This paper is devoted to study the energy management system in virtual power plant. Under the day-ahead market ,this project puts forward the maximum profit model, analyzes the operation condition of various elements in virtual power plant, and set restrictions for its operation and energy storage; According to the randomness of the energy resources such as wind and light in actual operation as well as the price in power market, the change of power grid load and electricity demand, and the fluctuations in the retail price of electricity, this paper adopts the proposed model of optimal allocation to coordinate and optimize the configuration of the elements in virtual power plant.

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Gil-González, Walter, Oscar Danilo Montoya, Andrés Escobar-Mejía, and Jesús C. Hernández. "LQR-Based Adaptive Virtual Inertia for Grid Integration of Wind Energy Conversion System Based on Synchronverter Model." Electronics 10, no. 9 (April 25, 2021): 1022. http://dx.doi.org/10.3390/electronics10091022.

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This paper proposes adaptive virtual inertia for the synchronverter model implemented in a wind turbine generator system integrated into the grid through a back-to-back converter. A linear dynamic system is developed for the proposed adaptive virtual inertia, which employs the frequency deviation and the rotor angle deviation of the synchronverter model as the state variables and the virtual inertia and frequency droop gain as the control variables. In addition, the proposed adaptive virtual inertia uses a linear quadratic regulator to ensure the optimal balance between fast frequency response and wind turbine generator system stress during disturbances. Hence, it minimizes frequency deviations with minimum effort. Several case simulations are proposed and carried out in MATLAB/Simulink software, and the results demonstrate the effectiveness and feasibility of the proposed adaptive virtual inertia synchronverter based on a linear quadratic regulator. The maximum and minimum frequency, the rate change of the frequency, and the integral of time-weighted absolute error are computed to quantify the performance of the proposed adaptive virtual inertia. These indexes are reduced by 46.61%, 52.67%, 79.41%, and 34.66%, in the worst case, when the proposed adaptive model is compared to the conventional synchronverter model.

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Li, Shupeng, Guangyao Yu, Xu Zhou, and Nannan Xing. "Research on New Urban Virtual Power Plant System." E3S Web of Conferences 248 (2021): 02004. http://dx.doi.org/10.1051/e3sconf/202124802004.

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With the continuous development of energy industry, the contradiction between supply and demand is becoming increasingly serious. In order to coordinate the contradiction between power system and distributed renewable energy, and deal with many challenges brought by new energy power to power system. We should fully exploit the value and benefits of new energy for power system and users. In this paper, a new urban virtual power plant system is proposed, which integrates distributed generation units, energy storage system and controllable load. It uses advanced data communication and coordinated control technology to realize the organic overall regulation and control of various types of distributed energy and load, to reduce the challenge of randomness and volatility of high penetration distributed generation to power grid operation and dispatching, and to alleviate the contradiction between supply and demand.

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Yang, Ling, Yandong Chen, Hongliang Wang, An Luo, and Kunshan Huai. "Oscillation Suppression Method by Two Notch Filters for Parallel Inverters under Weak Grid Conditions." Energies 11, no. 12 (December 8, 2018): 3441. http://dx.doi.org/10.3390/en11123441.

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With plenty of parallel inverters connected to a weak grid at the point of common coupling (PCC), the impedance coupling interactions between the inverters and the grid are enhanced, which may cause high-frequency harmonic oscillation and further aggravate the system instability. In this paper, a basic technique for inverter output impedance is proposed to suppress the oscillation, showing that the inverter output impedance should be designed relatively high at the harmonic oscillation frequency, while relatively low at other frequencies. On the basis of the proposed technique, two virtual impedances are added to be in parallel and in series with the original inverter output impedance, respectively. Thus, an oscillation suppression method by two notch filters is proposed to realize the virtual impedances and increase the whole system damping. The implementation forms of the virtual impedances are presented by the proposed PCC voltage feedforward and grid-side inductor current feedback with two notch filters. Finally, simulation and experimental results are provided to verify the validity of the proposed control method.

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Luo, Zhi Qun, Yan Qing Wang, Jian Ru Wan, and Shao Lun Huang. "Sliding Mode Variable Structure Direct Instantaneous Power Control of Grid-Connected Converter with an LCL Filter." Advanced Materials Research 1070-1072 (December 2014): 1234–40. http://dx.doi.org/10.4028/www.scientific.net/amr.1070-1072.1234.

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Aim at solving the complex computation and complicated circuit of grid-connected converter, the sliding mode variable structure theory is introduced into its direct instantaneous power control. By analysis and modeling of three-phase grid-connected converter with an LCL-filter, sliding mode variable structure control is constructed with the active power and reactive power. The chattering is weakened by using the exponential reaching law. Cost of LCL grid-connected converter system is reduced at the same time when unit power factor and low harmonic distortion are realized. In order to increase the stability of the system, the virtual flux variable is integrated with the sliding-mode variable structure direct power control algorithm, and the improved first-order low pass filter virtual flux is used to remove the voltage sensor. By simulation, the effectiveness and feasibility of the control method is proved.

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Journal articles on the topic 'Virtual GRID-system'

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