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Photovoltaic units that are connected to the grid through dc/dc converters and inverters in distributed generation, are controlled via a synchronous-generator-like voltage control mechanism. While other control schemes such Synchronverters are used to control the inverter frequency and power at a fixed dc link voltage, the proposed approach considers both the dc-link voltage dynamics and the inverter...
In this paper, the inverter control strategy based on Virtual Synchronous Generator (VSG) is analyzed and the power loops of VSG are explained. Then the eigenvalue method of small-signal modeling is used to prove the stability of the VSG. The key parameters including inertial coefficient, exciting coefficient, drooping coefficient and the virtual impedance were analyzed by the eigenvalues and sensitivity...
Conventional grid-interconnected inverters for variable-speed wind turbines cannot provide synchronous power as they do not have inertia. This paper proposes an application of model following controlled (MFC) PWM inverter to grid-connected variable-speed wind generators, which is based on the parallel-connected two-generator model. The wind generator system controlled by the proposed grid connected...
With the development of electrical control technology and the need of environmental protection, the marine shaft generating system based on PWM technology is developed and used. In shaft generator system, inverters parallel and parallel of inverter and diesel generator are key problems. Therefore, the paper proposes a control strategy based on virtual synchronous generator theory that simulates the...
As more and more distributed generators with intermittent characteristics are applied in microgrids, centralized control scheme encounters great challenges. In this paper, a fully distributed cooperative control scheme for Virtual Synchronous Generator based microgrid is proposed. Specifically, Virtual Synchronous Generator algorithm is developed as the primary controller of microgrid such that inverter...
The virtual synchronous generator (VSG) inverter implemented based on real-time workshop (RTW) is proposed. The design cycle of VSG implemented based on RTW is shown. Consulting the traditional mathematical model of synchronous generator in power system, the virtual synchronous generator model is built in MATLAB/Simulink, and realizing the model conversion to the code automatic. Then the Micro-source...
In this paper, a fast-synchronization between grid and inverter based on virtual synchronous converter (VSCon) technique is achieved in single-phase inverter. Consequently, this technique is designed and simulated in Matlab/Simulink platform to perceive the significances during variation of grid load parameters. The VSCon is implemented for inverter output control that has a behavior of grid voltage...
Virtual Synchronous Generator (VSG) can facilitate friendly integration of distributed generations. However, during voltage sags, traditional VSG control cannot provide reactive power support, or limit the peak current. To solve these problems, a general control strategy of VSG under voltage sags is proposed. First, the topology of VSG and its control scheme are described to formulate the key problem...
The Distributed power supply has an increasing influence on the stability of the micro-grid. Virtual synchronous generator technology can improve the stability of power grid with large inertia of synchronous generator. This paper describes the principle of virtual synchronous generator technology, as well as a detailed description of the control strategy of power frequency control and excitation control...
This paper extends the previous virtual synchronous generator (VSG) control for voltage-source converters to modular multilevel converters (MMCs). Compared with the ac synchronous generator (SG), the VSG-based MMC is embedded with a power-angle characteristic. Starting from this feature and with reference to the existing ac system coherency-based equivalence methods, this paper proposes a novel coherency...
Because of the increasing use of renewable energy technology, distributed power sources and greatly varying loads can be critical factors in power system destabilization. This problem has hampered the adoption of renewable energy; thus, researchers have studied various control method types that enable an inverter to be operated as a synchronous generator (SG). Some of these methods, referred to as...
This paper considers spectral mathematical model of the AC-AC converter scheme realized by switching functions method. Simulation results in steady state operation mode are presented in this paper.
The integration of renewable energy sources into an existing grid requires grid-tied inverters. The reliable and accurate dispatch of real and reactive power to the grid is achieved by controlling the inverters. Recent trend is to operate such grid-tied inverters as virtual synchronous generators. This requires time-intensive solution of the complex machine equations to control the inverter outputs...
Virtual synchronous generator (VSG) control strategy has received wide attention since it was proposed. In this article, the basis implementation of VSG, namely active and reactive power decoupling control, is discussed. Through analyzing the traditional power decoupling mechanism and its restriction in the medium and low voltage micro-grid, a new power decoupling scheme is proposed which combines...
Micro hydropower engineering, due to the relative stability of stream regime and high energy density of water workflow, has the best technical and economic characteristics in comparison to other renewable energy sources. Micro hydropower plants (micro HPPs) meet all environmental requirements and can make a significant contribution to the electrification of remote rural areas, tourist and agricultural...
The advent of multilevel inverters brings flexibility in the microgrids' design for numerous new applications. But, these static power electronic inverters possesses low moment of inertia, which effects the system resiliency in the event of uncertainties. This calls for a philosophy of emulating virtual inertia into the microgrid's operation while preserving the advantages of renewable energy and...
Dynamic frequency regulation and effect of penetration of static and inertial sources on system stability are important issues for islanded microgrid power quality and reliability. This work presents a novel strategy of utilizing an inverter based source as a voltage source inverter (VSI) or virtual synchronous generator (VSG). Electro-mechanical and power modes are critical for small signal stability...
Owing to the growth in penetration of DGs (distributed generators), inverters installed together with the DGs have been increasing rapidly. In general, these grid-connected inverters need a dedicated synchronization unit such as a phaselocked loop (PLL), which receives voltage phase, frequency, and amplitude of the grid voltage as reference from power grids. As the installation of inverters keeps...
The amount of inverter-interfaced distributed generation in the electrical networks is continuously increasing. However, the presence of a large amount of local generation is raising a number of issues referring to the power system stability. In particular, high sensitivity in the response to frequency variations after disturbances is emerging, because of the low inertia of the local generators. Recent...
Distributed energy resources (DERs) powered by natural gas engines are becoming more popular in several nations. This paper presents the modeling and analysis of engine fuel map limits on natural gas powered DERs installed at the CERTS Microgrid. A physics-based approach is used for correct modeling of the limiting conditions in DERs. The distinguishing characteristics of both inverter-based and synchronous...
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