scholarly journals The Novel Current Control for Virtual Synchronous Generator

2020 ◽  
Vol 08 (02) ◽  
pp. 78-89
Author(s):  
Atsushi Umemura ◽  
Rion Takahashi ◽  
Junji Tamura
2020 ◽  
Vol 2020 ◽  
pp. 1-8 ◽  
Author(s):  
Jie Wu ◽  
Chuanjiang Li

For a VSC-HVDC transmission system based on a hybrid topology converter of full-bridge and half-bridge, a kind of virtual synchronous generator (VSG) control strategy which can be applied to modular multilevel converter (MMC) grid-connected structure was researched and proposed. First, based on the conventional VSG control strategy, the energy stored in the equivalent capacitor of MMC power module was used to imitate the rotor inertia of synchronous generator. The characteristics of generator can be simulated during transient frequency fluctuations and it can help relieve the power fluctuations. Secondly, with respect to the structural characteristics of the direct grid connection through the reactor on the AC side of the MMC, which is unlike the microgrid inverter, there are no additional filter capacitors. So, the existing commonly used VSG control strategy of the microgrid inverter and double-closed-loop structure composed of filter capacitor voltage and AC current cannot be directly applied. For this, a method where the given values of inner current loop are calculated by grid impedance matrix was used. So, a double-closed-loop control structure composed of a power outer loop based on VSG control and a current inner loop is obtained. It can effectively improve the current control capability during the transient process. Finally, a hybrid MMC simulation model was built based on PSCAD to verify the correctness and effectiveness of the proposed methods.


2017 ◽  
Vol 137 (6) ◽  
pp. 546-552 ◽  
Author(s):  
Yuko Hirase ◽  
Osamu Noro ◽  
Shogo Katsura ◽  
Kensho Abe ◽  
Eiji Yoshimura ◽  
...  

2020 ◽  
Vol 140 (6) ◽  
pp. 531-538
Author(s):  
Kotaro Nagaushi ◽  
Atsushi Umemura ◽  
Rion Takahashi ◽  
Junji Tamura ◽  
Atsushi Sakahara ◽  
...  

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4581
Author(s):  
Yuko Hirase ◽  
Yuki Ohara ◽  
Naoya Matsuura ◽  
Takeaki Yamazaki

In the field of microgrids (MGs), steady-state power imbalances and frequency/voltage fluctuations in the transient state have been gaining prominence owing to the advancing distributed energy resources (DERs) connected to MGs via grid-connected inverters. Because a stable, safe power supply and demand must be maintained, accurate analyses of power system dynamics are crucial. However, the natural frequency components present in the dynamics make analyses complex. The nonlinearity and confidentiality of grid-connected inverters also hinder controllability. The MG considered in this study consisted of a synchronous generator (the main power source) and multiple grid-connected inverters with storage batteries and virtual synchronous generator (VSG) control. Although smart inverter controls such as VSG contribute to system stabilization, they induce system nonlinearity. Therefore, Koopman mode decomposition (KMD) was utilized in this study for consideration as a future method of data-driven analysis of the measured frequencies and voltages, and a frequency response analysis of the power system dynamics was performed. The Koopman operator is a linear operator on an infinite dimensional space, whereas the original dynamics is a nonlinear map on a finite state space. In other words, the proposed method can precisely analyze all the dynamics of the power system, which involve the complex nonlinearities caused by VSGs.


Author(s):  
Santhoshkumar Thenpennaisivem ◽  
V. Senthilkumar

In this article, a hybrid technique is proposed for improving the transient and small signal response in micro grid using virtual inertia. The proposed hybrid technique is the combined execution of both the emperor penguin optimizer (EPO) and butterfly optimization algorithm (BOA), and hence it is called EPOBOA technique. The major objective of the EPOBOA technique is to “optimize the control parameters to regulate the changes occurred in the grid parameter such as voltage and frequency based on the variations of inertia”. Here, the EPO is executed to modify the parameters of virtual synchronous generator units to achieve the objective function. The searching behaviour of the EPO is adapted by using the hunting behaviour of BOA. The proposed technique is executed in MATLAB/Simulink work site, and the experimental results are analyzed under three test cases: normal condition, irradiation change condition, and load change condition. The performance of the proposed technique is compared with different existing techniques and the calculated frequency deviation index of the proposed technique in all the cases is 0.0051, 0.0045, and 0.0047 and found to be very optimal compared with existing methods. Overall, the experimental outcomes show that the proposed EPOBOA method is more efficient and confirm its ability to solve the issues.


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