A Fundamental Study on Control Method of MMC Connected to Synchronous Generator for Offshore Wind Farm with DC Collection Grid.

2019 ◽  
Vol 45 (0) ◽  
pp. 197-197
Author(s):  
Tatsuya Matsuoka ◽  
Yuudai Yamashita ◽  
Hiroaki Kakigano
2020 ◽  
Vol 10 (20) ◽  
pp. 7282
Author(s):  
Zicong Zhang ◽  
Junghun Lee ◽  
Gilsoo Jang

With the continuous development of power electronics technology, variable-speed offshore wind turbines that penetrated the grid system caused the problem of inertia reduction. This study investigates the frequency stability of synchronous, offshore wind-farm integration through a modular-multilevel-converter high-voltage direct-current (MMC–HVDC) transmission system. When full-scale converter wind turbines (type 4) penetrate the AC grid, the AC system debilitates, and it becomes difficult to maintain the AC system frequency stability. In this paper, we present an improved inertial-response-control method to solve this problem. The mathematical model of the synchronous generator is based on the swing equation and is theoretically derived by establishing a MMC–HVDC. Based on the above model, the inertia constant is analyzed using a model that integrates the MMC–HVDC and offshore synchronous generator. With the new improved control method, a more sensitive and accurate inertia index can be obtained using the formula related to the effective short-circuit ratio of the AC system. Moreover, it is advantageous to provide a more accurate inertial control evaluation for AC systems under various conditions. Furthermore, the impact of the MMC–HVDC on system safety is assessed based on the capacitor time constant. This simulation was implemented using the PSCAD/EMTDC platform.


2019 ◽  
Vol 139 (4) ◽  
pp. 259-268
Author(s):  
Effat Jahan ◽  
Md. Rifat Hazari ◽  
Mohammad Abdul Mannan ◽  
Atsushi Umemura ◽  
Rion Takahashi ◽  
...  

2019 ◽  
Vol 2019 (17) ◽  
pp. 3848-3854
Author(s):  
Samir Milad Alagab ◽  
Sarath Tennakoon ◽  
Chris Gould

2021 ◽  
pp. 107532
Author(s):  
Muhammet Deveci ◽  
Ender Özcan ◽  
Robert John ◽  
Dragan Pamucar ◽  
Himmet Karaman

2021 ◽  
Vol 1754 (1) ◽  
pp. 012153
Author(s):  
YAN Quanchun ◽  
GU Wen ◽  
LIU Yanan ◽  
LI Chenglong ◽  
WU Tao

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2058
Author(s):  
Zheren Zhang ◽  
Yingjie Tang ◽  
Zheng Xu

Offshore wind power has great development potential, for which the key factors are reliable and economical wind farms and integration systems. This paper proposes a medium-frequency wind farm and MMC-HVDC integration system. In the proposed scheme, the operating frequency of the offshore wind farm and its power collection system is increased from the conventional 50/60 Hz rate to the medium-frequency range, i.e., 100–400 Hz; the offshore wind power is transmitted to the onshore grid via the modular multilevel converter-based high-voltage direct current transmission (MMC-HVDC). First, this paper explains the principles of the proposed scheme in terms of the system topology and control strategy aspects. Then, the impacts of increasing the offshore system operating frequency on the main parameters of the offshore station are discussed. As the frequency increases, it is shown that the actual value of the electrical equipment, such as the transformers, the arm inductors, and the SM capacitors of the rectifier MMC, can be reduced, which means smaller platforms are required for the step-up transformer station and the converter station. Then, the system operation characteristics are analyzed, with the results showing that the power losses in the system increase slightly with the increase of the offshore AC system frequency. Based on time domain simulation results from power systems computer aided design/electromagnetic transients including DC (PSCAD/EMTDC), it is noted that the dynamic behavior of the system is not significantly affected with the increase of the offshore AC system frequency in most scenarios. In this way, the technical feasibility of the proposed offshore platform miniaturization technology is proven.


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