Comparative economic analysis of low frequency AC transmission system for the integration of large offshore wind farms

Meng, Yongqing; Yan, Shuhao; Wu, Kang; Ning, Lipeng; Li, Xuan; Wang, Xiuli; Wang, Xifan

doi:10.1016/j.renene.2021.07.137

Cited by 31 publications

(7 citation statements)

References 29 publications

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“…The key equipment of the LFAC scheme is the interface between the low frequency and power frequency. There are many topologies to complete the frequency conversion, such as back-to-back modular multi-level converter (MMC) [24], modular multilevel matrix converter (M3C) [25,26] and hexagonal MMC (Hexverter) [27]. In [28][29][30], the authors pointed out that M3C has a vast applicative prospect in LFAC.…”

Section: Figurementioning

confidence: 99%

Frequency selection method for urban low frequency multi‐terminal interconnected systems

Zhang

2023

IET Generation Trans & Dist

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Large-scale urban power grid (LUPG) is normally under the operating mode by voltage layer and zone partition. One of the most important directions for the development of urban is to enhance the controllability by flexible low-frequency interconnection technology. In this study, a frequency selection method for urban low-frequency multi-terminal interconnected systems (ULFMIS) is proposed. Firstly, the required support power under different conditions, the index number of sending partition (SP) and receiving partition (RP) are determined. Secondly, by calculating the current distribution along the line under different support powers, the upper limit of the transmission frequency (ULTF) of each line is obtained. Finally, the smallest transmission frequency among the ULTFs of different tie lines is selected as the ULTF of the ULFMIS. The proposed method is validated in a typical four-terminal ULFMIS. The results demonstrate that the suggested method is suitable for calculating the ULTF taking account of the influence of the number of parallel lines on economic cost and provide guidance for future practical ULFMIS projects.

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Section: Figurementioning

confidence: 99%

Frequency selection method for urban low frequency multi‐terminal interconnected systems

Zhang

2023

IET Generation Trans & Dist

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“…In recent years, in the process of social and economic development, many advanced technologies have been applied to further improve the quality and efficiency of OPEN ACCESS EDITED BY Xin Ning, Institute of Semiconductors (CAS), China power transmission, thus promoting the growth of social economy. At present, there are three main transmission methods in the power system: high-voltage direct current (HVDC), high-voltage alternating current (HVAC), and low-frequency alternating current (LFAC) transmissions (Reed et al, 2013;Zhang et al, 2013;Yao et al, 2015;Meng et al, 2021). Among them, the application of HVDC technology has not only effectively improved the quality of power resource transmission to meet the requirements of people's daily life but also further optimized the operation performance of the power grid system (Li, 2010;Ma et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

Fault diagnosis of the HVDC system based on the CatBoost algorithm using knowledge graphs

Li²,

Chen³

et al. 2023

Front. Energy Res.

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In order to overcome the difficulty of fault diagnosis in the high-voltage direct current (HVDC) transmission system, a fault diagnosis method based on the categorical boosting (CatBoost) algorithm is proposed in this work. To make the research conform to the actual situation, three kinds of measured fault data in the HVDC system of the Southern Power Grid are selected as the original data set. First, the core role and significance of fault diagnosis in knowledge graphs (KGs) are given, and the characteristics and specific causes of the four fault types are explained in detail. Second, the fault dates are preprocessed and divided into the training data set and the test data set, and the CatBoost algorithm is employed to train and test fault data to realize fault diagnosis. Finally, to verify the progressiveness and effectiveness of the proposed method, the diagnostic results obtained by CatBoost are compared with those obtained by the BP neural network algorithm. The results show that the diagnostic accuracy of the CatBoost algorithm in the three test sets is always higher than that of the BP neural network algorithm; the accuracy rates in the three case studies of the CatBoost algorithm are 94.74%, 100.00%, and 98.21%, respectively, which fully proves that the CatBoost algorithm has a very good fault diagnosis effect on the HVDC system.

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“…Lower grid frequency dramatically reduces the transmission line impedance and significantly improves the transmission efficiency than HVAC, low cost than HVDC. 2 The AC/AC converter in FFTS is capable of AC conversion of different frequencies. Among these converters, the suppression method of circulation current in modular multilevel matrix converter (M3C) is more complicated.…”

Section: Introductionmentioning

confidence: 99%

Robustness improvement model predictive control strategy based on Luenberger observer for Y‐type modular multilevel converter

Yue

Cheng

2023

Circuit Theory & Apps

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SummaryThe Y‐type modular multilevel converter (Y‐MMC) has high reliability due to its high modularity. It can promise AC/AC conversion for high‐voltage and large‐capacity fractional frequency transmission systems (FFTS). The Y‐MMC under linear control has a poor ability to adapt to changing working conditions, resulting in unstable transmission, slow response, and large harmonics and overshoot. The Robustness Improvement Model Predictive Control strategy (RI‐MPC) for Y‐MMC under nonideal conditions is presented in this paper to enhance robustness under unbalanced conditions and adaptability to load changes. It points out that the conventional MPC has low robustness when Y‐MMC encounters parameters difference due to faulty line, designs an improved outer‐loop PI control to enhance robustness to provide an excellent reference value for the inner‐loop current, combines the Luenberger observer with MPC and limits the parameters with Jury criterion to improve stability, and uses a two‐step prediction to compensate for delay and reduce harmonics. Through software simulation and hardware experiments, it is proved that compared with the traditional PI and MPC method, the RI‐MPC method is more robust, faster, and has application value.

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Comparative economic analysis of low frequency AC transmission system for the integration of large offshore wind farms

Cited by 31 publications

References 29 publications

Frequency selection method for urban low frequency multi‐terminal interconnected systems

Frequency selection method for urban low frequency multi‐terminal interconnected systems

Fault diagnosis of the HVDC system based on the CatBoost algorithm using knowledge graphs

Robustness improvement model predictive control strategy based on Luenberger observer for Y‐type modular multilevel converter

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