Abstract ：

Reliable wind power and ramp event prediction is essential for the safe and stable operation of electric power systems. Previous prediction methods struggled to forecast large fluctuations in wind power caused by extreme weather conditions, severely limiting the development of wind power prediction ...

Keyword ：

Day-ahead Deep learning LSTM Numerical weather prediction Wind power forecast Wind power ramp event

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Abstract ：

To study the large disturbance stability of a grid-connected VSC with phase-locked loop, a simplified second order nonlinear model of a VSC is established based on the difference of response speed between inner loop current control and outer loop power control, and two Lyapunov functions are separately defined. The first Lyapunov function has clear kinetic energy and potential energy concepts but a small stable region, while the second Lyapunov function has a wider stable region but lacks clear physical concepts. Combining the two Lyapunov functions, a practical stability criterion is obtained, one which has both clear physical concepts and a relatively large stable region. If the state of the phase-locked loop is known at the time of the system’s last operation, the stability can be predicted. The simulation results well verify the accuracy of the derived stability criterion. © 2023 Power System Protection and Control Press. All rights reserved.

Keyword ：

grid-connected VSC; large disturbance stability; Lyapunov function; phase-locked loop

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Abstract ：

The cooperative work of multiple modules is an important technical stage in the practical process of inductive pulsed power supply (IPPS). This article proposes a novel configuration of multimodule system, in which the inductors of each module are arranged in a toroidal way. This configuration can greatly improve the energy storage by utilizing the mutual inductance between modules, and the electromagnetic interference can also be reduced. Based on the circuit analysis and formula derivation, the decoupling equivalent greatly simplifies the calculation of system performance. The genetic algorithm (GA) is used for the parametric design of the 2 MJ toroidal IPPS system, and one of the solutions achieves an output current of 361 kA and an energy density of 6.21 MJ/m3. In addition, the three configurations of multimodule IPPS system are compared, and it is found that the proposed toroidal scheme can achieve higher indicators. © 1973-2012 IEEE.

Keyword ：

Circuit equivalent; inductive pulsed power supply (IPPS); optimization method; toroidal scheme

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Abstract ：

To achieve the most efficient restoration of hybrid AC/DC distribution system, this paper proposes an outage management through co-optimizing service restoration with repair crew (RC) and mobile energy storage system (MESS) dispatch. Firstly, this paper proposes a hybrid AC/DC distribution system restoration (DSR) model considering network reconfiguration, distributed generation (DG) islanded operation and voltage source converter (VSC) based DSR, which means adjusting VSC control mode to realize uninterrupted power supply of loads. In the DSR model, a restoration coordination model that can coordinate network reconfiguration and the control modes of VSCs, DGs and MESS discharge stations is developed to ensure the radial configuration of the system. Moreover, to accurately calculate the power flow of the system during a failure of VSCs, a new power flow model considering VSC's operation status is proposed in the DSR model. Then, a bi-level co-optimization method is developed based on the DSR model and improved dispatch models of RC and MESS. The upper level co-optimizes hybrid AC/DC distribution system restoration with RC and MESS dispatch to maximize the restored loads. The lower level further optimizes the power outputs of VSCs and DGs to minimize the voltage deviation of the restored loads. Finally, simulations studies are performed to verify the effectiveness and superiority of the proposed method. © 2022 Elsevier Ltd

Keyword ：

Co-optimization; Distribution system restoration; Hybrid AC/DC distribution system; Mobile energy storage system; Repair crew; Voltage source converter

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Abstract ：

Reliable wind power and ramp event prediction is essential for the safe and stable operation of electric power systems. Previous prediction methods struggled to forecast large fluctuations in wind power caused by extreme weather conditions, severely limiting the development of wind power prediction techniques. Based on this problem, an improved hybrid model is presented in this study, that utilises long short-term memory (LSTM) by considering wind power ramp events (WPREs). First, the LSTM network was driven by numerical weather prediction (NWP) to forecast day-ahead wind power. Second, a novel improved dynamic swinging door algorithm (ImDSDA) and a fuzzy C-means (FCM) model were utilised for WPRE detection and classification respectively. Third, a similarity-matching mechanism was proposed to correct the predicted WPREs. Finally, the predicted wind power was reconstructed using the optimised WPREs.The model, which was validated in three mountainous wind farms in central China, can capture the temporal dynamics of wind power using deep learning and WPRE prediction. The proposed model's results outperformed a few existing methods and can provide scientific guidance for the safe dispatching and economic operation of power systems. © 2022 Elsevier Ltd

Keyword ：

Day-ahead; Deep learning; LSTM; Numerical weather prediction; Wind power forecast; Wind power ramp event

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Abstract ：

The uncertainty in electric power demand associated with the increasing penetration of electric vehicles can profoundly affect the stability of microgrids. Therefore, the present work addresses the need to reduce the operating cost of multi-microgrids and improve the convergence performance of the s...

Keyword ：

Electric vehicle aggregator Multi-microgrids Neural networks Robust optimization Uncertainty set

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Abstract ：

Fractional frequency offshore wind power system (FFOWPS) is a new type of offshore wind power system, which is proved to be more economical and has technological advantages for medium and long transmission lines. Modular multilevel matrix converter (M3C) is the most expected AC/AC converter that may be used in FFOWPS. However, there is no research published about the protection of M3C-based FFOWPS. In this paper, the challenges for the protection of M3C-based FFOWPS have been analyzed. They can be summarized as follows, (i) M3C and wind turbines are all electronic devices. Their intrinsic characteristics and control strategy will significantly complicate the fault characteristics, (ii) The decrease in system frequency will extend the time of phasor-based protection methods. To solve the above problems, the idea of model recognition is introduced in fault identification for FFOWPS based on M3C, which discriminates faults by model differences instead of comparison of voltage or current. Then a novel time-domain pilot protection is proposed for FFOWPS based on M3C. An M3C-based FFOWPS is built in MATLAB/Simulink and the simulations have verified the adaptability of the proposed method. © 2022 IEEE.

Keyword ：

Electric power system protection Electric power transmission MATLAB Matrix converters Offshore oil well production Time domain analysis Wind power

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Abstract ：

Active rectifier is commonly used in wireless power transfer system for improving efficiency. Synchronization technology is critical for active rectifier. The hardware of traditional synchronization method is instability or the hardware is complex. In this paper, a new synchronization method is proposed for the WPT system, in which the resonant current zero crossing doesn't need to be detected. The proposed method can avoid the false trigger caused by the zero-cross detection in traditional synchronization methods. Finally, a 1kW experimental prototype is built to verify the validity of the proposed method. © 2022 IEEE.

Keyword ：

Electric rectifiers Energy transfer Inductive power transmission Rectifying circuits Synchronization

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Abstract ：

The protection of new energy power generation in the power system is gradually increasing, offshore wind power acts as an important part of new energy power generation has broad development prospects. And the submarine cables have also been widely used with the development of offshore wind power technology. The submarine cables are often laid under the sea, so the repairment and replacement of the submarine cables require lots of material costs, and the cables have a high failure rate, so it's of great significance to identify the fault location of cables. In this paper, the topology and control strategies of offshore wind power system are firstly introduced. Secondly, it analyzes the working principle of the distance method based on negative sequence control and infers the calculation formula of fault distance. The distance method can calculate the fault distance and judge the fault location by using the negative sequence component at both ends of the cable. The PSCAD/EMTDC simulation results verify the distance protection method can effectively identify whether the fault occurs in the submarine cables which provides a theoretical basis for the construction of the protection scheme of offshore wind power system. © 2022 IEEE.

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Abstract ：

As one of the most potential renewable energy systems, the offshore wind power has broad research prospects in the world. To ensure the safe operation of the grid, it is very important to study the adaptability of protection of the offshore wind power system. For this reason, in this article, the topology of offshore wind power system is introduced firstly. On this basis, the control strategy and the fault characteristics of the system are analyzed. Second, the protection principles of directional relay, phase selection relay, distance protection and pilot protection are deduced, and the adaptability of the above protections in offshore wind power system are analyzed according to combining the fault characteristics of the system and the protection principle. The PSCAD/EMTDC simulation results verify the effectiveness of the conclusion of the adaptability analysis, it can provide a theoretical basis for the construction of the protection scheme of offshore wind power system. © 2022 IEEE.

Keyword ：

Electric power system protection Offshore oil well production Wind power

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