In order to enable the permanent magnet synchronous generator (PMSG)-based wind turbine (WT) to capture more wind energy while providing fast frequency supports effectively during disturbances, this paper proposes a time-sharing frequency coordinated control (TFCC) strategy. Firstly, a rotor virtual inertia control and a DC-link virtual inertia control are presented, and a new adaptive frequency droop control considering frequency deviation is proposed. Secondly, a novel TFCC strategy, which uses the frequency dead-band to coordinate the frequency regulation priority of above three controls, is proposed. With the proposed strategy, the electrostatic energy stored in the DC capacitor is always first utilized for frequency support, while the rotor rotational kinetic energy is only applied when the DC capacitor energy is used up. Finally, the control performance is studied in PSCAD/EMTDC, whose results indicate that the TFCC has better performance in terms of wind energy harvesting and system stability as compared to traditional coordinated control and cascading control, respectively.

Against the crippling assault of power grid, the impact of cyber attack on line-commutated converters based high voltage direct current (LCC-HVDC) system is investigated in this paper when the false data injection (FDI) attacks its control loops. Based on the basic control strategy of LCC-HVDC, the impact on each HVDC control mode is investigated when FDI occurs, including the rectifier side constant DC current control and supplementary damping control, the inverter side constant DC voltage control and constant extinction control. Through the theoretical analysis, it is found that the rectifier side FDI attack would limit the power transmission and increase HVDC’s reactive power demand, which will finally lead to instabilities, where the damping ratio could also be decreased if the rectifier supplementary damping control is attacked. Another important fact is that the inverter side attack could have much more severe impact when the false data is injected because the inverter extinction angle may be decreased and causes commutation failures. The above analysis and conclusions are validated by the simulations finally.

China is taking initiative in energy transition to cope with the long-term controversy of its enormous energy consumption, aiming to use less carbon. Wind power, especially offshore wind energy, has become a prevailing alternative due to its low carbon emissions, renewability, competitiveness, and operation security. The layout of a transmission channel is a key consideration in marine project implementation. This paper investigates the technical characteristics, application status, and viable advantages of a conventional AC transmission, voltage source converter-based high-voltage direct current (VSC-HVDC) transmission, gas-insulated line (GIL) transmission, and hybrid HVDC transmission. A component-resolved evaluation model was proposed to estimate the costs to be incurred of four electrical transmission options for offshore wind power along the coast of Eastern China, with technical feasibility and economical considerations. Cost comparisons and component sensitivity analyses were developed with different transmission distances and capacities. Results suggest HVAC transmission and VSC-HVDC are the preferable solutions for present offshore wind farm development in Eastern China, and the economic potential of the hybrid HVDC makes it feasible for future deployment. Some conclusions can be applied in disparate regions across the globe.

The ultra‐low‐frequency oscillation (ULFO) problem reappears in China recently, but its specific mechanism is not so clear. Although the hydraulic governor system is confirmed as the source of ULFO, the parameters’ impacts are not studied thoroughly. This study investigates the specific impact of the important parameter of governing system in different control modes based on the complex coefficient torque method including the parameters of regulator, actuator and the turbine in hydraulic governing system. The damping torques under different situations are illustrated when parameters and control modes change, and the ultra‐low‐frequency‐band dynamic characteristics of hydro generator are obtained. The simulations match well with the theoretical analysis, and the suggestions are made for parameter settings at last. The findings of this study are significant for ultra‐LFO elimination. Moreover, it can also help designers and operator identify the most influential parameters and develop effective control strategies.

Battery impedance contains valuable information concerning state estimation and fault diagnosis, while online impedance measurements attract increasing research interest. The Pseudo Random Sequence (PRS) signal enables a fast and low-complexity impedance measurement for Lithium-ion (Li-ion) batteries yet with the drawback of an inadequate Signal-to-Noise Ratio (SNR) that easily leads to a biased result, while very few studies have existed to process the non-uniformly distributed impedance data with large biases. Motivated by this, this work proposes a novel Measurement Evaluating Procedure (MEP) and a 2-Dimensional Gaussian Filter (2-DGF) for enhancing the performance of the PRS method. The MEP weights the impedance measurement data based on the signal power spectrum and determines the Gaussian Probability Distributions (GPDs) of the impedance data to eliminate interference from the abnormal data. The 2-DGF is further carried out on a semi-logarithmic scale to process the non-uniform impedance measurements, which avoids constantly adjusting the filtering windows. Experimental studies validate the proposed method under the different States of Charges (SOCs) and ambient temperatures. The results present the good accuracy and robustness of the proposed method under different cases.