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Electric vehicles have the advantages of zero emissions and high energy efficiency. They have a broad potential in today's social life, especially in China where they have been widely used. In the current situation, whereby the storage capacity of electric vehicles is continually increasing and the requirements for grid stability are getting higher and higher, V2G technology emerges to keep up with the times. Since the electric vehicle charging station is a large-scale electric vehicle cluster charging terminal, it is necessary to pay attention to the status and controllability of each charging pile. In view of the lack of attention to the actual operation of the electric vehicle charging station in the existing vehicle–network interaction mode, the charging state of the current electric vehicle charging station is fixed. In this paper, deep learning is used to establish a load perception model for electric vehicle charging stations, and K-means clustering is used to optimize the load perception model to realize random load perception and non-intrusive load monitoring stations for electric vehicle charging. The calculation example results show that the proposed method has good performance in the load perception and controllability evaluation of electric vehicle charging stations, and it provides a feasible solution for the practical realization of electric vehicle auxiliary response. [ABSTRACT FROM AUTHOR]

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Earlier calculations of geomagnetically induced currents (GICs) in Chinese power grids have mainly concentrated on the highest voltage-level system whose geomagnetic risk is considered to be the largest, thus ignoring secondary voltage-level systems. With the 1000-kV system being newly added to China's power system, it is significant to figure out the interaction between GIC in the 500 kV [extremely high voltage (EHV)] system and GIC in the 1000 kV [ultra-high voltage (UHV)] system. Based on the North China-Central China-East China Power Grids, this paper establishes a single-voltage grid by only considering the 1000-kV system and a dual-voltage grid by considering the 1000- and 500-kV systems and investigates GIC in these two grids by developing their GIC “Full-node models.” The impact of the 500-kV system on GIC in the 1000-kV system is analyzed. GIC risks in the UHV and EHV systems are assessed by comparing calculated GIC data with monitored values of GIC. The results show that the impact of the 500-kV system on GIC in the 1000-kV system is obvious, both the EHV and the UHV grid have a high GIC risk. So calculating GIC in the UHV system and in the EHV system should utilize GIC modeling methods for multivoltage power grids. [ABSTRACT FROM PUBLISHER]

The voltage sag problem in the distribution network seriously affects the charging quality of electric vehicles. Therefore, evaluating the impact of voltage sag on electric vehicle charging is crucial for the development of electric vehicles. However, existing researches based on simulation models or independent power battery design and testing experiments cannot accurately and reliably reflect the charging interference of voltage sag on electric vehicles. This paper proposes for the first time the issue of voltage sag in China's distribution network affecting electric vehicle charging, and designs test cases to test the performance of electric vehicle charging under four kinds of sag parameters, two models of Brilliance BMW electric vehicles, two different temperatures, three brands of charging piles, and two vehicles charging simultaneously on the same power grid. In addition, this paper proposes a comprehensive solution for analyzing the impact of voltage sag on electric vehicle charging. Finally, an evaluation method based on the attention mechanism and BIGRU network has been developed to evaluate the adverse effect of voltage sag on the charging current of electric vehicles, with an accuracy of about 96.01% and a operating time of 0.4s. The superiority of the proposed method was further verified through comparative experiments with five mainstream methods. • Proposes a solution for analyzing the impact of power quality on vehicle charging. • Develop a novel method to evaluate the effect of voltage sag on vehicle charging. • Design cases based on real scenarios and the characteristics of voltage sag in China. • Develop a RBA-Net framework based on Bi-GRU network and attention mechanism. • A preprocessing method suitable for electric vehicle charging data is proposed. [ABSTRACT FROM AUTHOR]

Current electric bus has become an important public transport for people in China, and its interior sound quality directly affects the driver's physical and mental health for a long working time and the comprehensive performance of the vehicle. Therefore, it is an inevitable and urgent trend to research electric bus interior sound quality. Aiming at the problem of subjective uncomfortable auditory sensation caused by different speeds, the noise signals near the driver's ears were collected under two constant speed conditions. On the basis of principle analysis of feed-forward adaptive control system, the primary and secondary path transfer functions were presented using Simulink module in MATLAB to construct three active noise control models for an electric bus based on least mean square (LMS), normalized LMS (NLMS) and filtered-x LMS (FxLMS). Numerical simulation results indicate that the established control models are convergent, and four acoustic parameters are effectively reduced after controls to achieve the effect of improving the sound quality. [ABSTRACT FROM AUTHOR]

This paper first introduces the development of arc suppression coil with automatic tracking and compensation (ATCASC) in China. Then the authors give different classification of the ATCASC, and describe in detail the configuration, the main advantages and disadvantages of each ATCASC. Finally the common problem that the current ATCASC cannot compensate for the active component and harmonic component of the single-phase-to-ground fault current is pointed out. Based on this, the authors indicate that the "zero residual current ASC" will be a new research direction of the neutral point grounding methods and the ATCASC in China. [ABSTRACT FROM AUTHOR]

After we developed a saturated iron core type 35 kV/90 MVA superconductive fault current limiter and installed the device in a transmission network at Puji substation of China Southern Power Grid for live-grid operation in 2007, we continued our efforts in advancing this technology. A 220 kV/300 MVA device has been designed, manufactured and factory tested. This device differs from the 35 kV device in its form of electrical insulation even though the two devices have the same working principle and similar core structure. Improvements in the dc magnetization circuit and the cryogenic system were also achieved. This 220 kV/300 MVA superconductive fault current limiter has been installed and has passed all field tests at Shigezhuang substation in Tianjin, China. Trial operation is underway. This paper introduces the major design parameters, key functional specifications and some testing results of the device. [ABSTRACT FROM AUTHOR]

For the superconducting magnet system of the International Thermonuclear Experimental Reactor, ITER, 60 current leads for a total current of more than 2500 kA are needed. The use of High Temperature Superconductor current leads (HTS-CL) will reduce the resultant large refrigerator load considerably. Within the EU Fusion Technology Programme, the Forschungszentrum Karlsruhe and CRPP have developed and built a 70 kA HTS-CL demonstrator optimized for 50 K Helium operation. In 2004-2005, the CL was successfully tested with 50 K as well as 80 K Helium, and finally with LN2. In the meantime, ITER has decided to use HTS-CLs for the magnet system and China has taken the responsibility to provide the sc feeders for ITER including the current leads. In this paper, the performance of a 70 kA HTS-CL in fault conditions will be analysed using the FZK-CRPP demonstrator as a model. In particular, the quench performance and the safety behavior in case of a loss-of-flow accident (LOFA) will be described and an extrapolation of the leads performance in real ITER conditions will be given. Finally the effect of different shunt materials is discussed. [ABSTRACT FROM AUTHOR]

The significant progresses in high Tc superconducting wires or tapes have excited a great deal of research interests in power application. This paper will review the recent progresses of power application of superconductor in China. An improved bridge-type fault current limiter was tested and a 10.5 kV/1.5 kA demonstrator has been operated at a substation in Hunan Province in 2005. A 75 meter, 10.5 kV/1.5 kA three phase HTS cable has been installed and operated at the Changtong Cable Headquarter in the end of 2004, and a 30 meter, 35 kV/2 kA HTS power cable was installed at substation and has been operated since July 2004. A 10.5 kV/400 V/630 kVA HTS transformer has been installed and operated at TBEA Electric Factory in 2005. A 500 k J/150 kVA SMES unit was developed and tested. 1.0 M J/0.5 MW SMES will be installed in a power grid in 2006. Besides, a new kind equipment of fault-current-limiting SMES is being developed and a 100 kJ/25 kW prototype has been made and tested. [ABSTRACT FROM AUTHOR]

With the development of the electric vehicle industry, electric vehicles have provided more choices for people. However, the performance of electric vehicles needs improvement, which makes most consumers take a wait-and-see attitude. Therefore, finding a method that can effectively improve the performance of electric vehicles is of great significance. To improve the current performance of electric vehicles, a convex optimization algorithm is proposed to optimize the motor model and power battery parameters of electric vehicles, improving the overall performance of electric vehicles. The performance of the proposed convex optimization algorithm, dual loop DP optimization algorithm, and nonlinear optimization algorithm is compared. The results show that the hydrogen consumption of electric vehicles optimized by the convex optimization algorithm is 95.364 g. This consumption is lower than 98.165 g of the DCDP optimization algorithm and 105.236 g of the nonlinear optimization algorithm before optimization. It is also significantly better than the 125.59 g of electric vehicles before optimization. The calculation time of the convex optimization algorithm optimization is 4.9 s, which is lower than the DCDP optimization algorithm and nonlinear optimization algorithm. The above results indicate that convex optimization algorithms have better optimization performance. After optimizing the power battery using a convex optimization algorithm, the overall performance of electric vehicles is higher. Therefore, this method can effectively improve the performance of current electric vehicle power batteries, make new energy vehicles develop rapidly, and improve the increasingly serious environmental pollution and energy crisis in China. [ABSTRACT FROM AUTHOR]

Development of renewable power generation systems (RPGSs) is continually increasing worldwide with Germany, China, Japan, Italy and the USA are the leaders contributing to the largest development in each region. Due to the increasing number of RPGSs connected to the utility grid, power quality, safe operation, and islanding protection of RPGSs are becoming important issues, among others. One of the most important elements is the current control technique that must meet the requirements for grid interconnection according to international standards and practices. The RPGS itself must be safe and highly efficient for reliable and secure grid interconnection operations. This paper presents a review of the state-of-the-art of the current control techniques for three-phase grid-interconnection of RPGSs. Several current control architectures, their operations including advantages and disadvantages were discussed. Performance comparison and evaluation of several controllers were also reviewed. [ABSTRACT FROM AUTHOR]

Bicycle-sharing plays an important role in solving the "last mile" problem of Chinese people and promoting the construction of an environment-friendly society. This study assesses the carbon emissions generated in the life cycle of bicycle-sharing, examines the substitution effect of bicycle-sharing, and quantifies the depletion rate of bicycle-sharing in combination with the current rate of electric vehicles in China. The depletion rate of shared bicycles in China is high, roughly 5–15% per year. In addition, we discuss scenarios where the annual growth rate of electric vehicles is 40%, 50%, and 60%. Results show that when electric vehicles' depletion rate is 5% and the annual growth rate of electric vehicles is 40%, the largest net emission reduction in 2025 is 1.96 million tons. Additionally, when electric vehicles' depletion rate is 5% and the annual growth rate of electric vehicles is 60%, the smallest net emission reduction totals 1.7 million tons. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes the overcurrent tests that were conducted on a copper wire used in ordinary life in China (AC 220V). These tests were conducted to evaluate the fire potential that may result from overcurrent faults. Results of these tests showed that the typical appearances of overcurrent fault could be divided into three steps, i.e. smoking, redness and breakdown etc. It also showed that the beginning time of smoking, redness and breakdown decreased as the power of the electrical applications increasing. After a person can find the overcurrent fault by seeing the smoke formed by the eroding of the insulation, a fire may begin in 4s to 7s. [Copyright &y& Elsevier]

Abstract: Hainan province is the only tropical and island province in China, with the unique climatic and geographical features. It has a different energy performance in public buildings from those in the inland areas. This paper investigated the current situation of energy consumption of the sampled public buildings, including 26 hotels, 24 office buildings and 7 department stores, through analyzing utility billing data, on-site survey and measurement, and site operational records. The breakdowns of energy consumption found out that the electricity dominated the energy consumption for all the sampled buildings and the air conditioning system played a key role in the energy consumption of major building services. By analyzing the main factors for building energy consumption, the annual average energy use indexes were calculated to be 141.63kWh/m2, 87.70kWh/m2, and 166.95kWh/m2 for hotels, office buildings and department stores, respectively. Besides, the comparison between Hainan province and other areas revealed that the building energy consumption of this tropical province was at a low level. Because indoor environment quality can influence the health and work efficiency of humans in buildings, field tests on the indoor environment quality were also carried out, and the performance of indoor environment quality was rated. [Copyright &y& Elsevier]

Abstract: This paper uses principal component analysis (PCA) to determine the spatial pattern of total electron content (TEC) anomalies in the ionosphere post the China’s Wenchuan Earthquake of 12 May, 2008 (UTC) (Mw =7.9). PCA and image processing are applied to the global ionospheric map (GIM) with transforms conducted for the time period 08:00–10:00UT on 12 May 2008. Results show that at a height of approximately 200km the anomaly is widespread and less intense; however, it becomes more localized with height reaching maximum intensity and localization at an altitude of 300km. The spatial distribution is remarkably similar to that reported for a TEC anomaly previously identified as a precursor anomaly on May 9, 2008 for the same time period. Potential causes of the results are discussed with emphasis given to vertical acoustic gravity waves based on the spatial pattern identified. [Copyright &y& Elsevier]

The vibration and friction triggered by the long-term operation of stacker inevitably lead to the damage problem of stacker’s track. In order to ensure the stable operation of the stacker, a novel scheme is proposed to address an accurate damage localization problem of the stacker’s track in industrial environment based on ensemble empirical mode decomposition-empirical mode decomposition (EEMD-EMD) and density-based spatial clustering of applications with noise (DBSCAN). First, the original electric current signal with unbalanced distribution is processed by fixed-interval smoothing and cubic Hermite interpolation algorithms. Second, the EEMD-EMD method, which solves the mode-mixing problem, is adopted to decompose the preprocessed signal into well-defined intrinsic mode functions (IMFs). Third, based on Hilbert–Huang transform (HHT) of the IMFs, the preprocessed signal and the difference of average instantaneous amplitudes in two adjacent time points are considered as the 2-D feature vector input of the DBSCAN algorithm. As such, damage locations of the stacker’s track are detected by means of the outliers that are obtained by the DBSCAN algorithm. The efficiency of the proposed localization scheme and its superiority over the existing cooperative damage localization methods, namely, the box-plot method, the pulse coupling neural network (PCNN) and wavelet transform (WT) theory method, and the box-plot and WT method, are verified through experiments using the data provided by State Grid Measuring Center of China. [ABSTRACT FROM AUTHOR]

We developed a saturated iron-core type 35 kV/90 MVA superconductive fault current limiter and installed the device in a transmission network at Puji substation of China Southern Power Grid for live-grid operation. Innovative design in the iron-core configuration ensures that 'the device has low, impedance in normal power transmission and sufficiently high impedance for a fault current limiting action. A magnetization control circuit allows the iron-core to be saturated or de-saturated depending upon the functional requirements. An energy release and voltage-surge protection unit can promptly discharge the magnetic energy accumulated in the iron-core and suppress the induced and surge voltages of the dc circuit in a current limiting event. This device has been designed to reduce the magnitude of a fault current by about 50%, which will prevent the breaking capacity of the existing circuit breakers in the transmission network from being exceeded in the predictable future. This article presents structural and functional specifications and reports up-to-date live-grid operation data of the device. [ABSTRACT FROM AUTHOR]

Depletion of fossil fuel deposits is the main current issue related to the world's power generation. Renewable energy sources integrated with energy efficiency represent an effective solution. The electrification of end-use coupled with renewable power generation integration is considered as an important tool to achieve these tasks. However, the current electric power system does not currently have the suitable features to allow this change. Therefore, in the future, it has to allow two-way direction power flows, communication, and automated controls to fully manage the system and customers. The resulting system is defined as the smart grid. This article analyses the smart grid state of play within China, the US, and the EU, assessing the completion state of each smart grid technology and integrated asset. The analysis related to these countries presented here shows that the smart grid overall state of play in China, the US, and the EU are equal to 18%, 15%, and 13%, respectively, unveiling the need related to further efforts and investments in these countries for the full smart grid development. [ABSTRACT FROM AUTHOR]

Superconducting Fault Current Limiter (SFCL) is an attractive appliance for modern electrical power system. A 10.5 kV/1.5 kA three-phase HTS fault current limiter was developed by IEE, CAS. This improved rectifier-type SFCL with HTS coil of 6.25 mH is going on a demonstrated long-term reliable operation in a real 10.5 kV substation located in Hunan, China. In a three-phase-to-ground short circuit test of grid, the prospective fault current of 3.5 kA was limited to 635 A at the pre-setup short-circuit point successfully. [ABSTRACT FROM AUTHOR]