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International Conference on High Voltage Engineering and Application, ICHVE

作者： Jiawen Zhou Wenxiu Gong Qingquan Li Hongru Zhang Bin An Mu Qiao Shandong Provincial Key Laboratory of UHV Transmission Technology and Equipment Shandong University Jinan China State Grid Shandong Electric Power Company Maintenance Company State Grid Shandong Electric Power Company Jinan China

ISBN: (数字)9781728155111

ISBN: (纸本)9781728155128

Oil paper insulation is the main insulation form of large transformers. Partial discharge(PD) in oil paper insulation will not only damage the insulation performance, but also is the precursor and manifestation of insulation deterioration. Weibull distribution parameter is an important characteristic parameter of PD. In this paper a method is proposed to extract the characteristic parameter of PD based on the three-parameter Weibull model, then gray wolf optimization algorithm and particle swarm optimization algorithm are used to calculate the parameters of the model. The result shows that the two algorithms can get the parameters quickly and accurately, and the model can effectively reflect the characteristics of the Hn(q) spectrum of PD times.

关键词： Partial discharges Discharges (electric) Optimization Weibull distribution Oils Particle swarm optimization power transformer insulation

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Partial Discharge Denoising Method Based on Improved Wavelet Threshold Optimized by Double Chain Quantum Genetic Algorithm

Partial Discharge Denoising Method Based on Improved Wavelet...

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International Conference on High Voltage Engineering and Application, ICHVE

作者： Mu Qiao Hongwei Wang Jianping Jiang Chao Li Wenxiu Gong Qingquan Li State Grid Shandong Electric Power Company Maintenance Company State Grid Shandong Electric Power Company Jinan China Shandong Provincial Key Laboratory of UHV Transmission Technology and Equipment Shandong University Jinan China

ISBN: (数字)9781728155111

ISBN: (纸本)9781728155128

Aiming at the problem of PD signal noise suppression, a new PD denoising method based on the improved wavelet threshold optimized by double chain quantum genetic algorithm is proposed. Based on the traditional wavelet thresholding method, a new thresholding function with adjusting factors α and β is constructed, and the adjusting factors α and β are optimized by double chain quantum genetic algorithm, so that the adjusting factors under different decomposition scales can be determined quickly and accurately, and the adaptive thresholding can be realized. Through the denoising of PD simulation signals and on-site detection signal, and compared with the soft threshold and hard threshold denoising algorithm, the results show that the algorithm has the best evaluation index of denoising effect, and can effectively denoise the white noise and narrow-band interference of PD signals. The denoising results have high accuracy and better retain the original characteristics of PD signals, which has practical application value.

关键词： Noise reduction Partial discharges Signal processing algorithms Companies Statistics Sociology Wavelet coefficients

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Influence of Unbalanced Secondary Burden on Voltage Error of Voltage Transformers in Distribution power System

Influence of Unbalanced Secondary Burden on Voltage Error of...

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IEEE Asia power and Energy Engineering Conference (APEEC)

作者： Liu Gang Qin Jian Liu Kun Ai Bing Zhang Jiefu He Na Hao Jian State Grid Sichuan electric power corporation metering canter Sichuan Power Grid Co. Ltd Chengdu China State Key Laboratory of Power Transmission Equipment & System Security and New Technology Chongqing University Chongqing China

ISBN: (数字)9781728167824

ISBN: (纸本)9781728167831

Voltage errors of three voltage transformers in three-phase four-line metering devices in ungrounded distribution power system are interrelate with each other, however, the error characteristics of each voltage transformer under unbalanced secondary burdens have scarcely been studied. In this paper, three-phase three-element combined transformer is taken as an example to analyze the influence of unbalanced secondary burdens on voltage errors of its three voltage transformers. Firstly, equivalent circuit of the three voltage transformers taken as a whole is established, and then voltage error is analyzed theoretically and tested to verify the validity of theoretical analysis. Results show that the change of the secondary burden of voltage transformer will results in the error of each voltage transformer changing linearly when the secondary burdens of two other voltage transformers remain unchanged, the primary current has some influence on the error of voltage transformer, however, the influence is much smaller compared with the influence of unbalanced secondary burdens on voltage error, the characteristics that unbalanced secondary burdens have a great influence on voltage errors can be utilized to optimize the power metering error of electric energy metering device.

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Comparative Study on Driving Switching Characteristics of GaN-FET and SiC-MOSFET in Transient High Voltage Pulse Discharge Circuit

Comparative Study on Driving Switching Characteristics of Ga...

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International Conference on High Voltage Engineering and Application, ICHVE

作者： Yingying Chen Jie Du Ling Feng Ji Xiao Jiaming Zhang Yingjiang He State Grid Chongqing Electric Power Company Chongqing China Chongqing University State Key Laboratory of Power Transmission Equipment & System Security and New Technology Chongqing China

ISBN: (数字)9781728155111

ISBN: (纸本)9781728155128

As a new type of wide band gap semiconductor device, GaN-FET has faster switching speed and higher power density than SiC-MOSFET. It has a good application prospect in the field of pulse power technology. Aiming at the effect of gate driving circuit (mainly gate on-resistance and off-resistance, gate-source capacitance and driving voltage) on the switching behavior of semiconductor devices, this paper designs a pulse discharge test circuit to build a GaN-FET switching process. The circuit model uses a mathematical model to analyze the typical characteristics of GaN-FET switching behavior. And using SiC-MOSFET with similar parameters in the data sheet for comparative experiments, revealing the difference in switching characteristics of the two semiconductor devices in the transient pulse loop based on driving regulation. It can provide reference for driving design of GaN-FET in high voltage pulse generator. In addition, based on the results of comparative experiments, the driving parameters are designed to build a 4-level Marx generator experimental prototype with GaN-FET and SiC-MOSFET as the main switches. It has been preliminarily verified that GaN-FET can generate faster leading-edge high-voltage nanosecond pulses and have greater stability at high repetition rates.

关键词： Silicon Logic gates Switches Capacitance Gallium nitride Transient analysis Discharges (electric)

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A framework for stochastic estimation of electric vehicle charging behavior for risk assessment of distribution networks

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Frontiers in Energy 2020年第2期14卷 298-317页

作者： Salman HABIB Muhammad Mansoor KHAN Farukh ABBAS Muhammad NUMAN Yaqoob ALI Houjun TANG Xuhui YAN Key Laboratory of Control of Power Transmission and Transformation of the Ministry of Education School of ElectronicInformation and Electrical EngineeringShanghai Jiao Tong UniversityShanghai 200240China Department of Electrical Engineering University of Engineering and TechnologyLahore 54890Pakistan State Grid Liyang Power Supply Company Liyang 213300China

power systems are being transformed to enhance the *** paper contributes to the knowledge regarding the operational process of future power networks by developing a realistic and stochastic charging model of electric vehicles(EVs).Large-scale integration of EVs into residential distribution networks(RDNs)is an evolving issue of paramount significance for utility *** voltages prevent effective and reliable operation of *** EV loads require a stochastic approach to predict EVs charging demand,consequently,a probabilistic model is developed to account several realistic aspects comprising charging time,battery capacity,driving mileage,state-of-charge,traveling frequency,charging power,and time-of-use mechanism under peak and off-peak charging *** attempt is made to examine risks associated with RDNs by applying a stochastic model of EVs charging *** output of EV stochastic model obtained from Monte-Carlo simulations is utilized to evaluate the power quality parameters of *** equipment capability of RDNs must be evaluated to determine the potential *** specifications of RDNs including voltage unbalance factor,voltage behavior,domestic transformer limits and feeder losses are assessed in context to EV charging scenarios with various charging power levels at different penetration ***,the impact assessment of EVs on RDNs is found to majorly rely on the type and location of a power network.

关键词： electric vehicles(EVs) residential distribution networks(RDNs) voltage unbalance factor(VUF) state-of charge(SOC) time-of-use(TOU)

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Research on the Optimal Economic Dispatching of Micro-grid with Hybrid Energy Storage

Research on the Optimal Economic Dispatching of Micro-grid w...

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2019 IEEE PES Innovative smart grid Technologies Asia, ISGT 2019

作者： Yu, Changqing Li, Chunyan Zhao, Chenyu Cai, Wenyue Wen, Lili Fan, Xuan State Key Laboratory of Power Transmission Equipment System Security and New Technology Chongqing University Chongqing China State Grid Xiamen Electric Power Supply Company Xiamen China State Grid Chongqing Economic Research Institute Chongqing China

ISBN: (纸本)9781728135205

An optimal economic dispatching model of micro-grid is established by considering the life loss cost of hybrid energy storage system, which can overcome the difficulty on charging and discharging with high frequency and different depths for single energy storage system. First, the basic filter control strategy is used to optimize the power and energy distribution between supercapacitors and lithium batteries based on the steady-state analysis model of hybrid energy storage system. Then, the life loss cost of hybrid energy storage system is determined by the times and depth of charging and discharging cycles using Rain Flow Counting Method. Finally, the economic dispatching model of micro-grid with hybrid energy storage system is established and solved by applying an improved particle swarm optimization algorithm based on natural selection. The simulation results show that the operation cost of micro-grid with hybrid energy storage system can be reduced compared with the single energy storage system. Moreover, the filter control strategy can effectively reduce the charging and discharging times of batteries and the operation cost. © 2019 IEEE.

关键词： Lithium batteries

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Bi-level Expansion Planning Method for Active Distribution Network Considering Dynamic Network Reconfiguration

Bi-level Expansion Planning Method for Active Distribution N...

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2019 IEEE Sustainable power and Energy Conference, iSPEC 2019

作者： Zhang, Liang Pan, Xuedong Zhao, Haoran Xu, Jing Li, Juan Xu, Zhengyang State Grid Tianjin Electric Power Company Economic Technology Research Institute Tianjin China Construction Company State Grid Tianjin Electric Power Company Tianjin China Tianjin University Key Laboratory of Smart Grid Ministry of Education Tianjin China

ISBN: (纸本)9781728149301

In order to study the expansion planning problem of distribution network with the active distribution network control technology, considering the flexible grid structure of active distribution network, a bi-level model of active distribution network expansion planning is established. Firstly, the main process framework of active distribution network expansion planning is considered, and the mathematical model of active distribution network bi-level expansion planning is constructed. In the model, the planning layer aims at the lowest annual comprehensive cost of distribution network, and the operational layer is targeted at the maximum amount of distributed power consumption. The effect of dynamic reconfiguration of the distribution network structure on the operation of the distribution network is transformed into the operation layer model, and the impact of the operational layer on the planning phase is simulated and quantified. Then, in the process of model solving, the algorithm of 'avoid circle' based on graph theory improves the grid coding of distribution network and improves the probability of generating feasible solutions. The model is solved by using the genetic algorithm and decimal integer the particle swarm algorithm. Finally, taking an actual distribution network in a city as a case, the rationality and validity of the model are verified. © 2019 IEEE.

关键词： Distributed power generation

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Study on Change Rule of Metering Performance of Three-wire and Four-wire powerMetering Device Under Different Single-Phase Ground Fault

Study on Change Rule of Metering Performance of Three-wire a...

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power and Electrical Engineering (ACPEE), 5th Asia Conference on

作者： Kun Liu Bing Ai Ping Yan Juan Hu Gang Liu Jian Hao State Grid Sichuan electric power corporation metering canter Chengdu China State Grid Sichuan Electric Power Maintenance Company Chengdu China State Key Laboratory of Power Transmission Equipment & System Security and New Technology Chongqing University Chongqing China

ISBN: (数字)9781728152813

ISBN: (纸本)9781728152820

Under the background of power interconnection, the accurate measurement of power metering device plays an important role in the lean management of distribution network line loss and the economic benefits of both power suppliers and power consumers. In this paper, the accuracy of electric energy measurement under single-phase ground fault was studied. Meanwhile, a 10 kV distribution network single-phase ground fault test platform was built to analyze the measurement performance changes of three-wire and four-wire power metering device under different single-phase ground fault types. The research results reveal that the single-phase ground fault does not affect the error of voltage transformer. On the power supply side, the power metering device PT adopts the V/v wiring mode, which would cause the energy metering inaccuracy under a single-phase ground fault. In addition, for the unground neutral system, the three-phase and three-wire connection can keep accurate measurement performance. However, for the ground system with neutral point passing through arc suppression coil, there may be measurement error in three-phase and three-wire power metering device.

关键词：

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Small Signal Stability Analysis and Control Optimization of Y-connected Modular Multilevel Converter for Fractional Frequency Offshore Wind power Application 8

Small Signal Stability Analysis and Control Optimization of ...

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8th IEEE International Conference on advanced power System Automation and Protection, APAP 2019

作者： Jia, Feng Meng, Yongqing Yu, Jianyang Yan, Shuhao Ye, Rong Tang, Yuchen Xi'an Jiaotong University Shannxi Key Laboratory of Smart Grid Xi'an China State Grid Fujian Electric Power Company Research Institute of Economics and Technology Fuzhou China

ISBN: (纸本)9781728117225

Y-connected modular multilevel converter(Y-MMC) is a new circuit topology of direct AC/AC power conversion, with competitive application prospects in fractional frequency offshore wind power system. Different from the previous converter topology, Y-MMC realizes the frequency conversion by single-phase voltage cancellation. Simultaneously, the voltages between main bridges and auxiliary bridges can be determined by the reactive power distribution coefficients. Considering the frequency leakage problem, this paper proposes the new mathematical model of Y-MMC and builds corresponding control strategy. Then, the state equation of the system and its small-signal models are established, the small distribution stability is analyzed. Furthermore, to improve the stability and dynamic performance of the closed-loop control system, the parameters of controller are optimized based on the particle swarm optimization algorithm. Finally, the effectiveness and superiority of the proposed control strategies are verified by simulation results. © 2019 IEEE.

关键词： Reactive power

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Fast Probabilistic Optimal power Flow Based on Modified Multi-Parametric Programming

Fast Probabilistic Optimal Power Flow Based on Modified Mult...

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International Conference on Probabilistic Methods Applied to power Systems (PMAPS)

作者： Wei Lin Juan Yu Zhifang Yang Xuebin Wang State Key Laboratory of Power Transmission Equipment & System Security and New Technology College of Electrical Engineering Chongqing University State Grid Qinghai Electric Power Company Xining China

ISBN: (数字)9781728128221

ISBN: (纸本)9781728128238

With the rapid increase of renewables and power demands, probabilistic optimal power flow (POPF) has become an important tool to investigate the stochastic characteristics of power systems. However, the POPF calculation requires repeatedly solving a tremendous number of optimization problems. The computational burden has been the main bottleneck for its practical applications. To overcome this problem, this paper adopts a linear OPF model with reactive power and voltage magnitude to construct the optimization model for samples. Then, a modified multi-parametric programming process is introduced to fast calculate the optimal solutions of samples by avoiding the iterative optimization process. Compared with the traditional multi-programming process, the reduced affine maps between the sample optimization solutions and the stochastic variables are explicitly formulated while keeping the desired accuracy. The IEEE 30-bus and 118-bus systems are used to demonstrate the effectiveness of the proposed method.

关键词： Programming Reactive power Optimization Computational modeling Stochastic processes Probabilistic logic Load flow

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