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XLPE cable health assessment based on Relief-F feature weighted FSVM

IOP Conference Series: Earth and Environmental Science 2021年第1期675卷

作者： Xiaohuan Wu Yang Liu Liqun Wang Xinzhuo Ren Xianjun Tan Hangzhou Power Equipment Manufacturing Co. Ltd. Hangzhou 310018 China Key Laboratory of Modern Power System Simulation and Control & Renewable Energy Technology Ministry of Education(Northeast Electric Power University) Jilin 132012 China

For the cross-linked polyethylene (XLPE) cable health status assessment process, there are noise data for each feature parameter and the importance of each dimension feature is difficult to determine, which leads to deviations in the cable status assessment results. An XLPE cable health assessment algorithm based on Relief-F feature weighted fuzzy support vector machine is proposed. The Relief-F algorithm is used to calculate the importance of each dimension feature. The feature quantity that is weakly related to the evaluation of the health status of the XLPE cable is deleted. Furthermore, the fuzzy support vector machine is used to evaluate the health status of the XLPE cable, which gives the noise data a smaller degree of membership and reduces the influence of the noise data on the evaluation results. Experimental analysis shows that this method can accurately assess the health status of XLPE cables. It can provide a reference value for relevant departments to carry out cable maintenance and replacement work and save the human resources, and material resources required for maintenance and replacement of cables.

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Prediction of dissolved gas in power transformer oil based on LSTM-GA

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IOP Conference Series: Earth and Environmental Science 2021年第1期675卷

作者： Xin Zhang Shengyuan Wang Yijun Jiang Feifei Wu Chenming Sun Hangzhou Power Equipment Manufacturing Co. Ltd. Hangzhou 310018 China Key Laboratory of Modern Power System Simulation and Control & Renewable Energy Technology Ministry of Education(Northeast Electric Power University) Jilin 132012 China

Because the change process of the content of dissolved gas in transformer oil is fluctuating and is affected by many factors such as oil temperature and external environment, the gas content does not increase exponentially and is nonlinear and non-stationary. This feature determines the current Prediction technology cannot accurately predict the concentration of dissolved gas in transformer oil. To improve the prediction accuracy of the dissolved gas content in the transformer oil, more accurately evaluate the transformer status and customize the entire preventive plan under the alarming development trend of the transformer, to minimize the prediction error, this paper proposes a transformer combining genetic algorithm and long short-term memory (LSTM)neural network Prediction model of dissolved gas content in oil. The genetic algorithm (GA) is used to optimize look back(lb), lstm nets(ls), epochs(ep), and the dropout(dp), and then the genetic algorithm is combined with the long short-term memory neural network. The gas content is predicted. This model overcomes the problem of low prediction accuracy caused by selecting parameters based on experience. The analysis result of the calculation example shows that compared with the traditional prediction algorithm, the proposed method can better track the change law of the dissolved gas concentration in the oil, improve the prediction accuracy, and provide a strong guarantee for the safe and stable operation of power transformers.

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A review of bearing fault diagnosis for wind turbines

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IOP Conference Series: Earth and Environmental Science 2021年第1期675卷

作者： Bing Liu Baixin Liu Qingbin Dai Huaping Liu AnHui JEP New Energy Co LTD AnHui 230000 China Key Laboratory of Modern Power System Simulation and Control & Renewable Energy Technology Ministry of Education (Northeast Electric Power University) Jilin 132012 China

Bearings are the core components of the wind turbine's mechanical transmission system, but the bearings of wind turbines are prone to wear and failure during vibration, and it is often difficult to determine the fault-bearing status and fault location. Therefore, the monitoring and fault diagnosis of wind turbine bearing status are very necessary. This paper introduces the types of bearings of wind turbines and common faults of bearings, analyzes from the aspects of bearing vibration data and supervisory control and data acquisition (SCADA) systems, summarizes the existing fault diagnosis methods and systems of wind turbine bearings, and points out the basics of these methods thought. Finally, the research focus of future bearing fault diagnosis is elaborated.

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Research on buffer circuit suitable for solid state DC circuit breaker

Research on buffer circuit suitable for solid state DC circu...

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The 16th IET International Conference on AC and DC power Transmission (ACDC 2020)

作者： W. Xie F. Xiao B. Liu R. Zeng W. Li L. Qu Z. Song Shandong Taikai High-Voltage Switchgear Co. Ltd. Tai’an China Tsinghua University State Key Laboratory of Control and Simulation of Power System and Generation Equipment (Department of Electrical Engineering Beijing China

Buffer circuit is one of the important parts to ensure the safe and reliable fault current breaking of the solid-state DC circuit breaker. Therefore, this paper conducts a research on the buffer circuit suitable for solid-state DC circuit breaker. Firstly, a low-loss solid state DC circuit breaker topology is proposed to meet the fault protection requirements of DC distribution network. Then, the circuit model of the breaking process of solid-state DC circuit breaker is established, and the calculation expression of transient current is deduced. Furthermore, the influence of the buffer circuit parameters on the current breaking characteristic of the solid-state DC circuit breaker is analysed. Finally, the feasibility of the design parameters of buffer circuit is verified by experiments, which lays the foundation for the development of solid-state DC circuit breaker.

关键词： circuit breakers fault currents DC distribution systems buffer circuits power distribution reliability

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Dynamic Security Assessment Method of power system Based on Improved XGBoost

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Journal of Physics: Conference Series 2021年第1期1750卷

作者： Jihong Ren Key Laboratory of Modern Power System Simulation and Control and Renewable Energy Technology Ministry of Education Northeast Electric Power University Jilin Jilin132012 China Department of Electrical Engineering Northeast Electric Power University Jilin Jilin 132012 China

With the deployment of wide-area measurement systems (WAMS) equipment, dynamic security assessment (DSA) based on artificial intelligence (AI) has more and more advantages. For the power system, the number of transient stable cases is much larger than that of unstable cases, which leads to insufficient learning of unstable cases and affects the evaluation effect of the model. In addition, during the stability assessment process of the power system, the misjudgment cost of unstable case is much higher than that of stable case. Based on the above two points, we proposed a DSA method of power system based on improved XGBoost. The proposed method introduces the weight adjustment factor into the loss function to balance the quantity variance of two type cases and the difference of misjudgment cost, which greatly reduces the misjudgment rate of unstable samples. The test results on IEEE 16-machine 68-bus test system and IEEE 50-machine 145-bus test system show that the proposed method can have higher recognition of the unstable samples and can be applied to DSA.

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Research on Aggregation Model of Wind Farm Based on SSO Complex Torque Coefficient Analysis

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Journal of Physics: Conference Series 2021年第1期1754卷

作者： SU Xunwen CUI Hanqing PEI Yuming ZHANG Dongni AN Pengyu Laboratory of Modern Power System Simulation and Control & Renewable Energy Technology Ministry of Education Northeast Electric Power University Jilin China School of Electrical & Control Engineering Heilongjiang University of Science & Technology Harbin Heilongjiang China

In order to study the influence of the clustering aggregation of doubly-fed wind turbines (DFIG) in the wind-fire bundling system on the system subsynchronous oscillation (SSO), the expression of the DFIG output active power on the electrical damping De of thermal power units is first derived. Then the wind-thermal bundling system is built based on the IEEE first bench mark, and the wind farm is aggregated to several groups according to the rated power. The complex torque coefficient method is used to analyze the two cases of the same running state of the wind turbine and the difference of wind speed between the turbine and verified by time-domain simulation. The results show that the difference in wind speed within the DFIG groups has little effect on the system oscillation frequency before and after the aggregation of the wind farm, but there may be a slight error in the electrical damping coefficient before and after the aggregation,but the error does not affect the trend and analysis of damping characteristics of system. When studying the influencing factors of wind-fire bundling system SSOthe aggregated model can be uesd to improve simulation efficiency.

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Short-term Optimized Operation of Multi-energy power system Based on Complementary Characteristics of power Sources

Short-term Optimized Operation of Multi-energy Power System ...

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2019 IEEE PES Innovative Smart Grid Technologies Asia, ISGT 2019

作者： Xiao, Bai Zheng, Jia Yan, Gangui Shi, Yonggang Jiao, Mingxi Wang, Yao Dong, Ling Wang, Maochun Yang, Hongzhi Key Laboratory of Modern Power System Simulation and Control Renewable Energy Technology Ministry of Education Northeast Electric Power University Jilin China Tonghua Power Supply Company State Grid Jilin Electric Power Co. Ltd. Tonghua China Changchun Power Supply Company State Grid Jilin Electric Power Co. Ltd. Changchun China State Grid Qinghai Electric Power Company Xining China

ISBN: (纸本)9781728135205

Aiming at the problem that uncertain power sources bring fluctuation to power system and cause lots of wind and photovoltaic curtailment, a short-term optimized operation method of multi-energy power system based on complementary characteristics of power sources is presented. The complementary mechanism of multi-energy power system is established. Based on the complementary mechanism, mathematical models of complementary objectives and complementary demands are established. Define renewable energy complementary power source. To minimize complementary demands, the capacity matching ratio of hydropower in renewable energy complementary power source is determined. According to the complementary objectives, a hierarchical optimal operation strategy for multi-energy power system is proposed. Particle swarm optimization is used to solve the optimization objective function. Taking a provincial power grid in northwest China as an example, the results show that the strategy makes full use of the complementarity of power sources and has the benefit of energy saving. © 2019 IEEE.

关键词： Energy conservation

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Research on Lithium-ion Battery Safety Risk Assessment Based on Measured Information

Research on Lithium-ion Battery Safety Risk Assessment Based...

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Sustainable power and Energy Conference (iSPEC)

作者： Xuyan Zhou Lin Cheng Yuxiang Wan Ning Qi Liting Tian Feng You State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing China Energy Storage System Business Unite Tianjin Lishen Battery Joint-Stock Co. Ltd. Tianjin China

ISBN: (数字)9781728191645

ISBN: (纸本)9781728191652

Lithium-ion batteries have the advantages of high energy density, fast power response, recyclability, and convenient to movement, which are unsurpassed by other energy storage systems. However, safety issues such as thermal runaway of lithium-ion batteries have become the main bottlenecks restricting the development of their extensive applications. In practical applications, the demand for battery energy storage scale and specific energy continues to increase, and the contradiction between battery high safety and battery safety has become increasingly prominent. This paper proposes a lithium-ion battery safety risk assessment method based on online information. Effective predictions are essiential to avoid irreversible damage to the battery and ensure the safe operation of the battery energy storage system before a failure occurs. This paper is expected to provide novel risk assessment method and research idea for the development and design of high-safety battery systems.

关键词： Lithium-ion batteries Temperature measurement Voltage measurement Thermal management Battery charge measurement Safety Risk management

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Transient Voltage Stability Assessment Method based on gcForest

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Journal of Physics: Conference Series 2021年第1期1914卷

作者： Sun Zhiyuan LI Mingpo Zhang Jie Hu Binjiang Qi Guo Zhu Yihua Guangxi Power Grid Electrical Power Research Institute Supported by the Science and Technology Project of Guangxi Power Grid (Contract No(***DL00006)). State Key Laboratory of HVDC Electric Power Research Institute CSG China Guangdong Provincial Key Laboratory of Intelligent Operation and Control for New Energy Power System CSG Key Laboratory of Power System Simulation

Aiming at the fact that the traditional method cannot quickly and accurately judge the power system transient voltage stability, and the deep neural network method needs many sample data sets and has a large number of hyperparameters, a power system transient voltage stability assessment method based on deep forest (gcForest) is proposed. gcForest effectively extracts features through ensemble learning, multi-layer feature transformation, and dynamically adjusting the number of model layers. Finally, this method is applied to transient voltage stability assessment of an electrolytic aluminium load-intensive area in Guangxi power Grid. The results show that the method has high accuracy, the feasibility and effectiveness of this method are verified. This method can assist dispatchers to judge the transient voltage stability of the power grid.

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An Adaptive Restart Method for DC Transmission Line in LCC-HVDC system

An Adaptive Restart Method for DC Transmission Line in LCC-H...

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International Conference on Advanced power system Automation and Protection (APAP)

作者： Jing CAI Xinzhou DONG State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China

ISBN: (数字)9781728117225

ISBN: (纸本)9781728117232

DC-line fault recovery sequence (DFRS) is widely implemented in LCC-HVDC system to realize fast recovery in case of temporary fault. When permanent fault occurs, restart still happens several times as preset, resulting in repeated impacts and reducing the stability and reliability of the system. An adaptive restart for DC line fault is studied in this paper to deal with this problem. Firstly, the converter valves states and DC voltage characteristics under temporary fault and permanent fault are analyzed respectively. Then, a method based on DC voltage control is proposed to distinguish different fault states. Current DFRS strategy is improved by adding this process, through which the fault pole will only restart after the temporary fault disappearing, while directly blocked when a permanent fault is recognized. Fault handling time can be shortened and negative effects of DC line fault are minimized. The simulation results verify feasibility and effectiveness of proposed method.

关键词： Firing HVDC transmission Inverters Voltage control Valves Rectifiers Thyristors

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