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7th IEEE International Conference on High Voltage Engineering and Application, ICHVE 2020

作者： Zhou, Yuanxiang Huang, Xin Zhang, Ling Zhang, Yunxiao Zhou, Zhongliu Teng, Chenyuan China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Department of Electrical Engineering Beijing China

ISBN: (纸本)9781728155111

Gas-to-liquid (GTL) transformer oil has been on trial in converter transformers. However, its influence on the space charge characteristic is not clear. This work aims at exploring space charge characteristics of GTL oil at different temperatures as well as comparing with commercial naphthenic oil (KI50X). Space charge distribution during the polarization and the dissipation process in the GTL oil-impregnated paper at different temperature was measured by the pulse electroacoustic method (PEA), which were contrasted with those of the KI50X oil-impregnated paper. Results illustrated that high temperature accelerated the injection and migration of charge carriers in the oil-impregnated paper. And the polarity of the accumulated charge in the vicinity of anode changed from positive to negative with the increase of temperature. It was perceived that oil-paper conductivity and carrier mobility grew with the increase of temperature, resulting in the easier migration of injected charge to another electrode. Furthermore, the space charge dissipation rate in the GTL oil-impregnated paper is lower than that in the naphthenic oil-impregnated paper at the same temperature. Thus, a longer time interval of tests or switch operation in the factory test and operation process may need if GTL oil is used rather than naphthenic oil. © 2020 IEEE.

关键词： Electric space charge

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A Joint Prediction Method of Multi-state Variables for High-Voltage Cables Based on GRU 10th

A Joint Prediction Method of Multi-State Variables for High-...

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10th Frontier Academic Forum of Electrical Engineering, FAFEE 2022

作者： Chen, Jianning Zhou, Yuanxiang Lin, Menglong Pan, Zehua Ge, Jiamin State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing100084 China

ISBN: (纸本)9789819934034

In order to carry out risk warning for high-voltage cable transmission system and realize differentiated operation and maintenance decision-making, it is necessary to carry out time series prediction for online monitoring state quantities of high-voltage cables such as load current, partial discharge, and grounding circulating current. Therefore, a joint prediction method for multi-state variables of high-voltage cables based on Gate Recurrent Unit (GRU) is proposed. Taking the online monitoring state quantities of a certain area in central China in May as the analysis data set, a GRU network is built to predict the sequence of multi-state quantities, compared with different models. Taking the phase A load current of a node of the cable as an example to carry out state prediction, the results show that compared with the Long Short Term Memory (LSTM) neural network, back-propagation neural network (BPNN), and Auto Regressive Integrated Moving Average (ARIMA) model, the accuracy of the sequence prediction model based on GRU is Higher. When predicting for 5 min, the MAE and RMSE are 1.94 and 2.65 A, respectively, with the MAPE of 0.54%. When predicting for 30 min, the MAE and RMSE are 9.81 and 15.36 A, respectively, with the MAPE of 2.89%. When predicting for 1 h, the MAE and RMSE are 17.05 and 27.47 A, respectively, with the MAPE of 4.91%. The GRU model performs better due to the suppression on over-fitting of training data with simpler model structure. © Beijing Paike Culture Commu. Co., Ltd. 2023.

关键词： Forecasting

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Research on the prediction-model of the surface-temperature of large oil-immersed power transformer

Research on the prediction-model of the surface-temperature ...

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ICEMS 2005: 8th International Conference on Electrical Machines nd systems

作者： Wang, H.Y. Su, P.S. Wang, X.H. Department of Electrical Engineering State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing 10084 China

ISBN: (纸本)7506274078

In order to detect the abnormal temperature of large oil-Immersed power transformer earlier, this paper presents a new prediction-model of surface-temperature for the transformer to predict the normal surf ace-temperature. And to compare the difference between the predicted value and the measured value can judge If the condition of the transformer Is fit to operate. The model parameters are estimated from the field data by using the Partial-Least-Square method, which overcomes the instability of results estimated by using the traditional Least-Square method. Furthermore, the appropriate amount of data for the parameter estimation was decided according to the principle of Heat Transfer and the characteristics of the predicted deviation, such as mean, variance and normal distribution. The prediction model is verified from the accuracy of results predicted with one year of field data.

关键词： Electric transformers

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Experimental research of the upward leader inception from transmission line

Experimental research of the upward leader inception from tr...

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2011 7th Asia-Pacific International Conference on Lightning, APL2011

作者： Zeng, Rong Li, Zhizhao Yu, Zhanqing Zhuang, Chijie State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 100084 China

ISBN: (纸本)9781457714665

Electro-Geometric Model (EGM) has been applied widely all over the world to evaluate the lightning shielding failure of transmission line. But with the increase of operation voltage to 1000 kV and tower height to more than 100 meters, some shortcomings of the traditional EGM model were found by many researchers. Leader Progression Model (LPM) was proposed to solve these problems. But some fundamental works, such as when the upward leader initiates and how it propagates, is still indistinct. An experiment was designed and implemented in this paper to simulate the electric field circumstance near the test transmission line while the lightning downward leader approached. The upward leader from the test transmission line was clearly observed. The inception voltage and characteristics was analyzed. The streamer and leader initiated from the ground wire and conductor bundle were compared. The experiment results show that the leader initiating from the ground wire is more active in the inception stage. The velocity of the upward leader acquired is about 1.2-3.0 cm/μs. © 2011 IEEE.

关键词： Electric lines

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Effects of temperature on creepage discharge characteristics in oil-impregnated pressboard insulation under combined AC–DC voltage

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Plasma Science and Technology 2019年第5期21卷 14-22页

作者： Fubao JIN Yuanxiang ZHOU Bin LIANG Zhongliu ZHOU Ling ZHANG Key Laboratory of Plateau Ecology and Agriculture College of Agriculture and Animal HusbandrySchool of Water Resources and Electric PowerQinghai UniversityXining 800016People's Republic of China State Key Lab of Control and Simulation of Power Systems and Generation Equipments Department of Electrical EngineeringTsinghua UniversityBeijing 100084People's Republic of China

Due to the complexity of the valve side winding voltage of the converter transformer, the insulation characteristics of the oil-impregnated pressboard(OIP) of the converter transformer are different from those of the traditional AC transformer. The study on effect of temperature on the creeping discharge characteristics of OIP under combined AC–DC voltage is seriously inadequate. Therefore, this paper investigates the characteristics of OIP creepage discharge under combined AC–DC voltage and discusses the influence of temperature on creepage discharge characteristics under different temperatures from 70 °C to 110 °C. The experimental results show that the partial discharge inception voltage and flashover voltage decrease with increasing temperature. The times of low amplitude discharge(LAD) decrease and amplitude of LAD increases. Simultaneously, the times of high amplitude discharge(HAD) gradually increase at each stage of creepage discharge with higher temperature. The analysis indicates that the charge carriers easily accumulate and quickly migrate directional movement along the electric field ahead of discharging. The residual charge carriers are more easily dissipated after *** ‘hump’ region of LAD moves to the direction of higher discharge magnitude. The interval time between two continuous discharges is shortened obviously. The concentration of HAD accelerates the development of OIP insulation creepage discharge. The temperature had an accelerating effect on the development of discharge in the OIP under applying voltage.

关键词： oil-impregnated pressboard insulation combined AC-DC voltage inception voltage creepage discharge temperature flashover voltage

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Modeling method of photovoltaic power generation grid connection based on particle swarm optimization neural network

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Energy Informatics 2024年第1期7卷 88页

作者： Zhang, Jie Lu, Yuanhong Huang, Libin Guo, Haiping Tu, Liang State Key Laboratory of HVDC China Southern Power Grid Guangzhou510000 China Guangdong Provincial Key Laboratory of Intelligent Operation and Control for New Energy Power System China Southern Power Grid Guangzhou510000 China CSG Key Laboratory for Power System Simulation China Southern Power Grid Guangzhou510000 China

Aiming at the complex structure, numerous equipment, intricate control and protection logic, as well as the existence of numerous unmodeled dynamics and black-box device models in photovoltaic (PV) grid-connected systems, a modeling method based on Particle Swarm Optimization Neural Network (PSO-NN) is proposed to address the inability of pure mechanism models to accurately simulate their operational dynamics. Utilizing the differences in active power response waveforms under Voltage-Frequency (Vf) control, power-Reactive power (PQ) control, and Droop control as criteria for control strategy identification, a PSO-NN model is constructed for PV grid-connected systems, with inputs comprising temperature, humidity, light intensity, voltage, and frequency disturbances, and outputs being active and reactive power. To validate the model's effectiveness, a PV grid-connected system model is built in a self-developed simulation software and connected to an IEEE 14-bus distribution network for simulation verification. The results demonstrate that the proposed PV grid-connected model can effectively identify the types of Vf control, PQ control, and Droop control strategies, and accurately reflect the dynamic response characteristics of active and reactive power under various voltage and frequency disturbances. © The Author(s) 2024.

关键词： Particle swarm optimization (PSO)

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Commutation Failure Mitigation Method Based on Improved Commutation Area in HVDC system 8

Commutation Failure Mitigation Method Based on Improved Comm...

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

作者： Wang, Haozong Dong, Xinzhou Tsinghua University State Key Lab of Control and Simulation of Power Systems and Generation Equipment Beijing China

ISBN: (纸本)9781728117225

Commutation failure (CF) is one of the major concerns in high-voltage direct current (HVDC) transmission system. Of many methods to mitigate CF, advancing firing angle is preferred one since it can be easily implemented in current HVDC controllers without extra hardware modification. However, methods in previous works either lack for quantitative analysis or based on much strong hypothesis. In this paper, we propose a novel CF mitigation method based on improved commutation area. The salient feature of proposed strategy is that DC current is not considered as a constant under fault conditions. simulations on PSCAD/EMTDC software demonstrate the good performance of proposed method. © 2019 IEEE.

关键词： Electric commutation

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The efficiency and toxicity of dodecafluoro-2-methylpentan-3-one in suppressing lithium-ion battery fire

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Journal of Energy Chemistry 2022年第2期31卷 532-540页

作者： Yujun Liu Kai Yang Mingjie Zhang Shi Li Fei Gao Qiangling Duan Jinhua Sun Qingsong Wang State Key Laboratory of Fire Science University of Science and Technology of ChinaHefei 230026AnhuiChina State Key Laboratory of Operation and Control of Renewable Energy&Storage Systems China Electric Power Research InstituteBeijing 100192China

Currently,the effective and clean suppression of lithium-ion battery(LIB)fires remains a *** present work investigates the use of various inhibitor doses(Xin)of dodecafluoro-2-methylpentan-3-one(C_(6) F_(12)O)in 300 Ah LIBs,and systematically examines the thermal and toxic hazards of the extinguished batteries via real scale combustion and gas *** inhibitor is shown to be completely *** inhibition mechanism involves a combination of chemical inhibition and physical *** the chemical inhibition effect tends to saturate with increasing Xin,the physical cooling remains effective at higher inhibitor ***,extinguishing the battery fire with a high Xin of C_(6)F_(12)O is found to incur serious toxicity *** results are expected to provide a guideline for the design of inhibitor doses for the suppression of LIB fires.

关键词： Lithium ion battery safety Thermal runaway Fire suppression C_(6)F_(12)O

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DC Bias Elimination and Soft Switching in Transient state of Dual-Active-Bridge DC-DC Converter 48

DC Bias Elimination and Soft Switching in Transient State of...

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48th Annual Conference of the IEEE Industrial Electronics Society, IECON 2022

作者： Wang, Zhe Li, Chi Liu, Jiye Zheng, Zedong Tsinghua University State Key Lab of Control and Simulation of Power Systems and Generation Equipments Beijing China

ISBN: (数字)9781665480253

ISBN: (纸本)9781665480253

Dual active bridge is a promising isolated bidirectional DC/DC converter which has attracted more and more attention due to its advantages of zero-voltage switching, great voltage regulation ability, high power density, and fast dynamic response. However, the DC bias problem is seldom mentioned, which may lead to system instability and decreased efficiency. Besides, whether the converter can realize soft switching in the dynamic process is unclear. This paper proposed a novel phase-shift loading mode which can not only realize the DC bias elimination but also achieve zero voltage switching (ZVS) during a transient state. Finally, a 4.5 kW prototype is built and experimental results are provided to verify the conclusion. © 2022 IEEE.

关键词： Zero voltage switching

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power Source Flexibility Margin Quantification Method for Multi-energy power systems Based on Blind Number Theory

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CSEE Journal of power and Energy systems 2023年第6期9卷 2321-2331页

作者： Bai Xiao Jialiang Wang Zhiwen Xiao Gangui Yan Ling Dong Maochun Wang Hongzhi Yang the Key Laboratory of Modern Power System Simulation and Control&Renewable Energy Technology Ministry of Education(Northeast Electric Power University)Jilin 132012China Chengde Power Supply Company State Grid Jibei Electric Power CompanyChengde 067000China State Grid Qinghai Electric Power Company Xining 810008China

The grid connection of a high proportion of re-newable energy generation increases the uncertainty in power ***,the flexibility margin of different energy sources needs to be quantified to cope with the uncertainty change and maintain the dynamic balance of power system *** this paper,first,the flexibility characteristics of source,net,load and power and load community(PLC)are *** dynamic equilibrium relationship among them is briefly ***,taking into full consideration the complex output characteristics of different energy sources and combining their respective flexibility characteristics,a quantitative model of the power source flexibility margin for thermal power,hydro-power,gas power and concentrating solar power is established.A quantitative model for a power source flexibility margin in PV and wind power based on blind number theory is ***,the calculation method of theoretical power generation capacity,which can reflect different characteristics of output power of various energy sources,is *** actual output power of each power source in each period is ***,a case study shows that the model and method can consider the operating characteristics of different types of power sources,and quickly and accurately quantify the adjustable range of flexibility margins of each power source at different periods of time,which can provide an important basis for evaluating the capacity of renewable energy consumption and the optimal operation of multi-energy power systems(MEPSs).

关键词： Load forecasting multi-energy power system power generation capacity power source flexibility margin

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