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SSRN 2022年

作者： Luo, Cong Xu, Yongqing Lu, Chuangao Wang, Guang Yan, Xiaopei Gao, Ge Lu, Bowen Wu, Fan Zhang, Liqi State Key Laboratory of Coal Combustion School of Energy and Power Engineering Huazhong University of Science and Technology Wuhan430074 China State Environment Protection Key Laboratory of Environmental Monitoring Quality Control China National Environmental Monitoring Centre Beijing100012 China State Grid Hebei Electric Power Research Institute Shijiazhuang050021 China

Effects of different CaO-based raw materials, and various organic acid modification on the conversion of CaO heat carriers in close-loop calcium looping process coupled thermochemical energy storage(CaLP-TCES) system are investigated. Besides, a novel CaLP-TCES system that integrates CO2 cycle and H2O steam cycle to make full use of the energy in the system was proposed. Natural CaO-based heat carriers underwent drastically deactivation over the CaLP-TCES cycles. Compared with other natural materials, limestone presented the best cyclic carbonation conversion, which retained 14.2% of conversion rate, while glycine modification doubled the conversion rate of it. The efficiency of the CaLP-TCES system presented "S" type growth with the increase of carbonation conversion and carbonation temperature, while it showed a parabolic growth with the increase of pressure ratio. In addition, the global system efficiencies in the fullday time mode are always ~72% higher than that in daytime mode. Hence, the glycine-limestone would be a promising heat carrier for the CaLP-TCES system, and CaLP-TCES in fullday time mode is more applicable for the concentrated solar power. 850 ℃ might be a good option for carbonation process, and the higher carbonation conversion rate and pressure ratio would be more benefit for the global system efficiency. © 2022, The Authors. All rights reserved.

关键词： Carbonation

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Developing Characteristics of Oil-immersed Transformer Internal Fault with Dignostic Method Using Convergence Patterns of Free Gas

Developing Characteristics of Oil-immersed Transformer Inter...

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Electrical Engineering (CIYCEE), IEEE China International Youth Conference on

作者： Yucheng Zhang Zhiguo Hao Yuping Zheng Shuyan Pan Boyu Li Zhongxin Xue Jinzhao Deng School of Electrical Engineering Xi’an Jiaotong University Xi’an China State Key Laboratory of Smart Grid Protection and Operation Control Nanjing China

ISBN: (纸本)9781665400657

Light gas protection only operates when gas within the transformer collection chamber reaches threshold volume. Such criterion failed to reflect transformer conditions accurately due to the lack of understanding for defect developing process and corresponding gas generation- convergence pattern, which has led to lower protection reliability and has caused several transformer explosions. To address current problem, an experimental tank with structure resembling that of a power transformer is set up, inside which the needle-plate oil-pressboard breakdown model is planted. Experimental results indicate that throughout fault development, voltage drops became more frequent until arcing occurs, so is HFCT signal; meanwhile gas generation rate increases through slight partial discharge, spark discharge and arcing stage, the collected gas volume corresponds with patterns above. The purpose of this study is to clarify the defect developing process and the gas generation-convergence pattern for oil-immersed transformer internal fault in guidance for a more reliable protection method.

关键词： Surface discharges Windings Oil insulation Discharges (electric) Reliability Sparks Plastics

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Analysis of assistant reactive shielding coil for electric vehicle wireless charging system

Analysis of assistant reactive shielding coil for electric v...

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2020 IEEE International Conference on Information Technology, Big Data and Artificial Intelligence, ICIBA 2020

作者： Hou, Shiliang Yu, Bo Yan, Wei Zhu, Chongming Wang, Ke Wu, Zhenghao College of Electrical and Automation Engineering Nanjing Normal University Nanjing China State Key Laboratory of Start Grid Protection and Control of NARI Group Corporation Nanjing China

ISBN: (纸本)9781728152240

To realize electromagnetic safety of wireless power transmission (WPT) system for electric vehicle (EV), the shielding methods should be analyzed. This paper proposes a method of using assistant reactive shielding coils to cancel the electromagnetic field (EMF) outside the working area of WPT system. By tuning compensation capacitance of shielding coil automatically, we design 3 cases with different location and shape of coils to achieve reactive shielding. By comparison and simulation, placing ring shielding coils above receiving (Rx) pad and under transmitting (Tx) pad is the best way to suppress EMF of WPT system's non-working area. The shielding coils' radius is slightly bigger than coupling coils' outer radius. This paper also provides a new method to realize WPT shielding system's automatic adjustment for resonance. Besides, assistant reactive shielding coils' cost is lower than traditional aluminum plate. © 2020 IEEE.

关键词： Electromagnetic fields

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Reliability analysis of autonomous controllable protection device in power system 8

Reliability analysis of autonomous controllable protection d...

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8th International Conference on Power Electronics Systems and Applications, PESA 2020

作者： Li, Chen. Yutao, Qiu. Jianing, Chen. Xuliang, Huang. State Key Laboratory of Smart Grid Protection and Control China Co. Ltd Nanjing China State Grid Zhe Jiang Electric Power Co .LTD. China State Grid Zhejiang Electric Power Company Hangzhou Power Supply Company China

ISBN: (纸本)9781728193823

With the deepening of the concept of autonomous control in the power system, more and more attention is paid to the stability of the protection device itself. Compared with the primary equipment condition monitoring, the fault of the secondary protection device will be more concealed. This paper analyzes the factors affecting the reliability of protection devices, forms the life cycle prediction method of substation protection devices, and ensures the safe and stable operation of intelligent substation. Analyzed the reliability of the relay protection device related concepts, from the failure mechanism, through the establishment of joint aging failure based on the Arrhenius model and Weibull distribution model, and based on grid relay protection device, the data is using LM method for joint failure rate estimate the parameters of the model, get old equipment failure rate model of concrete, to determine the reliability of the protection device and the effective service life. An example shows that the model proposed in this paper can effectively predict the failure trend and life boundary of the device, and provide a theoretical basis for the daily maintenance of smart substation. © 2020 IEEE.

关键词： Weibull distribution

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Modeling and Transient Stability Analysis of Mixed-GFM-GFL-Based Power System

Modeling and Transient Stability Analysis of Mixed-GFM-GFL-B...

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Sustainable Power and Energy Conference (iSPEC)

作者： Mingfei Li Xiangjun Quan Zaijun Wu Wei Li Ling Zhu Qinran Hu School of Electrical Engineering Southeast University Nanjing China State Key Laboratory of Smart Grid Protection and Control NARI Group Corporation/State Grid Electric Power Research Institute Nanjing China

ISBN: (纸本)9781665414401

The transient stability mechanism of grid-following inverter (GFL-inverter) and grid-forming inverter (GFM-inverter) in the power system has been extensively studied respectively, whereas the integration of GFM-inverters and GFL-inverters into the grid unavoidably change the transient stability of the power system. This paper aims to analyze the transient stability for the mixed-GFM-GFL power system (MGGPS). The equilibrium point of the MGGPS system is analyzed. The large-signal model of the system is established. Based on this model, an analysis of the transient stability is carried out. It is revealed that the change of GFM-inverter terminal voltage will move the position of GFL-inverter equilibrium points, and the increase of GFL-inverter terminal current will enhance the transient stability of GFM-inverter. With the simulation of phase portraits, the aforementioned transient stability mechanism is proved.

关键词： Analytical models Conferences Power system dynamics Power system stability Stability analysis Mathematical models Inverters

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Small-Signal Modeling and Analysis of Multi-GFM System

Small-Signal Modeling and Analysis of Multi-GFM System

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Sustainable Power and Energy Conference (iSPEC)

作者： Yang Zhao Xiangjun Quan Zaijun Wu Ling Zhu Wei Li School of Electrical Engineering Southeast University Nanjing China State Key Laboratory of Smart Grid Protection and Control NARI Group Corporation/State Grid Electric Power Research Institute Nanjing China

ISBN: (纸本)9781665414401

As the increasing penetration of inverter-based distributed generations (DG) reduces the inertia of the power system, the stability of the system under small disturbances is threatened. grid-forming (GFM) inverter, which can simulate inertia, damping and droop characteristics, is one of the most effective solutions. Virtual inertia and damping coefficient have important effects on the performance in primary frequency modulation. This paper presents an explicit and universal small-signal model for multi-GFM system based on the Newton-Raffson power flow algorithm in polar coordinates to realize the optimal design of virtual inertia and damping coefficient. The validity of the proposed model is demonstrated by comparing with the simulation model, and the effect of virtual inertia and damping coefficient on frequency response is analyzed in the end.

关键词： Damping Analytical models Fluctuations Power system dynamics Power system stability Frequency response Stability analysis

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Maximum Capacity Assessment for Multi-paralleled grid-connected Inverters using Global-Admittance based Harmonic Stability Analysis

Maximum Capacity Assessment for Multi-paralleled Grid-connec...

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Sustainable Power and Energy Conference (iSPEC)

作者： Ming Yang Fusuo Liu Yu Wang Wu Cao School of Electrical Engineering Southeast University Nanjing China State Key Laboratory of Smart Grid Protection and Control Nari Group Corporation Nanjing China

ISBN: (纸本)9781665414401

With the increasing demand for the renewable energy, the stability of the multi-paralleled grid-connected inverters is the important factor for evaluation the capacity of the inverters connected to power grid. In this paper the maximum capacity assessment for multi-paralleled grid-connected inverters using global-admittance based harmonic stability analysis is proposed. The stability analysis method with global admittance has clear physical concept and is convenient for real-time analysis and calculation. The global admittance method is illustrated first. The inverters are sorted by the capacity. The inverters sequence can be divided into two groups based on the stable critical point obtained by the global admittance method. The group with large capacity is taken as a unit. The stability of the combinations formed by this unit and other inverters in the other group is analyzed further. So the maximum capacity of the grid-connected inverters can be assessed. The application example is used to illustrate and verify the proposed method in this paper.

关键词： Renewable energy sources Systems operation Stability criteria Power system stability Harmonic analysis Inverters Power grids

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Typical Influence of Wind Power Capacity Expansion on the Transient Angle Stability and Feasible Explanations

Typical Influence of Wind Power Capacity Expansion on the Tr...

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Sustainable Power and Energy Conference (iSPEC)

作者： Tiangang Huang State Key Laboratory of Smart Grid Protection and Control Nanjing China

ISBN: (数字)9781728191645

ISBN: (纸本)9781728191652

The high proportion of renewable energy into the power grid, say, the large-scale wind power generation connected to the power grid, is the key approach to achieve the clean and low-carbon energy transition. Under the premise of ensuring power grid's safe and stable operation, it is necessary to study the influence of wind power capacity expansion on the transient angle stability (TAS). Aiming at several typical dominant modes in Qinghai power system, which holds many new energy resources, the sensitivity of wind power capacity expansion in different locations to the TAS, as well as its key influence factors and feasible explanations, are explored. It may lay the foundation of the location optimization of wind power capacity expansion.

关键词： Stability criteria Wind power generation Power system stability Power grids Transient analysis Thermal stability Optimization

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A Fault Ride-Through Method of Paralleled Synchronous and Virtual Synchronous Generators in Islanded Microgrids

A Fault Ride-Through Method of Paralleled Synchronous and Vi...

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IEEE Conference on Energy Internet and Energy System Integration (EI2)

作者： Yanfei Ru Feng Zhao Zhangtao Jin State Key Laboratory of Smart Grid Protection and Control Nari Group Corporation Nanjing China College of Electrical and Information Engineering Hunan University Changsha China

ISBN: (纸本)9781665434263

With the development of distributed power generation technologies, parallel operations of virtual synchronous generators (VSGs) and synchronous generators (SGs) become increasingly common in a microgrid. Due to the low overcurrent capacity of VSGs, fault ride-through (FRT) is necessary for microgrids, which makes the transient stability of SG-VSG-based microgrids be different from the traditional power system. In this paper, a new abnormal overcurrent phenomenon caused by FRT is discovered in SG-VSG-based islanded microgrids. Then, characteristics of the output current of the VSG which uses different parameters are compared and analyzed. Furthermore, an optimized FRT method is proposed, which suppresses the abnormal overcurrent. Finally, a simulation is performed to verify the effectiveness of the proposed method on the PSCAD/EMTDC.

关键词： Microgrids System integration Switches Power system stability Synchronous generators Inverters Stability analysis

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Tracking Status for Hardware-in-the-Loop Simulation Using RTDS

Tracking Status for Hardware-in-the-Loop Simulation Using RT...

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Sustainable Power and Energy Conference (iSPEC)

作者： Qitao Liu Yuqiang Hou Jianbing Xu Yongkang Liu NARI Technology Co. Ltd Nanjing China NARI Group Corporation(State Grid Electric Power Research Institute) Nanjing China State Key Laboratory of Smart Grid Protection and Control Nanjing China

ISBN: (纸本)9781665414401

The power system becomes more complex, due to the high penetration of renewable energy and more electronic devices are integrated to the traditional grid. SSCS is the critical task for power grid operation to ensure the control reliability and effectivity. It is inevitable to improve verification experiment technology for SSCS considering the development trend of the power system. RTDS is a powerful simulator for power system which is able to reflects the practical power system operation in real time. In this paper, a method for status tracking of power system model in RTDS is developed that SSCS is able to be verified under multiple operation conditions. It is found that the status cannot be tracked consistently as given, due to the limitations of RTDS models and raw data. The limitation in tracking reactive power output of generators is overcame in this paper. Besides, the development trend of online stability analysis and control is discussed as well as SSCS verification experiment technology.

关键词： Renewable energy sources Reactive power Power system stability Market research Stability analysis Real-time systems Power grids

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