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Frontiers of power and Energy (ACFPE), Asian Conference on

作者： Zimin Zhu Xiaofang Wu Yu Duan Zhen Liu Dongliang Nan Peili Liu Electric Power Research Institute State Grid Xinjiang Electric Power Co. Ltd. Xinjiang Key Laboratory of Whole Process Simulation for Power System Urumqi China College of Electrical Engineering Sichuan University Chengdu China

ISBN: (数字)9798350367676

ISBN: (纸本)9798350378467

Dynamic stability issues posed by large-scale photovoltaic (PV) generation can jeopardize the secure operation of renewable power systems. This paper establishes a PV solar farm equivalent model that considers the cluster effect of multiple PV generators with same dynamics. Mathematical analysis indicates that the dynamic characteristics of PV generators are central to the dynamic instability of large-scale grid-connected PV solar farms. While increasing the scale of PV generators and weakening the AC transmission line connections exacerbate dynamic instability, these factors amplify the effect but are not the root cause. A case study conducted in an actual power system with high PV generation penetration highlights that the phase-locked loop parameters of PV inverters are crucial for triggering oscillations caused by the cluster effect of multiple PV generators with same dynamics. As the number of PV generators increases and the AC transmission line connections weaken, the system’s dynamic stability deteriorates in the specific power system.

关键词： Damping Renewable energy sources power transmission lines power system dynamics Solar farms power system stability Dynamic scheduling Generators Stability analysis Oscillators

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Analysis of IGBT Junction Temperature Fluctuation in Modular Multilevel Matrix Converter

Analysis of IGBT Junction Temperature Fluctuation in Modular...

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International Conference on power Electronics and Motion Control (IPEMC)

作者： Qi Chen Yunfei Xu Guoliang Zhao Lei Qi Chao Ding State Key Laboratory of Advanced Power Transmission Technology State Grid Smart Grid Research Institute Co. Ltd Beijing China State Key Laboratory of Alternate Electrical Power System With Renewable Energy Sources North China Electric Power University Beijing China State Grid Zhejiang Electric Power Co. Ltd Research Institute Hangzhou China

ISBN: (数字)9798350351330

ISBN: (纸本)9798350351347

The modular multi-level matrix converter (M3C) is a crucial component of the flexible low-frequency transmission system. However, during AC-AC frequency conversion, the power of the AC system on both sides, with different frequencies, is directly coupled in the inverter. The converter bridge arm is subjected to two different frequencies of AC currents simultaneously, resulting in irregular thermal cycling on the power semiconductor device, which causes the IGBT junction temperature fluctuation to be more violent and complex, thereby accelerating its aging and reducing the overall reliability of the converter. In this paper, simulations based on thermal network and electro-thermal models are built to calculate the junction temperature of the IGBTs within the submodules on each bridge arm of the M3C, and their waveform characteristics are analysed, and then the rain-flow counting method is used to extract the thermal load of the IGBTs in one cycle, which contains three important parameters used for the life analysis.

关键词： Insulated gate bipolar transistors Analytical models Temperature Frequency conversion Temperature control Thermal analysis Thermal loading

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FPGA-based Adaptive Variable Step MPPT Real Time simulation for Photovoltaic systems

FPGA-based Adaptive Variable Step MPPT Real Time Simulation ...

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2020 International Conference on smart grid and Energy Engineering, SGEE 2020

作者： He, Ruxun Wang, Shouxiang Zhang, Chunyu Ma, Qi Key Laboratory of Smart Grid of Ministry of Education Tianjin University Tianjin300072 China Tianjin Key Laboratory of Power System Simulation and Control Tianjin University Tianjin300072 China State Grid Tianjin Electric Power Company Tianjin300010 China

In order to obtain more output power, maximum power point tracking (MPPT) control technology is usually designed to track the maximum power of photovoltaic (PV) array. The traditional power disturbance observation method tends to cause power oscillation loss, so an adaptive variable step algorithm is presented to balance the tracking accuracy and speed of PV system. Different from off-line simulation, the overall model is built on FPGA to complete the real time digital realization of MPPT control for PV system. Finally, the model is simulated and verified by ModelSim software. The experimental results show that the system can track the maximum power more quickly and accurately in real time. © Published under licence by IOP Publishing Ltd.

关键词： Field programmable gate arrays (FPGA)

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Space Charge Transport of Al2O3/Silicone Rubber Composites under Thermal Aging

Space Charge Transport of Al2O3/Silicone Rubber Composites u...

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2022 IEEE International Conference on High Voltage Engineering and Applications, ICHVE 2022

作者： Zhang, Yunxiao Yan, Chenning Wu, Kai Zhou, Yuanxiang Zhang, Tianfeng College of Electrical Engineering and Automation Fuzhou University Fujian Fuzhou China Tsinghua University State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Beijing China School of Electrical Engineering Xinjiang University The Wind Solar Storage Division State Key Laboratory of Power System and Generation Equipment Urumqi China Electric Power Research Institute Anhui Electric Power Company of State Grid Hefei China

ISBN: (纸本)9781665407502

Silicone rubber (SIR) has been widely used in the insulation of cable accessories due to its excellent performance. In this paper, pure SIR and nano Al2O3/SIR composites are thermally aged for 0-80 days at 200°C. The effects of long-term thermal aging on the space charge transport are analyzed. The results show that with the increase of thermal aging time, the accumulation of heteropolar charge of pure SIR and nano Al2O3/SIR composites gradually decreases and changes to the accumulation of homopolar charge. Compared with pure SIR, the space charge accumulation of Al2O3/SIR composites decreases significantly and changes little with the increase of thermal aging time. It is believed that when doped nano Al2O3 in SIR, the increase of carrier mobility and the introduction of metal oxides reacting with fallen free radicals to form stable compounds both lead to less space charge accumulation of Al2O3/SIR composites. © 2022 IEEE.

关键词： Aluminum oxide

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Application of Symmetric key Algorithm in Data Security Design of smart grid

Application of Symmetric Key Algorithm in Data Security Desi...

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Mechatronics, IoT and Industrial Informatics (ICMIII), International Conference on

作者： Yifan Zhang Chaoyu Yu Yuqiang Wang Junfei Han Ming Zhong Haijun An Ningping Yuan Inner Mongolia Enterprise Key Laboratory of Smart Grid Simulation of Electrical Power System Inner Mongolia Power Research Institute Hohhot China Inner Mongolia Tianda Tiancai Information Technology Co. Ltd. Hohhot China School of Computer Information Inner Mongolia Medical University Hohhot China

There are a large number of distributed transaction management in the smart grid. If the traditional centralized control method is adopted, it will cause problems such as low security level, privacy leakage and high maintenance cost. Protecting the privacy and security of data is the most important link in network transmission. The input of data parties will not interfere with each other, which protects the privacy of users. The research purpose of this paper is the application of symmetric key algorithm in smart grid data security design. In the experiment, according to the symmetric key security evaluation index, using the run-length test and frequency test methods, the data security design of the symmetric key algorithm in the smart grid is analyzed, thereby proving the security of the symmetric key algorithm.

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Research on Active Participation of Distributed Photovoltsics in power grid Primary Frequency Control Strategy

SSRN

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SSRN 2024年

作者： Zhang, Runtao Wang, Lei Zeng, Siming Cheng, Ziwei Su, Can Li, Zhiwei Zhang, Hao State Grid Hebei Electric Power Research Institute Shijiazhuang China Hebei Key Laboratory of Simulation Modeling and Control for Energy Internet Shijiazhuang China State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Baoding071003 China

Distributed photovoltaic systems can actively contribute to the primary frequency regulation of the power grid by reserving capacity. Traditional power reduction methods often employ fixed load reduction ratios, potentially resulting in inadequate frequency regulation capacity and unnecessary reserve power. This paper centers on optimizing power reserve control, starting with the construction of a two-stage model for a photovoltaic grid-connected inverter power generation system. It includes the design of a maximum power estimation method and the implementation of photovoltaic power reduction operation. The article proposes a strategy to utilize photovoltaic backup capacity for achieving primary frequency modulation effects in a short time scale. Additionally, it adopts a variable power reserve ratio operation strategy over the long term, aiming to enhance photovoltaic power generation and optimize solar energy utilization without compromising the grid's frequency and quality. Finally, a MATLAB/Simulink model is developed to validate the effectiveness of the control strategy. simulation results indicate that the proposed strategy satisfies frequency regulation requirements, enhances power generation efficiency, and improves the economic viability of photovoltaic operations. © 2024, The Authors. All rights reserved.

关键词： Frequency modulation

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The Function Mechanism of Virtual Impedance in grid-forming Droop Control and An Adaptive Parameter Tuning Method for Virtual Impedance Based on Network Equivalent Identification

The Function Mechanism of Virtual Impedance in Grid-forming ...

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power Science and Technology (ICPST), IEEE International Conference on

作者： Chenhui Fan Xiaohui Qin Lei Qi Hongzhi Liu Baodi Ding Zhengji Meng State Key Laboratory of Alternate Electrical Power System With Renewable Energy Sources North China Electric Power University Beijing China Carbon Neutrality Research Center of Power System China Electric Power Research Institute Beijing China Hebei Key Laboratory of Energy Internet Simulation Modeling and Control State Grid Hebei Electric Power Research Institute China

ISBN: (数字)9798350349030

ISBN: (纸本)9798350349047

The penetration rate of renewable energy and other power electronic sources in the system continues to increase, the strength of the power grid is weakened, and the system security is challenged. Some converters urgently need to adopt grid-forming control, for example, the droop control. However, due to the different impedance characteristics of the power system environment and the varying electrical distances between the grid source and load, the grid-forming converter cannot adapt to traditional droop control in multi-point parallel operation, this condition can be improved by adding virtual impedance. This paper first derives the main function mechanism of virtual impedance taking droop control as an example, and proposes a virtual impedance adaptive parameter tuning method based on network equivalent identification, then verifies the method through MATLAB/Simulink simulation. The proposal of this method is of great significance for reflecting the operational status of the system, improving the adaptability of renewable energy equipment and stations, and enhancing their fault ride-through ability. It also has important value for improving other grid-forming technologies.

关键词： Renewable energy sources Adaptive systems power system stability Stability analysis Impedance Security Proposals

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Transient voltage stability margin prediction method based on lightgbm 4

Transient voltage stability margin prediction method based o...

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4th International Conference on Advanced Electronic Materials, Computers and Software Engineering, AEMCSE 2021

作者： Jie, Zhang Binjiang, Hu Qi, Guo Yihua, Zhu Zhiyuan, Sun Mingpo, Li Yan, Sun Electric Power Research Institute CSG State Key Laboratory of HVDC China Guangdong Provincial Key Laboratory of Intelligent Operation and Control for New Energy Power System China CSG Key Laboratory of Power System Simulation Guangzhou China Guangxi Power Grid Electrical Power Research Institute Nanning China Guangxi Power Grid Dispatching Control Center Nanning China

ISBN: (纸本)9781665415965

Traditional time-domain simulation method has long calculation time on transient voltage stability margin prediction problem, the direct method is difficult to adapt to the complex power grid model, and the deep neural network method requires a large data set. In this paper, we propose the method based on LightGBM, which has the advantages of appropriate model complexity and less training time demand. Based on a regional subsystem of Guangxi power grid with more electrolytic aluminum load, and a power system transient voltage stability margin prediction model based on LightGBM is constructed. To solve the long tail distribution learning problem, target clipping and log transformation techniques are proposed to enhance the model. The effectiveness of them is verified by experiment results. And we propose a new metric, partial RMSE, to evaluate the performance of the model fitting the instability data. The experiment results also show that it has achieved better performance and training time than other machine learning models. © 2021 IEEE.

关键词： Forecasting

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A Low-Cost Resonant Circuit Breaker Employing Variable Oscillation Frequency with Low di/dt Interruption in Mechanical Switch

A Low-Cost Resonant Circuit Breaker Employing Variable Oscil...

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electrical, Electronics and Information Engineering (ISEEIE), International Symposium on

作者： Bei Zhang Pengzhi Li Qihao Zhou Xiangyu Zhang Lei Qi State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Beijing China State Grid Smart Grid Research Institute Co. Ltd Beijing China State Grid Inner Mongolia Eastern Power Co. Ltd Neimenggu China

ISBN: (数字)9798350355772

ISBN: (纸本)9798350355789

DC circuit breakers (DCCBs) play a critical role in maintaining the security and stability of DC systems. In recent times, resonant DC circuit breakers (RCBs) have attracted substantial interest, primarily due to their capability to produce several zero-crossing points for mechanical switches (MSs), which in turn, amplifies their dependability. For RCBs, higher oscillation frequencies allow for lower capacitance and inductance values, reducing overall cost and size. However, with increasing interruption capacity, the di/dt faced by mechanical switches during arc extinction at high oscillation frequencies becomes substantial, making arc extinction challenging. To address the aforementioned issues, this paper proposes a low-cost resonant circuit breaker that employs variable oscillation frequency and achieves low di/dt interruption in mechanical switch (VOF-RCB). Initially, a high oscillation frequency is selected for rapid oscillation to the fault current value. Subsequently, an inductance is introduced to lower the oscillation frequency to a range within which the MS can successfully extinguish the arc. This method significantly enhances oscillation efficiency through rapid initial oscillation, enabling the selection of lower capacitance values. Hence, this leads to a significant reduction in the cost and size of capacitors, as well as the total cost and volume. Initially, the topology structure and operational principle of the VOF-RCB are delineated, succeeded by a comprehensive parameter optimization design methodology. An 80 kV/25 kA simulation model is developed to validate the interruption performance of the proposed topology and the precision of the parameter design criteria.

关键词： Inductance Costs Capacitors Resonant frequency RLC circuits Switches Topology Integrated circuit reliability Oscillators Fault currents

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Conflict Mechanism Analysis Method for Electric Vehicles Participating in Multiple Types of power grid Ancillary Services

Conflict Mechanism Analysis Method for Electric Vehicles Par...

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International Conference on power system Technology (powerCON)

作者： Yinjuan Xue Qifang Chen Haiqing Cai Mingchao Xia Haohan Gu School of Electrical Engineering Beijing Jiaotong University Beijing China State Key Laboratory of HVDC Guangdong Provincial Key Laboratory of Intelligent Operation and Control for New Energy Power System CSG Key Laboratory for Power System Simulation Electric Power Research Institute China Southern Power Grid National Energy Power Grid Technology R&D Centre Electric Power Research Institute China Southern Power Grid Guangzhou China

As the high-quality flexible resource of the grid, electric vehicles (EVs) can provide multiple auxiliary services for the grid at the same time. However, due to the one-way charging and discharging of EVs, as well as the limitation of power and capacity, which may cause availability conflicts when EVs participate in different auxiliary services simultaneously. This paper focuses on the analysis of the conflict mechanism of EVs participating in the secondary frequency regulation and peak shaving ancillary services at the same time. The impact mechanism between different auxiliary services in this conflict mode is revealed from the two aspects of limit conflict and charging and discharging instruction conflict, and the results of availability conflict of the two types of auxiliary services are verified and analyzed through simulation examples.

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