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Maximum flow algorithm based on adjustment of net flow on nodes and its application

Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2008年第SUPPL.期28卷 31-34页

作者： He, Guang-Yu Sun, Ying-Yun Chen, Chao State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China

For calculating the maximum capacity transported from source node to sink node in a network, a maximum flow algorithm was proposed. Based on the concept of net flow on nodes (NFN) and layered increment network (LIN), the plus flow process (PFP) and minus flow process (MFP) on LIN were defined. By performing PFP and MFP on NLP over and over, the maximum flow problem was solved when the sink node can't get a mark again. Compare to the existing max flow algorithm, the proposed method needs no complex data structure in processing, which makes the algorithm implemented easily. Based on the algorithm, a thermal economic dispatch software package which includes fixed electricity plant was developed and had been put into practice and had a good performance. Furthermore, the algorithm runs in O(n2m) (n, m is the number of nodes and arcs of the network) was proved.

关键词： Scheduling

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A Gate Driver with a Negative Turn Off Bias Voltage for GaN HEMTs

A Gate Driver with a Negative Turn Off Bias Voltage for GaN ...

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International Conference on power Electronics and Motion control (IPEMC)

作者： Hang Zhou Matthew Priestley John Fletcher Kai Sun School of Electrical Engineering and Telecommunications University of New South Wales Sydney Australia State Key Lab of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China

ISBN: (数字)9781728153018

ISBN: (纸本)9781728153025

The GaN HEMT offers fast switching and low on-state resistance which makes it ideal for applications such as high efficiency and high power density power supplies. Unfortunately, the low threshold voltage makes GaN HEMT extremely vulnerable to false turn-on, which compromises the performance and potentially causes shoot-through. In the half-bridge circuit topology, the resonant circuit formed by the parasitic inductance and capacitance can trigger false turn-on with a fast commutation. A practical method to avoid this phenomenon is to apply a negative bias voltage during the commutation by either using a separate power supply or using a capacitor charge pump to produce the negative turn-off bias. The first method necessitates many extra components and the second method cannot provide a fixed negative voltage. This paper rectifies these issues by proposing a negative turn-off bias generator with a new charge pump based approach which offers a stable negative turn-off voltage under different switching frequencies and duty cycles. The proposed circuit has been practically implemented during experimental testing. These results demonstrate that false turn-on events are eliminated without compromising the high-frequency and highspeed characteristics of the GaN HEMT.

关键词： Resistance Charge pumps Switching frequency Capacitors HEMTs Threshold voltage Gallium nitride

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The Influence of Positive Temperature Coefficient Material on the DC Electric Field within Epoxy Composites

The Influence of Positive Temperature Coefficient Material o...

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Conference on Electrical Insulation and Dielectric Phenomena, (CEIDP)

作者： Chenyuan Teng Yuanxiang Zhou Ling Zhang Yunxiao Zhang Xuewei Wang Zixia Cheng Meng Huang China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China The Wind Solar Storage Division of State Key Laboratory of Power System and Generation Equipment School of Electrical Engineering Xinjiang University Urumqi China School of Electrical Engineering Zhengzhou University Zhengzhou China The State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Beijing China

ISBN: (纸本)9781728195728;9781728195735

Negative temperature (NT) coefficient electrical resistivity of insulating materials causes the distortion of DC electric field, increasing the design and manufacture difficulty of HVDC equipment. The ceramic with positive temperature coefficient (PTC) electrical resistivity was doped into epoxy resin to weaken its temperature dependence of electrical resistivity (0~35 wt%). The electric field and temperature distribution under temperature gradient were simulated. The PTC effect of fillers is able to mitigate the distortion of electric field under temperature gradient, which is through the synergistic optimization of both electrical resistivity-temperature characteristic and thermal conductivity. The optimization of electric field distribution within insulation via BT60/epoxy composites has potential to be used in HVDC electrical equipment.

关键词： Temperature sensors Temperature distribution Temperature dependence Thermal resistance HVDC transmission Conductivity Thermal conductivity

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Eigenvalue analysis of multi-mode sub-synchronous resonance for multimachine plant-to-grid transmission systems with fixed series compensation

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Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2008年第SUPPL.期28卷 13-18页

作者： Zhang, Shu-Qing Xie, Xiao-Rong Yang, Ting-Zhi Liu, Shi-Yu State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China

For some domestic large thermal power plants delivering electric energy over long distances, the sub-synchronous resonance (SSR), which is induced by the fixed series compensation (FSC), attracts much attention. Eigenvalue analysis is one of the primary methods to assess the risk and explore the countermeasure. However, for handling multi-machine and multi-mode SSR problems, no practical toolkit based on eigenvalue analysis is on hand for the moment. In this paper, a systematic modeling approach and analysis flows for the purpose of eigenvalue analysis of multimachine plant-to-grid transmission systems with FSC were proposed. The equating technique of machines and networks was presented, and the effect of the q-axis damping windings on the SSR was also explored. The applicability of the proposed method was verified with an actual multimachine system. Furthermore, its advantage over existing SMIB based eigenvalue analysis was clarified by a comparative study between the original multi-machine system and the simplified single-machine system.

关键词： Eigenvalues and eigenfunctions

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Realization and Application of PSASP-MATLAB Associated Mixed Step simulation based on Engine Calling Mode

Realization and Application of PSASP-MATLAB Associated Mixed...

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2017 International Electrical and Energy Conference (CIEEC 2017)

作者： Yiming ZHANG Qinglai GUO Wenlu ZHAO Tian XIA Haoqing XIONG Ran SUN Henan Electric Power Dispatching and Control Center State Grid Corporation of China(SGCC) State Key Lab of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Energy Internet Research Institute Tsinghua University

By calling MATLAB calculation engine function library,associated simulation between power System Analysis Software Package(PSASP) and MATLAB can be realized in parallel and serial *** could use different timing sequence from PSASP,and mixed step simulation can be *** calculation method was used in a 10-nodes power system case for the modeling and simulation of Automatic Voltage Regulator(AVR),and the correctness of the proposed approach is *** this foundation,the electromechanical transient model of Static Var Generator(SVG) was founded with MATLAB/Simulink,and it is of universal applicability and *** inner inverter model can also be used in general grid-connection simulating models of wind power generator,photovoltaic generation,energy storage,***,simulation and analysis for grid-connected wind farm by introducing the SVG model into PSASP were carried out via the proposed associated simulation method above,and the correctness of the model is verified via the calculation *** research results can be used to do assistant analysis for reactive voltage of grid-connected new energy power generation.

关键词： PSASP MATLAB engine static var generator reactive voltage mixed step simulation

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Study on the loss reduction of high-efficient high-voltage series induction motors

Study on the loss reduction of high-efficient high-voltage s...

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International Conference on Electrical Machines and systems (ICEMS)

作者： Bai Lingyun Zhao Zhengming Lei Yi Wang Shuping State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China Anhui Electrical Research Institute Hefei China

On the basis of analyzing the composition of losses in high-efficient high-voltage asynchronous motors, the approaches of increasing the efficiency of the motors is investigated in this paper. The approaches concern with the improvement of material, winding, fan, magnetic groove and so on. By taking the economy and efficiency into account synthetically, the design of the YKK series induction motors is carried on, and it is realized by software simulation.

关键词： Magnetic flux Windings Induction motors Rotors Perpendicular magnetic anisotropy Copper

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A Review on Virtual power Plants Interactive Resource Characteristics and Scheduling Optimization

A Review on Virtual Power Plants Interactive Resource Charac...

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

作者： Lin Cheng Xuyan Zhou Qiuchen Yun Liting Tian Xuanyuan Wang Zhen Liu State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing China Center of Electrical Laboratories and National Teching Center of Electrotechnics and Electronics Beijing Jiaotong University Beijing China Jibei Electric Power Company Power Exchange Center State Grid Jibei Electric Power Company Beijing China North China Electric Power Research Institute State Grid Jibei Electric Power Company Beijing China

ISBN: (数字)9781728131375

ISBN: (纸本)9781728131382

With a high penetration of distributed energy resources (DER) connected to the power grid, the reliability and safety of the power grid compromised by the uncertainty of energy output. Many utilities adopted strategies to abandon excessive wind and solar energy generation to ensure reliable operations of the power grid. The virtual power plant (VPP) is a way of aggregating various types of energy resources and optimizing resources utilization. It participates in the electricity market and improves the utilization of energy resources within the VPP. VPP provides services such as peak shaving, frequency regulation, and emergency power support for the power grid. It intends to prevent the negative impact caused by the uncertainty of power generation of the distributed energy resources. In this paper, three kinds of typical VPP interactive resource are introduced, which differ in characteristics, control modes, and output characteristics. In addition, the VPP achieves improved energy efficiency through rational optimized resource allocation and optimized scheduling, including internal and external scheduling optimization.

关键词： Uncertainty power grids Energy storage Load management Wind power generation

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The parameter design method of smoothing inductance based on MMC-MTDC with R-type superconducting fault current limiter

The parameter design method of smoothing inductance based on...

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

作者： P. Guo Z. Yuan G. Liu Y. Zhao Z. Shi Tsinghua University State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Beijing China Shenzhen Power Supply Corporation Shenzhen China Sichuan Energy Internet Research Institute Tsinghua University Chengdu China

The rapid increase of voltage sourced converter brings the great development of the multi-terminal DC technology, both in the DC transmission and DC distribution fields. However, because of the weak impedance characteristic of the VSC-HVDC system, how to suppress and clear DC fault currents becomes a challenge. Considering the stability, the response speed and the system structure, it is not possible to apply excessive inductance at the DC side, hence, the current limiting effectiveness is relatively restricted. On the one hand, with the effective properties, Resistive type Superconducting Fault Current Limiter (R-SFCL) becomes an effective device to solve the problem of VSC-HVDC system under DC faults. On the other hand, because of dynamic energy-impedance characteristics of R-SFCL, the fixed impedance selection method at a certain time to carry out dynamic current limiting analysis is no longer applicable. Therefore, the DC fault current research and R-SFCL characteristic are comprehensively analyzed firstly in this paper. Based on that, a smoothing inductance determination method is proposed to cut off the DC fault current by DC breaker and ensure the continuous operation of remaining parts. Finally, based on a multi-terminal DC system simulation, the improvement and effectiveness of the proposed method are validated.

关键词： power transmission faults HVDC power transmission superconducting fault current limiters HVDC power convertors voltage-source convertors

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Modeling and analysis of unit commitment considering RCAES system

Modeling and analysis of unit commitment considering RCAES s...

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Chinese control Conference (CCC)

作者： Bin Liu Laijun Chen Yu Zhang Chen Fang Shengwei Mei Yuan Zhou State Key Lab of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing Beijing CN Electric Power Research Institute State Grid Shanghai Municipal Electric Power Company China Key Laboratory of Cryogenics Technical Institute of Physics and Chemistry Chinese Academy of Sciences Beijing CN

Regenerative compressed air energy storage (RCAES) system is a practical and efficient solution to large-scale integration of renewable energy problems faced by power systems currently. Appropriately modeling of RCAES system is critical to its practical application, whereas research in this area has been very limited. According to the energy storage and transformation process, a concise model of RCAES system applicable to power scheduling field is proposed. Then, a unit commitment model with RCAES system is formulated as a MILP problem which can be accurately solved with high computation efficiency by CPLEX. A modified IEEE 39 bus system is used to study the impacts of parameters of RCAES system on unit commitment and the effectiveness of the proposed model is then validated. Furthermore, the proposed model can also be employed to optimize key parameters of RCAES system, e.g. efficiency and capacity of each part in an integrated way.

关键词： Energy storage Heating Computational modeling Wind power generation power grids Schedules

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Communication-Efficient Federated Learning for Connected Vehicles with Constrained Resources

Communication-Efficient Federated Learning for Connected Veh...

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International Wireless Communications and Mobile Computing Conference, IWCMC

作者： Shuaiqi Shen Chong Yu Kuan Zhang Xi Chen Huimin Chen Song Ci University of Nebraska-Lincoln Omaha NE USA Beijing Electric Power Research Institute State Grid Corporation of China State Key Laboratory for Safety Control and Simulation of Power Systems and Large Power Generation Equipment Tsinghua University Beijing P. R. China

With the upcoming next generation wireless network, vehicles are expected to be empowered by artificial intelligence (AI). By connecting vehicles and cloud server via wireless communication, federated learning (FL) allows vehicles to collaboratively train deep learning models to support intelligent services, such as autonomous driving. However, the large number of vehicles and increasing size of model parameters bring challenges to FL-empowered connected vehicles. Since communication bandwidth is insufficient to upload full-precision local models from numerous vehicles, model compression is usually conducted to reduce transmitted data size. Nevertheless, conventional model compression methods may not be practical for resource-constrained vehicles due to the increasing computational overhead for FL training. The overhead for downloading global model can also be omitted by existing methods since they are originally designed for centralized learning instead of FL. In this paper, we propose a ternary quantization based model compression method on communication-efficient FL for resource-constrained connected vehicles. Specifically, we firstly propose a ternary quantization based local model training algorithm that optimizes quantization factors and parameters simultaneously. Then, we design a communication-efficient FL approach that reduces overhead for both upstream and downstream communications. Finally, simulation results validate that the proposed method demands the lowest communication and computational overheads for FL training, while maintaining desired model accuracy compared to existing model compression methods.

关键词： Training Quantization (signal) Connected vehicles Computational modeling simulation Wireless networks Collaborative work

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