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International Conference on Electrical Machines and systems (ICEMS)

作者： Kui Wang Yongdong Li Zedong Zheng State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua University Beijing China

Five-level active neutral-point-clamped (ANPC) converter is a newly emerging topology which can overcome the drawbacks of traditional neutral-point clamped (NPC) converters and flying-capacitor (FC) converters. Its dc-link is subdivided into two equal parts and the main problem is the neutral-point (NP) potential balancing. In this paper, a NP potential balancing algorithm based on zero-sequence voltage injection is presented. By calculating the NP currents of all key zero-sequence voltages, the most appropriate zero-sequence voltage is selected to generate the demanded NP current. Moreover, by further limiting the span of injected zero-sequence voltages, the NP balancing algorithm can make the two IGBTs connected in series operate at fundamental frequency. A three-phase five-level ANPC inverter prototype was built up and experimental results are presented to verify the validity of this algorithm.

关键词： Capacitors Electric potential Switches Voltage control Inverters Insulated gate bipolar transistors Heuristic algorithms

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Optimized design of multivariable PID controllers for steam turbine generator sets

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Dongli Gongcheng/power Engineering 2005年第5期25卷 668-672+741页

作者： Xue, Ya-Li Li, Dong-Hai Lu, Chong-De Key Simulation Lab. for Power System and Generation Control Department of Thermal Engineering Tsinghua University Beijing 100084 China

A method, based on Genetic Algorithm, for optimizing multivariable PID controllers, is being proposed. The global parameters of the PID controller are optimized here by utilizing the generic framework of genetic algorithm. The only prerequisite asked for by the method is that the object function can be numerically evaluated, without any restrictions concerning the concrete form of the controlled object's model, and without requiring any analytical relationship between the object function and the control parameters as well. The method is therefore featured by superior universality. simulation of a steam turbine generator set' s control system shows that, though the decoupling effect of multivariable PID controllers, designed by the mentioned method, is somewhat inferior to the optimization of parameterized high order normal matrix design method, but has, in respect to decoupling effect, remarkable improvements in comparison with multi-loop PLD control. It has, in addition, a certain disturbance resistant capability, and robustness;is exhibiting good dynamic behavior and proves the method's feasibility.

关键词： Automatic control Decoupling Genetic algorithm PID controller Steam turbine generator set

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A phase-disposition PWM method for DC voltage balance in cascaded h-bridge rectifier

A phase-disposition PWM method for DC voltage balance in cas...

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2010 International Conference on Electrical Machines and systems, ICEMS2010

作者： Tao, Xinghua Li, Yongdong Sun, Min State Key Lab of Control and Simulation of Power System and Generation Equipments Dept. of Electrical Engineering Tsinghua University China Dept. of Electrical Engineering Naval Engineering University China

In this paper, a novel control scheme for cascaded H-Bridge rectifier (CHBR), which can be used as the primary end of high voltage high power multilevel converters, is presented. The controller is similar with the one for single phase rectifier. To improve the performance of the controller, notch filter and proportion resonance (PR) controller are employed and the discrete methods for them are discussed in detail. The different function of CHBR controller from the single rectifier is for voltage balancing. Therefore, the phase-disposition technology, which is used in the multilevel converter, is introduced to eliminate the voltage error from the expected value. With this approach, the states of the switches of the CHBR are decided correctly by the practical condition and then the DC-link capacitors of the cells are controlled to charge or discharge in the way which results to voltage balancing. The effectiveness of the proposed approach is verified by experimental results.

关键词： Cascaded H-bridge rectifier Phase-disposition PWM PR controller Voltage balance

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Analysis of Ant Colony Algorithm for Finding the Optimal Circuitous Route in the Communication Network of power system

Analysis of Ant Colony Algorithm for Finding the Optimal Cir...

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International Conference on Electric Utility Deregulation and Restructuring and power Technologies

作者： Xin Chen Zhiqian Bo Xinzhou Dong Shenxing Shi State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua University Beijing China

ISBN: (纸本)9781467371070

The communication network of power system is often damaged after a disaster. To solve this problem, this paper uses ant colony algorithm to find the optimal circuitous route. simulation results show that the method is fast, which can accelerate the recovery of the communication network. Besides, this paper does some research on the dead end problem, and analyses relationship between degree of adjacency and ratio of coming to a dead end. The result shows that the efficiency of ant colony algorithm can be improved only if it tries to avoid coming to dead ends.

关键词： ant colony algorithm circuitous route degree of adjacency dead end

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Study on coordinated voltage control strategy of DFIG wind farm

Study on coordinated voltage control strategy of DFIG wind f...

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IEEE General Meeting power& Energy Society

作者： Hui-fen Chen Ying Qiao Zong-xiang Lu State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua University Beijing China

ISBN: (纸本)9781467327275

This paper studies a combined voltage control strategy that coordinates a variety of reactive compensative devices such as fixed capacitors, SVC/Statcom, DFIGs (Double-fed Induction Generators) to improve voltage control performance in multi-time scale. Based on the control restraints and response performance, three modes - planning mode, online mode and emergency mode - are optimized for lower cost and higher security margin, respectively. The paper introduces wind power forecast into wind farm voltage planning for slow, discrete devices such as fixed capacitor, while engages devices that are capable of instantaneous response to smooth quick, small voltage fluctuation and track online voltage reference from dispatching centre. The feasibility, effectiveness and superiority of the proposed control strategy are verified with simulation.

关键词： Wind farms Reactive power Automatic voltage control Security Capacitors Static VAr compensators

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Cascaded battery energy storage system based on dual active bridges and a common DC bus

Cascaded battery energy storage system based on dual active ...

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International power Engineering Conference (IPEC)

作者： Yiding Jin Qiang Song Wenhua Liu Weixin Sun State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua University Beijing China

Along with the increasing system capacity, large-scaled energy storage systems are supposed to be connected into 10kV or higher networks. Urban network has strict criterions on power quality of the power electronic devices connected. Moreover, the occupancy and noise of industrial frequency transformers also become restraints to the promotion of urban network energy storage. For that reason, this paper proposes a battery energy storage system based on cascaded dc-ac converter, dual active bridges, and a common dc bus. High frequency transformers are used to replace the industrial frequency transformer for insulation, and battery groups are connected to the common dc bus with respective dc-dc interfaces. This multilevel converter system is easy to modularize, easy to extend, and allows different kinds of batteries to work together. The main circuit and proper control system are designed, with the soft-switching condition and current control issues of the dual active bridge analyzed in detail. The simulation results from EMTDC model verify the operation principles and corresponding control strategies.

关键词： Batteries Voltage control Converters Switches Bridge circuits

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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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2020 IEEE Sustainable power and Energy Conference, iSPEC 2020

作者： Zhou, Xuyan Cheng, Lin Wan, Yuxiang Qi, Ning Tian, Liting You, Feng 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: (纸本)9781728191645

Lithium-ion batteries have the advantages of high energy density, fast power response, recyclab.lity, 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. © 2020 IEEE.

关键词： Lithium-ion batteries

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Equivalent capacity of the lower voltage ride through for wind farm from overcurrent protection in power collection lines

Equivalent capacity of the lower voltage ride through for wi...

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11th IET International Conference on Developments in power systems Protection, DPSP 2012

作者： Wang, Bin Dong, Xinzhou Bo, Zhiqian State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China Alstom Grid Stafford ST17 4LX United Kingdom

ISBN: (纸本)9781849196208

Magnitude and duration of voltage sags are the most important two factors to the Lower Voltage Ride Through (LVRT) capacity of the wind generator. Since most voltage sags are caused by the system faults, and sag durations are controlled by the tripping time of overcurrent relay in power collection lines based on the sags' magnitude. The specification of the LVRT capacity of wind generator is introduced into the operation characteristics of the relay in power collection lines. The evaluation model of equivalent LVRT capacity to overcurrent protection is proposed in paper, and the equivalent LVRT capacities from zone I and zone II relay are quantified. Improvement measures are also proposed.

关键词： Overcurrent protection

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Research on reliability of Ad hoc network communication in UAVs formations 6

Research on reliability of Ad hoc network communication in U...

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6th IEEE International Symposium on Electromagnetic Compatibility, ISEMC 2019

作者： Li, Yanchu Li, Shufang Ding, Qingqing Wang, Chao School of Information and Communication Engineering Beijing University of Posts and Telecommunications Beijing China State Key Lab of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Dept. of Electrical Engineering Beijing China

ISBN: (纸本)9781728144160

As an important performance index of the UAV Ad hoc network, network reliability is a great significance for the performance evaluation of the UAV network system, and provides a direction for the selection of the UAVs formations. In this paper, based on the 3D Gauss Markov moving model, we modeled the motion mode of the UAV group. By using the Weibull distribution to sample the failure of the fleet, and through the correlation matrix which characterizes the connectivity state of network nodes in the time domain, we studied and compare the reliability of the self-organizing network of the UAV group with different formations. It provides a basis for selecting the formations of the UAVs for different network requirements. © 2019 IEEE.

关键词： Reliability

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Probabilistic evaluation of renewable energy curtailment under forward electricity market 10

Probabilistic evaluation of renewable energy curtailment und...

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2020 10th International Conference on power, Energy and Electrical Engineering, CPEEE 2020

作者： Jiang, Jiheng Qiao, Ying Lu, Zongxiang Ran, Liang Ma, Ming Li, Jin Wang, Feng State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Beijing100084 China State Grid Gansu Provincial Electric Power Company Lanzhou730000 China Key Laboratory of Wind Power Integration Operation and Control of Gansu Province Lanzhou730070 China

Forward electricity market has emerged as a pivotal section for the electricity transaction to keep stakeholders away from price risk and electricity shortage. But the forward contract of conventional unit partially limits the unit output before operation, leading to the curtailed generation share of renewable energy source (RES). Modeling and assessing this impact is of great significance for system planning and market supervision. The central thesis of this paper is to find out the impact of forward market on RES curtailment. A probabilistic evaluation model for RES accommodation is proposed, taking the curtailment rate as a main evaluation index. We mainly research financial contract and physical contract, modeling the impact of them on thermal unit minimum load capacity and power load in evaluation model. The simulation is conducted in a simplified system, which reveals the change of RES curtailment with renege penalty, contract price and execution generation curve. © 2020 The Authors, published by EDP Sciences.

关键词： power markets

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