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Feedback Linearization Based Nonlinear Control Strategy of VSC-HVDC

IFAC Proceedings Volumes 2009年第9期42卷 308-313页

作者： Gengyin Li Ming Yin Ming Zhou Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Beijing 102206 P.R. China (Tel: +86 10 80798551) State Power Economic Research Institute Beijing 100761 P.R. China Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Beijing 102206 P.R. China

The model of Voltage Source Converter (VSC) based HVDC in the synchronous dq reference frame is presented in this paper. The model includes the DC link model and the VSC models. The feedback linearization principle for Multi-input Multi-output plants is analyzed. Based on the analysis, nonlinear decoupling control strategies for the two VSCs are proposed. For one VSC, the proposed nonlinear control strategy enables it to decouple DC voltage and reactive power control, and for the other one, the strategy guarantees the control of active power and that of reactive power independently. Simulation was conducted with MATLAB/Simulink software to verify the proposed control strategies. The simulation results prove that the nonlinear decoupling control strategies are able to provide good performance.

关键词： Feedback linearization HVDC nonlinear control strategy voltage source converter (VSC)

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A fault location scheme based on spectrum characteristic of fault-generated high-frequency transient signals

A fault location scheme based on spectrum characteristic of ...

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IEEE General Meeting power& Energy Society

作者： S. F. Huang X. G. Wang Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Beijing China

When a fault occurs on a transmission line, fault-generated high-frequency signals contains a lot of information about fault. This paper proposes a fault location scheme for transmission lines based on spectrum characteristic of high-frequency components, the difference of adjacent two natural frequencies in one ends of transmission line is used to compute fault distance. This method need not identify arriving time of first traveling wave and traveling wave from fault point, it is insensitive to swings, fault type, fault resistance and system source parameters. The scheme performance was proven using power system computer aided design (PSCAD) simulations in 500-kV power system considering critical fault cases.

关键词： Fault location power transmission lines PSCAD power system simulation power system transients Frequency Fault diagnosis Computational modeling Computer simulation power system faults

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Measurement of micro-scale two-phase flow in a pulsating heat pipe using electrical capacitance tomography

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Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2009年第17期29卷 103-107页

作者： Li, Jing-Tao Xiao, Hai-Ping Dong, Xiang-Yuan Liu, Shi Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Changping District Beijing 102206 China School of Energy and Environmental Engineering Zhongyuan Institute of Technology Zhengzhou 450007 Henan Province China

The electrical capacitance tomography (ECT) system was used to the visualization of the two-phase flow as well as the measurement of the film thickness in a pulsating heat pipe (PHP). The new-developed micro-sensor was also applied as a part of the flow channel, with the characteristics of heat transfer and hydrodynamics similar to the measured tube. The measurement accuracy and the image resolving power were improved as compared with the conventional sensors. So the applied area of the ECT technology was widened. The experimental results indicate that there might exist three flow patterns, i.e. bubble-liquid slug flow, semi-annular flow and annular flow, corresponding to different operating conditions. The measurement results of the film thickness compare well with the actual conditions, and the trend of the film thickness can realize the identification of the flow patterns.

关键词： Two phase flow

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Vulnerability assessment for communication network of Substation Automation systems to cyber attack

Vulnerability assessment for communication network of Substa...

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IEEE PES power systems Conference and Exposition, PSCE

作者： Nian Liu Jianhua Zhang Hao Zhang Wenxia Liu Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Under Ministry of Education North China Electric Power University Beijing China Automation and information security North China Electric Power University China

The Substation Automation system (SAS) is a crucial element of power system control. The devices of SAS with remote-control functions are one of the main target of cyber attack. The vulnerability assessment for communication network of SASs that supporting the analysis of control process, is an unsolved problem. Combined with the characteristics of SAS and the vulnerability assessment of the distributed systems, a vulnerability assessment method for communication nework of SASs to cyber attack is proposed. The substation communication system has been classified into six basic models used to construct vulnerability state graph (VSG). The vulnerability of single action is defined based on exponential distribution function including parameters called vulnerability factor and equivalent attacking cost, and then the vulnerability value of target systems are calculated by four connection types of VSG. Furthermore, a vulnerability factor quantity method based on AHP-TOPSIS is designed. An evaluation instance is constructed from IEC 61850 standard, the proposed method is applicable to evaluate the vulnerability of communication network of SASs.

关键词： Communication networks Substation automation Synthetic aperture sonar IEC standards power system control Automatic control Process control Communication system control Exponential distribution Cost function

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Enhancement voltage stability of wind farm access to power grid by novel SVC

Enhancement voltage stability of wind farm access to power g...

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IEEE Conference on Industrial Electronics and Applications (ICIEA)

作者： Junjie Zhang Zhongdong Yin Xiangning Xiao Yajing Di Key Laboratory of Power System Protection and Dynamic Monitoring and Control under Ministry of Education North China Electric Power University Beijing China

ISBN: (纸本)9781424427994

This paper studies the voltage stability problems of wind farm access to electric grid. Based on the equivalent circuit of asynchronous machine, it deduces the relationship of wind turbine angular velocity rotation with the induction generator terminal voltage. Aiming at wind power for 10 kV distribution grid, a novel SVC is proposed to replace the fixed capacitors compensating devices. The reactive power can be detected based on the instantaneous reactive power theory and with this method the reactive power compensation is fast and continuous. The voltage level of wind farm access system is stable with a voltage feedback control strategy. The new SVC winding structure can achieve a multi-pulse, injecting the system small harmonic current component. Research results show that a corresponding control strategy of the novel SVC compensation device can be very good to improve voltage stability of wind farm access to the grid.

关键词： Voltage power system stability Wind farms power grids Static VAr compensators Reactive power Circuit stability Equivalent circuits Wind turbines Angular velocity

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Multi objectives operation of cascade inverter-based voltage quality compensator with PWM rectifier supply

Multi objectives operation of cascade inverter-based voltage...

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International Conference on power Electronics and Drive systems (PEDS)

作者： Renzhong Shan Zhongdong Yin Xiangning Xiao Yajing Di Ke Li Key Laboratory of Power System Protection and Dynamic Monitoring and Control under Ministry of Education North China Electric Power University Beijing China

A novel main circuit topology of voltage quality compensator (VQC) is proposed in this paper, composed of PWM rectifier and cascade H-bridges inverter. The three phase inverter is decoupling controlled. PWM rectifier is adopted to maintain the dc-bus voltage stably and provide or absorb real power. The inverter is controlled by carrier phase shifting with FPGA. The simulation model is set up on the platform of PSCAD/EMTDC, the voltage sag, swell and harmonic compensation is researched by theoretical and simulation. Finally, the simulation results show that the proposed main circuit topology and control strategy is feasible and efficient for multi objectives voltage quality compensation.

关键词： Pulse width modulation inverters Rectifiers Circuit simulation Circuit topology Pulse width modulation Voltage fluctuations Field programmable gate arrays PSCAD EMTDC Voltage control

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Comparison of pitch angle control models of wind farm for power system analysis

Comparison of pitch angle control models of wind farm for po...

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IEEE General Meeting power& Energy Society

作者： Li. Lin Jing. Zhang Yihan. Yang Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University Beijing China North China Grid Corporation Beijing China

With rapid development of wind power generation, the large capacity wind farms are built up and integrated into transmission network. The effect of wind farms on the grid becomes more serious and more extensive. In order to investigate the dynamic performances of the grid-connected wind farm and the interaction of the wind farms, it is necessary to present the appropriate models of wind farms, which can present the wind power characteristics completely and are not too complicated. In this paper, based on the detailed model of the pitch angle control system, two kinds of simplified pitch angle control models are deduced by mathematics equivalence method. Then the three models are adopted respectively, the relatively dynamic characteristics of the wind farm and the grid are compared. Later, the wind farm with different pitch angle control model is connected to the CIGRE B4-39 grid, and the simplified models are verified by simulation. Finally, the methods how to choice pitch angle control models are present.

关键词： power system modeling Wind farms power system analysis computing power system control power systems power system dynamics Mathematical model Wind power generation Wind energy Control system synthesis

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A Novel dynamic Var Compensator

A Novel Dynamic Var Compensator

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International Conference on Energy and Environment Technology (ICEET)

作者： Chengxin Dai Zhongdong Yin Renzhong Shan Key Laboratory of Power System Protection and Dynamic Monitoring and Control under Ministry of Education North China Electric Power University Beijing China

This paper proposed a novel dynamic reactive power compensation circuit topology which is applicable to low voltage distribution system. It described the composition, features, and working principle of dynamic reactive power compensation system. Open-loop SPWM control strategy is applied for the inverter, by adjusting the inverter output voltage to dynamically regulate the absorption or emission of reactive power by SVC, zero reactive power compensation of the system can be achieved. With the combination of fixed compensation capacitor the capacity of the inverter can be smaller when it compensates the reactive power dynamically, it can improve the power factor and voltage level fast, efficiently and reliably. It overcomes the switching oscillation and the shortcomings of inadequate compensation, at the same time, reduce power loss and improve the voltage quality.

关键词： Reactive power Inverters Reactive power control Circuit topology Low voltage Open loop systems Voltage control Control systems Absorption Static VAr compensators

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A Novel Hybrid dynamic Reactive power Compensator

A Novel Hybrid Dynamic Reactive Power Compensator

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IEEE PES Asia-Pacific power and Energy Engineering Conference (APPEEC)

作者： Renzhong Shan Zhongdong Yin Xiangning Xiao Chengxing Dai Key Laboratory of Power System Protection and Dynamic Monitoring and Control under Ministry of Education North China Electric Power University Beijing China

A novel dynamic reactive power compensation circuit topology suitable for low voltage distribution system was proposed. The efficient compensation of unbalanced load could be realized by the structure of three-phase four-leg inverter circuit. The sinusoidal pulse width modulation (SPWM) control of inverter could ensure the low distortion of voltage and current. Besides, by the regulation of the inverter's output voltage, the compensation reactive power could be dynamically regulated and the aim of system's zero reactive power compensation could be realized. Combined with fixed capacitor compensator, small capacity of inverter is required to compensate dynamic reactive power. The novel dynamic static var compensator (SVC) could improve the system's power factor and voltage stability. Finally, simulations are carried on the platform of PSCAD/EMTDC. The results show that the proposed control strategy is feasible and efficient.

关键词： Reactive power Pulse width modulation inverters Low voltage Static VAr compensators Circuit topology Pulse inverters Voltage control Capacitors Stability PSCAD

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Comparison of reactive power compensation strategy of wind farm based on optislip wind turbines

Comparison of reactive power compensation strategy of wind f...

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International Conference on Sustainable power Generation and Supply, SUPERGEN

作者： Li Lin Feng Sun Yihan Yang Qunju Li Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University Beijing China North China Electric Power Science Institute Beijing China

The paper studies reactive power compensation strategy of wind farm based on optislip wound rotor induction generators (WRIGs). The WRIGs wind farm shares high market occupancy in China, but academic researches on this grid-connected wind generation are few. Due to the WRIGs wind turbines not allowing the control of the reactive power, so it is necessary that reactive power compensation device is adopted in the large scale grid-connected wind farm. In the paper, from the perspective of system study, the compensation effects of three kind of static var compensation (SVC) are compared, and the influence of different ratings SVC on the voltage stability of the optislip wind farm is investigated. Finally, reactive power compensation strategy of the wind farm is proposed.

关键词： Reactive power Wind farms Wind turbines Induction generators Reactive power control Static VAr compensators Wounds Rotors Mesh generation Wind energy generation

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