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IEEE General Meeting power& Energy Society

作者： Ming Yin Gengyin Li Ming Zhou Chengyong Zhao Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China electric Power University Beijing China

The paper presents the dynamic model and control schemes of a variable speed pitch wind turbine with permanent magnet synchronous generator (PMSG). The model includes a PMSG model, a pitch-angled controlled wind turbine model and a drive train model. The drive train model uses one-mass model to represent the mechanical characteristics of the generator set. The generator model is established in the dq-synchronous rotating reference frame. The wind turbine model details the mechanism of variable speed operation of the turbine by a pitch control. The control schemes in the paper include a pitch angle control for the wind turbine and a speed control for the generator. The pitch angle control uses wind speeds and electric power output as the input signals to ensure normal operation in high wind speed. The speed control is realized through field orientation where the d-axis current is set to zero and the q-axis current is used to control the rotational speed of the generator according to the variation of wind speed. In order to verify the presented model and the control strategy, simulations with MATLAB/Simulink software have been conducted. Simulation results prove the validity of the model and the control schemes.

关键词： Wind turbines Permanent magnets Synchronous generators Mathematical model Mechanical variables control Electric variables control Wind speed Magnetic variables control Velocity control Wind energy generation

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Three design schemes of compensation currents for D-STATCOM used for unbalanced load

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Dianli Xitong Zidonghua/Automation of Electric power systems 2007年第1期31卷 75-79页

作者： Zhu, Yongqiang Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control School of Electric and Electronic Engineering North China Electric Power University Beijing 102206 China

Three design schemes of compensation currents for D-STATCOM in delta connection used for unbalanced load compensation are introduced. They are the schemes based on compensation principle of admittance, no zero sequence component design and an optional design method of maximum minimizing phase current. Comparisons are made considering technical indexes and engineering significance among the proposed three schemes. In serious unbalanced operating conditions, the obvious difference in amplitude among the compensation currents in three phases may lead to one or two phase overloading and the compensation capability is restricted. The optional design makes the compensation currents in three phases to be equal or close to each other as possible as it can, which is helpful to ensure the D-STATCOM having high-usage and desirable compensation effect. Similar performance can be obtained to some extent with the simpler scheme of no zero sequence component design.

关键词： Electric loads

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Multi-layer Disturbance Processing system based on Multiple Information Sources

Multi-layer Disturbance Processing System based on Multiple ...

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IEEE General Meeting power& Energy Society

作者： Tianshu Bi Qian Li Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Beijing China

More and more IEDs have been commissioned in power systems, such as digital relays, PMUs, metering and control devices, fault recorders and so on. Once there is a disturbance (for example, fault, low-frequency oscillation, etc.), large amount of information will pour into the control center. Therefore, how to identify the disturbance and then take corresponding countermeasures is crucial for power system security and reliability. A multi-layer disturbance processing system based on multiple information sources is proposed in this paper. Firstly, the characteristics of different kinds of information sources, including PMUs, RTUs, digital relays and fault recorders, are analyzed. Secondly, according to the arrival times of the information, the framework and functions of multi-layer fault diagnosis system is presented in detail. After a disturbance occurs, the suggested system could realize disturbance identification, fault element diagnosis and detailed post-fault analysis in succession at different time frames with the information coming, which fits the needs of operators well.

关键词： Fault diagnosis Digital relays Phasor measurement units power system reliability Information analysis power system faults power system relaying power system control power systems control systems

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Decoupling control for Multiterminal VSC-HVDC Based Wind Farm Interconnection

Decoupling Control for Multiterminal VSC-HVDC Based Wind Far...

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IEEE General Meeting power& Energy Society

作者： Gengyin Li Ming Yin Ming Zhou Chengyong Zhao Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Beijing China

In the paper multiterminal voltage source converter based HVDC (VSC-HVDC) is proposed to interconnect wind farms to AC grids. The method highlights the control at the level of wind generator cluster that comprises several permanent magnet synchronous generators without the primary converters on themselves. For the cluster control, active and reactive power decoupling scheme is applied to adjust the rotational speed of the cluster according to wind speed. The paper studies the schemes to control grid side converter based on the philosophy of linear decoupling control, which aims to control the DC voltage as well as the reactive power of VSC-HVDC. In the proposed control scheme, the two goals are achieved by controlling the q- and rf-axis components of the grid's fundamental current. Simulation has been performed using engineering software Matlab/Simulink to verify the interconnection method and validate the control scheme as well.

关键词： Wind farms Converters power conversion Voltage control Synchronous generators Reactive power control HVDC transmission Wind energy generation Permanent magnets Wind speed

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Research on PT Ferromagnetic Resonance Region and the controllable Damping

Research on PT Ferromagnetic Resonance Region and the Contro...

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power Tech Conference

作者： L. X. Zhou Z. D. Yin Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Beijing China

In the neutral ungrounded system, potential transformer (PT) ferro-magnetic resonance is a kind of interior overvoltage which is frequently appears and creates most of the accidents. Whether the elimination measures are reasonable and effective or not affects the security and stability of the power system directly. Fundamental research has been done on the resonance region changeable situation and the characteristics of each resonance region under different system parameter and PT saturation characteristics. According to the occurring principle of PT ferromagnetic resonance and the characteristics, a novel effective controllable damping device is designed, which will change the correlative parameter that lead to resonance to make the circuit parameter of the system get out of the resonance area to eliminate the resonance. The accuracy of the fundamental analysis and the effectiveness of the elimination measure have been verified by the digital simulation based on EMTDC/PSCAD and by the high voltage propotype experiment.

关键词： Magnetic resonance Damping power system security power system stability PSCAD Voltage transformers Voltage control Accidents power measurement power system measurements

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A Mathematic Model and its Iterative Algorithm on Obtaining Optimal Capacity of P-S Station

A Mathematic Model and its Iterative Algorithm on Obtaining ...

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2007 International power Engineering Conference (IPEC2007), vol.1

作者： Fang Cao Li-zi Zhang Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Beijing China

With rising electricity loading in developing country, measuring capacity of pumped-storage station (P-S station) is becoming more critical. This paper tries to establish mathematic model on obtaining capacity of P-S station for maximum cost sayings. The paper first deducts the relationship between capacity of P-S station, peak load and the vale load by simulating cost curve of thermoelectric unit, and then deducts the formula for calculating optimal capacity of P-S station. Based upon these findings and the load curve, the paper then develops the curve to describe the relationship between volume of generated electricity and capacity of the P-S station and provides the solution for obtaining optimal capacity of the P-S station. Finally, the paper discusses the impact of selecting initial solution or certain iterative solution on iterative speed and suggests the direction for further research.

关键词： Iterative methods Optimization methods Pumped storage power generation

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Hybrid Non-linear State Estimation with Voltage Phasor Measurements

Hybrid Non-linear State Estimation with Voltage Phasor Measu...

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IEEE General Meeting power& Energy Society

作者： Xiaohui Qin Tianshu Bi Qixun Yang Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Beijing China

In this paper, a new method of hybrid non-linear state estimation with PMU is proposed. Firstly, the voltage phasor measurements are transformed into indirect equivalent branch current measurements, with which the conventional state estimator takes the impact of PMU into consideration. Secondly, the indirect measurement errors caused by the measurement transforming are analyzed and calculated in detail. Thirdly, the accuracy of hybrid estimator is analyzed in the paper. The simulation results show that the proposed method improves the accuracy of estimator and the convergence speed also.

关键词： State estimation Voltage measurement Phasor measurement units Current measurement Fluid flow measurement Jacobian matrices power measurement Bismuth power system simulation Hybrid power systems

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HV power equipment running state detection based on image processing and recognition

HV power equipment running state detection based on image pr...

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2006 International Conference on power system Technology, powerCON2006

作者： Shutao, Zhao Baoshu, Li Xiaohui, Zhu North China Electric Power University Baoding 071003 China Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University Baoding 071003 Hebei Province China North China Electric University

ISBN: (纸本)1424401119

Aimed at the necessary on the automatic detection level in unattended substation, a new method which monitoring and diagnosis the high-voltage (HV) power equipment running state based on image processing is put forward. Image processing techniques realize and strengthen the capability of the human vision. It is a non-contact measurement method, which can monitor the HV power equipment running state online. In recent years, it is widely applied in many fields and gets plentiful and substantial success. The HV power equipment running state detection process is introduced in this paper. After image preprocesses and feature extraction, the automatic target recognition algorithm based on the radial basis function neural network (RBFNN) is presented. © 2006 IEEE.

关键词： HVDC power transmission

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Top Copy

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IEEE Women in Engineering Magazine 2007年第1期1卷 16-17页

作者： Leslie Prives Key Laboratoty of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Baoding Hebei Province China

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Phase-to-Phase Distance Relay Based on the Measured Impedance Trajectory

Phase-to-Phase Distance Relay Based on the Measured Impedanc...

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IEEE General Meeting power& Energy Society

作者： Huanzhang Liu Qiankuan Liu Shaofeng Huang Qixun Yang Huazhong Electric Power Dispatch and Communication Center Wuhan China Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University Beijing China Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Beijing China

The measured impedance trajectory changing with fault resistance during multi-phase faults and the reasons that fault resistance may cause unwanted impedance relay operations in two-source systems were analyzed in this paper. To improve the impedance relay adaptive ability and reliability during three phase fault, a combined phase-to-phase impedance relay based on the measured impedance trajectory was presented. The relay is composed of three criteria respectively called the reactance line based on the measured impedance trajectory, the sending end and the receiving end directional lines, whose transient and steady state operating characteristics have been analyzed for forward and reverse faults. The simulation test was made by RTDS on a 340 km long 750 kV line in a two-source system. Theoretical analysis and dynamic simulation test results show that the adaptive relay can respond to three phase faults and phase-to-phase faults, and has satisfactory performances.

关键词： Protective relaying Impedance measurement Phase measurement Relays Electrical resistance measurement Transient analysis Steady-state system testing Performance analysis Analytical models

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