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IEEE PES Transmission and Distribution Conference and Exposition

作者： Chang-you Yan Jian-fei Yang Liu Qi-Xun Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Beijing China

In this paper, a novel real time data compression and reconstruction method is proposed to process a large amount of steady state and transient data of power system. Based on the biorthogonality filters group with the linear wavelet (WT) of lifting scheme and Huffman coding approach, the new algorithm is studied and developed. The field data are used to test the method. The results prove that the method is valid with less data processing time and as high as about 9 times of compression ratio. This method is suitable for the real-time compression of mass data recorded continuously by dynamic monitoring devices of electric power system

关键词： Data compression Reconstruction algorithms Real time systems power system transients Steady-state Nonlinear filters Huffman coding Testing Data processing power system dynamics

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Perturbed trajectory prediction method based on wide area measurement systems

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Dianli Xitong Zidonghua/Automation of Electric power systems 2006年第23期30卷 27-32页

作者： Song, Fangfang Bi, Tianshu Yang, Qixun Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Beijing 102206 China Sifang Research Institute North China Electric Power University Beijing 102206 China

A novel method for perturbed trajectory prediction of post-fault rotor angle is presented in this paper, which is based on phasor measurement unit (PMU) measurements and trigonometric function curve fitting technique. A mathematical relationship of post-fault rotor angle and time is derived from a speed-governing system, which reveals that the perturbed trajectory of the post-fault rotor angle can be expressed by attenuation trigonometric functions. Using curve fitting technique and trigonometric function, a least square method to predict the perturbed trajectory is proposed. Numerical simulations are conducted in IEEE 9-bus system and the simplified north China grid to test the effectiveness of the proposed method. The proposed method can give more reasonable and more promising prediction results as compared with polynomial curve fitting technique.

关键词： Electric power systems

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A Practical Approach for Ride Through of Super Capacitor Energy Storage Based ASD system

A Practical Approach for Ride Through of Super Capacitor Ene...

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IEEE PES Transmission and Distribution Conference and Exposition

作者： Zhongdong Yin Minxiao Han Yunlong Du Zheran Zhang Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University China

A practical ride through scheme bases on super capacitor energy storage system for ASD (adjustable speed drive) equipment is presented in this paper. The topology of ASD discussed adopts AC-DC-AC structure and 12 pulses diode rectifier as input interface. Super capacitor (SC) module connects to inverter DC bus to support DC voltage while power quality problems such as voltage sag or short-term outage take place in power source. A SC energy storage system based 15 kVA ASD prototype was developed. Digital simulation and physical experiments were carried out to verify the correctness and validity of proposed ASD ride through topology and control strategies

关键词： Capacitors Energy storage Variable speed drives Topology Voltage fluctuations Diodes Rectifiers Inverters power quality Prototypes

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power factor and power quality improvement in distribution networks via a novel dynamic reactive compensation equipment

Power factor and power quality improvement in distribution n...

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7th IET International Conference on Advances in power system Control, Operation and Management, APSCOM 2006

作者： Ji, Hongquan Yang, Yihan Gu, Haibin Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education Changping District Beijing 102206 China School of Electrical Engineering North China Electric Power University Changping District Beijing 102206 China Power Design and Research Institute Baoding Power Supply Co. Hebei Province Baoding 071051 China

ISBN: (纸本)0863412467

In order to keep the power factor at a high level and maintain acceptable voltage quality in distribution systems, a novel dynamic reactive compensation equipment is proposed. This equipment, which consists of a special regulating autotransformer with a vacuum on-load tap-changer and an intelligent power factor controller (IPFC), adopts step-voltage- regulating control method. It bases on the principle of the capacitor bank's output is in direct ratio with the square of the voltage works on it. In the course of tap- changer switching, the capacitor bank is not cut-out from the power system all along, it is proved in theory that dangerous over-voltage and associated inrush current will not occur. Thus security of the operation on capacitor bank is improved greatly and its natural life will increase much too. Compared with any other dynamic reactive compensation this novel equipment is less expensive and would be more likely to be put to be practical use. In the end, experimental results are given to verify that the proposed equipment has good characteristic of dynamic reactive compensation.

关键词： power quality

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Research on the infnluence of load characteristic on voltage stability

Research on the infnluence of load characteristic on voltage...

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International Conference on power system Technology (powerCON)

作者： Zhang Yanping Zhang Jianhua Huang Wei Yu Han Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Beijing China

Induction-motors are the main component of the compositive load especially of the industry load and air- condition loads have been uppermost dynamic load in summer with the fast economy development, which are very important to analysis and control power system. So induction-motors and air-condition loads are studied seriously as dynamic loads in this paper. This paper studies the function mechanism and the influence of static and dynamic load characteristic on voltage stability by comparing the voltage stability simulation result of different loads based on a simple case of power system. The small disturbance analysis method is used and static load, induction-load and air-condition load are modelled in this paper. It is proved that power system get more and more voltage instability with induction-motor or air-condition load increasing, especially air-condition load.

关键词： Voltage power system stability power system dynamics power system simulation power system analysis computing power system modeling power system control Electrical equipment industry Industrial control Control system analysis

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Researches on the Load Representation of Hunan power Grid AC/DC system

Researches on the Load Representation of Hunan Power Grid AC...

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International Conference on power system Technology (powerCON)

作者： Z.y. Liu J. Wen M.x. Han L. Dong H. Ding Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Beijing China

Both static and dynamic electric load characteristics have considerable effect on short circuit ratio (SCR) or effective short circuit ratio (ESCR). This paper gives emphasis on the relationship between static/dynamic load characteristics and SCR (ESCR). Different power level with different power factor is considered for the impacts on SCR or ESCR of static load characteristics. Three-phase short-circuit current of induction motors is qualitative analyzed and simulation of the feeding current is carried out for the dynamic process of induction motor in the consideration of dynamic load characteristics. Case studies are carried out on WEPRI-36 system and Hunan power grid. Simulation results with power system analysis software package (PSASP) illustrates that load should be considered in calculating SCR.

关键词： power grids power system dynamics Thyristors power system simulation Induction motors Analytical models Reactive power Circuit simulation power system analysis computing Software packages

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Study on Secondary Voltage Control Based on Multi-agent Particle Swarm Optimization Algorithm

Study on Secondary Voltage Control Based on Multi-agent Part...

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International Conference on power system Technology (powerCON)

作者： Z. W. Jia J. Liu X. M. Xie Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Beijing China

Secondary voltage control system is a significant segment of the hierarchical voltage control in power systems. Though voltage controller has both constant voltage regulators, such as generators and static reactive power compensators, and discrete voltage regulators, such as OLTC and shunt capacitors/reactors, traditional secondary voltage control (SVC) only consider constant voltage regulators. A few of the papers consider discrete voltage regulators, but they are also treated as constant variable. In this paper, Considering the trait of continuous and discrete devices in secondary voltage control co-existing, a mixed secondary voltage control optimal model including continuous and discrete variables is established. The solution is gained by multi-agent particle swarm optimization algorithm. This method concerned with the advantages of multi-agent system and particle swarm optimization algorithm can get every setting value of regulator exactly and quickly. The proposed method is applied to the New England 39 nodes system. It is shown that by contrast to the traditional secondary voltage control, this method can achieve satisfactory controlling effort involved both constant and discrete controllers at the same time.

关键词： Voltage control Particle swarm optimization Regulators power system control power systems power generation Reactive power control Shunt (electrical) Capacitors Inductors

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Wams Based Flow Transferring Indentification Algorithm and its implementation

Wams Based Flow Transferring Indentification Algorithm and i...

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International Conference on power system Technology (powerCON)

作者： H. M. Xu T. S. Bi S. F. Huang Q. X. Yang Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Beijing China

When relays trip a faulted line in power system, the flow on the faulted line will be transferred to the other lines. Those lines might be overloaded and then cascading tripped by the backup relays, which worsen the system state and even cause blackout. Generally, these kind of cascading trips are the origins of a lot of well-known blackouts. In this paper, by analyzing the defects of traditional backup protections, a new wide area backup protection scheme based on WAMS is presented to identify flow transferring. A new concept of flow transferring relativity factor (FTRF) is proposed to estimate the flow distribution after flow transferring occurs; and the method of calculating FTRF matrix online is also deduced. The simulation of 10-unit and 39-bus New England network shows that the proposed wide area backup protection scheme can identify flow transferring successfully and hence be superior to the traditional backup protection.

关键词： power system protection power system relaying power system faults power system security Protective relaying Wide area measurements Fault diagnosis power system reliability Bismuth power system measurements

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A simple method for measuring complex transfer impedance and admittance of shielded cable in substations

A simple method for measuring complex transfer impedance and...

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International Zurich Symposium on Electromagnetic Compatibility (EMC Zurich)

作者： Lei Qi Xiang Cui Xuesong Gu Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control underMinistry of Education North China Electric Power University Baoding Hebei China

In substations, shielded cables are widely used to reduce transient electromagnetic interference to the relay and control equipments due to the switch operation. Both the transfer impedance and transfer admittance are quantities for expressing numerically the mechanism that allows the passage of electromagnetic energy across the cable shield. Theoretical models to compute both the quantities often rely on simplifying assumptions. This, together with the fact that the transfer impedance and admittance can vary considerably between cable samples of the same type, means that measurements become necessary. In this paper, based on the transmission line theory we present a simple method to measure the transfer impedance and admittance of shielded cable in magnitude as well as in phase over the frequency range (0.1 MHz-10 MHz) which covers the main interference frequencies in power system. To illustrate this method a coaxial cable with a braided shield has been measured and compared with the existing method. As an application, the proposed method is used to predict the induced voltage and current on the shielded cable due to the switch operation in substation

关键词： Admittance measurement Impedance measurement Cable shielding Substations Switches Electromagnetic measurements power cables Transmission line measurements Frequency power system transients

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Computation of power line tower lightning surge impedance using the electromagnetic field method

Computation of power line tower lightning surge impedance us...

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International Zurich Symposium on Electromagnetic Compatibility (EMC Zurich)

作者： Changzheng Gao Lin Li Bing Li Zhibin Zhao Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control underMinistry of Education North China Electric Power University Baoding Hebei China

The power line tower lightning surge impedance is computed using an electromagnetic field approach. After comparing the results computed by our method and those tested with both a vertical conductor and reduced scale 4-poles model of tower, the method we used is proved to be right and more practical as the soil and the grounding system of the tower can be considered in the method. Using this method, the lightning surge impedance of the full scale UHV tower with grounding system is analyzed and the results show that the lightning surge impedance of a tower on the perfect ground has a little difference with those of an actual tower considering both its grounding system and soil resistivity, and when the soil resistivity is changed, the surge impedance changes slightly. Furthermore, a circuit model of the tower is obtained by vector fitting method based on the results we computed. Using the circuit model, the lightning surge performance of a power transmission line can be analyzed more accurately by EMTP or other methods

关键词： Poles and towers Lightning Surges Impedance Electromagnetic fields power system modeling Soil Grounding Conductivity Circuits

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