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2005 IEEE/PES Transmission and DistributionConference and Exhibition - Asia and Pacific

作者： Sheng, Siqing Wang, Cong Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University Baoding 071003 Hebei Provinece China School of Electrical Engineering North China Electrical Power University Baoding Hebei 071003 China

ISBN: (纸本)0780391144

Short-term load forecasting of power system is not only the basis of scheduling of generating sets, but also the basis of working out the transaction schedule in electricity market. This paper proposes a short-term load forecasting method based on combination of Radial Basis Function (RBF) neural network and fuzzy control, uses on-line self-modify factor fuzzy control to eliminate forecast error on the basis of RBF neural network forecasting. The practical examples show that the accuracy of short-term load forecasting and training speed can be improved and gains the very satisfactory results by the proposed method. © 2005 IEEE.

关键词： Electric load forecasting

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Risk management on long-term electricity purchase allocation in China power markets

Risk management on long-term electricity purchase allocation...

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Sixth International Conference on Power Electronics and Drive systems, PEDS 2005

作者： Zhou, Ming Li, Gengyin Nie, Yanli Ni, Yixin Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Baoding 071003 Hebei Province China Department of Electrical and Electronic Engineering University of Hong Kong Hong Kong Hong Kong

ISBN: (纸本)0780392965

This paper presents an integrated framework for the optimal management of electricity purchase allocation and risk for load service entities (LSEs). To the practice of China Power Markets, we propose the framework of power portfolio of combined physical forward contract and spot market. The framework suggests that the forward contracts should have different prices on-peak and off-peak in accord with sale prices distinguish on-peak and off-peak. The optimal purchase problem is described by the utility maximum integrated the rate of return and risk tolerance level, and risk is evaluated by Value at Risk (VaR). The analytical solution is also conducted. The numerical results are reasonable with higher rate of return and better risk hedging compared with the corresponding results from the existing portfolio selection approach. The presented framework gives one possible and effective method for the optimal power portfolio and risk management in incomplete power markets. © 2005 IEEE.

关键词： Risk management

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Condition-based maintenance of electrical equipments based on ID3 algorithm and Monte Carlo stimulation

Condition-based maintenance of electrical equipments based o...

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2005 IEEE/PES Transmission and DistributionConference and Exhibition - Asia and Pacific

作者： Li, Ran Chen, Li Gu, Xueping Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric PowerPower University Baoding 071003 Hebei Province China Department of Electrical Engineering North China Electric Power University North China Electric Power University

ISBN: (纸本)0780391144

Condition-Based Maintenance is an advanced maintenance strategy which is based on the monitoring of equipments status and according to the results of monitoring and analysis people can arrange maintenance scientifically. When monitoring and analyzing the status of equipments, there are vast historical and on-line data to analyze. If we can find the main factors leading to equipment failure through analyzing the data and pay more attention to these factors, we can make maintenance decision more exactly and quickly. In this paper we propose to apply ID3 Algorithm to classify the data according to the importance of their influence to equipment failure and then find the factors which influence equipments most. After finding the most important factors, apply Monte Carlo Simulation to forecast the probability of equipment failure which occurs in their operational life span, and according to this we can pay more attention to monitor the factors which result in failure easily. © 2005 IEEE.

关键词： Electric equipment

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Monte Carlo simulation based available transmission capability calculation

Monte Carlo simulation based available transmission capabili...

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2005 IEEE/PES Transmission and DistributionConference and Exhibition - Asia and Pacific

作者： Gao, Yajing Zhou, Ming Li, Gengyin Huang, Yuekui Xiao, Limin Li, Rui IEEE Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University Baoding 071003 Hebei Province China Hebei Electric Power Company Shijiazhuang 050021 Hebei Province China

ISBN: (纸本)0780391144

With the further development of power markets, large amount of electric power wheeling and frequent transmission transaction is emerging, accurately determining Available Transmission Capability (ATC) and broadcasting the ATC information in time are very important to prevent and relieve transmission congestion effectively. In practical power markets, there are large amount of uncertainties involved in Transmission Reliability Margin (TRM) and Capacity Benefit Margin (CBM) of ATC. Considering calculation accuracy and time, a novel approach is proposed to calculate ATC based on Monte Carlo simulation and sensitivity analysis considering large amount of uncertainties impacting the value of ATC. The steady state constraints and voltage stability and transient stability constraints are taken into account. The iterative solution based on PSASP by China EPRI is developed. IEEE 14-bus test system is used to verify the presented approach. The results show that the model and algorithm is correct and effective. The research achievements are undergoing to transfer to the application in certain provincial power system in China, and some new problems are suggested in the end of paper. © 2005 IEEE.

关键词： Power transmission

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A Novel Structure of dynamic Reactive Power Source

A Novel Structure of Dynamic Reactive Power Source

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IEEE/PES Transmission and Distribution Conference and Exhibition: Asia and Pacific

作者： Zhongdong Yin Jianhua Zhang Xiangning Xiao Zhengpai Cui Yunbo Long Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University China

This paper puts forward a novel topology of controllable reactor, the structure is based on many small capacity thyristor controlled reactor (TCR) modules and a three-windings transformer connecting to system. The transformer secondary adopts duplex winding structure and each has multi-bank TCR modules being in delta connection. In this topology, the harmonic current injected into the power system is very small. It not only possesses all the functions a traditional TCR has, but also has many other merits such as occupying small floor space, generating little loss, easy implement control and protection scheme, and high reliability etc. A 500 kVar industrial prototype is under construction in Langfang, Hebei province of ***. Digital simulation based on EMTDC/PSCAD and field test were carried out to verify the perfect harmonics characteristics of topology proposed

关键词： Reactive power Topology Power system harmonics control systems Inductors Power system protection Power system reliability PSCAD Thyristors Joining processes

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New algorithm based on the distribution of the normalized equivalent instantaneous inductance for the discrimination of inrush

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Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2005年第23期25卷 47-53页

作者： Zheng, Tao Liu, Wan-Shun Zhuang, Heng-Jian Li, Xiao-Bo Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Beijing 102206 China SP Longyuan Environment Engineering Beijing 100761 China

Oriented to wye-delta connected three phase transformer, a new configuration of current transformer (CT) in transformer differential protection is proposed. In this configuration, only one single phase CT connected in any phase of the delta side is more needed than the traditional scheme. Worked with line currents measured by other current transformers connected in both sides of the transformer, any phase current in the delta side can be calculated based on the Kirchhoff's Current Law. This new scheme ensures the accurate calculation of the equivalent instantaneous inductance, which is immune to the loop current existed in the delta side of transformer, as well as no dead zone in transformer differential protection. A new algorithm based on the distribution of the normalized equivalent instantaneous inductance for the discrimination between inrush current and fault current is proposed. The normalization of equivalent instantaneous inductance makes the setting-value have little relation with the parameter of transformers, which has more universal meaning in the determination of setting values. Utilizing the distributive characteristic of the normalized equivalent instantaneous inductance, the variety of the normalized equivalent instantaneous inductance is effectively revealed. At last, experiment data obtained from HYBRISIM (Hybrid Simulator) validates the reliability and sensitivity of this algorithm. This algorithm has good prospect of engineering application in the EHV transformer protection.

关键词： Transformer protection

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Iterative Prony Method Based Power system Low Frequency Oscillation Mode Analysis and PSS Design

Iterative Prony Method Based Power System Low Frequency Osci...

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IEEE/PES Transmission and Distribution Conference and Exhibition: Asia and Pacific

作者： Hu Guoqiang He Renmu Yang Huachun Wang Peng Ma Rui Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University Beijing China

This paper presents an identification method based on the iterative Prony to identify transfer function and configure PSS parameters using residue way. The iterative Prony is a very useful method to acquire power system oscillation modes, by which the system eigenvalue, oscillation frequency, amplitude, damping and relative phase can be directly estimated using the response of given input signals. Considering the influence of input signal on output signal, the iterative Prony can acquire the transfer function of power system, then, according to the corresponding residues we conducted coordinated setting of power system stabilizer (PSS) by residue method. The simulation results for two testing system examples prove that this proposal method is effective in the power system oscillation mode analysis and parameters determination of PSS, can improve eigenvalues of system and can enhance system damping after PSSs whose parameters are optimized by above method are built into power system

关键词： Iterative methods Power system analysis computing Power system simulation Transfer functions Eigenvalues and eigenfunctions Frequency estimation Damping Amplitude estimation Phase estimation Analytical models

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A statistical method of improving the resolution of time-delay of UHF signals for PD location in transformers

A statistical method of improving the resolution of time-del...

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Conference on Electrical Insulation and Dielectric Phenomena, (CEIDP)

作者： Zhiguo Tang Chengrong Li Xu Cheng Wei Wang Jun Li Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University Beijing China

It's important to make an accurate PD location in transformers for fault diagnosis and maintenances of power systems. Theoretically it's possible to locate the PD source by measuring the differences in the arrival time at the UHF sensor array. The propagation velocity of EM wave in air is 30 cm/ns, which is extremely fast, so the resolution of the time-delay of UHF signals detected at the UHF sensor array is one of the key points to make an accurate PD location. Here, we propose a mathematical method: cross-correlation-shifting-averaging algorithm that can improve the resolution of the UHF signal's time-delay by increasing the signal to noise ratio and reducing the time dispersion caused by the random nature of PD. The practical processing results of experimental data from our laboratory indicate that the method can increase the time-delay resolution by nano-seconds in some cases, which improve PD location accuracy by tens of centimeters.

关键词： Statistical analysis Signal resolution Transformers Sensor arrays Microwave antenna arrays Fault diagnosis Power system faults Power system measurements Time measurement UHF measurements

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The fault diagnosis layer model of electric power grid based on weighted mean roughness

The fault diagnosis layer model of electric power grid based...

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IEEE/PES Transmission and Distribution Conference and Exhibition: Asia and Pacific

作者： Li Ran Ix Li Jinghua Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education China Electric Power University Baoding Hebei China

Based on rough set, this paper use discernibility matrix to reduce the condition attributes. The reduced samples are laid by weighted mean roughness to avoid blindness and redundancy. By this method, model space can be compressed greatly and weighted mean roughness is easy to calculate. Weighted mean roughness is used to separate attributes' priority in every lay, which make the diagnosis system had strong tolerant ability. When the electric power grid is fault, the result of diagnosis will be correct by searching every lay with priority level. The correctness and effectiveness are validated by the analysis result of emulation

关键词： Fault diagnosis Power systems Fault tolerance Redundancy Blindness Power system modeling Emulation Power grids Rough sets Power system reliability

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Research on DC Bias Due to Magnetic Storm and DC Transmission

Research on DC Bias Due to Magnetic Storm and DC Transmissio...

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IEEE/PES Transmission and Distribution Conference and Exhibition: Asia and Pacific

作者： Weiping Shi Lianguang Liu Qian Wang Zongqi Liu Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University Beijing China

This paper focuses on the research on the DC bias due to magnetic storm and HVDC. In the paper, we introduce the DC bias problem of Jiangsu Yang-Huai transmit electric system and Southern Power Grids, discuss the harmful effect of the transformer DC bias and the significance of research, and analyze the compensation, weakening and elimination of transformer bias current. Finally, the problems that should be paid attention to and some corresponding suggestions are proposed

关键词： Storms Power grids Substations HVDC transmission Grounding Power transmission lines Electrodes Magnetic analysis system testing Power generation

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