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【期刊论文】Multi-Agents Based Protection for Distributed Generation Systems
曾祥君, Zeng Xiangjun, Member IEEE, Li K.K, Senior Member IEEE, Chan W.L., Senior Member EEE, Su Sheng, Non-Member
2004 IEEE International Conference on Electric Utility Deregulation, Restructuring and Power Technologies (DRPT2004) April 2004 Hong Kong,-0001,():
-1年11月30日
As a result of deregulation, distributed generation(DG) systems with distributed generators installed in the middleor low voltage networks become popular in distribution systems.Traditional protections developed in radial systems are difficult incoordination and in protecting against high impedance fault(HIF), sometimes it may cause nuisance tripping in the DGsystems. A decentralized multi-agent based protection withcapability of HIF detection, fault location and load shedding forthe DG systems is proposed in the paper. Digital relay is designedas a relay agent which is capable of searching for informationfrom other relay agents, interacting with other relay agents andperforming tasks of protection with autonomy and cooperating.The agent based protection scheme is also presented. EMTPsimulation results show that the proposed agent based protectionscheme can remove the influence of load switching operations,protect against HIF, electric shock. The prototype of relay agentis developed, the research is now in progress on testing theprototype in dynamic power system.
Index Terms-Distributed Generator Systems, High Impedance Fault, Relay Agent, Power System Protection,
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【期刊论文】On-Site Safety Evaluation for Earth Fault in Mining Power Systems
曾祥君, Zeng Xiangjun, Member, IEEE, K. K. Li, Senior Member, W. L. Chan, and Yin Xianggen
IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL. 39, NO.6, NOVEMBER/DECEMBER 2003,-0001,():
-1年11月30日
Many mining power systems utilize ineffectivelygrounded sources to restrict the residual current of single-phaseearth fault in order to reduce outage and shock hazard. Inpractice, with the system expansion, topology changing, andinsulation aging, the potential residual current and zero-sequencevoltage for earth fault vary dynamically and some arcing earthfaults can easily cause over-voltage and induce multiple faults. Inorder to improve the system safety, on-site condition monitoring,safety evaluation, and preventive maintenance for earth fault areproposed in this paper. Some techniques for online parametersmeasurement based on resonance-measurement principle arepresented. Power system operation states are classified intonormal secure state, alert state, incipient fault state, and faultstate. Some security enhancement methods (preventive action andremedial action) for each state are implemented. The prototypefor safety evaluation has been developed and installed in industrypower systems for several years.
Index Terms-Condition monitoring, earth fault, mining power system, preventive maintenance, safety e, v, a, l, uation.,
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【期刊论文】Some Ground Fault Protection Schemes Implemented on FTU for Industrial Power Systems
曾祥君, Zeng Xiangjun, Li K.K, Guo Zigang, and Su Sheng
,-0001,():
-1年11月30日
Many industrial power systems have been operatedwith floating neutral or high resistance grounding. Withtraditional fault detection methods, based on zero sequencecurrent, it is difficult to satisfy the requirement of distributionautomation (DA). In order to improve this, some noveltechniques for ground fault feeder detection are presented in thispaper, and they are implemented by using the informationobtained from the feeder terminal unit (FTU). The faulty feederis identified with fuzzy analysis. These protection schemes havebeen verified by EMTP simulation. A prototype has beendeveloped and tested in a dynamic power system. Results showthat these proposed protection schemes have high sensitivity androbustness to detect all kinds of ground faults.
Distribution automation (, DA), , feeder terminal unit (, FTU), , faulty feeder detection, grounding protection.,
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【期刊论文】Some Novel Techniques for Improving Power Quality in Distribution Networks
曾祥君, Zeng Xiangjun, MIEEE, Li K.K, Senior MIEEE, Chan W.L., Yin Xianggen, Non-Member
2004 IEEE International Conference on Electric Utility Deregulation, Restructuring and Power Technologies (DRPT2004) April 2004 Hong Kong,-0001,():
-1年11月30日
Power quality is influenced by neutral grounding methods in distribution systems. Optimization for neutral grounding methods is discussed in the paper. Petersen-coil in parallel with high resistance earthed technique has a better performance in safety and power quality than other neutral point grounding techniques. To improve power quality, a novel method for measurement of zero sequence impedance in distribution systems is presented, Petersen-coil inductance is adjusted to compensate the total capacitance, and the resistor which is in parallel with the Petersen-coil is adjusted to control the over-voltage; some other novel techniques for grounding fault feeder protection based on testing the fault resistance or the energy dissipated in the fault point are also presented. The method of Petersen-coil tuning has been developed. Experimental results show that the optimization for neutral grounding methods and the protections proposed can improve the power quality by reducing the over-voltage, the residual current and the grounding fault duration
Index Terms-Power quality, Petersen-coil tuning, Protective relaying, Fault detection
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【期刊论文】Wavelet Analysis Based Protection for High Impedance Ground Fault in Supply Systems
曾祥君, ZengXiangjun and K.K.Li, W.L.Chan
,-0001,():
-1年11月30日
Many High impedance ground faults (HIGF) that happen in low voltage (LV) system often cause customer supply lost, fire and human safety hazard. Traditional ground fault protection is provided by Residual Current Circuit Breaker 0RCCB). The RCCB often causes nuisance tripping and is difficult to detect HIGF. Wavelet analysis based HIGF protection is developed in the paper. Wavelet transform is applied to filter out some frequency bands of harmonics from residual current and line current. The root mean square (RMS) value of harmonics are calculated using their wavelet coefficients directly. HIGF is identified from disturbance by the RMS difference between the residual current and the line current. The digital protection scheme is designed. EMTP simulation results show that the new protection is able to detect HIGF and prevent electric shock with high sensitivity and robustness.
Index Terms-Ground fault Protection, High impedance fault, Low voltage systems, Wavelet analysis.,
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