Synchronous generators are important components of power systems and are necessary to maintain its normal and stable operation.To perform the fault diagnosis of mild inter-turn short circuit in the excitation winding ...Synchronous generators are important components of power systems and are necessary to maintain its normal and stable operation.To perform the fault diagnosis of mild inter-turn short circuit in the excitation winding of a synchronous generator,a gate recurrent unit-convolutional neural network(GRU-CNN)model whose structural parameters were determined by improved particle swarm optimization(IPSO)is proposed.The outputs of the model are the excitation current and reactive power.The total offset distance,which is the fusion of the offset distance of the excitation current and offset distance of the reactive power,was selected as the fault judgment criterion.The fusion weights of the excitation current and reactive power were determined using the anti-entropy weighting method.The fault-warning threshold and fault-warning ratio were set according to the normal total offset distance,and the fault warning time was set according to the actual situation.The fault-warning time and fault-warning ratio were used to avoid misdiagnosis.The proposed method was verified experimentally.展开更多
To study the effects of wind generators on distribution system protection,the short-circuit current(SCC) characteristics of wind generators is important.Although there are many researches on the issue,a clear agreemen...To study the effects of wind generators on distribution system protection,the short-circuit current(SCC) characteristics of wind generators is important.Although there are many researches on the issue,a clear agreement has not been reached so far.The SCC characteristics for different wind generators are studied.PSCAD simulation is performed in the same system integrated with different kinds of wind generators,and their results are compared with those reported in IEEE papers.The detection possibility by overcurrent relay(OCR)is discussed based on the simulation results.展开更多
With the increasing penetration of distributed generations(DGs)into power grids,the fault ride-through ability of DG is attracting more and more attention.Recent grid codes require a DG to maintain its connection with...With the increasing penetration of distributed generations(DGs)into power grids,the fault ride-through ability of DG is attracting more and more attention.Recent grid codes require a DG to maintain its connection with the grid during grid faults and to play an active role in the recovery of grid voltage.This paper chooses the doublyfed induction generator(DFIG)as the typical wind turbine for study.Firstly,a dynamic reactive power control strategy is proposed to improve the fault ride-through characteristic of a DFIG.The contributions of a DFIG to the fault current under the dynamic reactive power control and the Crowbar control are analyzed and compared based on the mathematical expressions and control behaviors.The impacts of a DFIG under two control strategies on distribution protections are discussed.Studies show that although a DFIG under the dynamic reactive power control provides more fault current component than one under the Crowbar control,its impacts on distribution protections are acceptable.Finally,a 10kV distribution network with a DFIG is simulated in PowerFactory DIgSILENT.The simulation results prove the correctness of above theoretical analysis.展开更多
文摘Synchronous generators are important components of power systems and are necessary to maintain its normal and stable operation.To perform the fault diagnosis of mild inter-turn short circuit in the excitation winding of a synchronous generator,a gate recurrent unit-convolutional neural network(GRU-CNN)model whose structural parameters were determined by improved particle swarm optimization(IPSO)is proposed.The outputs of the model are the excitation current and reactive power.The total offset distance,which is the fusion of the offset distance of the excitation current and offset distance of the reactive power,was selected as the fault judgment criterion.The fusion weights of the excitation current and reactive power were determined using the anti-entropy weighting method.The fault-warning threshold and fault-warning ratio were set according to the normal total offset distance,and the fault warning time was set according to the actual situation.The fault-warning time and fault-warning ratio were used to avoid misdiagnosis.The proposed method was verified experimentally.
基金supported by the Power Generation & Electricity Delivery of the Korea Institute of Energy Technology and Planning(KETEP)grant funded by the Korea Government Ministry of Knowledge Economy(No.2009T100200067)
文摘To study the effects of wind generators on distribution system protection,the short-circuit current(SCC) characteristics of wind generators is important.Although there are many researches on the issue,a clear agreement has not been reached so far.The SCC characteristics for different wind generators are studied.PSCAD simulation is performed in the same system integrated with different kinds of wind generators,and their results are compared with those reported in IEEE papers.The detection possibility by overcurrent relay(OCR)is discussed based on the simulation results.
基金supported by the National Basic Research Program of China(973Program)(No.2009CB219704)the Crucial Field and Key Breakthrough Project in "Guangdong-Hong Kong"(No.2009A091300011)Guangdong Special Fund Project of Industry,University and Research Institute Collaboration(No.2011A090200127,No.2011A090200074)
文摘With the increasing penetration of distributed generations(DGs)into power grids,the fault ride-through ability of DG is attracting more and more attention.Recent grid codes require a DG to maintain its connection with the grid during grid faults and to play an active role in the recovery of grid voltage.This paper chooses the doublyfed induction generator(DFIG)as the typical wind turbine for study.Firstly,a dynamic reactive power control strategy is proposed to improve the fault ride-through characteristic of a DFIG.The contributions of a DFIG to the fault current under the dynamic reactive power control and the Crowbar control are analyzed and compared based on the mathematical expressions and control behaviors.The impacts of a DFIG under two control strategies on distribution protections are discussed.Studies show that although a DFIG under the dynamic reactive power control provides more fault current component than one under the Crowbar control,its impacts on distribution protections are acceptable.Finally,a 10kV distribution network with a DFIG is simulated in PowerFactory DIgSILENT.The simulation results prove the correctness of above theoretical analysis.
