Electrical and Electronics Engineering: An International Journal (ELELIJ) Vol 2, No 2, May 20131PROTECTION COORDINATION OF...
Electrical and Electronics Engineering: An International Journal (ELELIJ) Vol 2, No 2, May 20132N. Hadjsaid and et al in [...
Electrical and Electronics Engineering: An International Journal (ELELIJ) Vol 2, No 2, May 20133algorithm to coordinate th...
Electrical and Electronics Engineering: An International Journal (ELELIJ) Vol 2, No 2, May 201343. COORDINATION STUDY FOR ...
Electrical and Electronics Engineering: An International Journal (ELELIJ) Vol 2, No 2, May 20135ProtectionZonePrimaryprote...
Electrical and Electronics Engineering: An International Journal (ELELIJ) Vol 2, No 2, May 20136F9 zone Fuse F9 Fuse F4, r...
Electrical and Electronics Engineering: An International Journal (ELELIJ) Vol 2, No 2, May 20137with synchronization equip...
Electrical and Electronics Engineering: An International Journal (ELELIJ) Vol 2, No 2, May 20138Figure 3. New coordination...
Electrical and Electronics Engineering: An International Journal (ELELIJ) Vol 2, No 2, May 20139Recloser, fuse F10Fuse F15...
Electrical and Electronics Engineering: An International Journal (ELELIJ) Vol 2, No 2, May 201310DGsizeFault current contr...
Electrical and Electronics Engineering: An International Journal (ELELIJ) Vol 2, No 2, May 201311impact. The proposed appr...
Electrical and Electronics Engineering: An International Journal (ELELIJ) Vol 2, No 2, May 201312[13] K. Tuitemwong and S....
Electrical and Electronics Engineering: An International Journal (ELELIJ) Vol 2, No 2, May 201313Ahmed M. Azmy was born in...
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PROTECTION COORDINATION OF DISTRIBUTION SYSTEMS EQUIPPED WITH DISTRIBUTED GENERATIONS

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PROTECTION COORDINATION OF DISTRIBUTION SYSTEMS EQUIPPED WITH DISTRIBUTED GENERATIONS

  1. 1. Electrical and Electronics Engineering: An International Journal (ELELIJ) Vol 2, No 2, May 20131PROTECTION COORDINATION OF DISTRIBUTIONSYSTEMS EQUIPPED WITH DISTRIBUTEDGENERATIONSAhmed Kamel1, M. A. Alaam2, Ahmed M. Azmy3and A. Y. Abdelaziz41South Delta Electricity Distribution Company, Tanta, Egypte.akamel@yahoo.com2,3Department of Electrical Power & Machines Engineering, Faculty ofEngineering, Tanta University, Tanta, Egyptmhmd.aboelazm@gmail.comazmy.ahmed@hotmail.com4Electrical Power & Machines Department, Faculty of Engineering, Ain ShamsUniversity, Cairo, Egyptalmoatazabdelaziz@hotmail.comABSTRACTCoordination among protective devices in distribution systems will be affected by adding distributedgenerators (DGs) to the existing network. That is attributed to the changes in power flow directions andfault currents magnitudes and directions due to the insertion of DG units in the distribution system, whichmay cause mis-coordination between protection devices. This paper presents an approach to overcome theimpacts of DG units insertion on the protection system and to avoid the mis-coordination problem. Theproposed approach depends on activating the directional protection feature which is available in mosttypes of modern microprocessor-based reclosers. This will be accompanied by an updating of relays andreclosers settings to achieve the correct coordination. Its clear that this approach do not need any extracosts or any extra equipment to be installed in the distribution system. An existing 11 kV feeder, simulatedon ETAP package, is used to prove the suitability and effectiveness of the proposed approach. The resultsensure the possibility of achieving the proper coordination between protective devices after inserting DGunits if the proper and suitable settings of these devices are realized.KEYWORDSProtection Coordination, Distribution Networks, Distributed Generation (DG), ETAP, Recloser.1. INTRODUCTIONConnection of DGs to distribution systems brings up several environmental, economical andtechnical benefits such as reduced environmental pollution, improved voltage profile, reducedelectric losses, increased distribution system capacity and increased system reliability [1]. Theprevious studies [2-6] have shown that DGs insertion in distribution systems changes short circuitcurrent levels and direction of power flow. This may cause significant impact on the protectionsystem such as protection-devices mis-coordination and asynchronous reclosing. Protectionsystem for distribution networks uses simple protection devices such as over current relays,reclosers and fuses, where the coordination between these devices is well established assumingradial systems. Penetration of DGs in distribution system should be accompanied with changes inthe protection scheme to overcome the previously mentioned impacts.
  2. 2. Electrical and Electronics Engineering: An International Journal (ELELIJ) Vol 2, No 2, May 20132N. Hadjsaid and et al in [7] present an example to study the impact of DG penetration indistribution systems on the fault currents passing through protection devices. They suggested thatthe protection coordination should be checked after the connection of each DG unit. The effect ofdistributed generation on fuse-recloser coordination in distribution systems was studied in [8 and9], where it is stated that DG connection can result in loosing coordination between these devices.An adaptive protection scheme for optimal coordination of over-current relays taking in toaccount DG units insertion was introduced in [10], where new relay setting technique wasimplemented for changes in loads and generation. A study for the technical impacts of distributedgeneration on fuse based protection and an approach to avoid DG impacts was introduced in [11].A solution for the coordination problem was introduced in [12] based on dividing the distributionsystem into zones separated by remotely controlled breakers. The faulted zone is disconnected bytripping the appropriate breaker. The disadvantage of this approach is its high cost andcomplexity of communication and control especially for long feeders. An expert system forprotective-devices coordination in radial distribution networks with small power producers wasintroduced in [13]. This presents a very useful approach for coordinating multiple protectiverelays in a distribution system. However, computer program is just the assistant for the shortcircuit calculation. The configurations of the protective devices still have to be specified byhuman. So, the expert system is just the alternative way for the protective device coordination.Artificial Neural Network (ANN) has been used in protection coordination [14 and 15]. ANNmay be helpful in calculating power flow and fault levels, but coordination settings may be toocomplicated for ANN to deal with because they depend primarily on expertise of grid operator. Aprotection scheme for a distribution network with DG units considers the application of multi-layer perceptron neural network (MLPNN) for fault location [16] was introduced. However, dueto the structure and training algorithm of the MLPNN, the speed of this method is not suitable forfast and accurate protection.A classification technique for recloser-fuse coordination in distribution systems with distributedgeneration has been proposed [17]. This approach is based on two main steps: protectioncoordination assessment and protection coordination improvement. In the coordinationassessment step, the coordination status after integrating DG to the system is classified as eithercoordination holds or coordination lost. The coordination improvement step is based ondecreasing the number of cases where coordination is lost. The main disadvantage of thisapproach is its capability to decrease the number of cases where coordination is lost. This meansthat it does not present a solution for all possible faults with all possible DG locations and it doesnot take into account insertion of more than one DG. An expert system for protectioncoordination of distribution system with distributed generators was presented in [18]. The expertsystem employs a knowledge base and inference process to improve the coordination settings ofprotective devices to accommodate the penetration of distributed generators. However, thissystem produces preliminary settings and still need to be revised by an expert user. The authorsproposed in [19] an adaptive current protection scheme for distribution systems with distributedgeneration. The scope of this scheme concerned only with the coordination between protectiverelays but it does not take in to account coordination between relays and other protection devicesused in the distribution systems such as fuses and reclosers. A neural network and backtrackingbased protection coordination scheme was used for distribution system with distributedgeneration in [20]. An automated fault location method is developed using a two stage radialbasis function neural network (RBFNN) in which the first RBFNN determines the fault distancefrom each source while the second RBFNN identifies the exact faulty line. After identifying theexact faulty line, protection relay coordination is implemented. A new protection coordinationstrategy using the backtracking algorithm is proposed, which considers the main protection
  3. 3. Electrical and Electronics Engineering: An International Journal (ELELIJ) Vol 2, No 2, May 20133algorithm to coordinate the operating states of relays so as to isolate the faulty line. Then, abackup protection algorithm is considered to complete the protection coordination scheme forisolating the malfunction relays of the main protection system. The main disadvantage of usingneural networks in protection systems coordination is the low speed of data processing andcommunication, which is not suitable for fast and accurate protection decision.In this paper, the impact of DG on the coordination of protection system in distribution networkswill be investigated. In addition, a proposed approach is introduced to overcome the protection-devices mis-coordination problem, which results from the DGs insertion in distribution networks.The most severe impact of DGs insertion is the great change in power flow and fault currentsdirections, so obviously the solution of the mis-coordination problem will be the use ofdirectional protection. By activating this feature in reclosers and updating the fuses sizes andprotection devices settings in a proper way, the mis-coordination problem can be easily solvedwithout replacing the existing protective devices or changing the coordination methodology.2. DISTRIBUTION SYSTEM DESCRIPTIONTo study the impact of DG insertion in distribution systems on the protection coordination and tocheck the performance, accuracy and suitability of the proposed approach, a real distributionsystem is used. The system is a 75 node, 11 kV distribution feeder, which is an actual feeder inElgharbia electricity sector- Kotour city. The single line diagram and the protection deviceslocations for this feeder are shown in Figure 1. This feeder has been simulated using ETAP 6package to perform load flow, short circuit and protection coordination studies.Figure 1. Single line diagram the real 11 kV distribution feeder
  4. 4. Electrical and Electronics Engineering: An International Journal (ELELIJ) Vol 2, No 2, May 201343. COORDINATION STUDY FOR THE DISTRIBUTION SYSTEM WITHOUT DGThe total connected load of this feeder is 6536 kVA and hence, the maximum full load current is344 A. Overcurrent protection setting of the relay should be taken as 1.25 of this current [21],which equals 430 A. The total connected load downstream the recloser is 4514 kVA, thus, therecloser downstream maximum full load current is 237A. Overcurrent protection setting of therecloser should be taken as 1.25 of this current, which is 297A. Fuse size will be also taken as1.25 of the maximum full load current of the connected load on its lateral [21]. In order tocoordinate these devices with each other, the difference between the operating time of the primaryand backup protection should always be greater than 200 ms [21]. According to the previoussetting values and fuses sizes, the original coordination between the protection devices is shownin Figure 2.Figure 2. Original coordination without DG unitsFrom the protection point of view, this distribution system is divided into 20 protection zones.Relay protection zone is from node 1 to node 32 on the main feeder, while recloser protectionzone is from node 32 to node 75 on the main feeder. In addition, each one of the 18 lateralsrepresents a separate protection zone and will be named as its fuse name. From the coordinationcurves in Figure 2, Table 1 can be derived to summarize the primary and the backup protectiondevices for each zone.
  5. 5. Electrical and Electronics Engineering: An International Journal (ELELIJ) Vol 2, No 2, May 20135ProtectionZonePrimaryprotectiondeviceBackupprotectiondeviceProtectionZonePrimaryprotectiondeviceBackupprotectiondeviceRelayzoneRelayIncoming feederProtectionF9 zone Fuse F9 RecloserRecloserzoneRecloser Relay F10 zone Fuse F10 RecloserF1 zone Fuse F1 Relay F11 zone Fuse F11 RecloserF2 zone Fuse F2 Relay F12 zone Fuse F12 RecloserF3 zone Fuse F3 Relay F13 zone Fuse F13 RecloserF4 zone Fuse F4 Relay F14 zone Fuse F14 RecloserF5 zone Fuse F5 Relay F15 zone Fuse F15 RecloserF6 zone Fuse F6 Relay F16 zone Fuse F16 RecloserF7 zone Fuse F7 Relay F17 zone Fuse F17 RecloserF8 zone Fuse F8 Recloser F18 zone Fuse F18 RecloserTable 1. Primary and backup protection device for each zoneFrom this table, it is clear that there is a good coordination between protection devices in normaloperation.4. IMPACT OF DG ON THE PROTECTION COORDINATIONTo study the impact of DG insertion on the protection coordination of the previously describeddistribution feeder, two DGs are inserted in the feeder. DG1 is placed upstream the recloser atnode 11 and DG2 is placed downstream the recloser at node 46. Table 2 shows all possible faultsand the response operation of the protection system after DG insertion according to the originalcoordination.FaultedzoneProtection system operationActual tripping Correct trippingPrimary Backup Primary BackupRelayzoneRelay Incoming feeder protection Relay Incoming feeder protectionFuse F4 DG1 protection Fuse F4 DG1 protectionFuse F10 Recloser Recloser Fuse F10RecloserzoneFuse F4 DG1 protection Recloser Relay, fuse F4Recloser Relay fuse F10 DG2 protectionfuse F10 DG2 protection - -F1 zone Fuse F1 Relay, fuse F4, fuse F10 Fuse F1 Relay, fuse F4, recloserF2 zone Fuse F2 Relay, fuse F4, fuse F10 Fuse F2 Relay, fuse F4, recloserF3 zone Fuse F3 Relay, fuse F4, fuse F10 Fuse F3 Relay, fuse F4, recloserF4 zone Fuse F4 Relay, fuse F10 Fuse F4 Relay, recloserDG1protection- DG1protection-F5 zone Fuse F5 Relay, fuse F4, fuse F10 Fuse F5 Relay, fuse F4,recloserF6 zone Fuse F6 Relay, fuse F4, fuse F10 Fuse F6 Relay, fuse F4,recloserF7 zone Fuse F7 Relay, fuse F4, fuse F10 Fuse F7 Relay, fuse F4,recloserF8 zone Fuse F8 Fuse F4, recloser, fuse F10 Fuse F8 Recloser, fuse F10
  6. 6. Electrical and Electronics Engineering: An International Journal (ELELIJ) Vol 2, No 2, May 20136F9 zone Fuse F9 Fuse F4, recloser, fuse F10 Fuse F9 Recloser, fuse F10F10 zone Fuse F4 DG1 protection Fuse F10 recloserfuse F10 recloser DG2protection-DG2protection- - -F11 zone Fuse F11 Fuse F4, recloser, fuse F10 Fuse F11 Recloser, fuse F10F12 zone Fuse F12 Fuse F4, recloser, fuse F10 Fuse F12 Recloser, fuse F10F13 zone Fuse F13 Fuse F4, recloser, fuse F10 Fuse F13 Recloser, fuse F10F14 zone Fuse F14 Fuse F4, recloser, fuse F10 Fuse F14 Recloser, fuse F10F15 zone Fuse F15 Fuse F4, recloser, fuse F10 Fuse F15 Recloser, fuse F10F16 zone Fuse F4 DG1 protection Fuse F16 Recloser, fuse F10Fuse F16 Recloser, fuse F10 - -F17 zone Fuse F17 Fuse F4, recloser, fuse F10 Fuse F17 Recloser, fuse F10F18 zone Fuse F18 Fuse F4, recloser, fuse F10 Fuse F18 Recloser, fuse F10Table 2. Original protection system operation after DG insertionAny fault current anywhere in the system will be formed as a contribution of three sources: frommain distribution station, from DG1 and from DG2. Table 2, indicates that for a fault at the relayzone, from node1 to node 32 on the main feeder, the fault current coming from the distributionstation will be interrupted by the relay, which is a correct tripping decision. The fault currentcoming from DG1 will be interrupted by fuse F4 and the DG1 protection system will be itsbackup, which is also a correct tripping decision. For the fault current coming from DG2, on theother hand, fuse F10 will trip before the recloser operation, which is an incorrect tripping decisionsince the recloser is the closest protection device for this zone. In other words, the recloser is theprimary protection device for this zone and must operate before the fuse F10. This case representsan obvious situation, where the protection becomes mis-coordinated.From Table 2, it is clear that at least one device in each protection zone will operate out of thecoordination, where these devices are underlined in the table. This proves that the originalprotection system will lose the selectivity after DG insertion. This is attributed to theimpossibility to coordinate the fuse and the recloser to operate as primary and backup protectiondevices for each other at the same time.5. THE PROPOSED APPROACHAfter inserting the DG units, the distribution system becomes active and it will be characterizedby multi-directional power flow and multi-directional fault currents. For such systems, directionalprotection becomes the suitable choice for better selectivity, since directional protection operatesonly when the fault current flows in the desired tripping direction. Although they do not havedirectional nature, fuses located at the beginning of each lateral do not need to be directional sincethe flow current in fuses is unidirectional. Only fuse on the DGs laterals are subjected to faultcurrent flows in both directions. However, these fuses can be hold the selectivity by defining theappropriate size. The fault current passing in the relay that is located at the beginning of thedistribution feeder is unidirectional and hence, no need for directional protection with this relay.On the other hand, reclosers must have a directional nature since they are subjected tobidirectional fault currents. Modern microprocessor-based reclosers have a directional sensitiveelement and the directional protection feature is available. Reclosers also need to be equipped
  7. 7. Electrical and Electronics Engineering: An International Journal (ELELIJ) Vol 2, No 2, May 20137with synchronization equipment to block the reclosing process if the two sources are out ofsynchronism. It is clear that this approach can be considered as a general solution for all types ofradial distribution systems that use the same protection system configuration (relay at thebeginning of the feeder, recloser anywhere on the main feeder and fuses on laterals). Also, thisapproach does not need any extra costs or equipments except for the reclosers. Following theproposed modifications, recloser will have two settings: one for the downstream direction and theother is for the upstream direction. Total connected load upstream the recloser is 2022 kVA,which means that the recloser upstream maximum full load current is 107 A. Overcurrentprotection setting of the recloser should be taken as 1.25 of this current [21], which is about 133A. The downstream direction overcurrent setting will remain the same since there is no change inthe downstream load.For DG1 which is located upstream the recloser at node 11; Protection device on DG1 lateralshould be slower than the downstream direction setting of the recloser, which will prevent itstripping for a fault at the recloser zone. At the same time, the protection device on DG1 lateralmust be faster than the upstream direction setting of the recloser to prevent the recloser trippingfor a fault in its own zone. It is clear that it is impossible to achieve these conditions using a fuse.Therefore, fuse F10 must be replaced by a directional protection device such as a recloserequipped with a directional sensing element and a synchronization equipment to block thereclosing process if the two sources are out of synchronism. Protection system at DG1 lateraldownstream direction setting must be faster than the upstream direction setting of the recloser onthe main feeder. At the same time, upstream direction setting of this system must be slower thanthe downstream direction setting of the recloser on the main feeder. This will be sufficient to holdthe selectivity.For DG2 which is located downstream the recloser at node 46; fuse on DG2 lateral should befaster than the downstream direction setting of the recloser. This will prevent the recloser trippingfor a fault at zone F10. It should be also slower than the upstream direction setting of the recloser,this will allow the recloser tripping for a fault at the relay zone. Accordingly, a 100 A fuse will begood coordinated under these conditions. To coordinate the other fuses in the system with thesedevices, fuses on laterals upstream the recloser should be faster than the recloser upstream setting.This will ensure that each fuse will be the primary protection device for its zone and recloser willbe its backup for the fault current coming from DG2 and the relay will be its backup for the faultcurrent coming from the distribution station. However, fuses on laterals downstream the reclosershould be faster than the fuse on DG2 lateral. This will ensure that the fuse at the beginning ofeach lateral will be the primary protection device for its zone with the recloser is its backup forfault current coming from the distribution station and the fuse at the DG2 lateral will be a backupfor the recloser for the fault current coming from DG2.Total connected load downstream the recloser at DG1 lateral is 658 kVA and thus, thedownstream maximum full load current of the DG1 lateral recloser is 34.5 A. Overcurrentprotection setting of the recloser should be taken as 1.25 of this current, which is about 43 A. Onthe other hand, total connected load upstream DG1 lateral recloser is 5878 kVA, which causes anupstream maximum full load current of the DG1 lateral recloser of 308.5 A. Overcurrentprotection setting of the recloser should be taken as 1.25 of this current, which is about 385 A.Figure 3 shows the time current curves of the relay, recloser, DG1 lateral recloser and DG2 lateralfuse according to the proposed approach.Table 3 summarizes the primary and the backup protection devices for each zone to study theprotection devices coordination after applying the previously mentioned approach.
  8. 8. Electrical and Electronics Engineering: An International Journal (ELELIJ) Vol 2, No 2, May 20138Figure 3. New coordination after DGs insertion according to the proposed approachProtection system trippingFaultedzone BackupPrimary-RelayRelayzone DG1 protection systemDG1 lateral recloserFuse F10RecloserRelay , DG1 lateral recloserRecloserRecloserzone DG2 protection systemfuse F10Relay, DG1 lateral recloser, recloserFuse F1F1 zoneRelay, DG1 lateral recloser, recloserFuse F2F2 zoneRelay, DG1 lateral recloser, recloserFuse F3F3 zoneRelay, recloserDG1 lateral recloserF4 zone-DG1 protection systemRelay, DG1 lateral recloser, recloserFuse F5F5 zoneRelay, DG1 lateral recloser, recloserFuse F6F6 zoneRelay, DG1 lateral recloser, recloserFuse F7F7 zoneRecloser, fuse F10Fuse F8F8 zoneRecloser, fuse F10Fuse F9F9 zonerecloserFuse F10F10 zone-DG2 protection systemRecloser, fuse F10Fuse F11F11 zoneRecloser, fuse F10Fuse F12F12 zoneRecloser, fuse F10Fuse F13F13 zoneRecloser, fuse F10Fuse F14F14 zone
  9. 9. Electrical and Electronics Engineering: An International Journal (ELELIJ) Vol 2, No 2, May 20139Recloser, fuse F10Fuse F15F15 zoneRecloser, fuse F10Fuse F16F16 zoneRecloser, fuse F10Fuse F17F17 zoneRecloser, fuse F10Fuse F18F18 zoneTable 3. Primary and backup protection devices for each zone according to the proposed approachAccording to the proposed coordination approach, it is clear that the selectivity among protectivedevices will not be affected after DGs insertion in the distribution system. Regarding the first casein Table 3 for instance, for a fault at the relay zone (from node1 to node 30 on the main feeder)the fault current coming from the distribution station will be interrupted by the relay, this is acorrect tripping decision. The fault current coming from DG1 will be interrupted by the DG1lateral recloser and DG1 protection system will be its backup this is a correct tripping decision.The fault current coming from DG2 will be interrupted by the recloser and fuse F10 will be itsbackup this is also a correct tripping decision. Another example a fault at the recloser zone (fromnode32 to node 75 on the main feeder) the fault current coming from both the distribution stationand DG1 will be interrupted by the recloser and its backup will be DG1 lateral recloser and therelay this is a correct coordinated tripping decision. The fault current coming from DG2 will beinterrupted by the fuse F10 and the DG2 protection system will be its backup. Another example afault at F8 zone (from node 32 to node 33) the fault current coming from all sources will beinterrupted by the fuse F8 since it is the primary protection device for this zone and it is fasterthan all the protection devices that will sense this fault current, the recloser will be its backup forthe fault current coming from the distribution station and DG1, and fuse F10 will be its backupfor the fault current coming from DG2. Thus, it is clear that the correct coordination will beestablished after applying the proposed approach of coordination. To ensure that the proposedapproach will operate properly for any DG penetration level, a more detailed investigation aboutthe effect of changing the DG size on the fault current and then on the operating times of theprotection devices is performed as in the following section.6. EFFECT OF CHANGING DG SIZE ON THE PROPOSED APPROACHTo prove the validity of the proposed approach for any DG penetration level, the impact ofchanging DG size on the proposed protection scheme is studied in detail. By increasing the DGsize, its contribution in any fault current in the system will increase. This will cause a decrease inthe contribution of the distribution station fault current, which will lead to a higher relayoperating time. The fault current contribution of DG units for different DG sizes are given inTable 4 for a three-phase fault case just downstream the main recloser at node 34. Thecorresponding fault current contribution of each source is listed from the simulation results. Inaddition, the corresponding operating time of each protection device in the fault current path islisted from the coordination curves. For the sake of simplicity, each of the two DGs will have thesame size of 1MW, which will be increased in steps up to 6MW, i.e. approximately the totalconnected load of the feeder.
  10. 10. Electrical and Electronics Engineering: An International Journal (ELELIJ) Vol 2, No 2, May 201310DGsizeFault current contribution inamperesOperating time in secondsDistributionstationDG1 DG2 Relay MainrecloserDG1 lateralrecloserDG2 lateralfuse1MW 1720 802 544 2.72 0.268 4.68 3.02MW 1460 1310 1080 4 0.231 1.61 0.5673MW 1280 1660 1610 5.24 0.207 0.993 0.2684MW 1150 1920 2130 7.2 0.188 0.722 0.1755MW 1050 2110 2650 8.68 0.181 0.588 0.1296MW 976 2270 3160 10.9 0.105 0.506 0.105Table 4. Fault current contribution of each source and the corresponding operating time of each protectiondevice for a 3-phase fault at node 34 for different DG sizesFrom the operating times in the previous table, it is clear that the operating time of the mainrecloser is always less than the operating time of relay and DG1 lateral recloser. This willguarantee the correct coordination between these devices for any fault downstream the mainrecloser at any DG penetration level. The same verification will be repeated but for a three-phasefault located at a point upstream the main recloser, for example at node 25. Table 5 summarizesthe simulation results for the fault current contribution of each source and the operating times ofeach protection device.DGsizefault current contributionin amperesOperating time in secondsDistributionstationDG1 DG2 Relay MainrecloserDG1 lateralrecloserDG2 lateralfuse1MW 2800 1310 502 1.07 1.17 1.58 3.812MW 2550 2290 928 1.31 0.369 0.526 0.8083MW 2350 3040 1290 1.55 0.207 0.3 0.44MW 2190 3640 1610 1.74 0.148 0.227 0.275MW 2060 4130 1890 2.1 0.116 0.181 0.26MW 1950 4540 2130 2.34 0.099 0.153 0.17Table 5. Fault current contribution of each source and the corresponding operating time of each protectiondevice for a 3-phase fault at node 25 for different DG sizesAs listed in this table, the operating times of the main recloser is always less than the operatingtimes of the DG2 lateral fuse. This will guarantee the correct coordination for any fault upstreamthe main recloser for any DG penetration level.According to simulation results, it is clear that the proposed protection scheme will hold itscoordination for any DG penetration level and for faults anywhere in the system.7. CONCLUSIONThis paper has presented a study for the impact of distributed generation on protection devicescoordination of radial feeder distribution systems and proposed an approach to overcome this
  11. 11. Electrical and Electronics Engineering: An International Journal (ELELIJ) Vol 2, No 2, May 201311impact. The proposed approach depends on using directional protection feature in reclosers andupdating recloser setting and fuse size to achieve the correct coordination after DG insertion. Theproposed approach is tested on a real distribution feeder simulated on ETAP program. Thesimulation results demonstrate the correct coordination between all protective devices. The resultsensure the possibility of achieving the correct coordination between protective devices afterinserting the DG units when the proper choice of these devices with suitable settings isimplemented.REFERENCES[1] Barker, P. P. and R. W. De Mello (2000). “Determining the impact of distributed generationon power systems”, I. Radial distribution systems. Power Engineering Society SummerMeeting, 2000. IEEE.[2] Kauhaniemi K, Kumpulainen L. “Impact of distributed generation on the protection ofdistribution networks”. In: Eighth IEE international conference on developments in powersystem protection, vol. 1. 2004. pp. 315–8.[3] de Britto TM, Morais DR, Marin MA, Rolim JG, Zurn HH, Buendgens RF. “Distributedgeneration impacts on the coordination of protection systems in distribution networks”. In:IEEE/PES transmission and distribution conference and exposition: Latin America; 2004. p.623–8.[4] Boutsika TN, Papathanassiou SA. “Short-circuit calculations in networks with distributedgeneration”. Electric Power Syst Res 2008; 78(7):1181–91.[5] Conti S. “Analysis of distribution network protection issues in presence of dispersedgeneration”. Electric Power Syst Res 2009; 79 (1):49–56.[6] Ghosh S, Ghoshal SP, Ghosh S. “Optimal sizing and placement of distributed generation in anetwork system”. Int J Electric Power Energy Syst 2010; 32(8):849–56.[7] N. Hadjsaid, J. F. Canard, and F. Dumas, “Dispersed generation impact on distributionnetworks”, Computer Applications in Power, IEEE, vol. 12, pp. 22-28, 1999.[8] A. A. Girgis and S. M. Brahma, “Effect of distributed generation on protective devicecoordination in distribution system”, Proc. IEEE Large Eng. Syst. Conf., 2001, pp. 115–119.[9] S. M. Brahma and A. A. Girgis, “ Microprocessor-based reclosing to coordinate fuse andrecloser in a system with high penetration of distributed generation”, Power EngineeringSociety Winter Meeting, 2002. IEEE, 2002, pp. 453-458 vol.1.[10] A. Y. Abdelaziz, H. E. A. Talaat, A. I. Nosseir, and A. A. Hajjar, “An adaptive protectionscheme for optimal coordination of overcurrent relays”, Electric Power Systems Research,vol. 61, pp. 1-9, 2002.[11] T. Tran-Quoc, C. Andrieu, and N. Hadjsaid, “Technical impacts of small distributedgeneration units on LV networks”, in Power Engineering Society General Meeting, 2003,IEEE, 2003, p. 2464 Vol. 4.[12] S. M. Brahma and A. A. Girgis, “Development of adaptive protection scheme for distributionsystems with high penetration of distributed generation,” IEEE Trans. Power Del., vol. 19,no. 1, pp. 56–63, Jan. 2004.
  12. 12. Electrical and Electronics Engineering: An International Journal (ELELIJ) Vol 2, No 2, May 201312[13] K. Tuitemwong and S. Premrudeepreechacharn, “Expert System for Protective DevicesCoordination in Radial Distribution Network with Small Power Producers”, Power Tech,2007 IEEE Lausanne, 2007, pp. 1159-1164.[14] Sanaye-Pasand M, Khorashadi-Zadeh H. “An extended ANN-based high speed accuratedistance protection algorithm”. Int J Electric Power Energy Syst 2006; 28(6):387–95.[15] Rezaei N, Haghifam MR. “Protection scheme for a distribution system with distributedgeneration using neural networks”. Int J Electric Power Energy Syst 2008; 30(4):235–41.[16] Javadian SAM, Haghifam MR, Rezaei N. “A fault location and protection scheme fordistribution systems in presence of dg using MLP neural networks”, IEEE power & energysociety general meeting; 2009. p. 1–8.[17] A. F. Naiem, Y. Hegazy, A. Y. Abdelaziz and M. A. Elsharkawy “A ClassificationTechnique for Recloser-Fuse Coordination in Distribution Systems with DistributedGeneration,” IEEE Trans. Power Del., Vol. 27, No. 1, 2012.[18] K. Tuitemwong and S. Premrudeepreechacharn, "Expert system for protection coordinationof distribution system with distributed generators," International Journal of Electrical Power& Energy Systems, vol. 33, pp. 466–471, 2011.[19] Jing Ma and Xi Wang, "A novel adaptive current protection scheme for distribution systemswith distributed generation," International Journal of Electrical Power & Energy Systems,vol. 43, pp. 1460–1466, 2012.[20] H. Zayandehroodi and A. Mohamed, "A novel neural network and backtracking basedprotection coordination scheme for distribution system with distributed generation,"International Journal of Electrical Power & Energy Systems, vol. 43, pp. 868–879, 2012.[21] IEEE 242-2001 recommended practice for protection and coordination of industrial andcommercial power systems, 2001.AuthorsAhmed Kamel was born in Tanta, Egypt, in 1984. He received the B.Sc. degree inelectrical power engineering from Tanta University, Tanta, in 2006. Currently, he is aprotection engineer in South Delta Electricity Distribution Company, EgyptianMinistry of Electricity and Energy. His research interest is the impact of distributedgeneration on distribution systems’ protection.Mohamed A. Alaam was born in El-Gharbia, Egypt. He received the B.Sc., M.Sc. andPh.D. degrees in electrical engineering from the Tanta University, Egypt in 1997, 2003and 2008, respectively. He is associated professor in department of Electrical Powerand Machines Engineering- Tanta University. His research topics are directed to thepower system analysis, intelligent techniques, dynamic simulation, digital relaying, andpower system protection applications.
  13. 13. Electrical and Electronics Engineering: An International Journal (ELELIJ) Vol 2, No 2, May 201313Ahmed M. Azmy was born in El-Menoufya, Egypt. He received the B.Sc. and M.Sc.degrees in electrical engineering from the El-Menoufya University, Egypt in 1991 and1996, respectively. He received the Ph.D. degrees in electrical engineering from theuniversity Duisburg-Essen, Germany in 2005. He is the head of department ofElectrical Power and Machines Engineering- Tanta University, director of theautomated library project in Tanta University- director of the quality assurance unit andexecutive director of the continuous improvement and qualification for accreditationprogram. His research topics are directed to the intelligent techniques, dynamicsimulation, smart grids, distributed generating units and renewable energy resources. Dr. Azmy has beenawarded Tanta University Incentive Awards (2010) and Prizes for international publishing in 2010, 2012and 2013.Almoataz Y. Abdelaziz received the B. Sc. and M. Sc. degrees in electricalengineering from Ain Shams University, Cairo, Egypt in 1985, 1990 respectively andthe Ph. D. degree in electrical engineering according to the channel system betweenAin Shams University, Egypt and Brunel University, England in 1996. He is currentlya professor of electrical power engineering in Ain Shams University. His researchareas include the applications of artificial intelligence to power systems and protectionand new evolutionary & heuristic optimization techniques in power systems operation,planning and control. He has authored or coauthored more than 140 refereed journaland conference papers. Dr. Abdelaziz is a senior editor of Ain Shams Engineering Journal, member of theeditorial board and a reviewer of technical papers in several international journals and conferences. He isalso a member in IEEE, IET and the Egyptian Sub-Committees of IEC and CIGRE`. Dr. Abdelaziz hasbeen awarded Ain Shams University Prize for distinct researches in 2002 and for international publishing in2011 and 2012.

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