1300 S. Interocean Ave. Holyoke, CO

Transcription

1 1300 S. Intercean Ave. Hlyke, CO Intercnnectin Standard fr Small Generating Facilities N Larger Than 25kW and 600VAC Intrductin

2 This dcument prvides a standard fr intercnnectin f distributed resurces within the Highline Electric Assciatin (HEA) electric pwer system with aggregate capacity that is n larger than 25kW and 600VAC. It prvides requirements relevant t the perfrmance, peratin, testing, safety cnsideratins, and maintenance f the intercnnectin. This standard is established t assist the generating facility in understanding the requirements invlved in planning and designing an electrical intercnnectin with the HEA electric system. This standard is a general guideline and may nt cver all f the details f the installatin. If deviatins ccur frm this standard the changes must be apprved by HEA r their designated representative. All csts assciated with the intercnnectin will be paid by the generating facility including, but nt limited t, technical review and analysis by HEA and/r their designated representative. 2.0 General Requirements fr Intercnnectin 2.1 Cdes and Standards The generating facility and its assciated equipment must meet all applicable natinal, state and lcal cnstructin and safety cdes. The intercnnectin shall cnfrm t latest revisin but nt limited t the fllwing: Clrad Department f Regulatry Agencies Public Utilities Cmmissin s 4 Cde f Clrad Regulatins (CCR) 723-3, Part 3, Rules Regulating Electric Utilities, Sectin 3665, Small Generatin Intercnnectin Prcedures. IEEE Standard 1547, IEEE Standard fr Intercnnecting Distributed Resurces with Electric Pwer Systems. IEEE Standard 1453, IEEE Recmmended Practice fr Measurement and Limits f Vltage Fluctuatins and Assciated Light Flicker n AC Pwer Systems. IEEE Standard 519, IEEE Recmmended Practices and Requirements fr Harmnic Cntrl in Electric Pwer Systems. IEEE Standard 141(Red Bk), IEEE Recmmended Practice fr Electric Pwer Distributin fr Industrial Plants. IEEE Standard 142 (Green Bk), IEEE Recmmended Practice fr Grunding f Industrial and Cmmercial Pwer Systems. IEEE STD , Recmmended Practice fr Utility Interface f Phtvltaic Systems. UL 1741, Inverters, Cnverters, Cntrllers, and Intercnnectin System Equipment fr Use with Distributed Energy Resurces. IEEE C-2 (NESC), Natinal Electric Safety Cde. NFPA-70 (NEC), Natinal Electrical Cde. In the event f cnflict between these dcuments, the requirements f this Specificatin shall take precedence r the mre stringent requirement shall be fllwed. If clarificatin is necessary, HEA shall be ntified fr reslutin. 2.2 Intercnnectin Review The small generating facility shuld prvide HEA with electrical drawings fr review prir t equipment prcurement. As a minimum a single-line diagram is required indicating the pint-f-intercnnectin, size/type/rating f pwer cnversin device (generatr, inverter/kw, kva, etc.), vltage (single-phase r threephase), frequency, size/type/rating f fault interrupting device, size/type/rating f manual discnnecting switch, and energy surce (slar, wind, hydr, diesel, natural gas, prpane, fuel il, etc.) being used. If prtective relays are used, the drawing package shuld cnsist f meter and relay diagrams; three-line diagrams (AC) shwing cnnectivity f relays; and, schematics (DC) indicating tripping schemes fr any relays. The single-

3 line meter and relay diagram listing majr equipment shuld be prvided t HEA prir t rdering relays. The threeline diagrams and DC schematics shuld be prvided befre fabricating panels with prtective relays. These may cme frm the manufacturer and need nt be re-drawn. If prtective relays are used, relay settings fr the intercnnectin are t be submitted t HEA fr review. HEA will review the settings and may include changes r additins t the settings as warranted by the applicatin. Within three business days HEA will ntify by r fax prvided by the small generating facility that the intercnnectin request was received. Within ten business days HEA will ntify the small generating facility as t whether the intercnnectin request is cmplete r incmplete. If the intercnnectin request is incmplete a ntice that the intercnnectin request is incmplete will be prvided by HEA. The ntice will cntain a written list detailing infrmatin that must be prvided t cmplete the intercnnectin request. The small generating facility will have ten business days after receipt f the ntice t submit the listed infrmatin r t request an extensin. If the infrmatin r a request fr extensin is nt received within the ten business days the intercnnectin request will be deemed withdrawn. Within 15 days HEA will cnduct an initial review and determine which screening criteria will be used in accrdance with CCR 723-3, Part 3, Sectin 3665, Small Generatin Intercnnectin Prcedures. Prir t parallel peratin, HEA may inspect the small generating facility fr cmpliance with standards, which may include a witness test, and may schedule apprpriate metering replacement, if necessary. 2.3 Cnnectin Vltage Under this standard, small generating units shall be cnnected n the secndary lw vltage (600VAC and less) side f the HEA electrical system, and shall nt be cnnected directly nt the distributin circuit. On the HEA system this is typically 480VAC and less. A transfrmer is used by HEA t step-dwn the distributin vltage t the utilizatin vltage f the facility. The transfrmer als allws islatin between the generating facility and ther HEA custmers when a three-phase inverter is installed. The impedance f the step-dwn transfrmer limits fault currents n the generatr bus frm the HEA electric pwer system and limits fault currents n the HEA electric pwer system frm the generatr. Hence, it reduces the ptential damage t bth parties due t faults. Lightning arrestrs may be required at the pint f intercnnectin. 2.4 Fault-Interrupting Devices A lw vltage (less than 600VAC) three-phase/single-phase circuit breaker r cntactr at the pint f intercnnectin shall autmatically separate the small generatin facility frm the HEA electric pwer system upn detectin f a circuit fault. Additinal breakers and prtective relays may be installed in the small generatin facility fr ease in perating and prtecting the facility, but they are nt required fr the purpse f intercnnectin. The intercnnectin breaker r cntactr shall have sufficient capacity t interrupt the maximum available fault current at its lcatin. Generally, the intercnnectin must meet the requirements and latest versin f NEC, Article 705, Intercnnected Electric Pwer Prductin Surces and the fllwing specificatins apply: Nrmally a lw vltage thermal-magnetic circuit breaker is all that is required, hwever, it is up t the small generating facility t size and determine the fault interrupting capability fr the applicatin. A fused discnnect switch may be used and will be reviewed n a case by case basis. Cntactrs may be installed and will be reviewed n a case by case basis. An external trip signal (shunt trip) may be required t trip the breaker and will be reviewed n a case by case basis.

4 Fr three-phase intercnnectins, a three-ple device is required due t its simultaneus three-phase peratin and ability t crdinate with HEA transfrmer high-side prtectin. 2.5 Manual Discnnect Switch A manual discnnect switch is required fr the small generatin facility. An HEA-perated discnnect device must be prvided as a means f electrically islating the HEA electric pwer system frm the generatr. This device shall be used t establish visually pen wrking clearance fr maintenance and repair wrk in accrdance with HEA safety rules and practices. A separate discnnect device must be lcated at any and all pints f intercnnectin with HEA. The discnnect switch shall be a gang-perated, single-ple, duble-ple r three-ple lckable switch as determined by the type f intercnnectin: single-phase r three-phase. All switch devices must be apprved by HEA. HEA will inspect and apprve the installatin befre parallel peratin is permitted. In general, the fllwing specificatins apply: Discnnect switches shall be furnished and installed by the small generatin facility. Discnnect switches shall be physically lcated fr ease f access and visibility t HEA persnnel. Discnnect switches shall be rated fr the vltage and current requirements f the particular installatin. Discnnect switches shall be gang-perated (fr ther than single-ple switches). Discnnect switches shall be weatherprf and designed t withstand expsure t weather and ice. Discnnect switches shall be lckable in bth the pen/clsed psitins with a standard HEA pad lck. Discnnect switches may be fused and will be reviewed n a case by case basis. Discnnect switches shall nt be used t make r break parallel peratin between the HEA electric pwer system and the generatr(s). 2.6 Prtective Equipment Prtective Equipment specified in this standard, 4 CCR 723-3, and IEEE 1547 must be installed at lcatins where the generating facility wishes t perate in parallel with the HEA electric pwer system. This equipment is used t ensure safe and reliable pwer system peratin and t allw discnnectin f the facility s generatin in the event f a shrt circuit r ther malfunctin. The prtectin equipment fr a small generatin facility must prtect against faults within that facility and faults n the HEA electric pwer system. A small generatin facility must als trip ffline (discnnect frm the HEA electric pwer system autmatically) when pwer is discnnected frm the line int which the unit is generating. HEA uses line-prtective equipment t either; 1) autmatically clear a fault and restre pwer, r 2) rapidly islate nly the faulted sectin s that a minimum number f custmers are affected by any utages. HEA prtectin requirements are designed and intended t prtect the HEA electric pwer system nly. As a general rule, neither party shuld depend n the ther fr the prtectin f its wn equipment. Additinal prtective relays may be needed t prtect the generating facility adequately. It is the generating facility s respnsibility t prtect its wn system and equipment frm faults r interruptins riginating n bth HEA side and the small generating facility s side f the Intercnnectin. The small generating facility s system prtectin shall be designed, perated, and maintained t islate any fault r abnrmality that wuld adversely affect the HEA electric pwer system r the systems f ther entities cnnected t the HEA electric pwer system. The prtective relays used fr islating the small generatin facility frm the HEA electric pwer system at the Pint f Intercnnectin must be reviewed and apprved by HEA. Additinal requirements, as t the exact type and style f the prtective devices, may be impsed n the generating facility based n the prpsed cnfiguratin r the type f interrupting device clsest t the pint f cmmn cupling n the HEA system. Any additinal prtective equipment required will be at the generating facility s cst. A summary f prtective relaying that may be required by the small generating facility is included in Appendix 1. Nte: Inverters that cmply with IEEE STD , Recmmended Practice fr Utility Interface f Phtvltaic Systems, and UL 1741, Inverters, Cnverters, Cntrllers, and Intercnnectin System

5 Equipment fr Use with Distributed Energy Resurces, have built-in prtective relay functins and may nt require additinal prtectin. These systems will be reviewed n case by case basis. See Appendix 2 fr mre infrmatin n inverter based systems. HEA recmmends that the generating facility acquire the services f a qualified electrical engineer t review the electrical design f the prpsed small generatin facility and ensure that it will be adequately prtected. 2.7 Safety, Reliability and Pwer Quality The small generating facility must design, cnstruct and perate its equipment in a manner that will nt degrade the quality f electric service t ther HEA custmers. HEA reserves the right t specify the quality and determine the adequacy f the small generating facility s equipment, installatin and peratin in any respect that affects safety, reliability and quality f service. The generating facility is expected t perate within the limits f vltage, frequency and harmnic distrtin utlined in the latest revisin f IEEE Standard 1547, IEEE Standard 1453, IEEE Standard 519 and IEEE Standard 141 (Red Bk). Studies, such as a System Impact Study and assciated excitatin equipment settings shall be at the generating facility s expense. 2.8 Islated Operatin HEA des nt allw islated peratin f the HEA distributin system by a distributed resurce under any circumstances. T prevent islated peratin, HEA requires devices t detect and discnnect the distributed resurce in the event f a lss f electrical pwer at the pint f intercnnectin. If the cntrl system f the small generating facility is nt capable f detecting faults n the utility system, relays may be required s that the distributed resurce can be discnnected when the HEA breaker r reclser pens. In rare cases, transfer tripping equipment may be required and will be reviewed n a case by case basis. The small generating system is allwed t discnnect and perate independent f the HEA distributin system. Prper synchrnizing devices must be in place when the small generating facility parallels back t the HEA electrical system while energized. 2.9 Facility System Disturbances The small generating facility must discnnect in the event f a disturbance r malfunctin f facility equipment t prevent lss f service t ther HEA custmers Utility System Disturbances The small generating facility must prmptly discnnect frm the HEA electric pwer system in the event f a utility system disturbance. HEA prtective relaying will act t prmptly discnnect the affected line. The small generating facility n this affected line represents an additinal surce f pwer t energize the line. Therefre the generating facility must prvide a means t autmatically discnnect its generatr t avid islated peratin and prtect equipment and persnnel. 3.0 Cmmissining Test

6 3.1 Cmmissining Testing Cmmissining testing shall be perfrmed n-site t verify functinality and when used, prtective relay settings. HEA has the right t witness the cmmissining test, and may als require written certificatin by the installer describing which tests were perfrmed and their results. In sme cases testing may be verified by a certified factry test. In such cases cpies f all factry tests shall be submitted fr review by HEA. HEA will review the factry test reprts and determine if they are acceptable cmmissining tests r if mre testing is required. Test reprts will be reviewed n case by case basis. Testing shall include visual inspectins f the intercnnectin equipment and when used, prtective settings t cnfirm cmpliance with the intercnnectin requirements. The generating facility shall prvide HEA with cpies f test reprts fr the particular types f prtective devices applied befre the generating facility will be allwed t parallel. The cst f perfrming cmmissining testing is the respnsibility f the generating facility. Once cmplete and accepted the cmmissining tests d nt have t be repeated unless set pints are changed. 3.2 Scheduled Testing After cmmissining, the generating facility shuld perfrm peridic testing t demnstrating the functinality f the system. The interval between testing is usually specified by the manufacturer f the equipment. Cpies f any testing shall be kept by the small generating facility and made available t HEA if requested. If used, prtective relays shuld be checked and tested every five years. These tests shall demnstrate that the prtective relays are functinal and within calibratin. HEA will nt test the generating facility s equipment, but reserves the right t witness the testing perfrmed by a qualified testing firm retained by the generating facility. 3.3 Testing Qualificatins Individuals qualified in testing prtective equipment (prfessinal engineer, factry-certified technician, r licensed electrician with experience in testing prtective equipment) must perfrm cmmissining and scheduled testing. 4.0 References 1) Intercnnectin Standards fr Qualifying Facilities, Tri-State Generatin and Transmissin Assciatin, Inc. September, ) IEEE Standard 1547, IEEE Standard fr Intercnnecting Distributed Resurces with Electric Pwer Systems. 3) Clrad Department f Regulatry Agencies, Public Utilities Cmmissin, 4 Cde f Clrad Regulatins (CCR) 723-3, Part 3, Rules Regulating Electric Utilities. 4) IEEE Standard P1547.2, Draft Applicatin Guide fr IEEE Standard fr Intercnnecting Distributed Resurces with Electric Pwer Systems, Draft 9, September, ) PG&E GENERATION INTERCONNECTION HANDBOOK, Sectin G2, Prtectin and Cntrl Requirements fr Generatin Entities, August 6, ) IEEE Standard , Recmmended Practice fr Utility Interface f Phtvltaic Systems. 7) UL 1741, Inverters, Cnverters, Cntrllers, and Intercnnectin System Equipment fr Use With Distributed Energy Resurces,

7 Appendix 1 A Summary f Prtective Relaying 1.0 Prtective Relaying 1.1 General requirements As stated in Sectin 2.6 (Prtective Equipment) f this standard, HEA may require additinal equipment if the individual applicatin warrants the use f such equipment. The fllwing is intended as a guide that represents the minimum requirements t prvide a safe and reliable intercnnectin. If required, prtective relays shall be utility grade and must be submitted t HEA fr apprval. Industrial grade prtective relays fr intercnnectin may be acceptable n a case by case basis; hwever, utility grade relays are preferred. Utility grade relays, used by electric utilities, have much higher reliability and accuracy than industrial grade relays. All utility grade relays must include resettable relay targets, and have 5A nminal AC input current. All utility grade relay pwer supplies shuld be pwered by battery DC vltage, and the battery system shuld include a DC undervltage detectin device and alarm. 1.2 Line Prtectin If required, line-prtectin relays must crdinate with the prtective relays at the HEA reclser/breaker fr the line n which the generating facility is cnnected. HEA perates a 12.47/7.2kV grunded-wye distributin system. Typical HEA prtectin is fr a lng radial line where current can flw in ne directin nly; typical prtective relays fr this type f line need t be crdinated in nly ne directin and may nt be directinal elements. Hwever, there may be instances where current may flw in either directin depending n system cnditins. Relays n these prtins f the HEA electric pwer system must be directinal. Such mdificatins t existing relays will be at the generating facility s cst. The line prtectin schemes must be able t distinguish between generatin, lad, inrush and fault currents. HEA s existing relay schemes may have t be reset, replaced, r augmented with additinal relays at the small generatin facility s expense, t crdinate with the new generatin facility. The minimum prtectin that HEA typically uses n its wn installatin is phase vercurrent, grund vercurrent, and reclsing. If required, relays must be lcated s that a fault n any phase f HEA s intercnnected line(s) shall be detected. If transfer trip prtectin is required by HEA, the small generatin facility shall prvide all required cmmunicatin circuits at its expense. Sme prtins f the HEA electric pwer system have prvisins fr an alternate feed. In sme f these lcatins, generatin may nt be allwed n line while being fed frm an alternate surce due t prtectin crdinatin issues. Whenever pssible, the small generatin facility will be given the ptin f: 1. Paying fr any required upgrades s as t stay n line while transferred t the alternate surce, r 2. Accepting shutdwns when transferred t the alternate surce and nt incurring csts fr upgrades t the existing system. 1.3 Generatr/Intertie Prtectin and Cntrl Single-phase generatrs shuld be cnnected in grups s that an equal amunt f generatin capacity is applied t each phase f a three-phase circuit. Synchrnus generatrs f any size will require: a) synchrnizing relays (Device 15/25), synch check (Device 25), r aut synchrnizer t supervise generatr breaker clsing, and b) reclse blcking at the HEA side f the line t which the generatr is cnnected (applies t substatin breaker/reclser and line reclsers).

8 The prtectin classes fr generatr intercnnectin under this standard are: 5 kw and belw 6-25 kw The fllwing represents the minimum prtectin that shuld be used t prvide a safe and reliable intercnnectin. HEA may require additinal equipment if the individual applicatin warrants the use f such equipment. Additinal generatr prtectin may be determined by HEA n a case-by-case basis. Prtective Relaying, 5 kw and belw: Shrt Circuit Prtectin: Thermal-magnetic circuit breaker Devices 50/51 and 51V as applicable n case by case basis. Device 51V nt required n inductin machines. Islatin Prtectin: Devices 27, 32, 59, 81O, 81U Device 32 is required fr peak shaving and n-sale applicatins where the generating facility is perating in parallel with the HEA electric pwer system. May be nly prtectin required n inverters. Breaker Clsing/Reclsing Cntrl: Devices 25, 27R n any synchrnus machine. Device 25 nt required n inductin machines. Grund Fault Prtectin: Devices 51N r 51G as applicable n case by case basis. Overspeed prtectin if applicable. Prtective Relaying, 6-25 kw: Shrt Circuit Prtectin Thermal-magnetic circuit breaker Devices 50/51 and 51V as applicable n case by case basis. Device 51V nt required n inductin machines. Islatin Prtectin Devices 27, 59, 81O, 81U. Device 32 is required fr peak shaving and n-sale applicatins where the generating facility is perating in parallel with the HEA electric pwer system. Only prtectin required n inverters. Breaker Clsing/Reclsing Cntrl Devices 25, 27R n any synchrnus machine. Device 25 nt required n inductin machines. Grund Fault Prtectin Devices 51N r 51G as applicable n case by case basis. Over/under-speed cntrl fr inductin generatrs Device Circuit Breaker/Circuit Switcher (Device 52) A three-phase, three-ple, single-phase ne-r tw-ple circuit breaker is the preferred fault-interruptin device at the pint f intercnnectin due t its simultaneus peratin and ability t crdinate with HEA line-side devices.

9 1.5 Phase Overcurrent (Device 50/51) A phase vercurrent device prvides tripping f the circuit breaker in the event f a phase fault. Phase vercurrent relays are t be crdinated with HEA line-side devices. Overcurrent prtectin can als be used t detect a line-end fault cnditin. A phase instantaneus vercurrent relay that can see a line fault under sub-transient cnditins may als be used. A phase instantaneus vercurrent relay is generally nt required if a 51V relay is used. 1.6 Phase Overcurrent Relay with Vltage Restraint/Vltage Cntrl (Device 51V) These relays are used t detect multi-phase faults and initiate a generatr circuit breaker trip. These relays are lcated n the individual generatr feeder. An vercurrent relay with vltage cntrl may als be acceptable if it can be set t adequately detect end-f-line faults as verified by HEA prtectin studies. Phase Overcurrent with Vltage Restraint (51V) suggested settings: Pickup: % f generatr 100% Vltage Restraint. Time: Abve the knee f the generatr decrement curve with cnstant excitatin and crdinated with the dwnstream HEA feeder relay setting. Phase Overcurrent with Vltage Cntrl (51V) suggested settings: Pickup: 80-90% f generatr I d = 1/X d. Time: Abve the knee f the generatr decrement curve with cnstant excitatin and crdinated with the dwnstream HEA feeder relay setting. Nte: The 51V functin is nt useful fr inductin generatrs since, if the vltage is lw enugh t enable vercurrent prtectin, the generatr excitatin will nt be sustained. 1.7 Under/Overvltage Relay (Device 27/59) This prtectin is used t trip the circuit breaker when the vltage is abve r belw HEA s nrmal perating level. Relays will perate fr generatr prtectin and backup prtectin in the event that the generatr is carrying lad that has becme islated frm the HEA electric pwer system. Overvltage (59) settings: 110%< Vltage < 120% f 1.0 sec (60 cycles) Vltage > 120% f 0.16 sec ( 9.6 cycles) Undervltage (27) settings: Vltage < 50% f 0.16 sec (9.6 cycles) 50% < Vltage < 88% f 2.0 sec (120 cycles) Nte: Inverters that cmply with IEEE STD , Recmmended Practice fr Utility Interface f Phtvltaic Systems, and UL 1741, Inverters, Cnverters, Cntrllers, and Intercnnectin System Equipment fr Use with Distributed Energy Resurces, have built-in 27/59 functins. If an inverter lacks these functins, then 27/59 relay prtectin must be installed. See Appendix 2 fr mre infrmatin n inverter based systems. 1.8 Reverse Pwer Relay (Device 32) The reverse pwer relay is used when the small generating facility is perating in parallel with the HEA electric pwer system and pwer exprt is nt allwed. A directinal pwer element may be set t lk either frward r reverse. When set t detect pwer exprt (reverse pwer), the relay may be set t trip at a level belw the expected minimum utility feeder lad that the small generating facility wuld supply if islanded. When set t detect pwer imprt (frward pwer), the relay may be set t trip at a level belw the minimum expected pwer imprt level. This relay is nt used fr fault prtectin, but can prevent damage t ther HEA custmers. 1.9 Over/Under Frequency Relay (Device 81 O/U)

10 This prtectin is used t trip the circuit breaker when the frequency is abve r belw HEA's nrmal perating level. It is used fr generatr/turbine prtectin and backup prtectin. Generatr underfrequency relay settings are crdinated with ther utilities in the Western Electricity Crdinating Cuncil (WECC) t maintain generatin n line during system disturbances. Relays shall nt be set fr a higher frequency r shrter time delay than specified withut prir written apprval by HEA. Less than 25kW settings: Over Frequency (81O) sec (9.6 cycles). Under Frequency (81U) sec (9.6 cycles). Nte: Inverters that cmply with IEEE STD , Recmmended Practice fr Utility Interface f Phtvltaic Systems, and UL 1741, Inverters, Cnverters, Cntrllers, and Intercnnectin System Equipment fr Use with Distributed Energy Resurces, have built-in 81O/U functins. If an inverter lacks these functins, then 81O/U relay prtectin must be installed Synchrnizing (Device 15/25) and Synch-Check (Device 25) The applicatin f synchrnizing devices attempts t ensure that a synchrnus generatr will parallel with the utility electric system withut causing a disturbance t ther custmers and facilities (present and in the future) cnnected t the same system. The prtectin als wrks t ensure that the generatr itself will nt be damaged due t an imprper parallel actin. Synchrnus generatrs and ther generatrs with stand-alne capability shuld use ne f the fllwing methds t synchrnize with the HEA electric pwer system: Autmatic synchrnizatin (Device 15/25) supervised by a synch-check relay (Device 25) t synchrnize with the HEA electric pwer system. The synch-check relay must have the characteristics listed belw. Manual synchrnizatin with supervisin frm a synch-check relay (Device 25) t synchrnize with the HEA electric pwer system. The synch-check relay must have the characteristics listed belw. Manual synchrnizatin with synchrscpe and synch-check (Device 25) relay supervisin. The synchcheck relay must have the characteristics listed belw. The synch-check relay must have all f the fllwing characteristics: Slip frequency matching windw f 0.3 Hz r less Vltage matching windw f ± 10 percent r less Phase angle acceptance windw f ± 20 degrees r less Nte: A synch-check functin is nt needed n inductin generatrs. Unlike synchrnus generatrs, inductin generatrs are nt synchrnized befre paralleling t the electric utility system Grund Fault Sensing Scheme (Device 51G) The grund fault sensing scheme detects HEA electric pwer system grund faults and trips the generatr breaker r the generating facility s main circuit breaker, thus preventing the small generatin facility's generatr frm cntinuusly cntributing t a grund fault. This scheme shuld detect faults between the HEA system side f the dedicated transfrmer and the end f HEA's line. The fllwing transfrmer cnnectins, alng with apprpriate relaying equipment, are cmmnly used t detect system grund faults: System side - grunded wye; generatr side - delta System side - grunded wye; generatr side - wye; tertiary - delta

11 In general, a grund vercurrent relay (Device 51G) is installed in the step-up transfrmer neutral (primary vltage side). Grund vercurrent (51G): Pickup: must be set abve the HEA electric pwer system unbalance. Time: set abve feeder relays and crdinated with the slwest dwnstream feeder relay grund setting. Fr inductin generatrs less than 25kW cvered under this standard, grund fault detectin is nt required. Appendix 2 Generatin and Pwer Cnversin Technlgies 1.0 Generatin and Pwer Cnversin Technlgies 1.1 Synchrnus Generatrs The generating unit shuld meet all applicable American Natinal Standards Institute (ANSI) and Institute f Electrical and Electrnic Engineers (IEEE) standards. The prime mver and the generatr shuld perate within the nminal range f vltage and frequency excursins that may ccur n the HEA electric pwer system withut damage t them. The generating unit shuld be able t perate thrugh the specified frequency ranges fr the time duratins in this standard, t enhance system stability during a system disturbance. 1.2 Asynchrnus (Inductin) Generatrs Cnventinal inductin generatrs and ther generatrs with n inherent VAR (reactive pwer) cntrl capability require an amunt f reactive pwer t maintain pwer factr between 90 percent lagging and 95 percent leading t maintain the required vltage n the HEA electric pwer system. They may als be required t fllw a HEAspecified vltage r VAR schedule n an hurly, daily r seasnal basis, depending n the lcatin f the installatin. Nte: Duble-fed asynchrnus machines, als knwn as duble-fed inductin generatrs (DFIGs), are a distinct class f asynchrnus generatrs, emplying wund rtr inductin machines with static pwer cnverters t drive the rtr field currents. The physical rtatinal speed f the machine can be varied ver a wide range, bth faster and slwer than the synchrnus speed. Unlike an rdinary inductin machine, a duble-fed asynchrnus generatr can supply r absrb reactive pwer, which allws pwer factr r net reactive flw t be easily and quickly cntrlled. In general, DFIG technlgy is widely used in wind generatin Excitatin Cnventinal inductin machines will nt be allwed t be self-excited by nearby distributin capacitrs, r as the result f capacitive vltage n the distributin netwrk. Entities utilizing cnventinal inductin machines shall

12 prvide their wn excitatin VARs such that the generating facility will nt nrmally demand reactive pwer frm, nr supply reactive pwer t, the HEA electric pwer system. Pwer factr crrectin capacitrs (switched r fixed), pwer electrnics designed t supply a level f reactive capability, r a cmbinatin f devices used fr excitatin shall be prvided and installed at the generating facility s expense. The generating facility shall nt disable pwer factr equipment while inductin machines are in peratin Vltage Regulatin Speed matching may be by any means such that vltage regulatin and vltage flicker are held within tlerance Dynamic Vltage Supprt Wind farms r ther inductin technlgies shall als be able t prvide sufficient dynamic vltage supprt and autmatic vltage regulatin at the generatr excitatin system if it is determined that vltage supprt is required fr system safety and reliability Crwbar In sme duble-fed inductin generatrs (DFIG), a crwbar circuit can be added t the rtr side f the frequency cnverter t prvide vercurrent prtectin and vervltage cntrl t the rtr winding. The crwbar circuit limits the transient current in the statr and the rtr t less than 1 per unit fr clse-in and multiple-phase faults. It cnsists f a prtectin circuit that rapidly shrt-circuits (r crwbars ) the supply line if the vltage r current exceeds defined limits. 1.3 DC Generatrs Static pwer cnverters (inverters) cnvert DC electricity int AC electricity and ffer additinal electrnic pwer cnversin. They are smetimes referred t as pwer cnditining systems. Their fundamental rle is t cnvert DC r nn-synchrnus AC electricity frm a prime mver energy surce int a synchrnus AC system f vltages that can be smthly and easily intercnnected with the electric pwer system Inverters Capable f Stand-Alne Operatin Inverters capable f stand-alne peratin are capable f islanding peratin and shall have similar functinal requirements as synchrnus generatrs. Fr units less than 25 kw, usually it is acceptable t have the frequency and vltage functins built int the electrnics f the inverter if the set pints f these built-in prtective functins are tamper-prf and can be easily and reliably tested. These relay functins must receive HEA apprval befre they can be used t intercnnect with the HEA electric pwer system. The ttal harmnic distrtin in the utput current f the inverters will be required t meet ANSI/IEEE 519 requirements. Inverter-type generatrs that have been pre-apprved by HEA can be cnnected t the HEA electric pwer system. Fr units ver 10 kw, a dedicated transfrmer may be required t minimize the harmnics entering int the HEA electric pwer system. 1.4 Emergency Generatr Requirements There are tw methds f transferring electric pwer supply between the HEA surce and the emergency generatr system: pen transitin (break befre make) and clsed transitin (make befre break) Break Befre Make This methd can be accmplished via a duble thrw transfer switch r an interlck scheme that prevents the tw systems frm perating in parallel. The small generatin facility's main breaker shall nt be allwed t clse until the generatr breaker pens. This pen transitin methd des nt require any additinal prtectin equipment; hwever, it des cause the small generatin facility s lad t experience an utage while transferring back t HEA. The length f this transfer depends n the transfer equipment.

13 The break befre make transfer switch must be f a design, r have an interlck, that prevents the transfer switch frm clsing and cnnecting the custmer s system with HEA unless the emergency generatr is already remved frm the system Make Befre Break This methd is used when the custmer wants t minimize any lss f pwer r disturbance t the electric lad. With this scheme, the custmer's generatr and the HEA electric pwer system are in parallel fr a very shrt time interval during which the custmer's lad is being transferred between the HEA surce and the emergency generatr. Bth the transfer frm HEA t the emergency surce and the transfer back can be accmplished withut an utage. Make befre break transfer switches: The transfer switch is rated fr the maximum available fault duty in the event that the transfer switch clses int a fault cnditin. Have an interlck that will trip the main breaker r generatr in the event f a failure f the transfer switch s that the unit will nt remain paralleled t the HEA electric pwer system. One way t accmplish this functin is with a failure-t-pen timer. The cntrls fr the transfer switch prevent a parallel cnditin f the custmer generatr and the HEA electric pwer system frm existing fr an extended time perid. Any system that allws a parallel cnditin t exist fr greater than 100 millisecnds (6 cycles) n the distributin system will be subject t the additinal parallel peratin guidelines utlined in this standard. Discnnect switches: The custmer prvided manual discnnect is lcated at the pint f intercnnectin, which will establish a visually pen safety clearance fr HEA persnnel wrking n the HEA electric pwer system. The discnnect is lckable in either the pen r clsed psitins and perated nly by HEA. The discnnect is easily accessible, preferably lcated adjacent t the electric meter. The discnnect has full lad break capability. The make befre break transfer scheme must have adequate cntrl and prtectin t ensure the HEA and custmer electric systems are in synchrnism prir t making the parallel cnnectin. Synchrnizatin is accmplished thrugh the use f an aut-synchrnizer (Device 15/25) r a synchrnizing relay supervised by a synch-check relay (Device 25). Since the emergency generatrs are paralleled with the HEA electric pwer system, prtective devices are installed that will prevent the custmer s generatr frm remaining cnnected in the event f a fault n the HEA electric pwer system during the transitin. In sme installatins, the prtectin requirement may be satisfied thrugh the installatin f the reverse pwer relay (Device 32R). This relay shuld be installed n the custmer s side f the service transfrmer that is cnnected t the HEA electric pwer system. The relay shuld trip the custmer s main breaker and must be able t detect transfrmer cre magnetizing pwer. In this manner, reverse pwer flw is detected befre it actually enters the HEA electric pwer system and ther custmers equipment. This can be accmplished by setting the current level pick up equivalent t 60 percent f the transfrmer bank magnetizing current. Because this current value will be small, the current transfrmers assciated with the relay must be capable f accurately prviding these small currents t the relay. When transferring the custmer s lad back t the HEA electric pwer system, it is pssible t have incidental pwer flw back t HEA s system. By prperly setting the synchrnizing and/r generatr cntrl, this reverse flw can be avided. Hwever, a shrt time delay may be required n the reverse pwer relay t prevent it frm tripping the generatr unnecessarily each time a transfer is attempted. At n time shuld this time delay exceed 100 millisecnds (6 cycles).

14 Again, since the emergency generatr is briefly cnnected in parallel with the HEA electric pwer system, all transfer schemes f this type must have a dedicated transfrmer t reduce the pssibility that any transfer activities will affect ther HEA custmers. A dedicated transfrmer is als necessary t allw the installatin f the reverse pwer relay scheme.