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Distributed Generation and Power Quality-Continued. # Distributed Generation provides some capacity relief on the substation. # Distributed Generator should be sited away from the substation. # Distributed Generator (diesel genset) might be sited near the tie-point between two feeders.
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# Distributed Generation provides some capacity relief on the substation. # Distributed Generator should be sited away from the substation. # Distributed Generator (diesel genset) might be sited near the tie-point between two feeders. Siting Distributed Generation
Typical interconnection requirements for customer-owned DG • No voltage regulation while interconnected unless by special agreement • Anti-islanding frequency and voltage control (IEEE Standard 929-2000) • Relaying to detect resonant conditions in susceptible applications • Fault detection: relaying to detect faults on utility system and disconnect after delay. • Direct transfer trip (costly)
Typical requirement to detect faults on utility system and disconnect after delay (60 Hz system):
Small DG: Relays added to normal protection (overcurrent, etc.) for interconnection 81 OU load 27/59 DG 27: undervoltage 59: overvoltage 81: frequency (O=over, U=under)
Small DG: Relays would trip DG breaker if not used for backup. Relays would trip main breaker if used for backup, so that continued operation is possible (must coordinate with controls on DG)
50/51 81 O/U 47 59I 27/59 59N 46 25 46 50/51 87 32R 40 DG 51G resistance grounded to limit ground fault current 1-10 MW DG showing typical protection
25: synchronizing device 27: undervoltage 32R: reverse power 40: loss of field 46: negative sequence current 47: negative phase sequence 50: instantaneous overcurrent 51: time overcurrent 51G: ground overcurrent 59I: inst. overvoltage (if resonance is problem) 59N: overvoltage (on corner of broken delta) 87: differential (main generator overcurrent)