IMPACTS OF LARGE DISTRIBUTED GENERATORS ON CENTERPOINT ENERGY’S DISTRIBUTION SYSTEM 1 Presented by...
-
Upload
thomasina-collins -
Category
Documents
-
view
216 -
download
2
Transcript of IMPACTS OF LARGE DISTRIBUTED GENERATORS ON CENTERPOINT ENERGY’S DISTRIBUTION SYSTEM 1 Presented by...
IMPACTS OF LARGE DISTRIBUTED GENERATORS ON CENTERPOINT ENERGY’S
DISTRIBUTION SYSTEM
1
Presented by Ed Briggs, P.E.
Manager of Electric Distribution Planning
SWEDE Presentation May 9, 2014
CenterPoint Energy Proprietary and Confidential Information
SAFETY MOMENT
PUBLIC AND EMPLOYEE SAFETY IS THE MOST
IMPORTANT CONSIDERATION OF DG DESIGN, CONSTRUCTION
AND UTILITY INTERCONNECTION !
2
WHAT IS DISTRIBUTED GENERATION (DG) ?
3
Texas PUC Substantive Rule 25.211An electric generating facility located at a customer’s point of delivery (point of common couple) of ten megawatts (MW) or less and connected at a voltage less than 60 kilovolts (kV) which may be connected in parallel operation to the utility system.
4
DISTRIBUTED GENERATION BY FUEL TYPE
5
Total Pending and Connected DGs Through 4/16/14
Large DG (7500+ KW) Statistics
6
WHATS DRIVING THE LARGE DISTRIBUTED GENERATION
INTERCONNECTIONS?
• Emergency Response Service (ERS) or Demand Response
• Close transition-parallel with the utility grid for less than 1 second (closed transition switching)
• Parallel operation with power export option
• Parallel operation with no power export
7
• LOAD
• VOLTAGE
• POWER FACTOR
• FAULT CURRENT
• CIRCUIT PROTECTION
• LATERAL FUSE COORDINATION
• EFFECTIVE GROUNDING
• RELIABILITY
• SAFETY8
IMPACTS OF LARGE DISTRIBUTED GENERATION
DG SIZE RATING
A GENERATOR NAME PLATE RATING SHOWS
2500 kVA @ 80% POWER FACTOR
• WHAT IS THE DG kW CAPACITY ? 2000 kW or 2500 kW ?
SAME QUESTION AS ABOVE EXCEPT THE PRIME MOVER OF THE GENERATOR IS A DIESEL ENGINE RATED AT 1800kW
• WHAT IS THE DG kW CAPACITY ? 1800 kW or 2000 kW or 2500 kW ?
9
12.47 kV DISTRIBUTION FEEDER DG STUDY
• 7 GENERATORS RATED AT 2500 kW EACH (7 X 2500 = 17,500 kW)
• PRIME MOVER DIESEL ENGINE RATED AT 1800kW
• ACTIVE GENERATION = 7 X 1800 = 12,600 kW
• 12.47 kV FEEDER RATED AT 12,960 kW
• DG VOLTAGE CONTROL @ 100%PF
10
11
12.47kV FEEDER PEAK LOAD 10,260 kW 540 kVAR 99.9 PF
DG
SUB
DISTRIBUTIVE GENERATION SETUP (PCC IS POINT OF
COMMON COUPLING)
12
Utility sourceUtility Source
PCC 2
2500 kVA TRANSFORMER
PCC 1
12.47 kV BUS
TO SUBSTATION
2500 kW GENERATOR 480Y277V
DG TRIPS IF:
VOLTAGE = 126V FOR 30 SECONDS
VOLTAGE = 132V FOR 10 CYCLES
CUSTOMER WANTS TO OPERATE DG AT 100% PF
13
DG VOLTAGE TRIP SETTING
CNP SUBSTATION VOLTAGE REGULATION IS SET AT 122V TO 125V
FOUR CIRCUIT MODELING SENARIOS ARE:SUMMER PEAK LOADING
• SUB AT 125V
• SUB AT 122VOFF-PEAK LOADING
• SUB AT 125V
• SUB AT 122V14
DG ANALYSIS
LOCATION AT PCC WITH SUB AT 125 V WITH SUMMER PEAK LOAD
15
16
LOCATION AT PCC WITH SUB AT 122 V WITH SUMMER PEAK LOAD
17
LOCATION AT PCC WITH SUB AT 125 V WITH OFF-PEAK LOAD
18
LOCATION AT PCC WITH SUB AT 122 V WITH OFF-PEAK LOAD
19
LOCATION AT PCC WITH SUB AT 125 V WITH SUMMER PEAK LOAD & EFFECTS
OF CAPACITOR BANKS
20
DG CAN REDUCE THE VOLTAGE AT PCC BUT RESULTS IN INCREASED kVAR WHICH RESULTS IN A 394 kVA DEMAND THUS A $$
$$$ MONTHLY BILL
DURING OFF PEAK SEASON 4 DGs BACKFEEDS SUBSTATION
TRANSFORMER WITH 2279 kW
21
SubstationTransformer
Circuits #1 #2 #3
2279 kW
22
12.47kV FEEDER PEAK LOAD 10,260 kW 540 kVAR 99.9 PF
DG
SUB
DG
DG
At PCC with Sub at 125 V with Summer peak load & DG located
near Sub
23
At PCC with Sub at 125 V with Summer peak load & DG located at
end of circuit
24
25
DG INCREASES CIRCUIT FAULT CURRENTAND CAUSES 100T FUSE NOT TO COORDINATE
WITH 65T, MUST CHANGE LATERAL TO A FEEDER AT CUSTOMER EXPENSE
Without DGs, I LG max = 2578 A With 7 DGs, I LG max = 3976 A
100 T fuse
65T fuse
DG ELEVATES FAULT CURRENT ON SUBSTATION BUS AND ADJACENT
CIRCUITS
26
A FAULT ON ADJACENT CIRCUIT WILL BE FED BY DG CIRCUIT AND MAY RESULT IN TWO CIRCUITS OPERATING THUS IMPACTING RELIABILITY
LATERAL FUSE COORDINATION WILL NEED TO BE ASSESSED ON ADJACENT CIRCUITS DUE TO HIGHER FAULT CURRENT
Line to Ground Fault Currents
27
EFFECTIVELY GROUNDED SYSTEM PER IEEE STANDARD 142
28
EFFECTIVELY GROUNDED SYSTEM CHECK ?CUSTOMER’S HIGHSIDE RESISTIVE GROUNDING 24 OHM ON 12.47kV SIDE OF THE TRANSFORMER
29
CNP REQUIRES TRANSFER TRIP FOR DGs OVER 2000 kW. HOWEVER CIRCUIT
SWITCHING CAN SCUTTLE THIS
30
Sub 1 Sub 2
DG
N.C. N.O. (TIE)
N.C.Utility crew opens the N.C. switch
Utility crew closes the tie switch
DG will be transferredfrom a feeder from sub 1 to another feeder from sub 2
Lateral
SWEDE 2015
NEXT YEAR’S PRESENTATION DG ACTUAL DATA VERSUS MODELED
THANK YOU !
31
NEXT YEARDG ACTUAL VERSUS MODELED
THANK YOU !
32
Any Questions ?