Title: AMR Data vs. Load Allocation
1AMR Data vs. Load Allocation
Bill Kersting
2What is the purpose of an electric utility?
- Make money?
- Break even?
- Public Service Charity?
3ANSI Voltage Standards
- Range A Normal Steady-State
- Nominal Utilization Voltage 115 volts
- Maximum Utilization Voltage 126 volts
- Minimum Service Voltage 114 volts
- Minimum Utilization Voltage 110 volts
- Range B Emergency Steady-State
- Nominal Utilization Voltage 115 volts
- Maximum Utilization Voltage 127 volts
- Minimum Service Voltage 110 volts
- Minimum Utilization Voltage 107 volts
4Voltage Drop
5- Impedance (Z) and current (I) must be computed as
accurately as possible - Impedance best computed using Carsons Equations
- Current is a function of load
- If Z and I are not computed accurately, all bets
are off on the calculated system voltages
6Voltage Profile
7What is this thing called Load?
8Transformer Loading
9Customer 1
10Customer 2
11Customer 3
12Customer 4
13Transformer Diversified Demand
14Summary
15AMR Data
- May, June and July 2006 data recorded
- 314 customers
- 15 minute kW demand per customer
- 23 transformers
- 15 minute diversified kW demand computed
- Studies will involved using the 15 minute
diversified kW demand as the load for each
transformer - 90 power factor will be assumed
16Transformer kVA Rating and of Customers
17Peak Day
- July 17, 1006
- Time of max 15 min kW demand 1745
18Transformer Loading 7/17/2006
19Sum of Transformer Demands
207/17/2006 Transformer Data
21Load and Utilization Factors
22Time of max 15 minute Demands
23What to do with all of this Data?
- Model using the IEEE 34 node test feeder
- http//ewh.ieee.org/soc/pes/dsacom/testfeeders.ht
ml - Base case will model each transformer with its 15
minute demand at the time of the total peak
(1745, July 17, 2006) - Computed kW and kVAr at the substation will be
the same as if metered
24IEEE 34 Node Test Feeder
25IEEE 34 Node Test Feeder
- Nominal voltage 24.9 kV (line-to-line)
- Very long (35 miles) and lightly loaded
- Two in-line step voltage regulators
- One in-line transformer reducing voltage for a
short 4.16 kV feeder - Shunt capacitors
- Spot and distributed loads
26IEEE 34 Node Feeder Modifications
- Disconnect voltage regulators
- Disconnect shunt capacitors
- Represent each of the 23 transformers as a spot
constant wye connected PQ load
27Windmil 34 Node Test Feeder Model
28Base Case kW Demands 90 Power Factor Assumed
29Windmil IEEE 34 Node Feeder
- Base Case Results
- Sa 382.28 j 130.96 kVA
- Sb 377.16 j 127.73 kVA
- Sc 525.79 j 229.27 kVA
- Stotal 1,285.27 j 487.97 kVA
- Sloss 86 j 62 kVA
- Qcharging -j 154 kVAr
30Base Case Node Voltages
31Allocation Methods to Study
- The source control point will be set to hold the
phase complex powers constant for the following
allocation method - Daily kWH
- Monthly kWH
- Transformer kVA
- REA
32July 17, 2006 kWH
33July 2006 kWH
34Allocated Loads by Method
35Percent kW Demand Error
36Transformer T-01Percent kW Demand Error
37Transformer T-17Percent kW Demand Error
38Average kW Demand Percent Error
39Node Voltages (120 V base)
40Percent Node Voltage Errors
41Average Percent Node Voltage Error
42Major Conclusion to this Point
- Monthy kWH gives the closes load modeling to the
Base Case - What about lateral control points?
- Data from base case
- Line 824-T04 155 kW j 65 kVAr
- Line 834 T-15
- Phase B 78 kW j 37 kVAr
- Phase C 83 j 39 kVAr
43Monthly kWH with and without control points
44Percent kW Demand Error with and without Ctr.
Pts.Compared to Base Case
45Node Voltage Profile with Ctr. Pts.
46Percent Voltage Error with Ctr. Pts.Compared to
Base Case
47Final Conclusions
- AMR 15-minute kW demand readings give a wealth of
information about the loading of a distribution
feeder - The modeling of loads is critical to the accuracy
of the study - With the four methods of allocation the
allocation based upon monthly kWH gives the
smallest error - Use of control nodes makes the study even more
accurate