This document summarizes a presentation on developing new screening methods for photovoltaic (PV) distribution system modeling. It discusses hosting capacity analysis, limitations of current 15% of peak load and 100% of minimum load screening methods, and a project to develop alternative screening approaches using detailed modeling of 22 feeders. The project aims to select feeders representing utility configurations, analyze hosting capacity through stochastic modeling, and validate new simplified screening methods based on the detailed analysis results. The goal is to develop easier to apply screens that better account for feeder characteristics and high PV penetration scenarios.

1. Jeff Smith
Manager, Power System Studies
PV Distribution System Modeling Workshop
5/6/2014
Hosting Capacity Analysis and New
Screening Methods for PV
Alternatives to the 15% (or 100%) Rule

2. 2© 2014 Electric Power Research Institute, Inc. All rights reserved.
Overview
• Hosting capacity
– What is it?
– Typical hosting capacity – is there such a thing?
• Screening feeders for potential issues?
• Need for New Screening Methods
– How effective are current methods?
– How can the methods be refined?
• Developing new screening methods
– Feeder selection/clustering
– Hosting Capacity Determinations
– Screening Development and Validation

3. 3© 2014 Electric Power Research Institute, Inc. All rights reserved.
Detailed Hosting Capacity Analysis
Brief Overview
1.035
1.04
1.045
1.05
1.055
1.06
1.065
1.07
0 0.5 1 1.5 2
MaximumFeederVoltage(Vpu)
Total PV Penetraionof Deployment (MW)
Minimum Hosting Capacity
Maximum Hosting Capacity
A B C
Worst-CaseResultforEach
UniquePVDeployment
Increasing penetration (MW)
Threshold of violation
A – All penetrations in
this region are
acceptable, regardless
of location
B – Some penetrations
in this region are
acceptable, site specific
C – No penetrations in
this region are
acceptable, regardless
of location
Details on Hosting Capacity Approach:
Stochastic Analysis to Determine Feeder
Hosting Capacity for Distributed Solar PV.
EPRI, Palo Alto, CA: 2012. 1026640.
Feeder characteristics
Location of PV
Amount of PV
How much PV
a specific feeder can host

4. 4© 2014 Electric Power Research Institute, Inc. All rights reserved.
Detailed Hosting Capacity Analysis
Sample Findings
• Each feeder is found to
have a unique hosting
capacity for PV
• Feeder characteristics
determine issues that occur
Research Details found here:
Distributed Photovoltaic Feeder Analysis: Preliminary Findings
from Hosting Capacity Analysis of 18 Distribution Feeders. EPRI,
Palo Alto, CA: 2013. 3002001245.
0 5 10
J1
R1
R2
R3
R4
T1
T2
G1
G2
G3
P1
P2
P3
P4
P5
D1
D2
D3
Large Scale
Feeder
All penetrations in this
region are acceptable,
regardless of location
Some penetrations in
this region are
acceptable, site specific
No penetrations in this
region are acceptable,
regardless of location

5. 5© 2014 Electric Power Research Institute, Inc. All rights reserved.
Detailed Hosting Capacity Analysis
Can load be used to predict hosting capacity?
0
0.5
1
1.5
2
2.5
3
3.5
0 2 4 6 8 10 12 14 16 18
MinimumHostingCapacity(MW)
Peak Load (MW)
Not without knowledge of
other feeder characteristics
No correlation between hosting
capacity and peak load

6. 6© 2014 Electric Power Research Institute, Inc. All rights reserved.
0
1
2
3
4
5
6
J1 R1 R2 R3 R4 T1 T2 G1 G2 G3 P1 P2 P3 P4 P5 D1 D2 D3
MW
Feeder
MinimumHostingCapacity
100% of Daytime Minimum Load
How Effective are Current Screening Practices?
Keeping in mind, “screens” should be conservative by nature…
0
0.5
1
1.5
2
2.5
3
3.5
J1 R1 R2 R3 R4 T1 T2 G1 G2 G3 P1 P2 P3 P4 P5 D1 D2 D3
MW
Feeder
MinimumHostingCapacity
15% of MaximumLoad
0
0.5
1
1.5
2
2.5
3
3.5
J1 R1 R2 R3 R4 T1 T2 G1 G2 G3 P1 P2 P3 P4 P5 D1 D2 D3
MW
Feeder
MinimumHostingCapacity
100% of MinimumLoad
15% peak and 100% minimum
load overestimates hosting
capacity on some feeders
Feeders at risk for PV to
pass through screens
without issues being flagged

7. 7© 2014 Electric Power Research Institute, Inc. All rights reserved.
What feeder characteristics seem to matter
most when predicting PV impacts?
Voltage
• Line regulators
Impedance
• PV location
Initial analysis has shown that simplified
methods can be used to estimate hosting
capacity

8. 8© 2014 Electric Power Research Institute, Inc. All rights reserved.
Developing Alternatives to the 15% Screen
(or new 100% screen) – CPUC/CSI3 Project
• Overview
– Use rigorous modeling to
develop alternate simplified
screening methods for PV
interconnections
– Sample wide range of feeder
types
• Team
– EPRI, Sandia, NREL, SCE,
PG&E, SDGE, ITRON
• Timeline
– End of 2014
Feeder Selection
Hosting capacity
Analysis
Develop alternative
screening methods
Screening
validation

9. 9© 2014 Electric Power Research Institute, Inc. All rights reserved.
Feeder Selection
• Purpose of task
– Determine the range of feeder
configurations and
characteristics for CA utilities
– Select feeders from each
range/cluster
• Approach
– Cluster 1000’s of feeders
based upon topology
– Identify 20 feeders for
analysis application
• 15 for detailed analysis
• 5 for validation/verification

10. 10© 2014 Electric Power Research Institute, Inc. All rights reserved.
22 Feeders Selected
0
20
40
60
80
100
120
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
miles
Feeder
Total 3-ph ckt miles
0
2
4
6
8
10
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
#
Feeder
Number of Regulators
-
5,000
10,000
15,000
20,000
25,000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
#
Feeder
Connected kVA
0
20
40
60
80
100
120
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
miles
Feeder
Total 2-ph and 1-ph ckt miles
Voltage Class
4
12
16
21
33

11. 11© 2014 Electric Power Research Institute, Inc. All rights reserved.
Feeder Modeling
• Detailed distribution models
– Full three-phase
– Test and control feeders
• Work with participating utility to
obtain base feeder data
– Add secondary transformers and
service drops
– Incorporate time-series load data
• Convert model to OpenDSS
(open source)
• Validate/verify model with
measurement data
Feeder
Voltage Heat
Map

12. 12© 2014 Electric Power Research Institute, Inc. All rights reserved.
Detailed Hosting Capacity
Sample Results from 5 Feeders
0 2 4 6 8 10
P1
P2
P3
P4
P5
Small Consumer PV (MW)
Feeder
A – All penetrations in this region
are acceptable, regardless of
location
B – Some penetrations in this
region are acceptable, site specific
C – No penetrations in this region
are acceptable, regardless of
location

13. 13© 2014 Electric Power Research Institute, Inc. All rights reserved.
Development of Screening Methods
• Screening Method requirements
– Ease of use
– Based on readily available
data
– Conservative
• Overall Approach
– Develop screening
methodology/approach using
results from detailed hosting
capacity analysis
– Validate approach using
control group of feeders and
corresponding modeling and
simulation results with
measurement data
New
Screening
Methods

14. 14© 2014 Electric Power Research Institute, Inc. All rights reserved.
Summary
• Screening methods for DER need to evolve
– Account for feeder-specific characteristics
– Account for high-penetration scenarios
• Detailed hosting capacity calculations
– Have identified gaps in existing screening methods
– Can be used as basis for new screening methods

15. 15© 2014 Electric Power Research Institute, Inc. All rights reserved.
Questions
Contact:
Jeff Smith
Manager, Power System Studies
EPRI
jsmith@epri.com, +1.865.218.8069