This document discusses the need for new test feeders to model advanced inverters and distributed energy resources. It describes existing and new test feeders developed by the IEEE Distribution Test Feeder Working Group to evaluate distribution system modeling tools. New test feeders being developed include ones to model high penetration of distributed generation, microgrids, integrated transmission and distribution systems, and time-varying loads and generation. The document argues there is also a need for an advanced inverter test feeder to study the interactions of inverters with voltage control and protection systems under different operating conditions.

1. IEEE Test Feeders for
Advanced Inverter Analysis
JASON FULLER
Pacific Northwest National Laboratory
PV Distribution System Modeling Workshop
5/6/2014

2. A little background…
IEEE Distribution Test Feeder Working Group
Under Distribution Analysis Subcommittee
Informally started in 1991 with four radial test systems (fifth was added later)
Original models were designed to benchmark unbalanced power flow
solutions between tools
NOT designed to test optimization algorithms
NOT designed to test speed to solutions
NOT designed to test network systems
NOT designed to test “big” systems
etc.
New models were and are needed!
2

3. 3
New test systems are being added
8500 Node Test Feeder (2010)
Larger-scale to evaluate scalability of algorithms
Real system with multiple voltage control devices
Balanced and un-balanced versions
Includes service drops (120/240 V)
Courtesy of
EPRI’s OpenDSS
Comprehensive Test Feeder (2010)
Designed to test models of standard components
Cables, lines, transformers, regulators, induction
machines, substations, sources, parallel lines,
switches, triplex, quadraplex, etc.
Tests convergence, especially under various
switching schemes
Courtesy of W.H. Kersting

4. 4
New test systems are being added
Neutral-Earth-Voltage Test Feeder (2010)
Tests ability to determine NEV effects
Multi-phase system with
4 circuits, neutral, and 4 telecom circuits on a pole
Single- to three-phase laterals
Pole and load grounds
Substation neutral reactor
Solved in multiple frequencies (3rd harmonic)
Based on actual system near U.S. university
Test Feeder for DG Protection Analysis (2011)
Tests fault currents, voltages, etc. in presence
of distributed generation
With and without a utility source
Multiple reclosers and fuses
Based on actual 1.65 MW WT connected to a
12.47 kV feeder
Courtesy of T.E. McDermott

5. 5
New test systems are being added
Short-circuit test cases (2012)
Tests unbalanced short-circuit currents and voltages under given set of
assumptions (no sequence components!)
Results compared on original radial test feeders
Additional models are needed for distributed generation and inverters!
Network Test System (2014)
First case is a small, 390-node system (ideal)
Expanding to larger, more complicated ones
Tests the effectiveness of solvers and algorithms
on unbalanced, heavily meshed systems, including
Low-voltage meshes
Parallel transformers and cables
Spot networks
Normal and loss of primary feeder operations
CourtesyofK.P.Schneider

6. 6
In the works
Time-series test case
One-second resolution over a short time scale
One-minute resolution over a longer time scale
Load shapes to replace static loads (to include DG sources)
Variety of voltage control modes
Low voltage test case
Large meshed network test case
Inverter-based DG test case
Microgrid test case
Integrated transmission and distribution test case
GridLAB-D simulation of 123-node
with 30-second load shapes

7. 7
Do we need an advanced
inverter test feeder?
The research community may be able to:
Evaluate the interaction of existing and potential voltage
control systems?
Test the interaction of current and future protection
schemes?
Investigate islanding and/or ride-through behaviors
during grid disturbances?
Understand interactions with other advanced
technologies (DR, VVO, etc.)?
Evaluate business models, revenue recovery, and rate
design to support investigation of alternatives?

8. 8
What’s needed for an
advanced inverter test case?
Real (or realistic) feeder model with high
penetrations
Multiple voltage control devices (and
settings / configurations)
Unbalanced and balanced loading and
generation
Time-series load and generation data
High- and low-resolution
Agreed upon inverter performance model(s)
and parameters
With multiple control types (e.g., static PF,
dispatched Q, local voltage control, etc.)
Multiple testing regimes (steady-state, quasi-
steady-state, transient / dynamic, etc.)
“Effects of distributed energy resources
on conservation voltage reduction”

9. 9
How do we make a useful model?
Hardware-in-the-loop?
Hardware-in-the-Loop
Two Advanced Inverters with PV located right
after line regulator (80 kW each)
Rest of system simulated
1-second synchronization / timesteps
Courtesy of joint PNNL / NREL HIL Project

10. Questions / Comments?
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