|
Sandia National Laboratories Distributed Energy Technologies
Lab (DETL) and PV Systems Optimization Lab (PVSOL) have a long
history of working with Balance of Systems (BOS) component manufacturers
as they develop their products. Activities include evaluating
pre-production models (prototype, alpha, or beta) for code conformance,
performance, and compliance with utility interconnection standards.
We perform evaluations on power electronic inverters, packaged
PV systems, intelligent system controllers, battery charge controllers,
and hybrid systems.
Sandia’s test facilities, engineering staff, and equipment
will be used to evaluate Solar America Initiative contractor
progress at stage-gates 0 (Preliminary Investigations), 1 (Technology
R&D), and 2 (Prototype System Development). Often BOS manufacturers
do not possess sufficient resources such as test equipment,
data acquisition systems, test protocols, and engineering expertise.
Findings at the pre-production stage lead to improvements impacting
the cost and reliability of products much more efficiently than
waiting for issues to be identified in the field
PV
Systems Optimization Lab (PVSOL) Configurable Arrays
|
Facilities
and Test Descriptions
Evaluations
are conducted at the Distributed Energy Technologies Laboratory
(DETL) by staff engineers who are intimately involved with the
relevant requirements as a result of their membership and leadership
in various codes and standards organizations. DETL engineers
interact regularly with a variety of stakeholder groups such
as UL, CSA, CEC, and NFPA. Sandia assisted with the identification
of utility interconnection requirements through the development
of standards such as IEEE 929 (which defined a “non-islanding
inverter”), IEEE 1547, and UL 1741. Performance test protocols
developed at Sandia have been used as the foundation for developing
the inverter performance protocol adopted by the California
Energy Commission (CEC) as a basis for California’s PV
system rebates. Seven data-acquisition systems are in place
using 16-bit, 333 kHz digitizers. Three are in place using 1.25
MHz digitizers controlled by National Instruments LabView programs.
These systems are also used to control loads and to automate
test sequences. Microsoft Excel charts are created from the
reduced data representing both averages and high-speed waveforms.
Instruments independent of the LabView systems include oscilloscopes,
spectrum analyzers, digital multimeters, dynamic signal analyzers,
and audio analyzers. Specialized test equipment is used to measure
additional quantities including conducted and radiated radio-frequency
emissions, temperature, audible noise, response to high-voltage
surges, and variations in ac grid voltage and frequency.
Inverter
Testing
Inverters are key building blocks of photovoltaic
(PV) systems producing ac power. The balance of systems (BOS)
portion of a PV system can account for up to 50% of the system
cost, and its reliable operation is essential for a successful
PV system. These tests generally fall into three categories:
Top of page
Benchmark
Testing
Tests have been designed and performed
to benchmark the performance of inverters. The primary
goal of benchmark testing is to provide information
on inverter performance over a standardized set of tests.
This is important because of the variations in the manner
in which inverters have been rated and specified by
the manufacturers. For example, inverter efficiency
is often reported as a single number without regard
for load characteristics which significantly affect
efficiency. These tests are intended to provide information
which is useful to PV system integrators in selecting
an inverter for a specific application and in anticipating
an inverter’s performance under a variety of conditions.
Development
Testing
The purpose of development testing is to assist inverter
manufacturers in their development of a technological
innovation or refinement of their product. Consequently,
the manufacturers are the primary customers for development
test results. This service can be significant because
creating, equipping, maintaining, and operating a test
facility is, in many cases, prohibitively expensive.
Key elements of the facility which can be useful include
a variety of loads, dc and ac sources, and diagnostic
equipment.
Acceptance
Testing
In a few cases, inverters have been
tested to verify that their laboratory performance meets
government contractual requirements. The customers in
this case are the end users of the equipment. Since
some of the capabilities of the inverter may be new,
acceptance testing has typically followed a preliminary
period of development testing. Two examples of acceptance
testing are a 250-kVA Kenetech hybrid inverter for the
Dangling Rope Marina at Lake Powell, Utah, and a 300-kVA
Abacus Controls, Inc. hybrid inverter for the U.S. Navy’s
Superior Valley installation at China Lake, California
|
Distributed
Energy Technology Laboratory Specialized Equipment
Loads
| •
Resistive load banks: |
360
kW, |
480
V, 3-phase |
| |
|
150
kW, 480 V, 3-phase |
| |
|
55
kW 480 V, 3-phase |
| |
|
10
kW, 240 V, 1-phase |
| |
|
10
kW, 120 V, 1-phase |
| •
Inductive load banks: |
225
kvar, |
480
V, 3-phase |
| |
|
55
kvar, 480 V, 3-phase |
| •
Nonlinear load bank: |
50
kVA, |
277
V |
| •
Capacitive loads: |
|
50
kvar, 480 V, 3-phase |
| |
|
250
kvar, 480 V, 3-phase |
| •
Motors: |
|
20-hp
with fan load |
| |
|
3-phase
to 10 hp with dynamometer |
| |
|
1-phase
to ¾ hp with dynamometer |
AC
Sources
| •
Main utility service: |
500
kVA, |
480
Vac, 3-phase |
| •
Diesel generator: |
|
Caterpillar
92.5 kVA, 480 Vac, 3-phase, |
| |
|
(Woodward
EGCP1 grid-paralleling controller) |
| •
Natural gas generator: |
8.5 kVA, |
120/240
Vac, 1-phase |
| •
Gasoline generator: |
3
kVA, |
120/240
Vac, 1-phase |
| •
Programmable sources: |
|
60
kVA, 0-480 Vac, 3-phase |
| |
|
5.25
kVA, 0-480 Vac, 1-phase or 3-phase |
• Temporary generators:
|
|
provision
for up to 500 kVA, 480 Vac, 3-phase |
DC
Sources
| •
Photovoltaic arrays: |
30
kW |
configurable
crystalline Silicon |
| |
|
25
kW configurable crystalline Silicon |
| |
|
3
kW amorphous Silicon |
| •
PV simulator: |
|
64
kW |
| •
Power supplies: |
|
400
V, 12 A |
| |
|
350
V, 35 A (3 each) |
| |
|
55
V, 180 A (8 each) |
Battery
Storage
| •
Flooded lead-acid: |
600
kWh, 2-V |
increments to 480 Vdc |
| •
Valve-regulated lead-acid: |
200
kWh, 6-V |
increments to 480 Vdc |
| |
52
kWh, 6-V |
increments
to 48 Vdc |
| |
12
kWh, 6-V |
increments
to 48 Vdc |
Top
of page
Lightning Simulator
| •
Voltage and current surge generator: |
Haefely
Psurge 8000 |
| |
PIM 100 U: 1.2/50 I: 8/20 |
| |
PIM 110 U/I 100kHz |
Radio Frequency Interference Test Equipment
•
Farnell spectrum analyzer and FCC compliance software
|
Infrared
Camera
•
Flir ThermaCAM P60 thermal imaging camera and
analysis software
|
Temperature
Chamber |
•
Tenney T14C, -73 C to 200 C, 28” W x 34”
H x 26” D (14 ft3)
|
|
| •
Diesel generator: |
Caterpillar
92.5 kVA, 480 Vac, 3-phase, |
| |
(Woodward
EGCP2 grid-paralleling controller) |
| •
Microturbine: |
Capstone
330, 24 kW, dual mode, inverter output |
| •
Fuel cell: |
Plug
Power SU1, 5kW, 1-phase, dual mode, PEM,
natural gas reformer (5 each)
|
| •
Photovoltaic: |
Xantrex
PV20208, 20 kW, 480 Vac, 3-phase
Various manufacturers 1-phase, 1-5 kW
|
Top of page
DETL electrician configuring pulse tester |
Engineer Testing 75 kW Grid-Tied PV Inverter |
Sandia
engineer interpreting inverter waveforms
|
Links
www.sandia.gov/detl/
www.sandia.gov/pv/
www1.eere.energy.gov/solar/pdfs/inverter_II_workshop.pdf
www1.eere.energy.gov/solar/pdfs/sda_inverter.pdf
Top of page |
Residential
Grid-tied Inverters under long-term evaluation at 'PVSOL (PV
Systems Optimization Lab)
Contact
Sigifredo Gonzalez
(sgonza@sandia.gov)
(505)844-2890
|
