UET Witness Test Report-Public Version

A WHITE PAPER

1 Copyright © UniEnergy Technologies, LLC 2014

Witness Testing of the UniEnergy Technologies

Uni.System™

Utility Scale Energy Storage System

COMMISSIONED BY

UniEnergy Technologies

Mukilteo, Washington

PREPARED BY

Garth P. Corey, Consultant

Energy Storage Systems Engineer

Albuquerque, NM

July 31, 2014

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Introduction UniEnergy has commissioned me, a third party energy storage systems engineer, to produce a white paper reporting the results of witness testing for the Uni.System™ Vanadium Redox Flow Battery (VFB) onsite at the UET facilities in Mukilteo, Washington during the week of 21‐25 July, 2014. Specifications of the Uni.System VFB as tested are as follows:

SPECIFICATIONS OF UNI.SYSTEM™

Component Specification

Number of modules per battery (20 ft. containers) 4

Stacks per module 3

Voltage window 450~986 VDC

Current ‐1000~1000 ADC

Electrolyte volume 23 m3 per battery module

Operating temperature range ‐10~55 °C

PCS power ‐600~600 kW (see following charge profile)

The following photograph shows the 500 kW, 2 MWh Uni.System as installed at the UniEnergy Technologies facility in Mukilteo, Washington. The system consists of four each 20 ft. modules and one each 20 ft. electronics container. The system ran continuously throughout the testing activities with no down‐time. Human intervention was needed only for the purpose of activating the various tests reported here.

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Because of power limitations of the current Power Conditioning System (PCS), the maximum power available for charging is 400 kW; the maximum power available for discharging is 600 kW. The following graphic shows the limits in voltage at various states of charge. This limitation did not impact the results of the witness test and is scheduled to be addressed in the production version of the Uni.System system so that the maximum power available for discharging and charging will be 600 kW for both functions.

PCS CHARGE PROFILE

Third Party Witness Test Plan

Witness testing was planned for the following five utility scale application areas:

1. Regulation

Signal “Aggressive” was employed for this testing. The signal is consistent with the PNNL testing protocol. The starting SOC was controlled around 50%. The duration of regulation testing is scheduled for 2h.

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Regulation Signal

2. Capacity Testing The capacity testing included two discharge powers: 600kW and 400kW. The charge power was set to ‐400kW due to the de‐rating of the PCS. Because the regulation test (test #1) was centered around a 50% state‐of‐charge (SOC) point, the first charge cycle was started at that SOC. Roundtrip efficiency will be calculated based on the equation below:

Aux consumption includes everything except PCS, such as pump loss, electronic loss, cooling loss, et al. Testing was scheduled as follows: (Capacity testing was scheduled to run for 36~48 continuous hours)

Two cycles of 400 kW charging and 600 kW max power discharging

Two cycles of 400 kW charging and 400 kW discharges, the second includes CV discharge to get max energy

Power Quality Test (to be performed during the peak power points and low power points in the peak shaving test)

Power quality was tested at 4 points for the duration of ~ 15 minutes:

Peak power discharge (600 kW)

End of peak power discharge interval

Peak power charge (‐400 kW)

End of peak power charge interval

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3. Ramping (sine wave)

The California CPUC has mandated 1.325GW of storage by 2020 to overcome projected problems with generation and ramping. The duck curve shown below illustrates California’s looming 12GW ramping, over‐generation and peaking problem. The most serious aspects of these problems is the projected over capacity during mid‐day followed by an extreme ramp up of load of 13 GW in 3 hours and then followed by a peaking load. A battery could absorb the mid‐day over‐generation caused by the high penetration of renewables saving the energy for later use as needed. A battery could also supply the ramping power to assist in the regulation activity and then supply some of the shortfall during peaking.

4

Net Load Curve

Reduced Ramp

Battery Output

3GW/9GWhStorage

3GW/3h storage in 2020:

Halve ramping to2013 levels

Absorb over‐generation

Reduce system peak by 3GW

and also yield system wide

frequency regulation voltage control resiliency black start

6GW Flexible CapacityEquivalent performance to 12GW of fossil peakers

13GW ramp in 3 hours

2GW peak in under 3h

Big changes have already started!

Over-Generation

The sine wave signal was applied to test the system’s ability to follow a ramping application such as the California duck curve. The source of the load command signal was a signal generator which generated the signal as shown in the next graphic. The peak of discharge ramping is ‐400kW AC (due to PCS de‐rating) for charge and the peak for discharge was 600kW AC. Total energy in charging and discharging is equal to the area under the curve, in both charge and discharge, which equates to 1.6 MWh and 1.2 MWh respectively in each function. This test was scheduled to take about 13 hours.

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Power Ramping Signal

4. Combined Ramping and Regulation

The combined ramping and regulation function was tested with no interruption. The charge hours were 7 hours (‐400kW charge with regulation), followed by a 4 hours idle period (with regulation). Then continue with a discharge for 4 hours (400kW discharge with regulation) and another idle interval for 4 hours (with regulation). The total test time is 19 hours. The commanded signal is as follows:

Combined Ramping and Regulation Signal

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5. Power Quality Test

The power quality test will be carried out during the cycling and tracking. The meter will be set up to monitor the power quality.

Testing as scheduled for the 5‐days of witness testing:

21‐Jul 22‐Jul 23‐Jul 24‐Jul 25‐Jul

Monday Tuesday Wednesday Thursday Friday

0:00

Capacity testing‐

400kWCharge/600kW Discharge for two cycles

(around 24 hours)

Capacity testing‐


Peak shaving testing‐Sine wave cycling for one cycle

Combined function

1:00

2:00

3:00

4:00

5:00

6:00

7:00

8:00

9:00

10:00

11:00

12:00

13:00

Combined function

14:00 Regulation

15:00

16:00

Capacity testing‐


17:00 Capacity testing‐


18:00

19:00

20:00

21:00

22:00

23:00

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Witness Testing Results All planned testing activities scheduled for witness testing of the Uni.System was completed without interruption during the week. Results reported in this section are correlated with the numbered test in the preceding test plan.

1. Regulation

The regulation control signal from the test plan was directed to the system controller of the Uni.System system. The following trace is the resulting response of the system.

Of particular interest is the accuracy with which the system is tracking the AC command with one exception: because the 400 kW limit for the charge mode is present as indicated earlier in this report, the system was unable to track the signal for higher power charge commands that exceeded the 400 kW limit. This error will be corrected in the upgraded PCS scheduled for delivery with the production Uni.System system scheduled for delivery in late summer. Another item of interest is the Open Circuit Voltage (OCV), a voltage measurement on the electrolyte that very accurately indicates the state‐of‐charge of the battery in real time. In this “regulation only” application, the system initially begins operations slightly below the 50 % State of Charge (SOC) point, a point that is specifically selected to optimize the energy delivery for power dispatch for the energy storage system. The OCV varies slightly around the 45% SOC point indicating a changing SOC; however, as expected, there is a “net zero” consumption of energy during this 2‐hour regulation demonstration. Test 5, combined ramping and regulation is intended to show how the system can be used for regulation while dispatching in multiple modes simultaneously taking advantage of the energy available while in a regulation mode.

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The following table summarizes the key data points for the regulation test.

Regulation Data Data Units

Test Duration 2.0 hr

Aux Power Consumption 16.3 kWh

Charged AC Energy 230 kWh

Discharged AC Energy 185 kWh

Net Energy Consumed 246.3 kWh

Net Energy Produced 185 kWh

AC Efficiency 80.4 %

Roundtrip Efficiency incl aux loads 75.1 %

2. Capacity Testing

Capacity testing consisted of four round trip capacity tests for two different power discharges, two at 400 kW charge, 600 kW discharge and two at 400 kW charge and 400 kW discharge. Results shown here are for one test of each of the power settings. For each of the two power output settings, the two sets of data are very comparable. The system is unable to charge at 600 kW at this time because of a limit in the charge circuit of the inverter. This charging anomaly is scheduled to be corrected prior to deployment to a field demonstration scheduled for early fall, 2014. All testing proceeded as planned with no unusual or unexpected events.

During the first cycling stage of the first capacity testing sequence, the system tripped off at very near top‐of‐charge. It was noted that the voltage signal had fluctuated noticeably and an investigation was initiated to determine the cause of the trip. UET engineers reported the following finding and introduced a correction to mitigate any further tripping for all remaining tests:

During the cycling testing we experienced an unexpected shut down of the PCS close to the end of the charge cycle near 100% SOC. This seems to have been due to an instability in the DC voltage imposed by the constant voltage control mode. The instability was avoided by operating the PCS in constant power control mode and relying instead on the integrated voltage limiting function of the PCS to maintain stability during high Voltage charging at 100% SOC.

After this fix was implemented no further trips were experienced.

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The following table summarizes the capacity testing results for a 400 kW charge, 600 kW discharge capacity test:

The following graphic shows a full 400 kW charge and 600 kW discharge cycle. Details of power levels and efficiencies are shown in the preceding table. There were no remarkable events throughout the test cycle. The system operated as predicted.

The following table summarizes the capacity testing results for a 400 kW charge, 400 kW discharge capacity test:

StateTime

h

Aux

consumption

kWh

Charged

AC energy

kWh

Discharged

AC energy

kWh

Net

energy

consumed

kWh

Net

energy

produced

kWh

AC

efficiency

%

Roundtrip

efficiency

%

Idle 0.25 2.1

Charge 5.82 50.4

Idle 0.25 1.8

Discharge 1.95 22.2

1798 1163 1852 1141 64.7 61.6

StateTime

h

Aux

consumption

kWh

Charged

AC energy

kWh

Discharged

AC energy

kWh

Net

energy

consumed

kWh

Net

energy

produced

kWh

AC

efficiency

%

Roundtrip

efficiency

%

Idle 0.25 2.1

Charge 8.25 68.0

Idle 0.25 1.8

Discharge 4.73 49.0

2763 1893 2835 1844 68.5 65.0

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The following graphic shows a full 400 kW charge and 400 kW discharge cycle. Details of power levels and efficiencies are shown in the preceding table. There were no remarkable events throughout the test cycle. The system operated as predicted.

This test included a CV voltage discharge to get the max energy, which showed 2.1 MWh for max energy (graph below).

Throughout the four cycles of capacity testing, the system operated continuously interrupted only by the trips at near top of charge which are explained earlier in this report. Capacity delivered meets all claims and specifications.

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Ramping (Sine wave)

The following graphic shows the ramping tracking accuracy of the system as it would be applied for mitigation following the California duck curve discussed earlier.

3. Combined Ramping and Regulation

The following graphic shows the signals generated during combined ramping and regulation testing. Regulation was performed during charging, idle and discharging stages. The system performed as claimed and as specified showing that multiple applications can be performed simultaneously with the Uni.System system. Note the tracking of the SOC throughout the test indicating the actual SOC at any given point in time.

The following table summarizes the performance for the combined ramping and regulation test.

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Combined Ramping and Regulation Data Parameter Data Units

Test Duration 19.8 hr

Aux Power Consumption 184 kWh

Charged AC Energy 2824 kWh

Discharged AC Energy 1961 kWh

Net Energy Consumed 3008 kWh

Net Energy Produced 1961 kWh

AC Efficiency 69.4 %

Roundtrip Efficiency incl aux loads 65.2 %

All results meet all system claims and specifications.

4. Power Quality Test

Total harmonic distortion (THD) was measured for short periods of time at near top of charge, near the start of a discharge, near the end of a discharge and at near the start of charge during the peak shaving (sine wave) test sequence. The following table shows THD for an entire cycle showing the gradual increase in un‐normalized THD as the system moves through lower powers in both charge and discharge. Normalized THD is shown in the last column.

THD / %

AC power Phase 1 Phase 2 Phase 3 Average of 3 phases Normalized

‐417.37 5.69 6.97 6.33 6.33 4.40

‐401.14 6.09 7.42 6.73 6.75 4.51

‐350.93 6.96 8.52 7.55 7.68 4.49

‐301.21 8.25 9.94 8.75 8.98 4.51

‐250.16 9.72 11.93 10.14 10.60 4.42

‐200.84 11.12 13.70 11.51 12.11 4.05

‐151.11 14.13 17.40 14.61 15.38 3.87

‐101.37 20.15 24.69 20.82 21.89 3.70

‐51.63 36.85 45.60 36.97 39.81 3.43

52.19 49.64 52.69 45.39 49.24 4.28

104.52 23.95 25.38 22.30 23.88 4.16

149.38 16.37 17.28 15.27 16.31 4.06

201.71 11.89 12.31 10.87 11.69 3.93

252.34 9.98 10.39 9.18 9.85 4.14

298.32 8.39 8.67 7.65 8.24 4.10

350.88 7.33 7.59 6.65 7.19 4.20

402.21 6.51 6.68 5.81 6.33 4.25

451.93 5.78 5.91 5.11 5.60 4.22

499.15 4.92 5.06 4.36 4.78 3.98

549.64 4.41 4.56 3.94 4.30 3.94

587.99 4.67 4.82 4.41 4.63 4.54

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The graphics shown here are derived from the table on the preceding page. Harmonics generated are well within tolerance as shown. Note that harmonics are more prevalent at power levels approaching lowest levels as shown in these graphics.

This photo shows the voltage waveforms for the 3 phases at near mid‐charge taken from the isolation transformer secondary during a capacity test cycle.

Although there is some apparent distortion, it is insignificant and has little impact on the output voltage power quality. THD during this period was approximately 4.35 to 4.55.

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Strengths and Weaknesses of Uni.System In Witness Testing

Weaknesses: The only weakness I have seen in Uni.System is that it has not been field demonstrated in a utility application. That will be the final test for this emerging technology

Strengths: There are many strong points in the tested Uni.System system. Some of the more important points are enumerated here:

1. Since commissioning, the Uni.System has delivered nearly 100 MWh total power, without testing interruption to correct deficiencies noted during initial testing of the full scale Uni.System system.

2. With the exception of a system trip at near top of charge early in the capacity testing, all components and subsystems operated flawlessly throughout the witness test program which ran continuously from noon on Monday through noon on Friday with operator intervention only to change testing sequences.

3. The system exhibited high performance both in full and partial power settings and proved to be stable over the complete operational profiles tested.

4. The system was proven to be able to operate in multiple applications, delivering both energy and power at the same time, with no compromise in performance.

5. The strong UniEnergy design team consists of electrochemists and engineers with the necessary skills and attitude to bring the Uni.System development project to a successful completion. In my opinion, their efforts will result in the near term deployment of a fully qualified commercial product for the utility scale energy storage market.

Conclusions

Throughout the 5‐day witness testing program, the Uni.System operated continuously under the several witness test protocols scheduled with no interruptions in test operations. However; one event occurred that was not in the test plan providing an opportunity to confirm the functionality of the spill monitoring system in each of the eight electrolyte tanks. An unexpected overnight rainstorm occurred with the top covers of the container open allowing rain to collect in the top of the electrolyte service area which is continuously monitored for any liquid which might be present. Every spill monitor sensed the rain that gathered in the service area which resulted in the shutdown of all system pumps showing that the spill sensor subsystem operated as specified. Throughout the 5‐day testing program, no operational issues occurred which compromised the uninterrupted witness testing plan. All tests were successfully completed and all data correlated to expected results. In my opinion, with the updated PCS which will eliminate the 400 kW charging limit issues, the Uni.System system should be fully capable of meeting all application specifications and ready for a complete field demonstration program.

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Author Biography

Garth P. Corey, retired from Sandia National Laboratories in Nov, 2006 as a Principal Member of the Technical Staff. During his tenure at Sandia, he had project management responsibilities with the Energy Infrastructure and Distributed Energy Resources Department. Most of his Sandia career was dedicated to communicating his system engineering and battery system management knowledge to engineers involved in the integration of various energy storage technologies with the balance of plant needed for the development of a successful operational energy storage system.

During his more than 15 years at Sandia, Garth was involved in high technology energy storage R&D projects and energy storage systems development. He managed projects that spanned the utility scale energy storage arena including flywheels and ultracapacitor systems; sodium sulfur, nickel cadmium, lead acid, (including advanced lead‐acid technologies), and lithium ion batteries; and several flow battery technologies. Much of his time was dedicated to assisting Sandia Renewable Power engineers in the proper integration of batteries in both off‐grid and grid‐tied Photovoltaic systems. Since leaving Sandia, Garth has continued to stay current on new energy storage systems development.

Garth is an internationally recognized subject matter expert in utility scale energy storage applications and systems and is frequently sought out to provide expert advice on emerging energy storage systems and energy storage device development and deployment. He is also very active in conducting technology due diligence investigations to determine the status of emerging energy storage technologies. He is a member of the IEEE Power and Energy Society and is active in balloting energy storage related standards.

Documents

UET Witness Test Report-Public Version