1. Beckett Energy Systems
IEEE EnergyTech 2012
Suggested Test Protocol for Distributed Energy Storage Systems at “The Edge of the Grid”
John Butkowski
Beckett Energy Systems

2. Distributed Energy Storage at the Grid Edge
Scalable and Modular
In 25kW/25kWh increments
For 2 – 8 Homes
Utility Initiated Communications and Control
Grid Tied – Bidirectional
True Islanding Capability and Synchronous return

3. Test Protocol Objective
Develop a universal test protocol to ensure that a Distributed Energy Storage System (DESS) consisting of a Power Conversion and Battery System and can safely perform applications and grid compatibility functions required for “edge of grid” operation.

4. Test Protocol
Five “Basic” Tests - ensure the DESS is safe to connect to the power grid. The DESS SHOULD NOT be connected to the power grid until these tests are complete. These tests are performed using an isolated source such as a generator, MG set, and/or a programmable supply.
Seven “Power Quality” Tests – characterize the power quality of the DESS.
“Use Case” Tests - assess functions of the DESS that are not common to all systems but provide value to the utilities.

5. Basic Test Overview Hardware/Software Review Basic Command Review
Performance Review
Unintentional Islanding
Abnormal Voltage and Frequency

6. Test 1 - Hardware and Software Review
Basic Tests
Test 1 - Hardware and Software Review
Document hardware / software received
Review workmanship and internal topology
Review system documentation/training from the manufacturer

7. Test 2 - Basic Command Review
Basic Tests
Test 2 - Basic Command Review
Verify the DESS will turn on and off properly when it receives the charge and discharge commands
Confirm the function of any safety disconnects or Emergency Power Off features

8. Test 3 - Performance Review
Basic Tests
Test 3 - Performance Review
Record the utility bus AC waveforms with the DESS connected
Record the DC waveforms of the battery charge/discharge functions
Verify the ability of the system to charge and discharge at various range of power levels

9. Test 4 - Grid Compatibility: Unintentional Islanding
Basic Tests
Test 4 - Grid Compatibility:
Unintentional Islanding
Verify that the DESS disconnects from the grid within two seconds of an islanding condition. This test ensures that power will not be fed back into the grid in the event of a grid outage. (Note that this test does not address any downstream islanding capabilities, only loss of grid power.)

10. Test 5 - Grid Compatibility: Abnormal Voltage & Frequency
Basic Tests
Test 5 - Grid Compatibility: Abnormal Voltage & Frequency
Verify that the DESS must disconnect when presented with abnormal voltage and frequency. These tests will be performed while the DESS is discharging 100% rated power into the utility bus

11. Power Quality Tests DC Current Measurement Inrush Current
Transfer Profile
Reconnect Following Abnormal Condition Disconnect
Harmonics
Flicker
Efficiency / Parasitic Losses

12. Test 6 - DC Current Measurement
Power Quality Tests
Test 6 - DC Current Measurement
Verify that an inverter that connects to the grid complies with the DC injection limit specified in IEEE Std 1547 (DC current injection is less than 0.5% of the full rated output current)

13. Power Quality Tests Test 7 - Inrush Current
Measure the potential for inrush current when a DESS is energized. The result is particularly important for systems containing a transformer or certain types of input filters since the inrush can be significantly higher than the full load operating current.

14. Test 8 - Transfer Profile
Power Quality Tests
Test 8 - Transfer Profile
Characterize the DESS specific response for connecting and synchronizing to the grid during initiation of charge and discharge cycles.
During this test the voltage level before and after connection will be evaluated to ensure the system does not exceed the IEEE std allowance of 5% voltage fluctuation.

15. Test 9 - Reconnect Following Abnormal Condition Disconnect
Extended Power Quality Tests
Test 9 - Reconnect Following Abnormal Condition Disconnect
To evaluate the performance of the DESS reconnect timer which delays the reconnection to the utility bus following a trip event. Test is conducted at full rated output power.

16. Power Quality Tests Test 10 - Harmonics
This test measures the Total Harmonic Distortion (THD) present at the DESS input/output during charge and discharge at 100% of full rated discharge.

17. Power Quality Tests
Test 11 - Flicker
Characterize the flicker parameters (voltage fluctuations resulting in perceptible light flicker) associated with the DESS during start-up.

18. Test 12 – Efficiency / Parasitic Losses
Power Quality Tests
Test 12 – Efficiency / Parasitic Losses
Characterize round trip efficiency through a full charge/discharge cycle at unity power factor.
Measure the no-load losses of the DESS when it is not charging or discharging. This information can be used along with the round-trip efficiency data to estimate total losses based on use profiles.

19. Use Case Tests Watt and VAR Support Downstream Step Load
Downstream Overload
Downstream Island Initiation
Resynchronization Following Downstream Islanding
Downstream Voltage Total Harmonic Distortion

20. Test 13 - Watt and VAR Support
Use Case Tests
Test 13 - Watt and VAR Support
This test is designed for DESS’s that are capable of sourcing and sinking reactive power on command. This functionality is important to utilities since they can use DES systems with this capability to provide reactive power compensation to the grid as needed. This test will determine the limits of the DESS’s ability to transmit and receive power in all four quadrants (sourcing and sinking both watts and VARs).

21. Test 14 - Downstream Step Load
Use Case Tests
Test 14 - Downstream Step Load
This test assesses the system’s ability to regulate output voltage during step load changes. It should only be performed on DESS’s with downstream islanding capability, and should be performed during a downstream islanding condition. For a DESS system that is grid connected, a step load should not be a significant issue since the grid typically has much lower source impedance than the DESS inverter.

22. Test 15 - Downstream Overload
Use Case Tests
Test 15 - Downstream Overload
This test profiles the DESS inverter’s overload capability during an intentional islanding event and only applies to DESS’s with downstream islanding capability. This test is intended to verify the system can meet its overload rating. Test points (overload magnitude and time) should be chosen based on each system’s specifications, overload protection and anticipated use.

23. Test 16 - Downstream Island Initiation
Use Case Tests
Test 16 - Downstream Island Initiation
During unfavorable line conditions (outage, over- or under-voltage, frequency deviations, etc.), the system should disconnect from the utility bus. Systems with islanding functionality will continue to supply a downstream load with power until the stored energy runs out. This test records the PQ profile of this transfer to island mode. This should not be confused with the unintentional islanding test. In island mode, the DESS system has a separate island bus from the utility bus which it can keep energized during outages on the power grid. This test should only be performed on systems with islanding functionality.

24. Test 17 - Resynchronization Following Downstream Islanding
Use Case Tests
Test 17 - Resynchronization Following Downstream Islanding
Verify that after favorable line conditions return, DESS will resync the island bus to the utility bus and return downstream load to utility power following a 5 minute minimum time out. This test only applies to DESS’s with downstream islanding capability.

25. Test 18 - Downstream Voltage Total Harmonic Distortion (THD)
Use Case Tests
Test 18 - Downstream Voltage Total Harmonic Distortion (THD)
During an islanding condition, the DESS inverter serves as the source for downstream loads. This test determines the voltage THD of the DESS inverter. The measured THD will be compared with the recommended limits found in IEEE Std. 519.

26. Energy Storage
“Never before in history has innovation offered promise of so much to so many in so short a time.” Bill Gates