IEEE Power & Energy Magazine - July/August 2017 - 61

generators, natural gas generators, building loads (both interruptible as well as controllable loads), and tenants' BEMSs.
In addition, the system optimizes the dispatch of DERs to
reduce the total costs of energy and operation.

Microgrid Test Plan and Methodologies
The key objective of the microgrid test plan ensures the operational readiness of the hierarchal system for safe, reliable,
and economic operation in multiple modes and scenarios.
For example, the mode of intentional islanding operation
readiness requires simulated testing to verify the ability of
the microgrid controller to detect plausible fault conditions
that would de-energize the entire microgrid and for excessive voltage/frequency excursions defined in IEEE 1547a.
Simulated testing also demonstrates the microgrid's ability
to transition to islanded mode and to achieve stable operation within 0.160 s (approximately ten power system cycles
at 60 Hz). For the islanded mode of operation readiness testing, the microgrid controller must be test verified to maintain
acceptable voltage and frequency conditions on the islanded
microgrid for a period of at least 15-30 min. The testing will
demonstrate that the microgrid controller is capable of shedding load or adding supply as needed to extend service to
the most critical loads for the longest possible period before
available supply resources are exhausted.
These two examples pose a question: What should be the
appropriate methodology for such diverse testing requirements? The first example requires a combination of a software
simulation testing approach and a hardware logic testing
approach, whereas the second example can potentially be
managed within a well-designed hardware-in-the-loop (HIL)
testing approach. To address the full spectrum of testing
required to ensure the readiness of the hierarchal microgrid
control system, the test methodology includes a series of the
following test phases, as shown in Figure 8.

Test 1: Software Simulation Testing
Software simulation with microgrid DMS, Distributed Energy
Resources Customer Adoption Model (Lawrence Berkeley
National Lab platform), and GridLAB-D (Pacific Northwest
National Lab platform) will be performed to model and analyze the multimode microgrid operation. The model simulation
and analysis will be conducted using electrical models of the
microgrid components, the associated power system infrastructure, and customer loads. The software testing will verify that
the microgrid system can achieve stable operation of critical
loads within 0.16 s and can sustain operation of the microgrid
for a minimum of 30 min. The software analysis will determine the dynamic performance of the system and associated
microgrid assets following power system events requiring transition to islanded operation. The analysis will also verify that the
hierarchal microgrid system will prevent transition to islanded
operation for "external" events that do not require such a transition. The results of the software analysis will enable the GE
team to determine the configuration of all the subsystems: the
july/august 2017

(a)

(b)

figure 7. The GE microgrid controller and substation automation systems.

microgrid operation system, microgrid data interface management, and microgrid controller. In addition, appropriate settings
for all protective devices and asset controllers will be finalized.

Test 2: Hardware-in-the-Loop
Testing ("Factory" Lab Test)
HIL testing was done on the prototype microgrid controller.
During the control HIL (CHIL) testing (the factory test), the
microgrid controller subsystem will be tested in a laboratory
environment using a real-time simulator (RTS) developed by
Opal RT. This system will simulate the interactions between
the microgrid controller and the other microgrid components,
such as digital relays, energy storage asset controller, BEMS,
communication facilities, AMI system, and other facilities that
are only present in the field at TNY. The CHIL testing will
enable the GE team to verify the operation of the microgrid
controller in a realistic laboratory environment prior to installation. The RTS will simulate all field inputs and operation of all autonomous controllers (such as the Power Factor 250 battery energy management system and the Radius
Systems BEMS) that allows the team to thoroughly exercise
the performance of the microgrid controller under normal-,
emergency-, and equipment failure-mode conditions. The

1
Software
Simulation Testing

HIL Testing

Field/Integration/
System Testing

figure 8. The three test methodologies.
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Table of Contents for the Digital Edition of IEEE Power & Energy Magazine - July/August 2017