CERTS Microgrid Tecogen InVerde INV100 Test Report

The CERTS microgrid project at AEP is now in its third phase. One of the milestones of this phase is to install and commission a Tecogen InVerde INV100 genset. This is a natural gas fueled, combined heat and power “CHP” genset capable of producing 100kW of electrical load. Previous phases of the project included functional testing of Tecogen 60kW prototype units, and sufficient results were gained. During that period, Tecogen developed the commercially
available InVerde INV100. This new unit diverged enough from the prototype units to warrant the replacement of a prototype in the test bed with one of these commercial units.

The installation process for the InVerde INV100 utilized some of the existing connection points that belonged to the prototype unit. However, some conductor upgrades were required as well as an additional cooling tower to account for the increased electrical capacity. The associated circuit breaker, fused disconnect, and bus transformer were also replaced with larger sized equipment rated for the larger load.

With the InVerde INV100 installed in the test bed, testing was performed on the unit. This procedure was modeled after that developed for the Tecogen prototype units. For these tests, data was to be gathered on black start capacity, frequency droop, voltage droop, emergency shutdown functionality, load step response, load sharing capability, and pmax controller. Since continuous run tests were completed on the prototype units, that portion was omitted from the InVerde INV100 testing.

After the initial round of testing was complete, it was determined that the unit had voltage instability issues. In order to fix this issue, the bus transformer was taken out of service and replaced with a reactance panel. The unit was then changed from a 3 wire to a 4 wire configuration. The same run of tests was then performed, and more satisfactory results were obtained.