ower Laboratory. The inverter was operated at
a voltage of 780Vdc by setting the 150kW power supply at this voltage. The inverter output was
successfully connected to Circuit #2 of the 13.8kV/2.4kV ORNL Distribution System by closing the
AC contactor between the 480V/600A power panel and the three-phase inverter. The inverter was
able to provide approximately 40% of the loads reactive power demand by providing about
12kVars. The inverter was able to correct the power factor from 0.857 to 0.943 and raise the power
panels voltage by 0.8% by using a current control logic developed by ORNL for the dSpace Real-
Time Control System.
Technical Progress
On February 23, the milestone of injecting reactive power from the three-phase 75A (62kVA) inverter
was achieved and a highlights prepared. The inverter was operated to ~10A peak. Testing of the
inverter has continued and on March 29th, the inverter was operated at three different operating levels
of 30A, 45A and 60A peak. Data was collected for each of these operating levels and is being
analyzed. As the testing was coming to an end, the inverter failed with what appeared to be a failure
of its phase C terminal. The fault caused irreparable damage to the inverter, and the root cause of the
failure, which occurred with the inverter operating at less than 58% of its rating, is being pursued with
the inverter manufacturer. The inverter failure caused no personnel injury because the inverter is
operated in a Lexan isolation cabinet. Also, there was no damage to the contactor that interfaces the
AC output of the inverter to the AC system (electrical panel) or the 150kW DC power supply that
supplies the DC side of the inverter. In addition to following up with the manufacturer as to the
possible cause of the inverter failure, we are planning/implementing additional safety measures for
the next testing which include (1) adding more fan cooling that is more directed at the inverters heat
sink, and (2) placing external thermocouples or thermistor to monitor the inverter/heat sink
temperature as the inverters current is increased.
Status of Milestone(s)
The inverter has been demonstrated to be able to compensate for fundamental reactive power,
harmonics, and unbalanced load conditions for loads up to 45Arms (60A peak). We have met the
milestone of injecting reactive power for several power levels. We will continue to focus on higher
power levels and enhancing our controls both for individual inverter operation and paralleling with
the synchronous condenser. The inverter control system has been developed to provide voltage
regulation based on one variable, local voltage. The inverter controls have been programmed in D
space and are ready for testing.

Industry Interactions
On September 29
th
, we had a project review meeting to go over the status of activities for the Reactive
Power Project in FY05 and plans for FY06. As a result of this meeting, the industry participants
came up with a list of feedback items which we have responded to. We have assigned responsibilities
to the ORNL team for addressing these items which relate directly to the project tasks.