Cohocton Substation Project

First Wind – an energy company headquartered in Newton, Massachusetts – planned to build a wind turbine farm in Cohocton, New York, and connect it into New York State Electric & Gas (NYSEG) grid. First Wind tapped CG Power Solutions to design and build a new substation for NYSEG, as well as manage the details of the interconnection to their grid, and construct two other substations for the project that would be owned by First Wind.

Challenges:

While the project was still in its early design stage, New York State's regulations governing transmission interconnects were in the process of being revised. There were two other NYSEG substations serving the project that had been grandfathered under outdated NY grid reliability standards. However as the regulations changed, they were newly deemed to be non-conforming because of the significant amount of generation now being added to this region of the grid. As a result, the First Wind Cohocton project grew from constructing three new substations (one for NYSEG and two for First Wind) to building three - and renovating two 50-year old NYSEG substations.

But that was only the beginning as two other state regulations soon came into play. The lines that First Wind needed to run from its main wind turbine site to the new NYSEG interconnection substation would be transmitting power at 230 kV of power. But state law required that any transmission line operating above 115kv-or whose length exceeded 10 miles--had to obtain a special permit from the state Public Service Commission, known as an Article VII permit. Historically this permit has taken 18 months to 2 years to obtain, a period during which everything would go on hold, including First Wind's ability to generate not just power, but income.

CG Power Solutions Solution:

In response, CG Power Solutions devised two innovative solutions. The first was to position the new substation at the main turbine site at a distance of 9.9 miles from the new NYSEG interconnection substation. Secondly, CG Power Solutions added a transformer at a new First Wind substation adjacent to the NYSEG interconnection substation which dropped the system voltage from 230kV to 115kV. First Wind essentially was faced with the choice of adding $1.5 million in costs for the new line versus absorbing potentially $6 million in lost revenue while the permit process dragged on. The combination of these two changes achieved a short enough distance and low enough voltage that the Article VII permit was no longer required.

Still hanging over the project, though, was another challenge. First Wind had a few turbines that were close to the new NYSEG interconnect substation. These turbines needed to be connected at a voltage of 34.5kV. Unfortunately, the only substations in the immediate area were the new NYSEG interconnection station at 230kV, and the adjacent new First Wind substation designed to step down the voltage from 230kV to 115kV for the transmission line to the main turbine area. At the main turbine area, there was yet another substation to reduce the voltage from 115kV to 34.5kV for interconnection of the majority of the projects turbines.

After evaluating a number of ideas, CG Power Solutions decided to change the transformer at the step-down location to a 3-winding transformer. This transformer stepped NYSEG's 230kV system voltage down to 115kV, keeping the outgoing line to the main turbine area within the state's regulatory limit without the need for an Article VII permit. The third winding stepped the voltage to 34.5kV in the same substation to allow connection of the few turbines located in that immediate vicinity. This was an innovative solution that saved First Wind from having to install an additional main transformer at an additional cost that would exceed $1 million.

Results:

CG Power Solutions had originally specified 7 months from the design phase of the Cohocton project to its up-and-running completion. There were more than a few points in the process where it looked like the original timetable just couldn't be met. And, as usual, there were a couple of glitches that pushed back the start date a few months. Those glitches were effectively smoothed out, however, and the project was in fact completed in…7 months, exactly as promised. In September, 2008, the turbines started turning and the power started flowing.