United States

United States

New York grid can absorb a lot -- Integrating wind

The New York transmission system is capable of integrating 3300 MW of wind, 10% of the grid's current peak load, with little impact on transmission planning, operations and reliability, and with no additional need for major transmission upgrades. But that is only if the State of New York, which now has just 49 MW of wind in place, also adopts certain procedures governing wind project operations, says a phase one report by GE Energy's Power Systems Energy Consulting group.

The New York Independent System Operator (NYISO) will use the report's findings and a more detailed phase two report due late this year to determine how much wind energy can be added to the grid without reducing the system's reliability. The report, titled The Effects of Integrating Wind Power on Transmission System Planning, Reliability, and Operations, also provides the New York Public Service Commission with some of the information it needs to set a grid-friendly, yet stiff renewables penetration target.

Governor George Pataki has proposed that 25% of the state's electricity sales should come from renewable sources by 2013. If the proposal is approved, New York's minimum standard for renewables will be among the most ambitious in the country.

The initial study phase, commissioned in late November by the New York State Energy Research and Development Authority (NYSERDA) and NYISO, was intended to be a quick assessment of the grid's ability to incorporate wind resources, says Louie Powell of GE Energy's consulting group. The second phase, also to be completed by the group, will do an extensive performance evaluation of NYISO's system if 3300 MW of wind resources are added. GE Energy also owns GE Wind Energy, which it bought from Enron Corp in 2002.

To complete the study in the short time frame, GE Consulting used information compiled by AWS-Truewind Scientific Inc based on data from 101 potential wind sites to calculate New York's wind resource potential at 10,026 MW, says Ryan Moore of NYSERDA. GE determined the transmission system can accommodate as much as 5800 MW of new wind under peak load conditions or about 6100 MW under light load conditions. It then applied lessons learned from other areas of the world where there are substantial wind resources and settled on a more conservative 10% penetration rate, says Moore.

Grid support

To get there, however, the state must set procedures using both proven and emerging technologies that would govern operations and interconnections at each wind project. GE's recommendations include voltage regulation at the point of interconnection, low-voltage ride-through, a central wind forecasting system and curtailment capabilities. GE also recommends a protocol that sets ramping rates for back-up power as wind production drops off, among other emerging technologies. NYISO, it adds, could consider exempting wind installations smaller than 5-10 MW from all requirements

The analysis determines there could be transmission restrictions at some local sites, but not enough to preclude the system from reaching the 10% penetration level. But it did show that the 10% penetration will increase the net load variability on the NYISO's grid by 920-975 MW. That will not create operating problems because "any rapid drop in production from wind farms is not expected to exceed the existing limiting contingency," the study says.

Finally, the study shows that wind turbines in New York provide the system with little additional reliability, based on a loss of load probability. Wind farms typically contribute to the system during morning hours and provide little generation during the summer, while power system demand peaks on summer afternoons. But the wind additions could lower system reliability if existing, but marginal, thermal generators are retired, or if expected new generation is deferred or cancelled.

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