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Integrating New England Renewables

How to manage the green revolution.

Fortnightly Magazine - November 2009

percent of the proposed renewable projects in ISO New England’s generation interconnection queue (see Figure 3) . More than 2,800 MW of wind projects are currently in the pipeline: more than 800 MW of proposed offshore projects and 2,000 MW of proposed onshore projects. The level of nameplate wind capacity in New England could triple by the end of 2010, to 300 MW or more.

With zero emissions, wind resource development will help achieve the states’ environmental goals and lessen the region’s reliance on fossil fuels to produce electricity.

But integrating a large portfolio of wind power poses several challenges for grid operators. Since wind turbines produce power only when the wind blows and wind speed is variable and difficult to predict, forecasting output from wind resources is an inexact science. This uncertainty can lead to an over- or under-commitment of other resources on the system. In real time, a sudden change in wind speed or direction can lead to a change in output that would require corrective action by system operators. In addition, the wind blows longer and faster at night, while peak demand occurs during the day, thus making electricity storage a desirable future resource.

Earlier this year, ISO New England initiated the New England Wind Integration Study (NEWIS) to take a comprehensive look at how onshore and offshore wind energy, demand resources, traditional generation, and transmission will interact once operational. The study will model numerous scenarios of wind development and identify operating issues created or exacerbated by the variability and unpredictability of wind power output.

NEWIS is developing an accurate and flexible forecasting model based on three years of historical wind speed and directional data (2004 through 2006) and the possible location of onshore and offshore wind resources. This model will be used to run hypothetical scenarios of power system and wind generation interaction based on various levels of potential wind development, from 1,200 MW to 12,000 MW, representing 2.5 percent to 20 percent of projected consumption. The impact of each scenario on wind power forecasting, unit commitment, reserve requirements, automatic generation control, emissions, carbon costs, and locational marginal prices will be analyzed.

NEWIS also will evaluate the ability of wind facilities to provide grid support functions, such as regulation, and analyze potential reliability issues related to maintenance and scheduling requirements and the loss of energy output when wind speeds reach levels too high to operate turbines.

The results of the study, expected to become available next year, will be used to assess whether modifications will be needed in operating requirements, guidelines or standards, and whether new market rules would help to reliably integrate new wind generation.

New Transmission Needed

As the amount of renewable resources increases—in particular large amounts of wind power—new transmission lines will be needed to deliver these resources to market. In early 2009, the governors of the six New England states asked the ISO for technical assistance in creating a regional blueprint for integrating large-scale onshore and offshore renewable energy sources—mostly wind—into the region’s electric power grid. The technical analysis also looks beyond New England