Brattle Group Releases Wind Balancing Study

The Brattle Group estimates that approximately 1,000 MW of additional generator regulation service will be needed to balance an extra 50,000 MW of wind energy resources in a large regional transmission organization (RTO) power system.

Judy Chang and Kamen Madjarov, consultants with the Brattle Group, used the renewable integration model, which was jointly developed by the Brattle Group and Pacific Gas & Electric Co., to quantify the potential effects of integrating variable generation on power systems.

They created a case study that utilized empirical wind and load data from their California experience and applied them to a stylized 100,000 MW system to estimate the effects of a high wind penetration scenario that satisfied a 25% renewable portfolio standard.

By characterizing the statistical relationships between the forecasting errors and variability of generation and load over a range of time frames, the model estimates the regulation, load following, and day-ahead generation commitment requirements and costs of balancing variable energy resources on systems of various sizes and levels of intermittent generation and load.

In the case study, the additional regulation requirements to integrate an extra 50,000 MW of wind generation ranged from 500 MW during the fall to 1,300 MW during the spring, due to the different seasonal patterns of generation, according to the study.

‘Our estimates demonstrate that the additional generator regulation service needed to integrate significant amounts of wind generation is fairly modest on a large system, particularly when generation patterns are diverse,’ says Chang. ‘Smaller systems with more concentrated wind resources will tend to experience much larger effects.’

The simulations accommodate sub-hourly scheduling, various definitions of the required balancing services, and both RTO and non-RTO industry structures. The modeling tool also allows for simple updates of balancing needs as new operational and forecasting experience becomes available.

SOURCE: The Brattle Group