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Active Power Controls

NREL has teamed with a number of organizations, including the Electric Power Research Institute and the University of Colorado, to research the potential of wind power plants to provide active power control (also known as real power or frequency control) to the electric power system.

Released January 2014

Active Power Controls from Wind Power: Bridging the Gaps

Project study report explores how wind power can support power system reliability, and do so economically with negligible impacts on the lifetime of the machine.

Under this multiyear project, researchers are performing various simulations and field tests at the National Wind Technology Center to analyze system benefits and impacts on the operations of wind turbines and the electric power system. The project considers five topics:

  • Steady state and economics
  • Dynamic interconnection stability
  • Controls design and simulation
  • Controls testing and loads and structural impacts
  • Dissemination of results.

Some power system operators believe wind, as a variable generation source, is a burden on the electric power system. However, using active power controls, wind turbines can actually assist the power system and provide economic value and reliability. A primary goal of this project is to communicate these results to industry.

Diagram titled "Research and Demonstration: Bridging Gaps in Stakeholder Perspective" showing four groups of stakeholders and their perspectives. Enlarge image

Many different perspectives exist on the role of wind power providing active power control. The goal of the project is to bridge those gaps to ensure different parties understand the ways that efficient and reliable response can be achieved.

The project is evaluating the following types of active power control:

  • Inertial response

    Inertial response is the immediate response to a power disturbance based on a frequency change. This response is currently given by synchronous machines that immediately provide kinetic energy to the grid by slowing down their rotation. Tests will analyze how wind power can extract its inertia to provide immediate energy to reduce the frequency deviation.

  • Primary frequency response

    Primary frequency response is the response following inertial response that increases the output of generators to balance generation and load. This response—also called primary control, frequency-responsive reserve, and governor droop—is typically provided by conventional generators with governor controls that adjust output based on the frequency deviation and its governor droop characteristic. Tests will analyze how wind power can provide energy in this timeframe to assist in arresting frequency deviation, raising the frequency nadir for a given loss of supply, and stabilizing the system frequency at different time points following a disturbance.

  • Automatic generation control (regulation)

    Automatic generation control is used during emergency events and normal conditions. Automatic generation control, also called load frequency control and secondary control, is a response slower than primary frequency control that returns the frequency back to its nominal set point (which, in North America, is 60 Hz). It also reduces the area control error to ensure that frequency and interchange energy schedules between regions are kept to scheduled levels. Tests will analyze how wind power can provide this control to stabilize frequency and reduce area control error.

Graph showing wind power penetration and frequency nadir. Enlarge image

The lower the frequency nadir, the greater the risk of under-frequency load shedding. Greater penetrations of wind can drive frequency lower. Provision of active power control from wind power can increase the frequency, making the system more reliable.

For More Information

For more information about active power control from wind power, see the following resources. Additional publications can be found in the NREL Publications Database.

NREL Workshops

  • Second Workshop on Active Power Control From Wind Power
    In May 2013, NREL and the Electric Power Research Institute held a second active power workshop to discuss the impacts and benefits of allowing wind power provision of active power control capabilities.

  • Active Power Control from Wind Power Workshop
    NREL and the Electric Power Research Institute conducted a workshop in January 2011 to discuss the research needs and state of the art of active power control from wind turbines and wind plants. See the workshop proceedings and status update report. Feedback can be sent to Erik Ela.

Fact Sheet

Additional Reports

Contact

Erik Ela
303-384-7089