Active Power Controls
NREL has teamed with the Electric Power Research Institute, the Colorado School of Mines, the University of Colorado, and other industry members to research the potential of wind turbines and power plants to provide active power control (also known as real power or frequency control) to the electric power system.
Under this multiyear project, researchers will perform 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 in times of disturbance and provide economic value and reliability. A primary goal of this project is to communicate these results to industry.
The project will evaluate the following types of control:
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 given 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
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 set points. Tests will analyze how wind power can provide this control to stabilize frequency and reduce area control error.
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.
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.
Understanding Inertial and Frequency Response of Wind Power Plants
This paper analyzes and quantifies the inertia and frequency responses of wind power plants with different wind turbine technologies.
Combining Droop Curve Concepts With Control Systems for Wind Turbine Active Power Control
This paper focuses on the development and implementation of both static and dynamic droop curves to measure grid frequency and output delta power reference signals to a novel power set point tracking control system.
Alternative Approaches for Incentivizing the Frequency Responsive Reserve Ancillary Service
This paper discusses the issues that can occur without proper incentives and even disincentives for the provision of frequency responsive reserves and proposes alternatives to ensure an efficient and reliable power system.
Tutorial of Wind Turbine Control for Supporting Grid Frequency Through Active Power Control
This paper provides an overview of basic wind turbine control systems and highlights industry trends and research in wind turbine control systems for grid integration and frequency stability.