On November 19, 2015, the Federal Energy Regulatory Commission (FERC) issued a proposed rule to eliminate a decade-old exemption for wind plants from reactive power obligations imposed on other generators. Reactive power is essential to control system voltage to ensure efficient and reliable operations of an alternating current transmission system. The proposal would establish reactive power requirements for all newly interconnecting non-synchronous generators, including generator upgrades that require interconnection requests, as a condition of interconnection.
Synchronous generators have a mechanical rotor which generates voltage that corresponds to the system frequency and produces both real or usable power and reactive power—in simple terms, the ability to ensure the grid remains in phase—in response to system needs. They constitute the central generation around which much of the current grid was developed and have traditionally provided reactive power capability. Examples of synchronous generating facilities include nuclear power plants, large hydro plants, and natural-gas fired generators. Asynchronous resources include renewable resources such as solar and wind that do not produce voltage in sync with the rest of the grid. These resources lack inherent reactive power capability unless the inverters used to condition their output have integrated this feature. The FERC proposal draws on ongoing technological advances that have drastically reduced costs, and could contribute to advancing the role of wind energy in an economically optimal generation mix. According to FERC, if the share of wind generation continues growing or if the synchronous generators currently providing reactive power retire, the reliability of the grid might suffer.
Due to its inherent variability and uncertainty, wind power is not synchronized to the electrical frequency of the power grid and is generally unresponsive to system frequency, unlike conventional thermal and hydropower technologies. The characteristics of variability, uncertainty, and asynchronism have posed challenges to maintaining system reliability. Utilities, balancing area authorities, regional transmission organizations (RTOs), and independent system operators (ISOs) are developing improved strategies for better grid integration of wind and other variable generation. In recent years, demand response, energy storage, and improved wind power forecasting techniques have demonstrated potential for integrating intermittent resources into the grid while maintaining its reliability. These advances, together with reactive power capabilities, will facilitate system flexibility required to address fluctuations in renewable power output, thereby making renewable generation more predictable, controllable, and dispatchable.
Moving forward, with rising wind energy penetration, grid operators must explore ways of integrating large quantities of wind energy into system operations, while developing capabilities that enable new wind installations to actively enhance the power quality of the electric grid. Installed wind power capacity grew at a rate of eight percent in 2014 in the U.S., bringing the total to approximately 66 gigawatts (GW) and 4.9 percent of the U.S. end-use electricity demand. In addition, low wind energy prices are now competitive with wholesale power prices and traditional sources across several regions in the nation.
Originally published by EnerKnol.
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