Frequency Regulation

Executive Summary

In order to synchronize generationThe manner in which electricity is generated. The electricity that flows through California assets for electrical1. An adjective meaning “pertaining to electricity”. Electrical Engineer. 2. Related to, pertaining to or associated with electricity but not having its properties or characteristics. grid operation, the alternating currentFlow of electricity whose polarity/voltage changes (alternates) between positive and negative. The majority of powerThe rate at which energy is generated, converted, transmitted, distributed or delivered. produced by electricAn adjective meaning “needing electricity to operate” such as electric motor or wire. IEEE: Containing, producing , arising from, actuated by or carrying electricity. utilities in the U.S. the form of current that alternates at a rate of 60 cycles per second (Hz), also known as... (ac) frequency must be held within tight tolerance bounds. Different methods available for “frequency regulation” include generator inertia, adding and subtracting generation assets, dedicated demand1. The rate at which electric energy1. Energy is the potential of a physical system to perform work. (A common unit of work is foot-pound—the amount of energy needed to lift one pound up a distance of one foot.) Energy exists in several forms such as electromagnetic radiation ... is delivered to or by a system or part of a system, generally expressed in kilowatts or megawatts, at a given instant or averaged over any designated interval of time. 2. The rate at which energy is being used by... response and electricity storage. Each of these methods has pros and cons, and the implementation of these methods takes from a millisecond to 20 minutes. In the group of “ancillary services” provided in the open market management of the grid, frequency regulation has the highest value. Frequency regulation is mainly provided by ramping (up and/or down) of generation assets. This typically takes minutes rather than seconds. Electricity storage has the capability for doing the job in milliseconds, and Pacific Northwest National Laboratory (PNNL) has suggested millisecond electricity storage should have a value of at least twice that of 20 minute assets.

Discussion

Numerous reports are available addressing frequency regulation. Early reports come out of U.S. Department of Energy (DOE) national laboratories. Oak Ridge National Laboratory (ORNL) first proposed this be addresses in the early 2000’s. DOE has since sponsored investigations and reports including ones from PNNL, Sandia National Laboratories (SNL), Idaho National Laboratory (INL) and Lawrence Berkeley National Laboratory (LBL). 

Below are two charts from the report: Use of Frequency Response(Equipment) The ability of a system or elements of the system to react or respond to a change in system frequency. (System) The sum of the change in demand, plus the change in generation, divided by the change in frequency, expressed in megawatts per 0... Metrics to Assess the Planning and Operating Requirements for Reliable Integration of Variable Renewable Generation Joseph H. Eto, Principal Investigator Lawrence Berkeley National Laboratory, 2010. 

By nature, frequency regulation is a “power storage” application of electricity storage. It has been identified as one of the best “values” for increasing grid stabilityThe ability of an electric system to maintain a state of equilibrium during normal and abnormal conditions or disturbances. and is not considered “an energy arbitrage” play such as storing wind energy at night for day use. It typically costs between $10 and $60 per megawattA unit of power equal to one million watts. hour.