![Reservepower](https://upload.wikimedia.org/wikipedia/commons/9/90/Reservepower.png)
In
electricity networks, the operating reserve is the generating capacity available to the
system operator
A sysop (; an abbreviation of system operator) is an administrator of a multi-user computer system, such as a bulletin board system (BBS) or an online service virtual community.Jansen, E. & James,V. (2002). NetLingo: the Internet dictionary. Netl ...
within a short interval of time to meet demand in case a
generator
Generator may refer to:
* Signal generator, electronic devices that generate repeating or non-repeating electronic signals
* Electric generator, a device that converts mechanical energy to electrical energy.
* Generator (circuit theory), an eleme ...
goes down or there is another disruption to the supply. Most power systems are designed so that, under normal conditions, the operating reserve is always at least the capacity of the largest supplier plus a fraction of the
peak load
In electrical engineering, a load profile is a graph of the variation in the electrical load versus time. A load profile will vary according to customer type (typical examples include residential, commercial and industrial), temperature and holi ...
.
Types of operating reserve
The operating reserve is made up of the spinning reserve as well as the non-spinning or supplemental reserve:
* The spinning reserve is the extra generating capacity that is available by increasing the power output of generators that are already connected to the power system. For most generators, this increase in power output is achieved by increasing the
torque
In physics and mechanics, torque is the rotational equivalent of linear force. It is also referred to as the moment of force (also abbreviated to moment). It represents the capability of a force to produce change in the rotational motion of th ...
applied to the
turbine's rotor.
[Spinning Reserve and Non-Spinning Reserve]
California ISO, January 2006.
* The non-spinning reserve or supplemental reserve is the extra generating capacity that is not currently connected to the system but can be brought online after a short delay. In isolated power systems, this typically equates to the power available from fast-start generators.
However, in interconnected power systems, this may include the power available on short notice by importing power from other systems or retracting power that is currently being exported to other systems.
Generators that intend to provide either spinning and non-spinning reserve should be able to reach their promised capacity within roughly ten minutes. Most power system guidelines require a significant fraction of their operating reserve to come from spinning reserve.
This is because the spinning reserve is slightly more reliable (it doesn't suffer from start-up issues) and can respond immediately whereas with non-spinning reserve generators there is a delay as the generator starts-up offline.
Centrally controlled air conditioners and thermostats that are used in large residential areas can be used as a fast and considerable operating reserve. Advantages of this technology are under studies.
Operating reserve is a crucial concept for ensuring that the
day-ahead planning of generators' schedule can withstand the uncertainty due to unforeseen variations in the
load profile
In electrical engineering, a load profile is a graph of the variation in the electrical load versus time. A load profile will vary according to customer type (typical examples include residential, commercial and industrial), temperature and holi ...
or equipment (generators, transformers, transmission links) faults.
The
California Independent System Operator
The California Independent System Operator (CAISO) is a non-profit Independent System Operator (ISO) serving California. It oversees the operation of California's bulk electric power system, transmission lines, and electricity market generated a ...
has an operating reserve at 6% of the metered load. Included in that is a spinning reserve at 3% of the metered load.
Other types of reserve
In addition, there are two other kinds of reserve power that are often discussed in combination with the operating reserve: the frequency-response reserve and the replacement reserve.
* The frequency-response reserve (also known as regulating reserve) is provided as an automatic reaction to a loss in supply. It occurs because immediately following a loss of supply, the generators slow down due to the increased load. To combat this slowing, many generators have a
governor
A governor is an administrative leader and head of a polity or political region, ranking under the head of state and in some cases, such as governors-general, as the head of state's official representative. Depending on the type of political ...
. By helping the generators to speed up, these governors provide a small boost to both the output frequency and the power of each generator. However, because the frequency-response reserve is often small and not at the discretion of the system operator it is not considered part of the operating reserve.
[Eric Hirst]
Price-Responsive Demand as Reliability Resources
April 2002.
* The replacement reserve (also known as contingency reserve) is reserve power provided by generators that require a longer start-up time (typically thirty to sixty minutes). It is used to relieve the generators providing the spinning or non-spinning reserve and thus restore the operating reserve (confusingly the replacement reserve is sometimes known as the 30 or 60-minute operating reserve).
References
{{Authority control
Power engineering