Power System Control

Abstract

Summary of Invention In accordance with an aspect of the invention there is provided a method for allocating a plurality of power reserves to deliver power to a power network to meet a power reserve requirement for balancing a frequency of the power network. The method comprises obtaining, for a plurality of power reserves of a power network, power reserve flexibility characteristics associated with each power reserve. The method further comprises obtaining, for the plurality of power reserves, an indexing value associated with the delivery of power by each of the power reserves. The method further comprises determining a power reserve requirement associated with the power network. The method further comprises assigning one or more of the plurality of power reserves to deliver power to the power network, the plurality of power reserves assigned in accordance with the power reserve flexibility characteristics associated with each of the power reserves, the indexing value associated with each of the power reserves, and the power reserve requirement associated with the power network. The power reserve flexibility characteristics may be indicative of power deliverable to the power network by the respective power reserve with respect to time. The power reserve flexibility characteristics may include characteristics of positive and/or negative power reserve flexibility. The power reserve flexibility characteristics may include one or more of a maximum deliverable power, a period of time to provide the maximum deliverable power from receipt of an instruction for power delivery, a minimum duration for sustaining the maximum deliverable power and a period of time to reduce power delivery from the maximum deliverable power to a minimum deliverable power. The assigning of one or more of the plurality of power reserves may further comprise selecting one or more of the plurality power reserves to provide the power reserve requirement in order of the indexing value associated with the power reserve. The method may further comprise ordering the power reserves in accordance with the indexing value associated with each power reserve prior to selecting the one or more power reserves to provide the power reserve requirement. The assigning of one or more of the plurality of power reserves may further comprise determining a portion of the power reserve requirement of the power network provided by each selected power reserve in accordance with the respective power reserve flexibility characteristics of the power reserves. Assigning the one or more power reserves may further comprise determining if, for a particular instance in time, the power reserve requirement is met by the assigned one or more power reserves, assigning a next power reserve to deliver power to the power network if the power reserve requirement is not met, the next power reserve determined from the order of the indexing values associated with the respective power reserves and adjusting a power to be delivered to the power network by a most recently allocated reserve of the one or more power reserves that have been assigned to provide power at that instant in time to a level of power sufficient to meet the power reserve requirement at that instant in time if the power reserve requirement is met. The power to be delivered by the most recently allocated reserve may be adjusted by subtracting the difference between the power reserve requirement at that instant in time and a summation of a power to be delivered at that instant in time by each of the power reserves assigned to deliver power at that instant in time from the power to be delivered at that instant in time by the most recently allocated reserve assigned to deliver power at that instant in time. Assigning the one or more power reserves may further comprise determining if the one or more assigned power reserves provide the power reserve requirement, continuing assigning the reserves if the power reserve requirement is not met and stopping the assigning the reserves if the power reserve requirement is met. The method may further comprise determining, prior to assigning one or more of the power reserves, whether or not the plurality of power reserves will be able to provide the power reserve requirement from the power reserve flexibility characteristics associated with the plurality of power reserves. The power reserve requirement associated with the power network may be a power required to be delivered to the network over a period of time. The power reserve requirement associated with a power network may be determined by estimating a power reserve requirement associated with the power network. The power reserve flexibility characteristics may be obtained from a memory. The indexing value may be obtained from a memory. The method may further comprise receiving the power reserve flexibility characteristics and receiving the indexing values. The power reserve flexibility characteristics associated with the power reserves may be received from the respective power reserves. The method may further comprise instructing the power reserves to deliver power in accordance with the assignment of the power reserves. A power reserve may be a power generator or a power load. The indexing value may be a financial cost associated with the power reserve delivering the power. The indexing value may be an environmental impact associated with the power reserve delivering the power. In accordance with another aspect of the invention there is provided an apparatus for allocating a plurality of power reserves to deliver power to a power network to meet a power reserve requirement of the power network. The apparatus comprises a processor arranged to perform any method disclosed herein. The apparatus may be a central controller associated with management of the power network. In accordance with another aspect of the invention there is provided a computer readable medium comprising computer readable code operable, in use, to instruct a computer to perform any method disclosed herein. According to an aspect of the invention there is provided a method for allocating power reserves in a power network. The method comprises determining a power reserve requirement associated with the power network. The method then comprises assigning power reserves associated with the network to deliver power for meeting the power reserve requirement, the power reserves assigned according to an indexing value associated with delivery of power by respective power reserves. Throughout this disclosure it will be understood that each indexing value assigned to a power reserve may correspond to a financial cost associated with that reserve. According to another aspect of the invention there is provided a method for allocating power reserves in a power network. The method comprises determining a power reserve requirement associated with the power network. The method then comprises assigning power reserves associated with the network for meeting the determined power reserve requirement, the power reserves assigned according to a power response characteristic associated with each of the power reserves. According to a further aspect of the invention a method for allocating power resources provided by a plurality of power reserves in a power network to meet a power reserve requirement of the power network is provided. The method comprises obtaining, for a plurality of power reserves, information indicative of power response characteristics associated with power resources provided by the respective power reserves. The method also comprises obtaining, for the plurality of power reserves, information indicative of an indexing value associated with the power resources provided by the respective power reserves. In addition, the method comprises determining a power reserve requirement associated with a power network. The method also comprises assigning one or more power resources provided by the plurality of power reserves in accordance with the power response characteristics and the indexing value associated with each power resource provided by the plurality of power reserves to provide the power resource requirement. The power response characteristic may be considered as a deliverable power response of a power reserve. Also the power response characteristic may be considered as a mapping of the highest power and longest duration positive and negative power response with respect to time associated with a power reserve. Such a system of mapping of power reserve supply and reserve requirement allows for simple description of any flexible resource, intermittent source or frequency service regardless of their particular dynamic response. Once the method is complete, the reserve requirement may be fully accounted for by the cumulative supply provided by the least expensive available reserves. The method may be applicable to forecasted worst-case intermittency, or can be applied to state of the art frequency control services such that reserves are allocated to individual FCR, FRR or RR services. The cumulative supply can be decomposed to determine and share cost of intermittency. The method may provide intuitive visual reserve adequacy assessment and user input allocation via a user interface. The methods described herein allow for available resources to be used to their fullest which can bring down the price of reserves and may lead to a significant cost reduction for the various system operators by enlarging the pool of available reserves. A system for defining resources irrespective of type is disclosed. Consequently, a single definition system is provided to identify the power characteristics of flexible resources, intermittent resources, or frequency services regardless of their particular dynamic response. A system that enables a user to be provided with a visual reserve adequacy assessment and reserve distribution is disclosed.