Framework for capacity credit assessment of electrical energy storage and demand response

Abstract

The use of electrical energy storage (EES) and demand response (DR) to support system capacity is attracting increasing attention. However, little work has been done to investigate the capability of EES/DR to displace generation while providing prescribed levels of system reliability. In this context, this study extends the generation-oriented concept of capacity credit (CC) to EES/DR, with the aim of assessing their contribution to adequacy of supply. A comprehensive framework and relevant numerical algorithms are proposed for the evaluation of EES/DR CC, with different 'traditional' generation-oriented CC metrics being extended and a new CC metric defined to formally quantify the capability of EES/DR to displace conventional generation for different applications (system expansion, reliability increase etc.). In particular, specific technology-agnostic models have been developed to illustrate the implications of energy capacity, power ratings, and efficiency of EES, as well as payback characteristics and customer flexibility (that often also depend on different forms of storage available to customers) of DR. Case studies are performed on the IEEE RTS to demonstrate how the different characteristics of EES/DR can impact on their CC. The framework developed can thus support the important debates on the role of EES/DR for smart grid planning and market development.

System-Level Operational and Adequacy Impact Assessment of Photovoltaic and Distributed Energy Storage, with Consideration of Inertial Constraints, Dynamic Reserve and Interconnection Flexibility

“…As mentioned in [40], although the economic aspects have not been explicitly modelled, the above optimisation is in line with realistic commercial arrangements (e.g., the capacity payments proposed in the GB electricity market reform [41]) that might be available to incentivise consumers with batteries and PV panels to shift PV generation to supply the demand at peak times, while the minimisation in the second stage is also in line with the minimisation of the potential system cost for deploying these resources (this is because the extra solar PV energy shifted could not further reduce the peak demand and thus bring no additional contribution to generation capacity; however, it would cause more energy losses and unnecessary economic penalties to the consumers).…”

“…As mentioned in [40], although the economic aspects have not been explicitly modelled, the above optimisation is in line with realistic commercial arrangements (e.g., the capacity payments proposed in the GB electricity market reform [41]) that might be available to incentivise consumers More specifically, the peak clipping operation and the joint maximisation of self-consumption and minimisation of power injection are optimised on a daily basis.…”

“…In this light, the following dual-stage optimisation formulation is proposed for utilisation of solar PV to contribute to the system demand at peak times, which is developed based on the relevant optimisation in [39,40]. The first stage in Equations (19) and (20) determines the minimum daily peak demand that can be achieved, while the second stage minimises the energy charged to achieve the minimum daily peak demand.…”

Assessment Method for Substation Capacity Credit of Generalized Power Source Considering Grid Structure

“…At present, the main methods of credible capacity evaluation are the bisection method [6,17] and Newton method [18]. Considering that there is no specific function formula for derivation, this paper uses the secant method [4,19], which has a fast computing speed.…”

Interconnector participation in capacity mechanisms: A new de-rating approach

“…Application of the ELCC methodology to non-dispatchable wind generators [11] has been recommended for obtaining capacity value, also known as capacity credit, of wind power, which is equivalent to the de-rated value of the wind generator. The concept of capacity credit has also been extended to assess the contribution of electrical energy storage and demand response to adequacy of supply [12].…”