The use of battery storage for increasing the hosting capacity of the grid for renewable electricity production

This paper defines a step-by-step systematic decision making process to define operant conditions and applications for which battery storage is an option for electrical power grids. The set of rules is based on a number of research studies performed by the authors focusing mainly on sub-transmission grids. Battery storage is expensive so the focus in this paper is on comparing storage with other ways of achieving the same increase in the hosting capacity (HC) of grid. The approach is to find niche applications for which battery storage has unique advantages i.e. it provides a unique alternative for grid operator planning, which is unachievable in other ways. The first step is to assess the grid’s capacity to host new loads or production. This constitutes a baseline for evaluation of improvements from storage. The next step is to define applications for battery energy storage. Integrating new loads/production without increasing the hosting capacity may result in reduced performance and ultimately loss of production or consumption. The cost and severity of exceeding the hosting capacity will also affect the type of solution required. After this define the conventional planning solutions that would be adopted without storage option available. Such measures may include upgrading of transformer or construction of new power line. Curtailment, tariff based incentives or contracted load shedding as well as techniques like dynamic line rating can also be included in the comparison at this stage. Based on assessments of these alternatives it is possible to compare increase in hosting capacity with and without storage as well as comparing gains with storage to what can be achieved with conventional grid planning options or other novel methods. It is also important to investigate the regulatory framework and constraints regarding ownership and operation of a battery energy storage. Should the grid operator own the battery storage? Or should the task be outsourced on a service contract or the service purchased in the market place? Storage capacity may only be utilized during certain periods. Can all or part of the storage capacity or the power electronic inverters perform additional functions and increase the return on investment for the installation? Regulatory aspects regarding the possibilities for different actors to pursue such additional income streams should be included in the assessment to correctly determine the return of investment of battery storage.The final step should include control algorithm development, tested in a flexible but realistic environment and should establish whether the system actually delivers the predicted outcomes when exposed to real-time data. This may require building a pilot installation as a research and development activity before commercial deployment.Godkänd; 2014; 20131205 (niceth)SmartGrid Energilage