The effect of including power converter losses when modelling energy storage systems: A UK domestic study

Abstract

Keywords«Battery Management Systems (BMS) », « Energy system management », « Energy storage». AbstractEnergy storage systems (ESS) are seen as an increasingly important technology for managing electrical distribution systems, and there is now much research into both the underlying technologies of these systems, and their "optimum" management especially for applications within a single household. Optimum management usually depends on many factors and assumptions, for example what should be optimized (self-consumption of local renewable resources, consumer cost, peak reduction), prediction of local generation and load patterns, and the assumptions concerning the operation of the ESS itself. This paper aims to quantify one of the usual assumptions made (especially by non-electrical engineers) i.e. that the assumption that the power converter in the ESS is 100% efficient does not lead to substantial errors in the ESS performance and cost-benefit analysis. Three different ESS power converter models have been created and their behaviour as part of a house based ESS management system over a one year period has been analysed using five different control approaches, a variety of battery and solar panel sizes and employing a time of use tariff (Economy 7). By observing the ESS charging pattern through the year and monitoring of the annual electricity cost along with the system's losses for the household, relationships between the battery and PV size, the control algorithms, the electricity cost and the system losses were created.

Sizing guidelines for grid‐connected decentralised energy storage systems: single house application

“…The decentralised energy storage system which was used for this work can be found in [11]. The examined system is designed to investigate different configurations/sizes of single residential dwellings with installed PV on their roof that limits its size and a battery that is grid‐connected via a power converter, both components need to be viably sized.…”

“…The power converter rating limits the power which will be exchanged between the battery, the house, and the power grid, and it strongly affects the charging pattern of the battery and the energy flow between the system's components. Therefore, a cost‐effective sizing design requires building in an appropriate designing analysis rather than simply oversizing the ESS components [11].…”

Grid-Scale BESS for Ancillary Services Provision: SoC Restoration Strategies

“…This kind of model has already shown a reduction in computational effort and an acceptable accuracy in predicting battery behavior [20]. Furthermore, to simulate BESS behavior, not only battery cells but also the complementary part of the system should be considered since it has a nonnegligible impact on operational losses, as highlighted by [21,22]. It includes, usually, a power conversion system (PCS) and other loads providing auxiliary services (e.g., monitoring system, alarms and HVAC system).…”

Design recommendations for energy systems: A UK energy community study

“…The converter losses was modelled by the same equation as for model 2 in [9] and can be described by (1).…”

“…On the other hand, if the overnight charge level is too high, any excess PV energy must be exported back to the grid. To solve this problem, in addition to the constant fully charged overnight control algorithm, a more intelligent algorithm (the 'one day before adjusted control algorithm' described in [9]) was used which is expected to minimise the effects of the overnight charging setting and PV penetration in the CES utilisation efficacy. Fig.8 illustrates the charging pattern differences for the intelligent control algorithm when different PV penetration percentages are considered.…”