# Model-Based Assessment of Energy Efficiency in Industrial Pump Systems: A Case Study Approach
## 8 Conclusions  
The proposed method for modelling the efficiency of VSDP systems enables a comprehensive analysis of energy consumption under variable-speed conditions. By utilisingmanufacturer data, accurate 2D efficiency maps can be created for motors, converters, and pumps. These maps are then combined into an overall system efficiency map that can be used to predict total energy consumption based on a historical dataset of operating points (OPs) for a particular application. Similarly, an efficiency model can be developed for older VSDP systems by using data from equivalent VSDPs or by taking specific measurements of the system in operation.  
The estimated differences in energy consumption for the VSDP analysed in this paper, using an annual dataset of OPs, show that energy savings of up to 30% are possible--even though the original VSDP was already operating with a variable flux motor control that allows energy optimisation for quadratic loads. Interestingly, the results showed that a moderately oversized, highly efficient SRM-based VSDP outperformed a more appropriately sized variant in terms of efficiency for the dataset analysed. When comparing the energy efficiency between the five VSDP combinations, the motor efficiency classes were taken into account and identical load profiles and variable flux motor control were used to ensure a fair and reliable assessment through simulations.  
As the method allows the development of very precise models, the differences in consumption between correctly dimensioned and partially (or heavily) oversized drives can be determined by simulations. Furthermore, with such precise models, we can accurately assess the impact of replacing a single component on the efficiency of the entire system. The method makes it possible to implement various strategies for drive dimensioning with a view to maximising energy efficiency:  
* Precise dimensioning for the intended operating points or load profile.
* Oversizing the drives for possible future load increases (later expansion of production capacity) for different scenarios; for example, where expansion is less likely, therefore aiming for a system with the highest possible energy efficiency at lower loads; or where expansion is very likely and will happen soon, therefore aiming for a system with the best possible energy efficiency over an extended operating range, etc.
* Drive dimensioning with LCC optimisation, finding a compromise between machine price and energy costs--machines with high energy efficiency are more expensive but consume less in operation.  
Due to its relative complexity, our method is not the most suitable for cases where a sufficiently large set of input data is not available for one or more components of the system or the set of operating points is too small.  
The best scenario for the further development of the method presented here would be if its usefulness were recognised by pump and motor manufacturers. By implementing it correctly and linking it to the relevant databases of their products, a web application could be created and made available to potential users.  
Conceptualisation, H.L.; methodology, H.L. and K.D.; software, K.D.; validation, H.L. and K.D.; investigation, H.L. and K.D.; data curation, H.L.; writing--original draft preparation, H.L. and K.D.; writing--review and editing, H.L. and R.F.; visualisation, K.D.; funding acquisition, R.F. All authors have read and agreed to the published version of the manuscript.  
This research and APC was funded by the Slovenian Research and Innovation Agency (ARIS), grant number P2-0258.  
Not applicable.  
The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author.  
The authors declare no conflicts of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.