Piping Network Design And Pumping Scheme Optimizaiton In Constructing A Megawatt Redox Flow Battery System

With the development of renewable energy power generation,the peak regulation of power grid is becoming increasingly prominent.As a result,the application of large-scale energy storage technologies is prevalent,in which the flow battery system is particularly promising due to its advantages of high efficiency,ability of deeply charged and discharged,independence between of power and capacity.Electrolyte feeding is necessary for a running flow battery system,and its related pipelines and flow rates exert great effects on the system performance.Connection and size of pipes determine pumping loss and shunt current loss,and also influence the flow uniformity and the system compactness.When optimizing the flow rate,we should consider its effects on battery efficiency and pumping loss.With the scale of system up to megawatt class,those trade-off problems become tougher.Accordingly,pipeline design and flow rate optimization are the basis of constructing a high efficient flow battery system.In this thesis,we propose a pipeline design method for the flow battery system,and the modular design method in constructing a megawatt class system.Firstly,we set up battery model,flow model and analogy circuit model with Matlab,and study the relationships between flow rate and cell performance,size of common pipes and flow uniformity,multi-stack structure and shunt current loss.We can reduce pumping loss and shunt current loss by using thicker and longer pipes,which brings the problem of compact design.Thus,compactness factors of pipes are defined.Then,we design pipelines for an 80kW/250 V flow battery system,and compare design results of different stacks and compactness factors.Finally,we design a 1.2MW/1000 V system with battery cubes,which improves efficiency and makes installation and transportation easier.By comparing efficiency and capacity of battery systems feeding with different constant flow rate schemes,we propose an optimal stage-varied flow rate scheme implemented with multi-pumps,which improves performance of system and reliability of electrolyte feeding.And pipelines are redesigned to match the optimal flow rate scheme,which indicates the importance of pipeline design.