A predictive optimal dispatch and optimal sizing method for a grid-connected PV-diesel-storage system

摘要

Hybrid energy systems are becoming a popular means of exploiting natural sourcesudof energy and increasing electrical efficiency in urban settlements. However, effectiveudimplementation of these systems relies on a means of optimally sizing and operating theudsystem to ensure the lifetime costs of the system are minimised.udThis dissertation addresses the problem of minimising the lifetime costs of a gridconnectedudhybrid system with diesel generation, photovoltaic array (PV) and an energyudstorage component.udTo minimise the operational costs a predictive generator-storage scheduling strategy isudproposed. The dispatch strategy seeks to minimise the operational costs by schedulingudthe generator and storage unit to: 1) Minimise the total energy requested from theudgrid; 2) Minimise the peak energy requested from the grid; 3) Minimise the fuel used byudthe generator. The dispatch strategy is developed in two papers. In the first paper auddemand prediction algorithm is developed which is required by the proposed predictiveuddispatch strategy. In the second paper, the actual dispatch strategy for the generatorudand storage unit is formulated. The dispatch strategy takes the form of an integratedudconvex optimisation model which, when solved, provides the dispatch strategy for theudgenerator and storage.udAn optimal sizing method is then developed to take into account the capital costs ofudthe components. The purpose of the optimal sizing method is to balance the trade-offudbetween the increased capital costs incurred by larger PV and storage units and theudcorresponding decrease in operational costs.udThe optimal dispatch strategy and sizing method are then tested on an example caseudstudy which investigates the possibility of operating a hybrid on the campus of theudUniversity of the Witwatersrand.