Quasi-dynamic Load and Battery Sizing and Scheduling for Stand-Alone Solar System Using Mixed-integer Linear Programming

TL;DR

This paper presents a mixed-integer linear programming model for optimizing load and battery sizing and scheduling in off-grid solar systems, considering quasi-dynamic unit operation to enhance solar energy utilization.

Contribution

It introduces a novel quasi-dynamic unit modeling approach and analyzes the effects of solar profiles and operational constraints on system sizing and scheduling.

Findings

Battery size decreases with more units and flexibility.

Quasi-dynamic units improve solar energy utilization.

Optimal unit and battery sizes depend on solar profile and constraints.

Abstract

Considering the intermittency of renewable energy systems, a sizing and scheduling model is proposed for a finite number of static electric loads. The model objective is to maximize solar energy utilization with and without storage. For the application of optimal load size selection, the energy production of a solar photovoltaic is assumed to be consumed by a finite number of discrete loads in an off-grid system using mixed-integer linear programming. Additional constraints are battery charge and discharge limitations and minimum uptime and downtime for each unit. For a certain solar power profile the model outputs optimal unit size as well as the optimal scheduling for both units and battery charge and discharge (if applicable). The impact of different solar power profiles and minimum up and down time constraints on the optimal unit and battery sizes are studied. The battery size required to achieve full solar energy utilization decreases with the number of units and with increased flexibility of the units (shorter on and off-time). A novel formulation is introduced to model quasi-dynamic units that gradually start and stop and the quasi-dynamic units increase solar energy utilization. The model can also be applied to search for the optimal number of units for a given cost function.