Optimal energy management of PV system with hydrogen technology -

Abstract

This thesis addresses the modeling, optimization, and sizing of a grid connected Hybrid Renewable Energy System (HRES) that consists of a Photovoltaic (PV) array that operates as a main source of generation, and two types of back-up systems. The first is a long-term back-up storage consisting of an Alkaline Fuel Cell (AFC) that gets its hydrogen from an Electrolyzer (EL), supplied from the main PV source. The second is an Ultra Capacitor (UC) which is considered as a short-term backup device. After modeling each component an optimal Energy Management System (EMS) was applied in order to minimize the cost of purchasing electricity from the grid and the CO2 emissions. The optimizing method being implemented is based on Linear Programming (LP) and it is subject to a number of constraints which are the power balance equation, upper and lower limits of power delivered by the various devices, ramp rate limits, hydrogen storage limitation, and the UC charge limits. These constraints will assure the reliability and the safety of the system while meeting the load requirements at the lowest cost. The reason behind choosing an LP technique is the linear nature of the objective function and the near linearity of the constraints. In addition to minimizing the cost, this system will allow the hazardous emissions to be reduced by using the clean alternative PV-based power generating system. The size of the PV modules is selected to give output power that is enough to feed the peak load when the solar radiation is available. The size of other components is set choosing the least solar radiation days of the year which represent the worst days that require the highest sizes of backups. A case study is presented for a village in Lebanon called Anjar where the unreliable nature of the grid is solved using HRES with different scenarios of operation.