Optimal Operation Control of Microgrid Connected Photovoltaic-Diesel Generator Backup System Under Time of Use Tariff

Abstract

With the exponentially increasing demand of electrical energy, many developing countries are struggling to provide electricity to the end-users. This challenge has mainly strained traditional power systems. To mitigate against this strain, governments are diversifying and liberalizing the energy market to meet future energy demand. In addition, end-users have several alternatives to reduce electricity cost at demand side. This can be realized either by using efficient devices or incorporating renewable energy sources while scheduling their powers economically. Within this framework, microgrids are considered as efficient power systems to exploit renewable energy sources with demand side management program. Nowadays, microgrids which can harness photovoltaic solar source at low cost are becoming an attractive option for reduction in electricity cost at demand side. To ensure uninterrupted power supply, diesel generators are often used as backup energy systems in most large-scale or industrial applications in Kenya. Therefore, this paper proposes a constrained optimal operation control strategy of microgrid connected photovoltaic with diesel generator backup system related to commercial and industrial (C&I) setups in Kenya. Particularly, the objective function simultaneously aims at reducing energy purchased from utility grid and the fuel consumption cost of the conventional diesel generator. The constraints related to control variables are taken in the context of C&I in Kenya. The optimal operation control is carried out using FMINCON interior-point algorithm, and two scenarios are analysed. The first scenario is carried out by considering the intermittent mode from 7:00 hrs to 18:00 hrs, while the second scenario is considered in the intermittent connected mode. A case study is done based on the daily load profile of the Engineering workshops at Jomo Kenyatta University of Agriculture and Technology (JKUAT) located at $$-$$ 1.099 $$^{\circ } $$ latitude and 37.014 $$^{\circ } $$ longitude. The optimal operation control has shown great benefits in terms of energy saving, cost saving as well as daily revenue. The daily energy saving is increased up to 52.1%, the daily cost saving is 20%, and daily energy sold is found to be 142.4 kWh which can generate daily income of $17.