PV generation control to enhance the energy efficiency of local power supply systems

Abstract

Relevance: in recent years, an increasing number of commercial and industrial (C&I) organizations in Uzbekistan have been installing small-scale grid-tied photovoltaic (PV) power plants. Typically, photovoltaic modules (PVMs) are installed on the rooftops of C&I buildings where the main electricity consumers are concentrated. Therefore, from the standpoint of reducing electricity losses, the most rational solution is to connect the PV plant to the building’s own main distribution board (MDB). However, in many implemented projects, in accordance with the issued technical specifications, the PV plant is connected via a new cable to the low-voltage busbars of a transformer substation (TS) located at a certain distance from the building. Such an arrangement leads to additional electricity losses both in the cable between the grid-tied inverter and the TS, and in the cable running from the TS to the MDB.

Aim: to study the advantages of connecting a grid-tied PV plant directly to the MDB compared to connecting it to the TS, as well as to examine the technical limitations of such a connection and possible methods for their mitigation.

Methods: development and implementation of an automatic control system that regulates PV generation and consumer loads to ensure the stability of a local isolated power system (microgrid) with two generation sources — a diesel generator (DG) and a grid-tied PV plant.

Results: reduction of electricity losses by minimizing the distance between the generation source (PV plant) and the main consumers powered from the MDB, as well as by unloading the feeder cable between the TS and the MDB. Reduction of diesel fuel consumption by up to 60% during emergency power supply from the DG.