Power management and coordinated control of standalone active PV generator for isolated agriculture area-case study in the South of Algeria

Abstract

This paper aims to elaborate a local energy management and coordinated control of a 15 kW Standalone Active PV Generator (SAAPG), dedicated to the electrical supply of a remote farm in southern Algeria. The SAAPG is composed of four sources: Photovoltaics, Lead Acid Batteries, Ultra-capacitors, and Diesel generators (DGs); all these sources are coupled together in the DC-link (VDC-ref = 700 V). This agricultural area is mainly equipped with unpredictable high dynamic (transient) loads composed of two cold room compressors, an immersed pump and a watering pump. Unlike usual, a DC side coupling structure of the DG is proposed in this paper in order to ensure two dominant advantages: the first one is to slow the dynamics of the DG output power, which will be imposed by the DG boost converter instead of the load (like AC side coupling), allowing a low maintenance frequency in the diesel engine by reducing thermo-mechanical stresses in diesel engine cylinder heads due to transients. The second one guarantees both efficiency and cost effectiveness of the system by operating the DG near to its rated power in either transient or steady state conditions, and thus, such an oversizing of the DG will be avoided unlike the AC coupling case. The four power sources are managed in coordination, according to their dynamics, to maintain the DC-link voltage value regulated around its reference. A three-phase DC-AC PWM converter operates independently considering the DC link as a fixed DC source voltage in order to power supply AC loads.