Reliability assessments of an islanded hybrid PV-diesel-battery system for a typical rural community in Nigeria

Abstract

This paper presents the use of a novel approach in assessing the generation reliability of a hybrid mini-grid system (HMS) based on the optimal design result obtained from the HOMER software. A typical Nigerian rural community – Lade II in Kwara State was used as a case study where the energy demand for the residential and commercial loads was 2.5MWh/day and 171kWh/day respectively. The optimized HMS results from HOMER comprising of a solar photovoltaic (PV) array (1.5MW), diesel generators (350kW) and battery storage (1200 units) has a combined least net present cost of $4,909,206 and a levelized electricity tariff of $0.396 per kWh. Contrasting the HMS with a diesel-only system for the community, an approximate 97% reduction in all pollutant emissions was observed. Furthermore, fluctuations in diesel fuel prices, variations in average solar insolation, and variations in the solar PV's capital/replacement costs were utilized in conducting a sensitivity analysis for the HMS. The capacity outage probability table (COPT) was utilized in validating the reliability of the simulation results obtained from HOMER. The HMS was observed to experience a load loss of 0.769MW, 0.594MW & 0.419MW when zero, one and two diesel generator(s) respectively were operational for all of the Solar PV's and Batteries being off-line. The loss of load probability (LOLP), loss of load expectation (LOLE), and total expected load loss (ELL) obtained from the COPT were 5.76 × 10 −8 , 5.0457 × 10 −4 hr/yr and 0.025344Watt respectively. The results show the reliability of the HMS and also depicts a highly economical and feasible hybrid energy system.

Feasibility and optimal design of a hybrid power system for rural electrification for a small village

“…HOMER is the most commom cost analysis and validation test for stand alone hybrid system [5,7,23,35]. The HPS model was then validated by comparing its results with that of HOMER, using it as a benchmark [36].…”

“…There is no single energy generating system (composing of RES alone) that is reliable and cost-effective due to its fluctuating nature. A hybrid system of RES optimally combined with other conventional energy resources like diesel generator (DG) will serve as a better alternative [2,7].…”

“…Some of the common types of softwares used for simulation and optimization of hybrid systems are HOMER, RETScreen, SOLES, INSEL, TRANSYS, HYBRID2, IMBY, SOLSIM, CREST, RAPSYS and SAM. Out of all these, HOMER developed by the National Renewable Energy Laboratory is the most widely used [5][6][7][20][21][22]. So many works have been done on HRES, both off-grid [7-13, 16, 23-28] and grid connected [17,22,29].…”

“…Barakat et.al [22] examined the viability of grid-connected hybrid system consisting of Solar PV/Wind and Biomass in a rural village in Egypt using HOMER. Esan et.al [7] conducted a reliability assessment of an off-grid hybrid system consisting of Solar PV-BATT-DG system in a rural community-Lade II, Nigeria. The reliability of the results from HOMER simulations was validated using capacity outage table.…”

“…Even though, several authors have worked on HPS technology, very few papers have been published on Pumped hydro-SHP-Solar PV-BATT-DG hybrid system using water supply infrastructures [5,7,10]. The level of accuracy of the models described above depends largely on the assumptions made [4].…”