Page 263 - Hybrid-Renewable Energy Systems in Microgrids

240 Hybrid-Renewable Energy Systems in Microgrids

iHOGA software includes advanced optimization methodology of genetic algorithms,
which implies the possibility of obtaining the optimum system using very low com-
putational times.
The software HYBRIDS, produced by Solaris Homes, assess the technical poten-
tial of renewable energy system for a given configuration and determines the poten-
tial renewable fraction and evaluates the economic viability based on Net Present
Cost (NPC). HYBRIDS is a Microsoft Excel spreadsheet-based RES design tool that
requires daily-average load and environmental data estimated for each month of the
year. Unlike HOMER or iHOGA, HYBRIDS can only simulate one system configura-
tion at a time, and it is unable to provide an optimised configuration. This software is
comprehensive in terms of RES variables and the level of detail required and demands
a higher level of knowledge of renewable energy system configurations than HOMER.
RETScreen is a Microsoft Excel based software tool which can evaluate the energy
efficiency and the technical and financial viability of the RES projects. This tool is
used to analyse the energy efficiency of the integrated system covering mainly energy
production, life-cycle costs and greenhouse gas emission reduction [106].
Some more computer tools are also available for designing the components of
HRES [107,108], such as The General Algebraic Modelling System (GAMS) [109],
Opt Quest [110], LINDO [110,111], WDILOG2 [112], Simulation of Photovoltaic
Energy Systems (Sim Pho Sys) [113], Grid-connected Renewable Hybrid Systems
Optimization (GRHYSO) [114,115], and H2RES [116].

5 Control of HRES

While designing these HRES, one must consider the fact that the dynamic interaction
between load demand and the HRES can lead to critical stability and power qual-
ity problems, that is not very common in conventional power systems [14,117]. To
assure continuous power supply for the load demand, proper management of energy
flow throughout the proposed hybrid system is essential. Hence, the control technique
takes a very important role in improving the system efficiency and energy genera-
tion of a plant. In other words, by choosing proper control technique in the system
design process, the power availability from an HRES can be economically maxi-
mized. Therefore, the power flow management in HRES is very important to ensure
the continuous energy flow between system components. This is also required to
increase the operating life of the HRES and to ensure the quality of energy flow.
Studies have been reported in literature related to the power management of hybrid
power systems [118].
The conventional approach for controlling the power supply to the load requirement
according to the demand has been used in many HRES. The conventional approach
uses power electronics based DC–DC converter to extract maximum energy from solar
and wind energy resources and control the complete HRES. Besides the conventional
approaches, some advanced controlling techniques have been reported in the literature
that can compensate the power fluctuations caused by the variability of the renewable
energy sources that may affect the quality of the power delivered to the load.