University of South Wales Master of Sciences Thesis
Standalone hybrid generation system for the remote area of Thar, Pakistan
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- 2.2.1. Solar Photovoltaic
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Standalone hybrid generation system for the remote area of Thar, Pakistan Meteorological conditions of THAR location. (a) Solar irradiation on horizontal plane, (b) wind speed and (c) Ambient temperature. 2.2. Components of the Hybrid generation System The hybrid power system, described here, basically includes the following main elements: - • Renewable energy sources: PV-system, Wind generator • Energy storage bank: Battery bank • Permanent magnet synchronous generator (PMSG) • Power electronics The following sections give the basic descriptions for the main components used in the proposed system. 2.2.1. Solar Photovoltaic In the generation of energy from solar irradiation, the PV-arrays trap the photons of solar light and convert the light energy into electrical energy. The energy obtained from the PV-systems can be utilized in different applications. DC power is the direct output of PV-arrays and this DC form power can be directly used with DC appliances. For AC appliances, this DC power has to be changed into AC form using power electronic inverters. The building block of the PV array is the solar cell, which is basically a P-N semiconductor junction that directly converts solar radiation into DC current using the photovoltaic effect. PV cells are grouped together in larger units known as PV modules or arrays, which are combined in series and Standalone hybrid generation system for the remote area of Thar, Pakistan parallel to provide the desired output voltage and current. The well-known equivalent circuit of solar cells arranged in NP-parallel and NS-series is shown in Fig. 2.3. It is composed of a light-generated current source, a diode representing the nonlinear impedance of the pen junction, and series and parallel intrinsic resistances. The mathematical model that predicts the power production of the PV generator becomes an algebraically simply model, being the current-voltage relationship defined in Eq. (1) [6,7] Where: IA: PV array output current VA: PV array output voltage IPh: Solar cell photocurrent Fig. 2.3 Equivalent circuit of solar cell Irs: Solar cell reverse saturation current (aka dark current). q: Electron charge, 1.60217733ee19 Cb. A: P-N junction ideality factor, between 1 and 5. k: Boltzmann’s constant, 1.380658ee23 J/K. Tc: Solar cell absolute operating temperature, K. Rs: Cell intrinsic series resistance. Rp: Cell intrinsic shunt or parallel resistance. The photocurrent Iph for any operating conditions of the PV array is assumed to be related to the photocurrent at standard test conditions (STC) as follows: f AM a : Absolute air mass function describing solar spectral influence on the photocurrent I Ph. f IA : Incidence angle function describing influence on the photocurrent I Ph. I SC : Cell short-circuit current at STC. a Isc : Cell temperature coefficient of the short-circuit current, A/module/diff. temp. (K). T R : Solar cell absolute reference temperature at STC, K. S: Total solar radiation absorbed at the plane-of-array, W/m 2. S R : Total solar reference radiation at STC, 1000 W/m 2. |