**2.3 Power converter**

56 Electrical Generation and Distribution Systems and Power Quality Disturbances

Fig. 2. Temperature and irradiance effects on I-V characteristics of PV arrays/cells [46]

High solar intensity

Low Solar intensity Low Temperature

4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 Time

Fig. 3. Variations of solar irradiance and temperature throughout a day conditioning PVGCS

Firstly, under a steady state condition, input, load and utility under consideration are treated as being constant with slightly change weather condition. Installed capacities of PV systems in a steady state are low, medium and high capacity. According to the weather conditions throughout a day as shown in Fig. 3 [47-48], a low radiation about 0-400 W/m2 is common in an early morning (6:00 AM-9:00 AM) and early evening (16:00 PM-19:00 PM), medium radiation of 400-800 W/m2 in late morning (9:00 AM-11:00 PM) and early afternoon (14:00 PM-16:00 PM) and high radiation of 800-1000 W/m2 around noon (11.00

High Temperature Medium solar

intensity Medium Temperature

200

400

600

Solar Irridiance (W/m2)

operation

800

1000

There are several topologies for converting a DC to DC voltage with desired values, for example, Push-Pull, Flyback, Forward, Half Bridge and Full Bridge [49]. The choice for a specific application is often based on many considerations such as size, weight of switching converter, generation interference and economic evaluation [50-51]. Inverters can be classified into two types, i.e. voltage source inverter (VSI) if an input voltage remains constant and a current source inverter (CSI) if input current remains constant [52-53]. The CSI is mostly used in large motor applications, whereas the VSI is adopted for and alone systems. The CSI is a dual of a VSI. A control technique for voltage source inverters consists of two types, a voltage control inverter, shown in Fig. 4(a) and a current control inverter, Fig. 4(b) [54].

Fig. 4. Control techniques for an inverter
