This article proposes a topology for single-phase two stage grid connected solar photovoltaic (PV) inverter for residential applications. Our proposed grid-connected power converter consists of a switch mode DC-DC boost converter and a H-bridge inverter. The switching strategy of proposed inverter consists with a combination of sinusoidal pulse width modulation (SPWM) and square wave along with grid synchronization condition. The performance of the proposed inverter is simulated under grid connected scenario via PSIM. Furthermore, the intelligent PV module system is implemented using a simple maximum power point tracking (MPPT) method utilizing power balance is also employed in order to increase the systems efficiency.
- DC-DC Boost Converter
- Grid Connected
- Power Electronics
- Grid Tie Inverter(GTI)
Figure 1. Block diagram of two-stage grid connected PV system
EXPECTED SIMULATION RESULTS:
Figure 2. Output voltage of the inverter without filtering
Figure 3. Output current of the inverter
Figure 4. Output voltage after connected to grid
Figure 5. Output real power
Figure 6. Output voltage’s FFT (a) before filtering and (b) after filtering
The main purpose of this paper is to establish a model for the grid-connected photovoltaic system with maximum power point tracking function for residential application. A single phase two-stage grid-connected photovoltaic inverter with a combination of SPWM and square-wave switching strategy is designed using PSIM. In the proposed design, an MPPT algorithm using a boost converter is designed to operate using (P&O) method to control the PWM signals of the boost converter, which is adapted to the maximum power tracking in our PV system. Instead of using line frequency transformer at the inverter output terminals, a DC-DC boost converter is used between solar panel and inverter that efficiently amplify the 24V PV arrays output into 312V DC, which is then transformed into line frequency (50Hz) sinusoidal ac 220V rms voltage by the inverter and thereby reducing the system losses and ensures high voltage gain and higher efficiency output. The simulation results show that the proposed grid connected photovoltaic inverter trace the maximum point of solar cell array power and then converts it to a high quality ripple free sinusoidal ac power with a voltage THD below 0.1% which is very much lower than IEEE 519 standard. The simulation also confirms the proposed photovoltaic inverter can be applied as a GTI and able to supplies the AC power to utility grid line with nearly unity power factor.
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