The simulation platform used in this experiment is PSIM9.0, which is a simulation software specifically designed for power electronics. It has a large library of power electronic devices, including many solar grid connected circuit specific devices, such as solar panels, which saves a lot of time for simulation analysis. Firstly, the MPPT simulation model based on PSIM is shown in Figure 1.
From the simulation images, it can be visually seen that the simulation circuit mainly consists of a solar panel, a Boost boost circuit, and a DLL module. Since the other two parts have been introduced earlier, here is a brief introduction to the DLL module:
DLL is the carrier for implementing MPPT in simulation circuits. By writing the algorithm program for MPPT in Microsoft Visual C++6.0 and adding the C language program source code file to the empty DLL module, MPPT can be implemented in simulation circuits.
By running the simulation, the changes in the output voltage of the photovoltaic module and the tracking effect of the MPPT can be observed. As shown in Figure 2:
As shown in Figure 2, the MPPT algorithm is effective in tracking, where the red curve represents the tracking curve of the maximum power value, and the blue curve represents the adjustment of the output voltage.
Through research and learning, the following conclusions have been drawn based on the understanding of household solar photovoltaic grid connected power generation systems:
1) After studying the output characteristics of solar cells, DC/DC circuits, classification and working principles of inverters, an overall scheme of a solar photovoltaic grid connected power generation system was designed within the author’s level.
2) Single crystal silicon solar cells were selected as the batteries used in this project, and the main parameters of the boost circuit were designed. Based on the actual situation of this project, the main components of the inverter circuit were set and selected.
3) We studied the maximum power tracking point control, and based on this, we introduced an improved MPPT control method for this topic. We also designed a control circuit for a solar photovoltaic grid connected power generation system within the author’s level.
4) The MPPT simulation shows that the tracking of the maximum power point is effective, and the adjustment of the output voltage of the photovoltaic panel is clearly visible.
We have conducted the most preliminary exploration and design of a 5kW household solar photovoltaic grid connected power generation system. Regarding the future development trend of household solar grid connected power generation systems and the feasibility of designing solar photovoltaic grid connected power generation systems, further research is needed on the following aspects in the future:
1) Strive to assemble finished products within three years to verify the feasibility and economy of practical applications.
2) The solar panels in this project are fixedly installed. To maximize the energy conversion rate, it is also worth studying the steering device for solar panels to rotate with the movement of the sun.
3) Research more efficient and reliable MPPT to improve efficiency.
4) Research to improve the waveform quality of grid connected current and reduce harmonic output.