Overall design of grid connected photovoltaic power generation system

The grid connected photovoltaic power generation system converts the DC output by the solar cell array into AC with the same amplitude, frequency and phase as the grid voltage, and realizes the connection with the grid to transmit electric energy to the grid. Battery pack can improve the reliability of system power supply. Photovoltaic power generation in strong sunshine

The system first meets the power consumption of AC load, and then sends the excess power to the power grid; When the sunlight is insufficient and the solar cell array cannot provide enough power for the load, it can be obtained from the power grid or battery pack to supply power to the load.

Of course, if the cost is taken into account, the battery can not be connected. When the light is insufficient, it can directly ask the power grid for power supply for the load.

Compared with independent system, grid connected AC power generation system eliminates energy storage equipment.

There is also a grid connected extended hybrid power generation system. Hybrid type is between grid connected type and independent type. This system is usually integrated with the controller and inverter. The computer chip can be used to control the whole system to achieve the best working state. Figure 32 shows the hybrid photovoltaic power generation system. The difference between it and the above two systems is that there is an additional standby generator set. When the photovoltaic array power generation is insufficient or the storage battery is insufficient, the standby generator set can be started. It can not only directly supply power to the AC load, but also charge the battery through the rectifier. Hybrid photovoltaic power generation system is mainly used for the combination of electric fields far away from the power grid and ensuring the continuity of power supply, such as field hospitals, scientific investigation stations, etc. Once there is insufficient light or rainy weather, the solar cell cannot work, and the power stored by the battery cannot meet the needs, the generator set will replace the solar cell to supply power to the system.

Different levels of photovoltaic grid connected voltages are different. For example, grid connected photovoltaic power stations above MWP level generally need to be connected to public power grid above 10kV, and other designs are roughly the same.

The photovoltaic module converts solar energy into DC electric energy under the photovoltaic effect,can be used for solar street lights

Then it flows into the grid connected inverter through the lightning protection distribution cabinet, which reverses it into AC meeting the power quality requirements of the power grid, and is connected to the 380V / 150Hz three-phase AC station power system for grid connected power generation. During the day, photovoltaic power generation will supply power to the power load of the station and feed the excess power into the power grid; When the power generation is insufficient in the evening or rainy days, the public power grid will supply power to the station power load. The photovoltaic grid connected power generation system is equipped with a set of local monitoring device with Ethernet communication interface, and the working state and operation data of the system are provided to the integrated automation system of unattended station through the interface to realize remote centralized control station monitoring.