Grid connected system theory of PV system

Grid solar power system basic principle:

Grid connected Solar system mainly consists of solar arrays and grid-connected inverter composed.

(1) Solar Array: Solar array invert sunlight into electrical energy,and invert DC powder to AC power by grid-connected inverter when sunlight is enough,and then input into grid.

(2) Grid-connected inverter: grid-connected inverter is to convert DC to AC devices, input termination is connected to solar array, and output termination is connected to AC grid. Grid-connected inverter not only has normal function of inverting ,but also has the following features:

1) Pure sine wave synchronization and grid transmission: Through DC / AC voltage inverter to realize current transient control,control current into a 50Hz sine wave,and then is automatically synchronized with the grid  and sent into the grid.It would not produce harmonic interference and excessive reactive component by the way of Sinusoidal current approaching  to grid-power transmission grid.

2) The solar cell maximum power tracking technology: solar cells with basic material of crystalline silicon has different IV characteristic curves when different irradiation intensity and temperature, and there is a maximum power output of the corresponding point between output and IV characteristics, therefore,it is to be key point of the whole system that the  tracking MPPT (Maximum Power Point Trace) to solar maximum output power point.
3) Anti-island techniques:when running grid-connected, power grids stop working due to unforeseen factors, at this time, grid-connected equipments should be able to detect and find the power outage situation and then seperate grid columns and  stop transmiting power to grid in order to protect person and equipment to be safety.

4) The technology of independent power supping and automatically synchronize the Grid: when system meet stopping to supply by grid, it can automatically disconnect with grid, independently supply high-quality AC power to important appliance.After equip with battery, the system can provide uninterrupted power during the night.When grid come back to supply electricity ,then the voltage is synchronized with the grid, it will switch to the grid operating mode automatically without any affect on appliance.