Adjustment function of MPPT equipment in photovoltaic system

According to different judgment methods and standards, traditional MPPT methods are divided into open-loop and closed-loop MPPT methods. Open loop includes constant voltage tracking method, short-circuit current proportional coefficient method and difference calculation method; Closed loop includes disturbance observation method and conductance increment method.

So far, there are intelligent MPPT methods.

Grid-connected inverters are mainly divided into two types according to the topology structure and implementation position of MPPT tracking: two-stage grid-connected photovoltaic and single-stage grid-connected photovoltaic.

Two-stage: the DC output by the battery panel is boosted by the boost conversion in the previous stage and then output to the grid-side inverter in the latter stage, and the AC output by the grid-side inverter is merged into the power grid through control. Because there are two power conversion units in the two-stage grid-connected photovoltaic inverter, the maximum power tracking point control can be completed by the Boost of the previous stage or the grid-side inverter of the latter stage. The MPPT control with DC-DC conversion should be based on the previous stage, which is also a common control scheme in practice. In this control, the former Boost realizes MPPT control and the latter Boost realizes DC bus voltage stability control.

Single stage: MPPT, grid voltage synchronization, sinusoidal control of output current is directly realized through DC- AC link, and the control is relatively complicated.

Generally speaking, the perturbation observation method (P & amp； O), admittance increment method (INCond).

There is also a parallel power compensation method; Composite MPPT algorithm combined with conventional algorithm: current scanning method; Short circuit current pulse method; Fibonacci search method; MPPT algorithm based on state space, etc.