Seven basic protection functions of solar photovoltaic inverters

The photovoltaic grid-connected power generation system consists of solar cell components, grid-connected inverter, metering device and power distribution system (as shown below. Solar energy is converted into DC power through solar cell components, and then the DC power is converted into DC power through the grid-connected photovoltaic inverter. The sine wave current is synchronized with the grid frequency and phase, and this power is fed into the grid. The photovoltaic grid-connected inverter is a key device in the solar power generation system.

As an important electrical equipment within the photovoltaic power generation system, the photovoltaic inverter is equipped with various protection functions, including the following basic protection functions.

(1) Enter the overvoltage policy holder:

When the input voltage is higher than 130% of the rated voltage, the inverter should have protection and display.

(2) Enter the undervoltage policyholder:

When the input voltage is lower than 85% of the rated voltage, the inverter should have protection and display.

(3) Input reverse connection protection:

When the positive and negative input terminals are connected reversely, the inverter should have protection functions and displays.

(4) Lightning protection:

The inverter should have lightning protection.

(5) Overcurrent protection:

The overcurrent protection of the inverter should be able to ensure timely action when the load is short-circuited or the current exceeds the allowable value to protect it from damage by surge current. When the operating current exceeds 150% of the rating, the inverter should be able to automatically protect.

(6) Output short circuit insured

The inverter short-circuit protection action time should not exceed 0.5s.

(7) Over-temperature protection, etc.

In addition, for inverters without voltage stabilization measures, the inverter should also have output over-voltage protection measures to protect the load from over-voltage damage.

An inverter with excellent performance should have complete protection functions or measures to deal with various abnormal situations that occur during actual use, so as to protect the inverter itself and other components of the system from damage.