(1) Low insulation resistance
Use exclusion. Unplug all the strings on the input side of the
inverter, and then connect them one by one. Use the function of the inverter to start up to detect the insulation resistance to detect the faulty strings. After finding the faulty strings, check whether the DC connectors are flooded with short-circuit brackets. Or burn the short-circuit bracket, and also check whether the component itself has black spots on the edge burned out, causing the component to leak electricity to the ground grid through the frame.
(2) Low bus voltage
If it occurs in the morning/evening period, it is a normal problem, because the
inverter is trying to limit power generation conditions. If it occurs in normal daytime, the detection method is still the exclusion method, and the detection method is the same as item 1.
(3) Leakage current fault
If the leakage current is too large, remove the PV array input terminal, then check the peripheral AC power grid, disconnect the DC terminal and the AC terminal, and let the inverter power off for 30 minutes. To contact a professional engineer.
(4) DC overvoltage protection
With the pursuit of high-efficiency process improvement of components, the power level is constantly updated and increased, and the open-circuit voltage and operating voltage of components are also rising. The temperature coefficient problem must be considered in the design stage to avoid hard damage to the equipment caused by overvoltage at low temperature.
(5) There is no response when the
inverter is turned on
Please make sure that the DC input line is not reversed. Generally, the DC connector has a foolproof effect, but the crimping terminal has no foolproof effect. It is very important to read the
inverter manual carefully to ensure that the positive and negative poles are crimped. The inverter has built-in reverse short-circuit protection, and it starts normally after the normal wiring is restored.
(6) Power grid failure
The work of early-stage investigation of heavy load (large working time of electricity consumption)/light load (less rest time of electricity consumption) of the power grid is reflected here. Check the voltage health of the grid connection point in advance, and communicate with the
inverter manufacturer about the grid situation. The combination of technologies can ensure that the project design is within a reasonable range, especially in the rural power grid. The inverter has strict requirements on the grid-connected voltage, grid-connected waveform, and grid-connected distance. Most of the grid overvoltage problems are due to the light load of the original grid. The voltage exceeds or is close to the safety protection value. If the grid-connected line is too long or the crimping is not good, the line impedance/inductive reactance is too large, and the power station cannot operate normally and stably.
