Whether the single-phase inverter and three-phase inverter can be connected together

A customer installed a 3-phase 15kw inverter and recently wanted to add 10 300W 3KW modules. He wants to use a single-phase inverter. May I ask if the electrical connection is OK?

1. There are three grounding forms for low-voltage power distribution systems, namely IT system, TT system and TN system. The IT system has no neutral line, while the TT system and the TN system have a neutral line. In industrial, commercial and civil systems, most are TN systems. The grid-tied inverter is connected to the grid. A three-phase inverter has three live conductors, a neutral and a ground. A single-phase inverter has a live wire, a neutral wire, and a ground wire. If there is a three-phase grid, a single-phase inverter only needs to be connected to one phase wire (ie live wire), one neutral wire and one ground wire. Therefore, there are no electrical problems.

2. There is no problem with the three-phase four-wire watt-hour meter. Three-phase watt-hour meters are used to measure power output (or load consumption) in three-phase AC circuits. Its working principle is exactly the same as that of the single-phase electric energy meter, but its structure adopts multiple sets of driving components and multiple aluminum disks fixed on the rotating shaft to realize the measurement of three-phase electric energy. The difference between a three-phase four-wire active energy meter and a single-phase energy meter is that it consists of three drive elements and three aluminum discs mounted on the same shaft. Its reading directly reflects the electric energy consumed by the three-phase. Three phases are measured separately. Three phases are allowed to be different.
Therefore, the power of one phase is increased, while the other two phases are not affected. Matters needing attention: Two issues should be paid attention to when the single-phase inverter is connected to the grid. One is the three-phase imbalance problem. Therefore, the single-phase inverter should be connected to the phase with the largest load as far as possible. If the three-phase load is balanced, the single-phase power should not be too large, and it is best not to exceed the load power. If the photovoltaic power is greater than the load power, when the photovoltaic system is connected to the grid, if the local load cannot be consumed, it is sent to the remote load or to the grid, which will cause the inverter voltage to rise. The higher the output power, the higher the voltage. In severe cases, it may cause inverter overvoltage protection and shutdown.