Operating principle of PV, BESS, DG and EV charger system
Definition
PV: Photovoltaic, solar panel.
BESS: Battery energy storage system.
DG: Disel generator.
Follow: The voltage, frequency and phase of power source A, is tracking and equal to power source B.
EV charger is a load, just like a regular load. The main principle of the new energy system with AC coupling is the synchronization of voltage, frequency, and phase of various AC power sources.
1.DG power off status
PCS operates independently and in off-grid mode, PV inverter follows the PCS.
2.DG power on
If the SOC of batteries is lower than a certain set value, for example 20%, the EMS will command the DG start, at the same time STS opens;
After DG reach the rated voltage and rated frequency, the PCS switches from off-grid mode to on-grid mode, then PCS and PV inverter follow the DG, STS closes.
3.DG power off
If the SOC of batteries exceeds a certain set value, for example 80%, the EMS will command the STS opens, then the DG power off.
The PCS switches from on-grid mode to off-grid mode, PV inverter follows the PCS.