Analysis of Center of Inertial Frequency in a Power Grid that Includes Distributed Energy Resources Connected via Smart Inverters

In recent years, the control function of grid-connected inverters called “smart inverters” has increased in sophistication, and the function of stabilization of the system frequency and terminal voltage is implemented. The stability of the entire system could be ensured if these high-performance grid-connected inverters are utilized efficiently. However, the control function of such an inverter generally differs across manufacturers, and the details are not disclosed. Therefore, in this study, a power system with grid-connected inverters and synchronous generator is considered for classifying these characteristics and establishing a grid code for each control type without depending on the method of implementing inverter control. The power system is analyzed, and its performance is indexed using the concept of “center of inertia frequency.”