Characteristics of Parallel Operation of Inverter-Type Distributed Generators Operated by a Virtual Synchronous Generator

SUMMARY The capacity of distributed generators (DGs) connected to a grid by inverters is growing. The inverters are generally controlled by a phase locked loop (PLL) in order to achieve synchronization with the power system frequency. They cannot have synchronous power. Power systems become unstable if the capacity of the inverter‐type DGs is increased. The concept of controlling inverters to behave like a synchronous generator is studied in this paper. The result is referred to as a “virtual synchronous generator” (VSG). The VSG has synchronous power. Power systems become stable as a result of using the VSG. The VSG is useful in the parallel operation of DGs. The VSG can synchronize with other VSGs, synchronous generators, or the grid. In this paper, a method for the synchronous operation of a VSG is studied, and experimental results on a VSG running in parallel with a synchronous generator and other VSGs are presented.