Distributed Hybrid Secondary Control of Virtual Synchronous Generators for Isolated AC Microgrids with Low Bandwidth Communication

Due to the high penetration of renewable energy based distributed generators (DGs), AC microgrids (MGs) exhibit a low-inertia characteristic. Thus, a novel control algorithm called virtual synchronous generator (VSG) is widely integrated to meet the demands of stabilizing MGs operation as well as providing ancillary regulation performance. In this paper, a distributed hybrid secondary control of VSGs for isolated AC MGs with low bandwidth communication is proposed to achieve frequency restoration and fair power sharing. We first model the VSG by imitating the operation of synchronous generators. Considering the nonlinear character of VSGs, distributed hybrid secondary control with inertial-support is then established for flexible frequency restoration under load disturbances. Moreover, by introducing a self-triggered communication mechanism, active power is fairly shared among VSGs with rarely communications, and hence the communication and computation burden of local controllers is considerably reduced. Finally, a test MG is constructed to illustrate the efficacy of the proposed hybrid control method, aligning well with the Lyapunov stability analysis.