The frequency stability of islanded microgrid is easily affected by the uncertain load and renewable energy fluctuations, which puts forward higher requirements for the regulation ability of traditional synchronous generators with continuous power regulation ability. In addition, because the information interaction between the generators and the microgrid control center needs to pass through the open communication network, the uncertain delay problem will also have an adverse impact on the frequency stability. Therefore, a networked frequency control strategy is proposed. Firstly, based on the deterministic network calculus theory, the analytical relationship between the upper boundary of transmission delay and the key network parameters is derived. Secondly, by constructing the Lyapunov function, the constraints of the controller to ensure the frequency asymptotic stability of the microgrid are derived. The simulation results show that the proposed method has good robustness to the random fluctuation of new energy and load demand and bounded random transmission delay.
This work is supported by Science and Technology Project of State Grid Corporation of China.