SoC regulator and DOB-based load frequency control of a microgrid by coordination of diesel generator and battery storage

In this paper, the load-frequency control problem of microgrid is discussed. The control is applied to maintain a balance between electric-power demand and supply by controlling the outputs of generators in power systems. However, because of the large-scale introduction of energy from renewable-energy sources, it has become more difficult to maintain this balance. To solve this problem, we consider introducing batteries to microgrid. Therefore, we focus on a microgrid that comprises wind-turbine generators, loads, diesel generators, and batteries. First, we design a generalized plant including the diesel generators and batteries. Then, we apply disturbance observer to decide a reference input to diesel generators and batteries. And, we split the reference input into that for diesel generators and that for batteries considering the differences in the response speeds by applying low-pass filter. Furthermore, we apply SoC regulator for the state of charge of batteries reaching maximum capacity or minimum capacity. Finally, we perform numerical simulations to verify that the control method can suppress the frequency deviations and deviations in the residual capacity of the battery.