Virtual synchronous machine (VSM) can be used in micro-grids (MGs) for supporting virtual inertia to mitigate frequency fluctuations in the system. The performance of VSM depends on the performance of the current controlled voltage source inverter. Generally used proportional-integral (PI) controller has limited transient performance in current control. Adaptive dynamic programming (ADP) controller has been investigated, designed and tested to improve transient stability in the electric power system. In this paper, ADP controller has been proposed as a supplementary controller for fine tuning conventional PI current controller thereby improving the performance of VSM. The grid connected inverter system was simulated in MATLAB/Simulink to analyze transient stability problems. ADP as a supplementary controller not only reduced the overshoot of d-axis current at sudden load changes but also increased the speed of the current control. Furthermore, the system was tested for single phase line to ground fault and performed well based on the proposed ADP supplementary control approach.
['Naresh Malla', 'Dipesh Shrestha', 'Zhen Ni', 'Reinaldo Tonkoski']
Supplementary control for virtual synchronous machine based on adaptive dynamic programming