-Normally, the artificial intelligence algorithms are widely applied to the optimal controller design. Then, it is expected that the best output performance is achieved. Unfortunately, when resulting controller parameters are implemented by using the practical devices, the output performance cannot be the best as expected. Therefore, the paper presents the optimal controller design using the combination between the state-space averaging model and the adaptive Tabu search algorithm with the new criteria as two penalty conditions to handle the mentioned problem. The buck-boost converter regulated by the cascade PI controllers is used as the example power system. The results show that the output performance is better than those from the conventional design method for both input and load variations. Moreover, it is confirmed that the reported controllers can be implemented using the realistic devices without the limitation and the stable operation is also guaranteed. The results are also validated by the simulation using the topology model of MATLAB and also experimentally verified by the testing rig.

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DC micro-grid systems feed power to constant power loads via transmission lines. Although these systems are commonly used worldwide, constant power loads have negative impedance effects. These loads can significantly degrade the system stability. Therefore, stability study is very important to avoid inefficient operations. The model proposed in this paper can be derived by using a combination of the DQ method and the generalized state-space averaging method. This model is suitable for analyzing the system stability using the eigenvalue theorem. For stability analysis, the proposed DC micro-grid system will be unstable before reaching the rated power when the irradiance is equal to 0 W/m 2 . Consequently, the loop-cancellation technique is applied to mitigate the unstable operation until the operation at the rated power can be achieved. Experimental and simulation results were used to confirm the theoretical analysis. The system performed well, and the results proved that the system could be stabilized by using the proposed technique.

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