Optimization of Cascaded Control to Stabilize the Inverter-based Distribution Network

With the growing number of renewable energies in the power grid, the use of inverters is increasing rapidly. Due to this, the power system, because of the switching process caused harmonic by the inverters, is becoming more and more unstable. The reasons for it are various, one of them is due to the control structure of the inverter and its control parameters which may lead to the extending of harmonic effects in the grid if they are not properly parameterized. Accordingly, the efficient methods for parameterizing and optimizing the controllers in the inverter are required. The present paper focuses on the optimization of the controller parameters of the inverter (INV) in the distribution grid levels to improve the stability of the system. The optimization of the controller parameters in this paper is referred to as the global optimization in the multi-inverter system. To operate the process, the effect of the voltage at each grid connection point (PCC)is considered for the controller parameterization in each INV, and based on this, a dynamic concept for global optimization is proposed and investigated. In this study, the existing reference networks are selected in the average value mode and their stability in the small signal range will be investigated. Finally, the study shows that the global optimization of the INVs in the multi-inverter system with small signal excitations is achieved by considering the influence of the PCC voltage on each INV.