Modelagem e projeto dos controladores da malha interna de inversores formadores de rede

Abstract

This work aims to propose a methodology to define and calculate the gains of the current and voltage controllers of the internal loops of a grid-forming converter (CFR), ensuring the stability of the system under different operating conditions. The methodology for the design and validation of the current and voltage control loop is based on the V model that allows a progressive evaluation of the control from the theoretical formulation to the implementation and performance verification. As a result, methods were developed for the design of the internal loops of the grid-forming converter based on the multivariable system and transfer function techniques. The analysis of the results showed that the multivariable method presented the best performance, standing out for its greater stability for different test scenarios. The multivariable method when analyzed by active and reactive power steps presented the best results, with a lower overshoot of 8.89% and settling time of 0.015 s unlike the transfer function methods that reached a maximum overshoot during the simulation of 36.46% and rise time of 0.0495 s. Furthermore, it was found that the transfer function-based method, where the crossover terms were considered compensated, had inferior performance when subjected to dVOC control with oscillation in the power curves of up to more than 1 second during the simulations, compromising the stability of the system. And when the CFR was analyzed connected to a load that requires an active power of 5000 W and a reactive power of 2000 V Ar, all methods were able to deliver the power requested by the load. Therefore, the multivariable method proved to be the most robust approach, providing better results in both the droop control strategy and the dVOC and ensuring the stability of the CFR.