Harmonic Compensation Optimization for Multiple Parallel Distributed Generators

The interest in distributed generators (DGs), especially those associated with renewable energies, has increased in recent years. The number of functionalities that their commonly associated voltage source inverters (VSIs) can deal with is rising, harmonic currents compensation being one of them. VSI control is in charge of accomplishing the different capabilities, and it must be done without exceeding the limited and variable dc voltage margin, if undesirable effects want to be avoided. If limitations are reached, capabilities will be reduced in order to remain within the limitations. At the same time, as the number of DGs is also increasing, when capabilities are not able to be coped with exclusively one VSI, the cooperation among VSIs appears as a solution. A key point is to establish a strategy in this kind of topology when one of the VSI is brought to its limits. In this paper, a new strategy is proposed, where even under limited situation VSIs always try to inject the maximum power extracted from the DG and achieve the harmonic compensation (multifrequency) by cooperation among the different parallel VSIs. Newest multifrequency saturation strategies are studied, modified, and applied to cooperative applications. Simulations, hardware in the loop (HiL), and experimental results are included and compared.