Enabling Different GCC Functionalities During Nominal and Subnominal Grid Conditions

The grid-connected converter's fundamental purpose during nominal grid conditions is to inject to the electrical grid the energy available in the primary energy source. This goal should be also realized during some noncritical, but subnominal grid conditions, such as asymmetrical load and power production in the local grid. Furthermore, the grid-connected converter should partake in grid-voltage conditions regulation, both during non-critical and critical grid disturbances. In addition, the various functionalities defined in grid codes and elsewhere, regarding frequency drift, local load reactive power compensation, fault-ride through etc., must be incorporated in the control algorithm governing the converter. Framework enabling these functionalities is developed in this paper. Special attention was given to the regimes with the unbalanced voltage conditions. Representative experimental results provided in the paper corroborate the stated assertion and demonstrate the advantages of the proposed approach over the related research papers that address singular or a narrow range of control objectives.