Reactive Power Transfer via Matrix Converter Controlled by the “One Periodical” Algorithm

The article describes the application of a straight forward energy converter, a multiphase matrix converter (MC), as part of a device, connected parallel to the power grid, and able to supply variable reactive power flow to the power system. The research performed by authors included the development of control procedures for a multiphase MC, based on a new approach and power system (application) requirements. The multiphase MC structure (6 × 6, 12 × 12) was used since the proposed control procedure creates output as the combination of input voltages. The increased number of phases decreases the order of harmonics in the MC converter similarly as in multilevel converters. This manuscript concentrates on the mathematical analysis of MC work under the “one periodical” algorithm and links it introduces in the power system. The previously developed, spatial-temporal mathematical model of the MC was limited to the dominant (first) harmonic and applied between the grid and reactive load. The results obtained from the analysis of the model showed that, for the applied control procedure (one periodical algorithm), the output voltage is built only from positive or negative sequences of input voltage. Three cases were recognized where the sign input power factor depends on input voltage and control sequence as well as on the value of control frequency. The effects of the model simulation were compared to those obtained from the MATLAB simulation and from the real laboratory 30 kVA-rated model. The main factors analyzed during this research include the expected value and distortion of input current and sign of reactive input power.