Development of Fractional Order Modeling of Voltage Source Converters

This paper proposes a mathematical fractional order modelling of Voltage Source Converters (VSC). Fractional behaviour helps to model and describe a real object more accurately than the integer order model. State-space equations of VSC is obtained using fractional calculus in d-q domain. The Caputo derivative method is employed to eliminate complex definitions of fractional calculus and to get approximate solution with optimal design of parameters. A detailed analysis is performed on developed mathematical fractional order model of VSC including small-signal analysis and DC analysis. The stability and time-domain transient analysis is carried out to validate the fractional order VSC for its application as Distribution STATtic COMpensator (DSTATCOM) in power distribution system, using real-time simulator. Fractional-order capacitor and inductor are designed and modelled for verification of fractional order VSC through simulations. The real-time simulation results verify the effectiveness of proposed model. It shows that fractional order model can describe the operating characteristics of VSC more accurately. The comparative performance analysis demonstrates superior transient response in case of fractional order devices as compared to integer order.