Computation of the Periodic Steady State in Systems with Nonlinear Components Using a Hybrid Time and Frequency Domain Methodology

The basic principles of an eficient new methodology for the calculation of the non-sinusoidal periodic steady state in system with nonlinear and timevarying components are described. All linear parts, including the network and part of he loads. are represented in the frequency domain, while nonlinear and time-varying components, mainly loads, are represented in the time domain. This hybrid procegp b iterative, with periodic, non-sinusoidal, bus voltages U inputs for both fiqumcy domain solutions and time domain simulations: a current mismatch is calculated at each bus and used to update the voltages until convergence is reached. Thus the process, but not the solution, is decoupled for the individual harmonics. Its efficiency is enhand by the use of Newton type algorithms for fast convergence lo the periodic stcady stale in the time domain simulations. Potential applications of this methodology are in the oomputation of a HannoNc Power Flow and in the Steady State Initialization needed in the calculation of electromagnetic transients. Keywordr: Periodic steady state, Harmonic power flow. Initialization for transients, Hybrid solution, Decoupled solution, Newton's method.