Fast Steady-State Computation of Electrical Networks Involving Nonlinear and Photovoltaic Components

Electromagnetic transients (EMT) analysis heavily relies on computational simulation of power networks. Initialization of simulation at a given operating point, i.e., stationary state, requires either long simulation time-windows, especially for poorly damped networks or networks with very distinct time delays, or the use of alternative software tools. EMT-type programs are computationally very intensive as nonlinear components have to be brought to steady state and, in case of power electronic devices (PEDs)-based networks, a very small time-step has to be utilized. This article proposes a fast methodology to calculate steady state of networks involving both nonlinear loads and PEDs. The proposed approach relies on: (a) frequency-domain representation of PEDs via the chain-matrix and (b) using Fast Fourier Transform/Inverse Fast Fourier Transform (FFT/IFFT) operations for the nonlinear elements, thus avoiding problems with transients. The fact that the methodology uses frequency-domain operations permits to naturally obtain harmonics and/or interharmonics. A test system including a nonlinear reactor and a photovoltaic (PV) generator is used to illustrate the performance of the proposed methodology.