An exact method for analysis and component design of grid connected VSC-based power devices

摘要

Most of the passive component design approaches for VSC-based devices do not explicitly consider its nonlinear and discontinuous interaction with the power network. In addition, only an operating point is considered in those designs approaches, but in practical applications, the performance over an operating region has to be ensured due to operative changes in the grid. These situations lead to conservative filter designs with oversized passive elements that require iterations between the design and the simulation/implementation stages to meet the imposed power quality restrictions, with no guarantee of proper performance if the grid parameters are changed. This paper presents the calculation of steady state modulation parameters (CSSMPs) and the exact design (ED) approaches to perform steady state analysis and component design in grid connected VSC-based systems. The proposed formulation is based on the extended harmonic domain (EHD) and explicitly considers the switching process and their constant steady state modulation parameters. Although the proposed approach is applicable for any passive filters configuration, an L-filter active rectifier is used as the test system. The design results are the passive components values and modulating parameters required to meet the design restrictions, explicitly considering the modulation technique used. Time domain simulations validate this design proposal in all the presented cases. The performed analysis gives very useful information about feasible operating region, the number of control solutions, the operating limits of the system under load and voltage source variations, and the effect of the modulation technique. (C) 2015 Elsevier Ltd. All rights reserved.