Methodology and results of analysis of output energy quality of autonomous AC power supply systems with modular static converters in steady-state mode

Abstract

Modern autonomous power supply systems (APSS) of alternating voltage with high-frequency modular static converters (SC) operate under conditions of a large range of changes of the parameters of the primary source of electrical energy and load with modes of intermittent phase currents of the SC modules. APSS with high-frequency modular SC are characterized by a complex spectral distribution of the output energy coordinates with the dominance of canonical harmonics. Thus, the task to develop methods for analyzing the quality of generated electric power of such type of APSS in a wide range of disturbing factors with the dominance of canonical harmonics in the coordinates of the output energy is relevant. For the specified type of APSS, it is reasonable to use the time deformation method for the average values of the coordinates of the output energy under the sinusoidal modulation law on the interval of constancy of the SC structure. The procedure to investigate the influence of APSS operating modes and methods of correction of the modulation law on the quality of output energy is demonstrated by the example of two types of systems. The authors have defined the conditions of the worst value of the harmonic coefficient of the output current in APSS with cycloconverter and multiphase permanent magnets synchronous generator. The authors have demonstrated the effect of modifying the control law by shifting the modulation center and introducing negative current feedback on the possibility to improve the coefficient by 50 %. The authors have defined the conditions of the worst value of the harmonic coefficients of the internal EMF and output current in APSS with an intermediate DC voltage link and a modular two-level voltage inverter. The proposed method to analyze the steady-state operation of APSS with high-frequency modular SC makes it possible to identify the conditions of the worst quality of generated electrical energy and assess the impact of control methods of APSS in a wide range of system parameters, considering the presence of intermittent currents.