КПД трехфазных систем электроснабжения с двунаправленным потоком энергии

Abstract

Получены аналитические соотношения, позволяющие рассчитать максимально возможный и реальный коэффициент полезного действия трехфазных трехпроводных систем электроснабжения с двунаправленным потоком энергии. Показано, что даже при высоких значениях КПД в однонаправленных прямом и обратном потоках, общий КПД двунаправленной системы электроснабжения может оказаться незначительным. Корректность полученных соотношений проверена при помощи компьютерной Matlab-модели трехфазной системы электроснабжения с силовым активным фильтром.

The aim of this article is to derive analytical relationships for determining the efficiency of a three-phase energy supply system with a bi-directional energy flow in which forward and reverse flows are not superimposed in the repeatability period. The following methods were used in the work: the theory of electrical circuits, modern power theory, mathematical and computer modeling in applied software. We have established the admissibility of an independent consideration of the system operation in a unidirectional forward and unidirectional backflow in determining the energy efficiency of an energy supply system with bidirectional energy flow. We have obtained the exact relations, which allow to calculate the maximum possible and real efficiency of a three-phase three-wire energy supply system with symmetric sinusoidal source voltages in direct, reverse, and bi-directional flows. Relations for determining the limiting value of the energy recovery coefficient were also obtained. Verification of the obtained relationships showed that the relationships for calculating the maximum possible efficiency of energy supply system do not give errors, the error in calculating the real efficiency does not exceed 1%. The efficiency of a three-phase three-wire energy supply system with symmetric sinusoidal voltage sources in a bi-directional flow depends on the energy transfer coefficient, the energy transmission rate coefficient, the maximum possible efficiency in the forward unidirectional flow, and the additional loss fa ctors in the forward and reverse flows. We have shown that the overall efficiency of a bi-directional energy supply system is negligible even with high efficiency values in unidirectional forward and reverse flows.