A Novel Strategy of High Power Utility Interactive Inverter with Series Active Filter

Large power utility interactive inverters used for large energy storage system are composed of the multiple connected inverters, in order to realize the high efficiency and the high performance on the harmonic elimination characteristic simultaneously. Some disadvantages on the multiple connected inverters, such as harmonic current flowing from an inverter unit to the other one, and increase of the number of inverter units, cannot be overcome easily. In this paper, a novel strategy of the high power utility interactive inverter, which is composed of a large power with low switching frequency PWM inverter (High Power PWM Inverter), a LC passive filter and a series active filter (Series AF), is presented. Because harmonic components contained in the utility line current is absorbed by the series AF, the switching frequency of the PWM inverter can be selected to about I kHz. And, because the power capacity and the output voltage of the series AF can be suppressed lower than 10% of the power capacity and the output voltage of PWM inverter, low voltage and high-speed power devises can be applied to the series AF. Consequently high power, high efficiency and high harmonics elimination performance can be realized without increasing the number of inverter units.