Power control of a bi-directional AC/DC rectifier used for telecom backup systems

This paper presents a novel control scheme to control the flow of active and reactive power through a single-phase bi-directional AC/DC converters used for telecom backup systems. The proposed controller enables the telecom facilities to control the power flow in both directions from grid to telecom and telecom to grid. In this paper the fuel cell system coupled with ultra-capacitors has been used as telecom backup system. By using 10% of the backup storage capacity, not only telecom companies can ensure their high standard reliability, but they can also benefit from their assets, as well as participating in ancillary services market. The main purpose of this paper is to achieve this feature by using the proposed converter configuration and its control scheme. So the proposed control scheme is implemented in D-Q rotating frame. Due to the lack of freedom degrees in single phase converters using the D-Q frame is challenging. In this paper, to cope with this problem the all-pas-filter has been used to generate the orthogonal system required for D-Q frame. Also A hybrid estimator has been used in this paper to estimate the real-time amount of active/reactive power. This estimator can estimate real-time power values very fast and reliable, which can improve the dynamic abilities of the proposed controller. The performance of the proposed controller is evaluated by using simulation and experimental results. Also the application of the proposed controller in implementation of energy management strategies in a typical telecommunication backup system has been proved by simulation results.