This paper deals with a three-phase power system with hybrid transformer (HT) installed between two AC sources. The main aim of this paper is analyze the basic properties of HT with active load and ability to bidirectional energy flow. The HT contains two main units - a conventional transformer with electromagnetic coupling and PWM AC line chopper connected with secondary windings with electric coupling. The HT is located between the distribution system and a Local Balancing Area (LBA) with low power local energy sources. After describing the HT circuit and three-phase, twosources power system, the mathematical and circuit models of the AC source with HT are presented. These models are verified by means of the simulation and experimental test results obtained for a three-phase HT of about 3 kVA rated power.