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The voltage stabilization systems are often used in electrotechnical complexes. Paper describes design a mathematical model of the system of automatic regulation of an active front-end (AFE) operating in generator mode. The main task of the control is to stabilize of limited power electrical grid when the load is connected to it in parallel. Note that the active front-end AFE model is made as four-wire semiconductor device with eight transistors connected to the reactor. The AFE control system is a control system in a rotating d-q reference frame with a rotation frequency equal to the network frequency. The control system consists of a channel for regulating the current at the output of the AFE and a channel for regulating the network voltage by controlling the phase and amplitude of the EMF of the AFE. The proposed model allows to stabilize voltage in a limited power electrical grid when a load is included in it. This makes it possible to ensure the stable operation of the entire system.

Neutral wire is used in multiple active front-end application. Some of these applications are single phase loads and maintaining system stability in case of emerging unsymmetrical components, which can lead to malfunction and device failure. In such cases neutral wire potential can be middle point of DC-link, what leads to capacitor separation, but also can be implemented as additional arm, leading to full DC-link voltage utilization and additional control channel for zero symmetrical component in case of unsymmetrical load. In order to perform control system synthesis for such a complicated object, knowledge of its complex mathematical model is required. Four arms active front-end mathematical model is developed for analysis and control system development, featuring phase-coordinates usage and taking into account multiple peculiarities of this converter. Diagrams of main voltages and currents components are derived from model research.

The article presents the comparative analysis of influence of different power sources connected to an active front end on processes in the supply grid of limited capacity. The mathematical model of an active front end control system for cases with different power sources (generators) is developed and analyzed. The algorithms of forming generic control system of active front end are described and analyzed. The results show that power sources, such as ideal DC power source, battery and induction motor in the slip power recovery mode, have almost similar power quality characteristics It allows using simpler methods of power supply system analysis in case of presence of additional power sources based on active front end.