Approaches to Construction of Active Distribution Networks with Distributed Power Sources Based on Solid-State Transformers

Current trends in power distribution are aimed at the development and implementation of approaches to improving the quality of electricity and reliability of power supply. The integration of distributed power sources (DPS) including those based on renewable energy sources (RES) with the existing distribution networks creates a number of problems. The increase in the share of DPS, including microgeneration, calls for the transformation of the existing distribution networks into active distribution networks (ADN) through the introduction of controlled power transformers and automatic control systems. In ADNs, the direction and amplitude of the power flow may change multiple times during the day depending on the output of DPS electricity and its consumption in the network, which can cause power transformers to overload. The reverse power flows have an adverse effect on obsolete power transformers and damage them leading to complete or partial disruptions in power supply. This article presents approaches to the construction of ADNs based on solid-state transformers (SST) and their control. The use of SSTs can compensate for the drops, fluctuations, and disruptions of voltage, help control the voltage, current, frequency, and power factor in low-voltage networks, and reduce the level of higher harmonic components in currents and voltages through electronic power converters (EPC) and condensers in the DC link. The use of SSTs in new ADNs and the renovation of the existing distribution networks shall help improve the quality of electricity and reliability of power supply.