Possibility of Distributed Generation Integration Through Composite AC-DC Scheme

In the past, electricity was generated solely at large centralized generating stations and transmitted through transmission and distribution networks in order to reach customers. However, emerging trend is towards distributed generation where local energy sources play a vital role in electricity supply. Since this transition required bidirectional converters to interconnect AC and DC grids, which results in lower efficiencies, increased harmonics, and multiple conversion issues. To address these challenges, this paper provides the concept of composite AC-DC transmission, where ac and dc power flows are integrated within the same line to establish a composite AC-DC distribution grid. The composite AC-DC grid provides a grid-connected interface for a large number of distributed generations, making it possible for local consumption of distributed generation. The composite AC-DC grid serves as an interface for distributed generation sources, facilitating local energy consumption and seamless integration into the larger utility grid. In this paper, the Composite AC-DC Grid is simulated in a PSCAD/EMTDC environment incorporating solar PV plants, mini Hydro plant, wind turbine generations with synchronous generator and diesel generator. Simulation results demonstrate the feasibility and effectiveness of implementing the composite AC-DC distributed grid.