Structure Analytics
Agents: system analysts, business analysts;
Moves: Design and configure
Smart microgrid
AC / DC Sources and loads
Renewable energy system
Energy storage system
Technology forums
National level : Government (E-governance model), research organizations;
International level : strategic alliance among global organizations
Dr. Paolo Maradona is discussing the structure of solar power system in terms of smart microgrid, various topologies such as AC coupled, DC coupled and ACDC coupled hybrid microgrids, AC/ DC sources and loads, renewable energy system (e.g. PV or solar power system), capacity and access oriented energy storage system, stand alone and grid connected operation mode, power management strategies and control schemes for both steady state and transient conditions [ refer: appendix].
Smart grids are considered as next generation power systems which interconnect a set of microgrids consisting of Distributed generations (DGs) and renewable energy (RE) resources (e.g. solar, wind, tidel, clean alternative energy sources. Hybrid AC/DC microgrid contains both AC/DC power sources and AC/DC loads. It can be classified into three categories based on how the sources and loads are connected to the system and how AC and DC buses are configured into low and high frequency AC-coupled, DC-coupled and AC-DC-coupled microgrids [38-43]. In AC-coupled hybrid microgrids, DGs and SEs are connected to the common AC bus through their interfacing converters. In DC-coupled hybrid microgrids, DGs and SEs are connected to the common DC bus and an Interfacing Converter (IFC) links DC and AC buses. In AC-DC-coupled hybrid microgrids, DGs and SEs are connected to DC and AC buses and the buses are linked by Interlinking Converter (ILC). The basic objective of energy management is to match demand and supply of power optimizing cost (e.g. fuel, capital and maintenance costs), voltage and frequency regulations and real-time power dispatching among different power sources in micrograms. Microgrid architectures can be classified utility, industrial, commercial and remote type based on applications. In the appendix, table 7.1 compares various structures of microgrids based on a set of evaluation parameters such as topology, structural complexity, operation mode, control schema, power management strategies, cost and benefits.
Hybrid DC- and AC-Coupled microgrids integrate a variety of DER units into existing distribution system. It connects the distributed energy storage systems like batteries and fuel cells to bidirectional AC-DC converters and PV systems connected through DC-DC Boost converters. Microgrids can be classified into single and two stages power conversion systems [Appendix: Figure 6.12]. In single-Stage power conversion systems, a transformer is used for isolation or voltage conversion . It is a very simple structure having high efficiency, small size and weight and reduced cost. Two-Stage Power Conversion is the most common configuration for all electronically coupled DER units and it consists of a DC-DC converter for energy sources with DC output voltage or an AC-DC converter for energy sources with AC output voltage with a grid-connected DC-AC converter. The converter on the energy source side extract the maximum power from the primary energy source and the grid side converter is controlled to follow grid requirements. Multilevel converter reduces the cost and improves the efficiency of power conversion systems. A power electronics enabled microgrid consists of a static transfer switch (STS), distributed critical and noncritical loads, multiple DER units with various power electronics interfaces, protection devices and measurement, monitoring, and control units. DC microgrids are used in telecommunication systems, electric vehicles office buildings, commercial facilities, Photovoltaic (PV) and fuel cell system. HFAC Microgrids are generally used in distributed power systems for military and aircraft systems working in single-phase 400 Hz. It is an interesting agenda to explore the use of solar power for DC microgrids application.
Microgrid is the basic building block of the future flexible, reliable and smart power grid with increased penetration of Distributed Energy Resources (DER) such as solar or PV panels. The entire architecture of future electrical power system may consider three possible concept models : Microgrids, ICT driven Active Networks and Internet. Microgrid paradigm interconnects multiple customers to multiple DER units including DG and Distributed Storage (DS) units and form an intentional or non-intentional energetic island in the electrical distribution network. The customers and DER units can operate in parallel with the main grid and supports a smooth transition during abnormal grid conditions. The evolution and rapid development of efficient power electronics technology improves the transient response, Digital Signal Processors (DSP) reduce the processing time and support complex control algorithms and efficient power electronic converters enable cost- effective and flexible control, power management and energy flows efficiently. This structural analysis is the basis of the vision of an efficient solar microgrid or solar park for rural electrification and agricultural application.