A reliable micro-grid with seamless transition between grid connected and islanded mode for residential community with enhanced power quality

This paper presents a reliable micro-grid for residential community with modified control techniques to achieve enhanced operation during grid connected, islanded and resynchronization mode. The proposed micro-grid is a combination of solar photo-voltaic (PV), battery storage system and locally distributed DG systems with residential local loads. A modified power control technique is developed such that, local load reactive power demand, harmonic currents and load unbalance is compensated by respective residential local DG. However, active power demand of all local residential load is shared between the micro-grid and respective local DG. This control technique also achieves constant active power loading on the micro-grid by supporting additional active power local load demand of respective residential DG. Hence, proposed modified power control technique achieves transient free operation of the micro-grid during residential load disturbances. An additional modified control technique is also developed to achieve seamless transition of micro-grid between grid connected mode and islanded mode. The dynamic performance of this micro-grid during grid connected, islanded and re-synchronization mode under linear and non-linear load variations is verified using real time simulator (RTS)

A Modified Control Scheme for Power Management in an AC Microgrid with Integration of Multiple Nanogrids

This paper proposes a modified control scheme for a grid connected microgrid, which is contrived by integrating multiple nanogrids. In the considered system, each nanogrid consists of a generation unit from solar photovoltaic (PV) along with battery energy storage (BES) system and local loads. The nanogrid has the flexibility to operate in microgrid connected mode or islanded operating mode. Similarly, the microgrid can also be operated in grid connected mode or islanded mode. To achieve appropriate load sharing between different nanogrids considering local load demands and source power availability, a modified control scheme is developed. The proposed scheme compensates for the required reactive power, harmonics and unbalanced currents locally which are demanded by the local loads in nanogrids in order to improve the power quality in the microgrid. The smooth transition between the modes of operation of nanogrids and microgrid is achieved with the proposed modified control scheme. In addition, the proposed modified control scheme allows the microgrid and main grid to remain free from transients generated by load disturbances in nanogrid and disturbances in the microgrid respectively. Therefore, the effect of disturbances on voltage and frequency of the microgrid is reduced. A simple control scheme is developed to address the challenging issues for smooth operation of the microgrid such as active power sharing among the sources based on their ratings, power quality enhancement (compensation of harmonic components, unbalanced current and reactive power) and seamless transition between the modes of operation (during islanding from grid and re-synchronisation with grid). The performance of the proposed modified control scheme is verified in a real time simulator during variable loading conditions

A Modified Control Scheme for Power Management in an AC Microgrid with Integration of Multiple Nanogrids

This paper proposes a modified control scheme for a grid connected microgrid, which is contrived by integrating multiple nanogrids. In the considered system, each nanogrid consists of a generation unit from solar photovoltaic (PV) along with battery energy storage (BES) system and local loads. The nanogrid has the flexibility to operate in microgrid connected mode or islanded operating mode. Similarly, the microgrid can also be operated in grid connected mode or islanded mode. To achieve appropriate load sharing between different nanogrids considering local load demands and source power availability, a modified control scheme is developed. The proposed scheme compensates for the required reactive power, harmonics and unbalanced currents locally which are demanded by the local loads in nanogrids in order to improve the power quality in the microgrid. The smooth transition between the modes of operation of nanogrids and microgrid is achieved with the proposed modified control scheme. In addition, the proposed modified control scheme allows the microgrid and main grid to remain free from transients generated by load disturbances in nanogrid and disturbances in the microgrid respectively. Therefore, the effect of disturbances on voltage and frequency of the microgrid is reduced. A simple control scheme is developed to address the challenging issues for smooth operation of the microgrid such as active power sharing among the sources based on their ratings, power quality enhancement (compensation of harmonic components, unbalanced current and reactive power) and seamless transition between the modes of operation (during islanding from grid and re-synchronisation with grid). The performance of the proposed modified control scheme is verified in a real time simulator during variable loading conditions