Research On Microgrid Power Quality Monitoring And Control Strategy

A microgrid consists of generation units, energy storage and loads. It is a regionally limited power system and represents the new tendencies that is to protect and mitigate the impact on the environment. Power quality is the main key to maintain the microgrid supply power stability, however, Distributed generations (DGs) and power electronics would bring some power quality problems to the microgrid, especially in the islanded operation where dynamic characters are strongly dependent on the connected sources and on the power regulation control of the grid interfacing converters. This thesis comes from the practical engineering project "Microgrid research on power quality control algorithm and development of a monitoring device ".In this thesis, a real-time monitoring system is developed, and research on inverter control strategy was used to improve power quality of the isolated microgrid.1. A power quality monitoring system for microgrid is developed in the thesis. The system was developed in Lab VIEW, solving the problems that original’s system had. Real-time data are acquiring through a DAQ card, and power quality indices are calculating and analyzing at the same time. The system was tested in a Microgrid Laboratory, verifying the real-time and feasibility.2. In this thesis, an droop control strategy is proposed to control the inverter when there is a DG in island microgrid. The control strategy consists of a droop controller, voltage and current loop controller, and SVPWM is used to drive the IGBTs of the inverter. Simulation was done by Matlab/Simulink, the results compared with the system without droop control strategy, verifying the proposed strategy can improve the inverter output voltage fluctuation and the harmonic distortion.3. The peer to peer control strategy is used when multiple inverters are paralleled in an isolated microgrid. Each DG operates autonomously with no communication with others. And the droop control is still used to control every signal DG. Some cases are simulated in simulation. Results verify the proposed strategy can sharing power of loads, and also can keep stability when DG and loads connected or cut off from the system. The strategy improved power quality by coordinated controlling of inverters.