Simulation Analysis On The Operation And Control Strategy Of Microgrid

The centralized large power grid that is of high voltage and long distance has the potential problems of safety, reliability, economical efficiency and flexibility, which promotes the development of distributed generation based on renewable energy technology. With the gradual development of the separate distributed generation, it also highlights a number of shortcomings, such as needing to quit running when the system failures, affecting the surrounding customers intermittently, hard to achieve the energy comprehensive optimization. In order to reduce the adverse effects of distributed generation and exploit the positive role of distributed generation at the same time, the best method is system view, which regards the distributed generation and load as a subsystem or a’microgrid’. Microgrid represents a new development direction of the power system, which is becoming a research focus.Firstly, the thesis analyzed simply the principle of distributed generation, the topology and key technology of microgrid, concluding that micro-sources in the microgrid can be divided into the inverter interface and synchronous generators interface, intermittent and stability. Aim at various forms of micro-sources, the author give the universal circuit topology paralleling in the grid, analyzed the design method of LC filter’s parameters and verified its validity by simulation. The mathematical model of the grid-connected inverter controlled by voltage based on the three-phase SPWM was analyzed. According to the different operating conditions of the microgrid, the three microsource control strategies were proposed:PQ control, V/f control, Droop control, first their principle was analyzed, the model structure and the parameters design method was given. Then the respective decoupling control method and the disturbance compensation method were proposed. For the common problem of three control strategies, the parameters design method of PI regulator was proposed, the principle of the three-phase PLL was introduced and its validity was verified by simulation. Combined with the three microsource control strategies’features, the overall operation control strategies of the microgrid were given:master-slave control and peer-to-peer control, analyzed their advantages and disadvantages and their application scope. Finally, in order to establish the simulation platform of microgrid operation control, the simulation models of three kinds of typical microsource control strategy which is PQ, V/f and Droop were established in the Matlab/Simulink. The validity and correctness of the models were verified through an example. At last, to verify the master-slave control and peer-to-peer control strategy’s effectiveness, two simulation platform of microgrid operation control were designed. The simulation example of Master-slave control showed that the V/f model can track the load fluctuations in island operation and ensure the stable operation of the microgrid. The simulation example of peer-to-peer control verified that the droop control can achieve the power sharing and guarantee the frequency and voltage stability.