Research On The Control Technology Of Parallel Inverter In Microgrid

With the wide application of distributed generation technology, the large amounts of dispersed DG systems bring influences on the grid security and reliability. According to this situation, the scholars put forward"microgrid"concept, which can make use of distributed generation systems better.Distributed resources are usually connected to microgrid through inverters. So research on the control strategy of inverters in microgrid to solve the problem of inverters parallel connection is one of key technologies for microgrid development. In this paper, on the basis of analyzing operation condition of microgrid and referring to the available operation modes of power system, the mathematic model and control characteristics of synchronous generator are studied. And the control system of inverter is designed, which has the output characteristics similar to synchronous generator.The main contents of this dissertation are as follows:1. On the basis of understanding the concept of micrigrid and distributed generation, the background and significance of the paper are described.2. According to analyzing the inverter's operation condition in micrigrid, an inverter control strategy to simulate the synchronous generator is proposed.3. A virtual synchronous generator algorithm is designed, which is based on the mathematic model of synchronous generator; the power-frequency controller and voltage regulator of virtual synchronous generator are designed by referring to speed regulator and excitation system of synchronous generator, then inverter virtual synchronous generator and control system is completed.4. The model of inverter virtual synchronous generator and control system is established by Matlab. Both dynamic and steady simulation results show that inverter virtual synchronous generator possesses the characteristics of real synchronous generator, is applicable to microgrid.5. The hardware circuits of inverter are designed for further experiment.