Research On Micro - Grid Operation Control Strategy Based On Wide Area Information

In order to solve the "energy crisis", protect the environment and save energy, as well as to be an effective solution to the drawbacks of the large interconnected power grid, Distributed generation (Distributed Generator, DG) get people’s attention, by virtue of the advantages such as high quality of power supply, high reliability, environmental benefits. However, DG is not controllable power source for large power grid; its access will bring many adverse effects to large power grid. The way large power grid takes of isolation and restrictions greatly limits the power to take the isolation and greatly limits the development of DG. In order to effectively solve the contradictions between DG and the power grid, give full play to the environmental benefits and the potential value of the distributed power generation technology, people put forward the concept of "Micro-grid". Micro-grid is a small power system that includes micro-power supply and load, it can be parallel working by interconnection with large power grid, and can also be island working when it is isolated from the big power grid. The micro-grid system based on distributed generation technology, not only effectively forms complementary advantages with the traditional centralized interconnected power grid, but also relieves the energy crisis and improves the environment, generates environmental benefits and the potential value, received extensive attention all over the world.The study about the distributed generation technology and operation controlling of micro-grid, has got a lot of research results around domestic and foreign, and has e established some micro-grid demonstration project. This paper is to build a typical micro-grid simulation test platform as the purpose, on the basis of full analysis of current research, analyzes basic principle of the two kinds of the most mainstream DG:the wind power and photovoltaic power generation, and carries on the modeling and gets theirs various features; And the basic principle of photovoltaic power generation, and carries on the modeling and its various characteristics, then analyzes three control methods of DG:constant power Control (PQ Control), constant voltage and constant frequency Control (V/f Control) and droop Control (Droop Control), and establishes their simulation models. On the basis of the above simulation models, a simple micro-grid system simulation model is established, controlled by master-slave control strategy and point-to-point control strategy, setting up the conditions such as grid/island working mode switch, change of distributed power output, load shedding/increase. Through detailed analysis of the information that monitored frequency, bus voltage and DG’s output of the micro-grid, gets the existing problem of general control strategy. On this basis, the power balance control strategy based on wide-area information is proposed. Through wide-area information fully obtain the information such as circuit breaker status of PCC node control method and output of the DG, load. The micro power source and load in the micro-grid are under effective control and regulation during the island running, make the voltage and frequency of micro-grid system to steady state quickly and satisfy the requirements of DG working.Finally, the effectiveness of the proposed control strategy based on wide-area information is verified indeed feasibility and effectiveness. Through the adjustment and control, ensure the voltage and frequency in the micro-grid system accord with the operational standards, and ensure the important load in the micro-grid system working continuously and reliably.