Study On The Coupling Mechanism Between Small Electrical Distanced Large-scale Wind Power And The Dc Systems

The large-scale development and use of clean energy is an important measure to ensure the energy security of our country, to develop low carbon economy and optimize the structure of primary energy. New energy power generation has become the fastest growing, of the best commercial prospects and the most mature technology of the development of clean energy, especially wind power generation. According to The Twelfth Five Year Plan of northwest China, until the target year 2016, there will be about 12000 MW of wind power and solar power access to the grid, among them the capacity of wind power will be 8300 MW. With the put of ±800kV Ningshao HVDC, adding to the built of ± 660 kV Ningdong HVDC, Ningxia power grid will form large-scale high-permeability wind-thermal power AC and DC delivery power system.Large-scale wind power and HVDC of short electrical distance will influence each other, which will bring the operation risk of the safe and stable operation of the grid and the risk need to be studied and controlled. As a result, the study on the coupling mechanism between small electrical distanced large-scale wind power and HVDC systems is of important theoretical and practical significance to Ningxia grid.This paper summarizes the study of the export of large-scale wind power via HVDC, based on a typical system and considering the wind-thermal power ratio, wind turbine reactive power control mode, the fault ride through capability of wind power and other boundary conditions, the influence of wind power fluctuation on HVDC system and the influence of fault in HVDC system on wind power are analyzed and simulated. Based on actual Ningxia power grid data, the transaction of wind power and HVDC system of different boundary conditions is simulated and analyzed, and the coupling mechanism is summarized. The main contributions of this paper are as follows:1. The DFIG model, wind turbine output model, equivalent model of wind farm and HVDC transmission system model are established for the system of wind power HVDC delivery, and a typical system of large-scale power HVDC is built based on the power system simulation software PSD-BPA.2. The coupling mechanism between small electrical distanced large-scale wind power and the DC system is studied from wind power fluctuation and DC system fault two aspects. Based the typical system, and considering many kinds of simulation boundaries and the characteristics of large-scale wind power transmission, the coupling mechanism is studied from wind power fluctuation and DC system fault two aspects, including different reactive power control mode of wind turbine, dynamic reactive power compensation(SVC) control of wind field side, different proportions of wind power and thermal power, different control mode of DC system and so on. Under the condition of DC system fault, considering many kinds of simulation boundaries, the security and stability of power grid and the fault ride through capability after DC system fault is simulated, and the reliability of wind power integration of different simulation boundaries is studied.3. Combining with the actual situation of Ningxia large-scale wind power via HVDC, the influence of wind power fluctuation to HVDC system in large-scale wind power base of the actual power system, the fault ride through capability of wind power base under the condition of DC system fault, and the reliability of wind power integration of different simulation boundaries are studied, which promotes the access and consumption of wind power.