Study On Topology Structure Of Large Wind Power Base

In recent years, along with the decrease of fossil fuels and the improvement of new energy technologies, wind power, as one of a more mature new energy, has entered every household. Wind energy is a clean renewable energy resource, and wind power is the most mature one in the field of new energy technology. Besides, it has the largest development condition and commercial prospects. Therefore, the development of wind power has very important significance on adjusting the energy structure and reducing environment pollution. The areas rich in wind energy resources in China are often far apart from the load centres, so the energy from the general wind farms should be transmitted to the load centre over a long distance.Because the wind has spatial and temporal differences, and is more concentrated in some areas, it is suitable for the establishment of large-scale wind power bases to concentrate to the power grid. Wind power base is made up of several wind farm group, while wind farm group consists of several wind farms by a certain topology, so the choice of topology will be directly related to the impact after the wind power base connecting to the grid.In this paper, the math models of wind speed probability, wind speed correlation and wind power conversion are built. And the spatial and temporal differences of wind power base are analyzed. Then the paper summarizes the topology structure of our country’s represent nine 10-millionkW degree wind power bases, and picks three typical topology structures including chain topology, radial topology and hybrid topology.Then the paper analyzes the different topology structures under the steady state. First, the paper does some research on the reactive voltage characteristics of DFIG wind farm, SCIG wind farm and direct-drive wind farm. Then the paper calculates the power flow of the wind power base under two different geographical locations which are scattered distribution type and linear distribution type. And the calculation results are used to compare the impact on power flow distribution of wind power base by different topology structures. Next, the paper uses PSD-BPA to build a wind power base with 12wind farms, and analyzes different topology structures’ reactions of voltage, power and losses under two situations which are active power increasing gradually and active power increasing followed the wind speed.Next, the paper also analyzes the characteristic differences of different topology structures under transient state. The paper begins in the part of wind farm’s transient state reactions. Then the voltage fluctuation and fault critical cleaning time are chosen as the indicators to evaluate the ability of transient state stability and fault recovery. The paper still uses PSD-BPA to run a simulation calculation, and analyzes the transient state response characteristics of different topology structures with large or small active power output when there is a three-phase short circuit fault happening in the PCC point.Last but not least, the paper puts forward the demand from wind power base to the topology structures both in steady state and transient state.In general, the radial topology can meet the requirement of electric system in most situations. However, if there are a little wind farms in some areas and they are very far to the collection center, the chain topology and the hybrid topology can also be a good choice.