Xie Da

Combination of Data Mining and Ant Colony Algorithm for Reactive Power Optimization

The management of reactive resources plays an important role in maintaining voltage stability and system reliability. This paper presents a new method to find the optimal solution to reactive regulation in power system, using the daily data collected in power substations. The new algorithm is combined with improved ant colony algorithm and Apriori data mining technique. The mathematic models of reactive optimization are described and applied to the reactive optimal compensation in an example electric system. Test results show that the application of the new algorithm proposed in this paper for determining the plan of reactive optimization operation can raise the system’s operation efficiency and reduce the power loss.

Three-level inverter based on direct power control connecting offshore wind farm

VSC-HVDC system based on voltage source converter connecting large-scale offshore wind farm is illustrated in the paper. To improve the transmission capacity and solve power quality problem, multilevel inverter is used in VSC-HVDC system. The simulation system is built on the basis of power control algorithm, implementing the independent control on bilateral sides. On wind turbine side, three are wind generators with respective converter, adopting the power control method based on hysteresis comparison and the three-level converter on system side adopts multi-level direct power control, achieved by three hysteresis control devices for active power, reactive power and midpoint voltage. The results on the simulation prove that under large transmission capacity, VSC-HVDC system connecting large-scale offshore wind farm and power system can operate under a normal and stable situation. Owing to the three-level inverter on system side, the power quality is better such as low harmonics and high power factor.

The small wind turbine characteristics test

A small wind turbine characteristics test platform is designed and realized. It includes low speed opening wind tunnel, and data acquisition systems. The wind tunnel with 3.5m caliber is designed into direct-action wind tunnel, and its experiment sement is circular section. Multi-fans are adopted to provide wind energy in the power segment, which improves wind flow effective and reliability after wind flow pass through a celluar device. The data acquisition systems collect and deal with wind speed, wind turbine rotation rate, output voltage and current by data board. The test results for the small wind turbine prove the platform can meet testing requests of small wind turbine characteristics tests, which helps students to understand new energy using and enlarge knowledge.