Research Of Reactive Optimization In Power System Considering Reactive Power Regulation Of DFIG Wind Farm

In the background of energy shortage, wind power as the most widely used way of clean energy conversion, penetration increased every year. Due to the complexity of the control technology, as well as wind power output fluctuation and randomness, high technical difficulties such as integration and the impact on power system are faced. How to achieve reasonable control and effective configuration are the keys to solve the problem of large-scale wind power integration. In this paper, studies are involed with the following aspects of wind power modeling, voltage partitioning and reactive optimization of the system integrated with wind farm, and economic issues for wind farm to provide reactive power as ancillary services.First, the model compositions of DFIG is introduced in detail, and thus summarizes the limiting factors which affect the reactive power capacity of DFIG, combined with these constraints as well as wind turbines equivalent circuit the calculation method of DFIG reactive power capacity is derived, and the corresponding PQ capacity curve is obtained.Secondly, based on wind farms participation of reactive power voltage regulation, a novel two-phase reactive power & voltage partitioning methods is developed considering the characteristics of random fluctuations of wind farm output and load, with Ward clustering and system static reactive power balance constraints. Case studies on IEEE39 standard test system using the proposed method and the conventional voltage partitioning method is presented, indicating the effectiveness and superiority of the proposed method.Then, on the basis of the proposed voltage partitioning method, combining with the volatility characteristics of wind farm active power output, reactive power optimization with PSO algorithom is developed, according to the indicators of network losses and system static voltage stability margin, case studies on IEEE standard test system verifies the validation.Finally, different cost components are identified, and subsequently, a generalized reactive power cost model is developed for wind farm as ancillary service. A novel reactive power optimization is proposed considering reactive power cost of generators as well as wind farm. Network loss of power system and static voltage stability margin are also taken into account. The results show that the proposed method is possible to coordinate conventional synchronous generators and wind farm of reactive power in consideration of the cost of the, to achieve the optimal reactive power costs.