The Optimizing Power Flow Calculation Of Large-scale Cluster-type Wind Power System And It’s Fault Analysis

Wind power is a renewable energy that nature gives to humans. It is causing worldwide concern and attention because wind power is a new clean energy source with the greatest large-scale development and commercialization prospects. Wind power industry has made considerable progress with the rapid development of wind power technology in the world, and also has brought new challenges and research to the safe operation of power system.Firstly, two different wind power models were presented, Doubly-fed wind power generator and Direct drive permanent magnet synchronous generator. The principles of operation, advantages and disadvantages in modern wind power system, as well as equivalent methods and models of wind farms were outlined. The introduction of an improved homotopy algorithm with convergence stability can solve the power flow and optimal power flow. This algorithm has global convergence to solve nonlinear problems by generating a series of homotopy curves. Unlike the Newton-Raphson method, the homotopy method for the selection of initial value is not so sensitive. The complex alternating current power flow (ACPF) was simplified into simple direct current power flow (DCPF), and changed back to nonlinear ACPF to achieve alternating current power flow homotopy (ACPFH) through gradually introducing homotopy participation factors in the linear DCPF. This makes the ACPF become more stable and provides a way for complicated problems to be solved. The optimal power flow calculation also uses homotopy algorithm in order to achieve alternating current optimal power flow calculation. The computing speed can now be faster due to homotopy interchanging of ACPF and DCPF.Secondly, the principle of wind power generators and several common models were introduced. The application of simplified RX model, using the improved homotopy algorithm, were used to do the power flow calculation. The power flow calculation of each node voltage and each branch net loss, after IEEE-36node system access to wind power generator, is based on the improved homotopy algorithm. The results are more accurate and the calculation speed is same as the Newton-Raphson method. However, the improved homotopy algorithm has stronger convergence capability than the traditional Newton-Raphson method and PQ decomposition method. That is why the improved homotopy algorithm has wide application prospects.Finally, two types of faults, horizontal and vertical, were announced. The single-phase ground fault was used as an example of horizontal faults for calculations of the voltage changes when failure occurs in IEEE-14node system. To obtain the result of power flow calculation on the terminal voltage, the wind farm terminal voltage changes when horizontal faults occur in the nodes of wind power generator access system are also analyzed.