Separation Of High-Voltage Air Core Smoothing Reactor Under Harmonic Magnetic Fields

Smoothing reactor is one of the most important equipments in the system of High Voltage Direct Current (HVDC) transmission. With the development of HVDC, the research of smoothing reactor becomes more and more deeply. Compared with oil smoothing reactor, air core smoothing reactor has some advantages. This thesis has done research deeply on separation calculation of air core smoothing reactor, and the achievements are listed as follow:The structure and operating environment of air core smoothing reactor is introduced in the thesis firstly, and the scheme of losses separation calculation is proposed. And then some key points of the scheme is analysed, including self-inductance and mutual-inductance calculations of coaxial multilayer winding, axial and radial magnetic flux density calculation in the areas of windings, eddy losses calculation of round conductor and so on. The eddy current of spider arms for air core smoothing reactor is simulated with ANSYS software.The self-inductance and mutual inductance are calculated with self-compiling program base on Bartkey transformation. The result is close to the results with ANSYS program, and the solution speed of the former is faster than the latter. According to the Biot-Savart Law, analytic calculation method for magnetic field can be gotten , which is suitable to the air core reactor. This method is not only with simply formulation, faster solving speed ,but also with more accurate results. The problem of fast calculation of magnetic field and losses for air core reactor can be solved with this method. As the current densities of each layer in the same encapsulation of reactor are similar, and air gap between layers is small, encapsulation can be modeled straightly for the model of coils as a whole component, mesh generation speeds can be accelerated with it when simulating eddy losses of air core reactor spider arm with ANSYS software.A example of air core reactor with ten layers coils which is loaded second harmonic current are taken in the ending of the paper. The inductance and magnetic flux density as well as the current of each winding which is as the exciting current in eddy losses simulation are calculated with the method above. The harmonic losses, circulating current loss,eddy losses of the coils and eddy losses of the spider arms are calculated . The second harmonic losses of reactor are separated at last.