改进漏感电动势法计算换位线棒股线电流及环流损耗

Improved Method of Leakage Susceptible Electromotive Potential to Calculate Strand Current and Circulation Current Losses in Transposition Windings

针对大型水轮发电机定子绕组换位线棒股线电流及环流损耗的计算问题,提出了一种解析计算方法——改进漏感电动势法,解决了现有计算定子换位线棒股线电流分布及环流损耗的漏感电动势法(又称漏感电势法)中存在的漏磁场假设不合理、电路约束不完整以及忽略了股线的实际换位路径等问题。将定子线棒中的每根股线看成由股线电阻和漏感电动势组成,分别给出了槽部漏感电动势和端部漏感电动势的计算方法。以一台140 MW大型水轮发电机为例,采用改进漏感电动势法计算360°全换位和不足换位时的每根股线的电流分布,进而求解定子线棒的环流损耗。通过解析计算结果与实验测量结果对比表明,改进漏感电动势法计算的电流分布及环流损耗值与实验测量值基本一致,验证了解析法的正确性。

Aiming at the calculation of the strand current and circulation current losses in the transposition stator windings of large hydro generator,a new analytic method is proposed which is called the improved leakage susceptible electromotive potential method.The method solves the issue of traditional method that the unreasonable assumption of leakage magnetic field with incomplete circuit constraints which also ignored the actual path of the transposition strands.The equivalent circuit of each strand in the stator bar is considered as a branch which is composed of a resistance and leakage inductive electromotive force.The calculation methods of leakage inductive electromotive force in slot part and end part of the strand are given respectively.Taking a 140 MW large hydro generator for instance,the current distribution of each strand which had 360° complete transposition and deficient transposition in the stator slot is calculated by the improved leakage susceptible electromotive potential method.Additionally,the circulation current losses can be solved according to the current distribution.By comparing with the experimental results,the distribution of the strand current and the circulation current losses are basically consistent,which proves the correctness of the analytical algorithm.