Study on High Rsponse Excitation of Superconducting Generator

超导发电机的低同步阻抗提高了电力系统的稳定性。如果能在SCG中实现高响应励磁，将大大提高电力系统的稳定性。对于高响应激励的SCG，我们有许多问题需要解决。其中一个问题是如何设计出口器。由于SCG励磁电路的时间常数很大，励磁器的容量可能很大。晶闸管变换器作为传统发电机的励磁器，存在容量大、无功功率大、电流谐波等问题。本文提出了一种用小功率电源和超导线圈之间的能量传递电路作为励磁器的新方法。其中一个用于存储，另一个用于SCG的现场绕组。电源由晶闸管变换器组成，向线圈提供能量进行存储。能量通过能量传递电路从线圈存储转移到磁场绕组。电源的容量很小，因为它只提供很小的能量，以弥补系统在稳定状态下的损失。在磁场电流变化快的情况下，为获得高响应励磁，电流由线圈提供以进行存储。虽然从交流侧来看变流器很小，但励磁机在励磁绕组中看起来容量很大。利用两个超导线圈进行了能量传递试验、阶跃响应试验、频率响应试验等基础试验。他们证实这台激振器运转良好。此外，我们还考虑了SCG的现场电路特性和SCG的电力系统特性。

Low synchronous impedance of superconducting generators (SCG's) improves power system stability. If high response exitation is possible in SCG, it could improve power system stability much more. For SCG with high response exitation, wer have many problems to be solved. One of the problems is how to design the exiciter. Since time constant of field circuit of SCG is very large, the capacity of the exciter may be very large. Thyristor convertors, which are used as exciters of the conventinal generators bring some problems, that is large capacity, reactive power, current harmonics and so on. Here we propose a new method of exciter with a small power supply and an energy transfer circuit between two superconducting coils. one of them is for storage and the other is field winding of SCG. The power supply, which consists of thyristor converter, supplies energy to the coil for storage. The energy is transfered from the coil for storage to the field winding through energy transfer circuit. The capacity of the power supply is rather small since it supplies only small energy for the loss of the system in the steady state. In rapid change of the field current for high response excitation, the current is supplied from the coil for storage. Though the converer is small from a point of AC side, the exciter looks large capacity for the field winding. The fundamental tests, that is, tests for energy tranfer, step response test, frequency response test and so on, were carried out by use of two superconducting coils. They confirmed that the exciter can operate well.Furthermore, we considered characteristics of field circuit of SCG and power system characteristics of SCG.