Excitation Control System Design of High Response Excitation Type Superconducting Generator for Improving Power System Dynamics

Abstract

Superconducting generator (SCG) with superconducting field winding has many advantages such as small size, light weight, high generation efficiency. A prominent advantage is to improve power system stability owing to lower synchronous reactance compared with the conventional generator. High response excitation type SCG has a rotor with thermal radiation shield without damping effect; it can enable very rapid change in field current and the magnetic flux due to the change of the field current can reach the armature winding quickly. The excitation power is large and has a rapid change enough to affect the conditions of power system in self-excited operation of the generator. This effect is equivalent to the effect of a superconducting magnetic energy storage (SMES), then so-called “SMES effect", and it is expected to contribuite to transient stabilty improvement. In this paper, excitation control system design for high response excitation type SCG in consideration of SMES effect is proposed for improving power system dynamics by employing eigenvalue sensitivity. The SMES effect is considered to couple with the power system as a nonlinear load. The control performance of the proposed excitation control system is examined in IEEJ East 10-machine and West 10-machine systems. It is made clear that the SMES effect of SCG is utilized effectively and results in both transient and dynamic stability improvement. However, the performance depends on the locations of SCGs and fault contingencies.