Optimization Comparison of DC-Excited Vernier Reluctance Machine Synchronous Condensers

This paper forms part of a broader study that investigates the use of DC-Excited Vernier Reluctance Machine technology as synchronous condensers. Synchronous condensers have received significant attention in recent years due to the increased integration of renewable energy sources and the well-known stability problems associated with them. In this paper, four DC-VRM structures with different outer diameters and stack lengths are optimized as synchronous condensers. The performance of the machines are determined through dq-axes mathematical modeling and finite element analysis. The performance of the design-optimized machines are then evaluated and compared. The paper concludes with a discussion of the optimized machine structures that perform best in terms of reactive power per loss (VAR/W) and reactive power per volume (kVAR/m³). It is shown that the large DC-VRM synchronous condenser can have reactive power performance of close to 50 VAR/W and 400 kVAR/m³.

I. Introduction

Synchronous condenser (SC) technology has been used in electricity utilities since the early 1900s [1]. With the explosion in developments in the power electronic converter sector, SCs were deemed obsolete. Power electronic converters offered a similar static solution at a lower cost without the expensive maintenance requirements associated with these machines.