Improved simulation of HVDC converter transformers in electromagnetic transient programs

In electromagnetic transient simulation HVDC converter transformers are normally represented as magnetically independent single-phase units. However, three-limb converter transformers are often used in HVDC schemes. Single-phase and three-limb three-phase transformer models are derived using a unified magnetic equivalent circuit concept. The new models are verified with laboratory and field data. Also, a comparison is made between the transient performance of HVDC converters with conventional and proposed transformer models.