The “IEEE 39 bus system is well known as 10-machine New-England Power System. Generator 1 represents the aggregation of a large number of generators. All parameters shown below” are taken “from the book titled ‘Energy Function Analysis for Power System Stability’” . The original paper with the IEEE 39-bus system is by T. Athay et al. 
The IEEE 39-bus system has 10 generators and 46 lines.
 http://sys.elec.kitami-it.ac.jp/ueda/demo/WebPF/39-New-England.pdf  Anantha Pai. Energy Function Analysis for Power System Stability. Springer, 1989. Cited in .  T. Athay, R. Podmore, and S. Virmani, “A Practical Method for the Direct Analysis of Transient Stability,” IEEE Transactions on Power Apparatus and Systems, vol. PAS-98, no. 2, March/April 1979, pp. 573-584. Cited in .