Improvement of dynamic stability of Yunnan Province and South-China power system by power system stabilizer (PSS)

For solving the dynamic instability problem of Yunnan Province Power System (YNPS) and the South China Interconnected Power System (SCIPS), Lubuge hydropower plant was chosen to install a power system stabilizer (PSS). The philosophy to set the parameters of PSS is to provide positive damping within the frequency of 0.4~1.6 HZ specially 0.4~1.0 HZ and to be adaptive to various operating conditions. Based on the phase compensation and the root-locus method the setting of PSS was chosen. Further eigenvalue and the time domain simulation studies show that the setting is well adaptive to different operating conditions and can significantly improve the system damping. In the field tests, the frequency response measurements and the performance of PSS under different operating condition were carried out. The test results show that the PSS installed can significantly improve the system damping. The PSSs of Lubuge power plant have been put into service in August, 1995 and working well since then. There were several incidents of serious faults occurred in YNPS and SCIPS, no apparent power oscillation observed in generators or tie lines