When a national transmission system operator needed to accommodate a 40 per cent increase in generation capacity coupled with a large increasing constant load, it created a major challenge. The transmission network already had long transmission lines and weak electrical interconnections and had experienced longstanding problems with low frequency oscillations.
The operator approached Psymetrix to work with its staff to obtain detailed information about the dynamics of the network and introduce power system stabilisers safely without disturbance to the system. Psymetrix deployed its Wide-Area Monitoring System (WAMS) across the network and with its advance oscillatory stability monitoring application quickly establishing a dynamics baseline.
Once the baseline had been achieved, Psymetrix determined PSS settings for PSSs at key locations identified as being the most suitable for controlling the modes in question. Using Psymetrix's PhasorPoint, network conditions before, during and after the installation of the PSS's was monitored. The effects of the controllers could be seen clearly across the transmission network with PhasorPoint. This wide area dynamics view highlighted the importance of close monitoring of the transmission system to prevent problems elsewhere on the network. After the commissioning tests, the robustness of the design was checked by reviewing damping over a period of months.
The stabiliser tuning was a resounding success, and the diagram below shows the damping for a 1.2Hz mode, before (red) and after (blue) PSS commissioning.