Modern analysis criteria and software tools for planning large interconnected systems

The benefits of the interconnections among different power systems are well known and involve both economic and security aspects. To achieve the above mentioned benefits, the pooling operation requires the establishment of precise rules to be met by each partner. The choice of the technology (AC vs. DC) to be used for a systems interconnection is quite a complex problem, which includes both technical and economic considerations. FACTS (flexible AC transmission systems) devices might be the answer to the needs to improve both controllability and stability of the AC interconnections. TCSCs (thyristor controlled series capacitors), in addition to their ability to mitigate SSR (subsynchronous resonance), offer several benefits for transmission system interconnection operation: power oscillation damping; improved transfer capability and stability; and power flow control. The computational tools required to carry out the technical analyses, shall be very sophisticated in order to meet the requirements due to large interconnected power systems and to the presence of newly conceived equipment such as TCSC devices; the most important features of the CESI software, recently improved to meet these requirements, are presented in this paper. As an example, the methodology to investigate the impact on the SADI (Argentinian Interconnection System) of a 4th interconnecting line between Comahue and Buenos Aires areas is explained.