Inter-Area Oscillations in the CE/Turkey and IPS/UPS Power Systems

摘要

The possible expansion of the Continental Europe “CE” synchronous system, nowadays includingTurkey, toward the IPS/UPS system of Russian Confederation could provide multiple advantages interms of operation security, integration of renewable energy as well as energy trading. The operationreliability of the whole merged system is one of the main topics analyzed in the ICOEUR project(Intelligent Coordination of Operation and Emergency Control of EU and Russian Power Grids) cofoundedby the European Commission within the 7th Framework Program, and by Russia. In thiscontext, a prototype tool for the assessment of possible inter-area electromechanical oscillations, bymeans of eigenvalues calculation, is developed and applied on a detailed dynamic model of themerged system, also considering the presence of the new available technologies for flexible energytransmission (FACTS and HVDC).Power oscillations could be critical (poorly damped or undamped) on weak/long distance systemsand/or highly exploited systems. They could be triggered also by small disturbances like normalvariations of load and/or generation and mainly consist of fluctuation of power flow on criticalcorridors with possible serious consequences like system separation in islanded areas, load shedding,up to possible black-out. These phenomena are emphasized in large interconnected power systems, inparticular in case of high utilisation of critical corridors also due to market liberalisation.Oscillations could be hampered by means of i) decreasing of power flow on critical corridors(uneconomic, and against the market constraints), ii) strengthening of transmission system by newlinks (expensive), iii) equipment of suitable additional damping controls (PSS) on FACTS devices andHVDC links, in addition to conventional PSS on generators.This paper presents some considerations obtained applying the developed tool on the whole mergedgrid model. The effort has been to highlight the influence on the critical power oscillations of i) powerflows on interconnection between the two systems, ii) interconnection solutions (AC or hybridAC/DC, DC), iii) technologies for the AC system devices suitable to mitigate the consequences of gridbottlenecks on oscillations (like TCSC). The model representing the CE and Turkey system wasprovided by the two TSOs TERNA and TE?A?, while ESI supplied the IPS/UPS network model.These two separated network representations were upgraded to medium-long term and mergedhypothesizing some new HVDC back-to-back links and/or closing some existing AC tie-linespresently out of operation or in service with a radial scheme from CE toward West Island of Ukraine.The considerations described in the paper represent a contribution for the assessment of the besttechnically interconnection solutions aimed to improve the damping of critical inter-area oscillationsthat could affect the whole system CE/Turkey plus IPS/UPS.