Expo Milano 2015: Grid planning and synergies for developing metropolitan transmission grid
By developing the National Transmission Grid (NTG), the Italian transmission system operator TERNA pursues the aims of security, reliability, efficiency, continuity of electrical energy supply and cost reduction of transmission and of supplies. This aim is pursued through suitable planning of the NTG development, aimed at reaching an appropriate level of quality of the transmission service and reduction of possible grid congestion, while complying with environmental and landscape law restrictions. The planning process begins with the collection, selection and analysis of essential information about: - forecasts of increases in electricity demand and its geographical distribution; - location and power capacity of new power generation plants; - forecasts of electrical energy exchanges with other countries; - development programmes of other grids with third party access interoperating with the NTG. TERNA verifies the operating conditions of the forecasting grid in static security, using the so-called N – 1 security criterion. This criterion enables an initial sizing of the forecasting transmission grid, providing for an adequate redundancy of the elements, so that the following conditions are satisfied: - in typical load situations for the forecasting grid, with related foreseeable production programmes and with all elements of the system in service (fully operational grid), supplies at all points of withdrawal are guaranteed without violating the normal operating limits (current and voltage) of the grid elements in continuous operating conditions; - starting from the operating states in the above mentioned typical situations, a contingent (or anyhow non-deferrable) out of service of any element of the NTG does not simultaneously cause: - exceeding of the permitted operating limits for the grid (current and voltage) in continuous operating conditions; - load interruptions, except for interruptions that concern only the out-of-service element (connection in antenna). TERNA already owner of about 92％ of the transmission grid, in 2006 acquired part of 220 kV grid functional to the supply of the major Italian metropolitan area (i.e. Milan, Turin and Rome); the classic criteria for planning and developing the transmission has immediately shown itself not suitable for such metropolitan grid. A new approach has been used as a pilot project in the Milan Area, and it was adopted successively for Turin and Naples areas. In the urban context, the transmission grid planning rises new kinds of problems. At first, the problem are technologies: the new infrastructures planning couldn’t consider the environmental context, in which they will be collocated; so that the using of solutions like cable and/or using of hybrid plant and, however, compatible with the architecture context (i.e. substations in historical buildings). At second, the using of the new technologies, cable or hybrid plant (GIS), rises new problems: new reactive power or redundancy of the grid in order to assure a continuous of supply of electrical energy in case of failure of the cable, that as know needs more time the overhead solution. At last, it is relevant the cooperation that will be developed with local distribution company, that has got more information on the new urban developing plans and on its outcomes in metropolitan transmission grid.
Planning reliability metropolitan grid cables security of supply energy not supplied critical section cost/benefit analyses
E.M.Carlini F.Vedovelli Ch.Vergine
Terna SpA Italy
国际会议
桂林
英文
1-8
2009-10-28（万方平台首次上网日期，不代表论文的发表时间）