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Effects of volatile RES on Power Systems Alessandro Clerici Chairman WEC Study Group “Energy Resources and Technologies” ABB Italy.
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Effects of volatile RES on Power Systems Alessandro Clerici Chairman WEC Study Group “Energy Resources and Technologies” ABB Italy
With the aim of reducing CO2 emissions and dependency from fossil fuels, in various countries the sharp increase of electrical RES (Renewable Energy Sources) as a result of substantial subsidies, is creating problems to an efficient and reliable operation of the electrical power system. • Both transmission and distribution systems have to face an increasingly variable production of intermittent renewable energy sources with special reference to wind and photovoltaic; the problem is not however limited to T&D but involves also the thermal fleet of a country which is required of a “flexible operation” (start-up time, ramps of power increase / decrease, reduced hours of operation) by far beyond technical and economic limits of the great majority of the present plants in service. And bottlenecks in transmission and distribution aggravate the problems.
In the last decade the Italian generation mix dramatically changed
The change was driven by a “dash for gas” which built an efficient thermal generation fleet with no peers in Europe
But the change was also driven by Italian RES incentives, greater than rest of Europe, which spurred a “dash for RES”
…as a results of over-remuneration the installed PV capacity is facing a boom
Post-crisis demand’s decrease together with rapid RES growth have squeezed thermo generation, especially the new CCGTs
As a consequence, creating a “distorted” new price curve which disrupts old “conventions”
Greater RES penetration, together with low demand and with expensive and relatively unflexible CCGT induce greater price volatility in the market
Need for additional reserve to cope with the intermittency of non-programmable RES generation
Excess of non-programmable RES generation in periods with low demand can lead to over-generation
Over-generation and quick “ramp-ups” create a new need: Energy Storage facilities
Sun and wind are location dependent and often remote locations from the demand centers
A sudden risk of black-out due to RES disconnection when frequency is outside the grid code limits
Options for Increasing Power System Flexibility to Accommodate Renewables