Renewables Integration in Transmission Grids

Production and Distribution of Electricity and Heat

In recent years, due to the increased fossil fuel demand, international awareness has been focusing on the security of energy supply and on energy-related CO2 emissions, which are expected to more than double by 2050. To deal with these issues, interest in developing renewable energy sources (RES) has been intensifying, together with the technologies to allow the integration of these sources in electrical grids. Programmable renewable sources (hydropower, geothermal, biomass) have similar technical characteristics to traditional power plants (thermoelectric), which can be controlled to match the electric demand. On the other hand, wind and solar are variable renewable energy (VRE) sources, characterized by intermittent production, since it varies with weather conditions. The non-programmability in the production of these power plants poses serious problems to the electricity system, especially when a considerable share of the electricity demand is covered by VRE. Another frequent problem is grid congestion, caused by the concentration of VRE plants in particular geographical areas, e.g. the large wind power generation in southern Italy. These problems can be mitigated or solved by the use of digital technologies, synergistically combined with the electrical components of transmission networks. They are smart grids: intelligent grids that allow the monitoring, real-time management and optimization of energy production and power flows. Wind and photovoltaic power plants connected to transmission grids have increased dramatically in recent years, and the increase is expected to accelerate. In Italy, from 2006 to 2021, RES production increased from 45 to 115 TWh, i.e. from 15% to 42% in the coverage of electricity demand. Requests for the connection of wind farms to the transmission grid increased from 46 in 2017 to over 300 in 2020, requests for the connection of photovoltaic plants increased from 11 in 2017 to almost 950 in 2020. This shows a strong need for the development of smart grids, without which it will not be possible to accept all the energy produced by these new power plants. Currently, many Transmission System Operators (TSO) have to cut RES production (especially wind) to ensure grid security and reduce the risk of blackout. In 2020, the total curtailed wind energy in Italy was over 820 TWh, compared to about 370 TWh in 2017, 100 TWh in 2014. The regulation states that in these cases the TSO has to pay the producer, as he cannot sell his energy on the market. In Italy, the compensation for curtailed energy is around 5 k€/MWh. Smart grid technologies can be classified into technology areas, with different maturity levels: wide-area and monitoring and control (in rapid development), Information and Communication Technology integration (mature), renewables integration (in rapid development), transmission enhancement (mature), Advanced Metering Infrastructure (mature). The deployment of these technologies is expected to create improvements in six key-value areas: reliability, cost-effectiveness, environmental impact, safety and security

07-07-2022

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