European Transmission Grid Research Articles

Impacts of electric vehicles on the European high and extra high voltage power grid

AbstractThe impact of electric vehicles on the electricity grid has been focused on by the literature in many facets, comprising considerations of the electricity system of a single household up to the highest voltage grid level. But each of these analyses is focusing on a single grid level. While the impact on the local level depends strongly on the specific environment and is consequently diverse, there is strong evidence that the impact on the highest grid level is non‐critical. So far, there is no study considering several voltage levels together. Consequently, we analyzed here for the first time all voltage levels between 60 and 380 kV together for the European transmission grid and included, besides the load flexibilities from home charging, also the load from fast charging stations for the year 2050 with a completely replaced car fleet by electric vehicles. While the impact on the security of supply is rather marginal, with a slight increase of load shedding on some distribution grid nodes, the impact on nodal prices and greenhouse gas emission is—with up to 9%—more severe. When applying the model on the highest grid level alone, our results show significantly smaller impacts. These results endorse our comprehensive approach, which considers several grid levels and their comprehensive interactions—an isolated consideration of grid levels seems inappropriate for our research questions.

Considering distribution grids and local flexibilities in the prospective development of the European power system by 2050

Previous works proposed a tool coupling models of a prospective outlook on long-term energy systems and a transmission grid investment and dispatch, focusing on the representation of the European transmission grid and its development on the horizon 2050–2100. In this paper, this prospective tool is further improved with the capacity to compute voltage as well as active and reactive power flows at the level of the distribution grid. This added capacity allows analyzing various issues related to the integration of variable energy resources in three representative real medium voltage distribution grids (urban, rural and semi-urban). Technical flexibility solutions such as on-load tap changers, variable energy resources curtailment and storage technologies are modeled and compared to reinforcement. A cost comparison between these flexibility solutions is also carried out. Finally, the new version of the tool is used to evaluate the CO2−eq emissions linked to the development of the European power system infrastructure, with flexibility solutions, up to the year 2050 (both high voltage alternative and direct current lines reinforcement being considered) under a 2 °C climate energy policy scenario. Results show that it exists various options for the development of the European grid infrastructure, which are clearly sensitive to the level of accuracy in the representation of the physical infrastructures and their technical limitations. Being able to represent the distribution grid, in addition to the transmission one, has a noticeable impact on the prospective outlook of the European power systems both in terms of infrastructure reinforcement and estimation of the needs of flexibility solutions.

European transmission grid expansion as a flexibility option in a scenario of large scale variable renewable energies integration

This paper presents a new power sector module, called EUTGRID, which is coupled with the long-term energy model POLES to deliver a suitable framework for considering grid aspects in energy modelling allowing for more distinct analysis of energy technology development and energy policy. It includes a mechanism of investment in transmission grids based on nodal prices together with a DC-load flow and a more detailed description of the European transmission grid. The methodology goes beyond “conventional” energy systems modelling, where the electricity grid is usually represented as a copper plate.

Inertia location and slow network modes determine disturbance propagation in large-scale power grids.

Conventional generators in power grids are steadily substituted with new renewable sources of electric power. The latter are connected to the grid via inverters and as such have little, if any rotational inertia. The resulting reduction of total inertia raises important issues of power grid stability, especially over short-time scales. With the motivation in mind to investigate how inertia reduction influences the transient dynamics following a fault in a large-scale electric power grid, we have constructed a model of the high voltage synchronous grid of continental Europe. To assess grid stability and resilience against disturbance, we numerically investigate frequency deviations as well as rates of change of frequency (RoCoF) following abrupt power losses. The magnitude of RoCoF’s and frequency deviations strongly depend on the fault location, and we find the largest effects for faults located on the support of the slowest mode—the Fiedler mode—of the network Laplacian matrix. This mode essentially vanishes over Belgium, Eastern France, Western Germany, northern Italy and Switzerland. Buses inside these regions are only weakly affected by faults occuring outside. Conversely, faults inside these regions have only a local effect and disturb only weakly outside buses. Following this observation, we reduce rotational inertia through three different procedures by either (i) reducing inertia on the Fiedler mode, (ii) reducing inertia homogeneously and (iii) reducing inertia outside the Fiedler mode. We find that procedure (iii) has little effect on disturbance propagation, while procedure (i) leads to the strongest increase of RoCoF and frequency deviations. This shows that, beyond absorbing frequency disturbances following nearby faults, inertia also mitigates frequency disturbances from distant power losses, provided both the fault and the inertia are located on the support of the slowest modes of the grid Laplacian. These results for our model of the European transmission grid are corroborated by numerical investigations on the ERCOT transmission grid.

Implications of the integration of renewable energies into the electricity market of Greece

The main purpose of this paper is a comprehensive investigation of the Greek electricity production and transmission system with a focus on the integration of renewable energy sources. A techno-economic model of the Continental European electricity sector called ATLANTIS is used to analyse the development of the Greek power system. Several different projections—including national, ENTSO-E and European scenarios—have been investigated and the officially published national development strategy of Greece until 2027 has been chosen for the simulation. Starting with the modelling of the technical system, that considers a pre-defined development path for the power plant park and the transmission grid, several techno-economic investigations are performed. These include the effects of an increasing electricity demand on the electricity production with respect to several technologies, the imports, the load flows and the CO2 emissions. Additionally, the age structure and the value of the power plant park are analysed. The results illustrate a remarkable shift from a fossil fuel dominated electricity structure to an electricity system with a high share of renewable energies. The integration of the wind power and solar/PV production capacities requires a corresponding enhancement of the Greek transmission grid including several new cross-border connections to the neighbouring countries. Therefore, all important transmission grid projects based on the TYNDP and the national grid operator have been included in the physical transmission system, which covers long distance connections between the islands and the mainland as well as connections between the islands themselves by using also the HVDC technology. Furthermore, it is shown that due to the reduced lifetime of the RES technologies compared to the fossil-fuelled and the hydro power plants the up-coming re-investment cycles have to be planned carefully. Finally, the paper closes with a comprehensive discussion of the outcomes and gives an outlook of the ongoing and the future works, which cover e.g. a stronger linkage of the whole Mediterranean electricity systems to the European transmission grid according to a European energy strategy.

Impact of Considering 110 kV Grid Structures on the Congestion Management in the German Transmission Grid

The structural changes in the European energy system lead to an increase of renewable energy sources that are primarily connected to the distribution grid. Hence the stationary analysis of the transmission grid and the regionalization of generation capacities are strongly influenced by subordinate grid structures. To quantify the impact on the congestion management in the German transmission grid, a 110 kV grid model is derived using publicly available data delivered by Open Street Map and integrated into an existing model of the European transmission grid. Power flow and redispatch simulations are performed for three different regionalization methods and grid configurations. The results show a significant impact of the 110 kV system and prove an overestimation of power flows in the transmission grid when neglecting subordinate grids. Thus, the redispatch volume in Germany to dissolve bottlenecks in case of N-1 contingencies decreases by 38 % when considering the 110 kV grid.

North Europe power transmission system vulnerability during extreme space weather

Space weather driven by solar activity can induce geomagnetic disturbances at the Earth's surface that can affect power transmission systems. Variations in the geomagnetic field result in geomagnetically induced currents that can enter the system through its grounding connections, saturate transformers and lead to system instability and possibly collapse. This study analyzes the impact of extreme space weather on the northern part of the European power transmission grid for different transformer designs to understand its vulnerability in case of an extreme event. The behavior of the system was analyzed in its operational mode during a severe geomagnetic storm, and mitigation measures, like line compensation, were also considered. These measures change the topology of the system, thus varying the path of geomagnetically induced currents and inducing a local imbalance in the voltage stability superimposed on the grid operational flow. Our analysis shows that the North European power transmission system is fairly robust against extreme space weather events. When considering transformers more vulnerable to geomagnetic storms, only few episodes of instability were found in correspondence with an existing voltage instability due to the underlying system load. The presence of mitigation measures limited the areas of the network in which bus voltage instabilities arise with respect to the system in which mitigation measures are absent.

The effect of high levels of solar generation on congestion in the European electricity transmission grid

The increasing levels of solar power affect the usage and development of electricity grids, both at local distribution level and with respect to potential congestion within the transmission grid. We use a cost-minimising investment model (ELIN) to determine the development of the European electricity generation system up to Year 2050, for two renewable-dominated scenarios: the Green Base scenario, with a Europe-wide, technology-neutral renewable certificate scheme; and the Net Metering scenario, with an additional net metering support scheme for solar power. The system compositions are extracted from the ELIN results for the years 2022 and 2032, and analysed in an hourly dispatch model (EPOD) to study the effects of solar power on marginal electricity costs and transmission congestion. From the results of the investment model, it is clear that the presence of a net metering subsidy scheme significantly affects both the pace at which solar power continues to expand and the geographical distribution of the new capacity. In the dispatch modelling, it can be seen that high penetration levels of solar power have a strong effect on the marginal costs of electricity, since production is concentrated around a few hours each day. At penetration levels of 20–30% of annual electricity demand, solar power production entails a predictable daily marginal cost difference between the solar peak and the evening price peak, which could make short-term storage competitive. Transmission congestion during summer is consistently higher in the systems from the Net Metering scenario than in those from the Green Base scenario, while the opposite is true during winter. Solar power production correlates strongly with congestion 6–9h after the solar peak, whereas wind power correlates with congestion with respect to more slowly evolving and longer-term variations.

Enabling European electrical transmission and distribution smart grids by standards

Smart electrical transmission and distribution grids are seen as key facilitators of the industry innovation that are required to meet the challenges of de-carbonization, operation performance excellence, and consumer centricity. Electricity grids represent a complex system of systems with intense interactions between them and require the collection of large amounts of data from a variety of sources to improve the energy ecosystem operation. In this paper, we describe an IBM framework that combines industry standards and advanced technologies—including analytics, mobile, and IoT (Internet of Things)—to meet the smart grid industry challenge. The Smart Grid Architecture Model (SGAM) and accompanying standards are used as a reference to ensure the openness, loose coupling, and flexibility of the framework. A consolidated and standardized data model bridging traditional utility silos is essential for analytics in this framework and represents a canonical model for integration. While offering advanced service-oriented architecture and application-programming interface integration concepts, the framework allows for retention of traditional utilities' legacy applications, preserving investments made. The framework permits for mix-and-match of the flexible building blocks linked by industry standards, promoting an incremental deployment of services as per utility needs.

A European Perspective: Potential of Grid and Storage for Balancing Renewable Power Systems

AbstractIncreasing transmission grid capacities and the use of storage devices are two options often considered to balance the fluctuations originating from variable renewable energy sources (VRES) in power supply systems. We investigate which storage characteristics are most beneficial for integrating a high share of VRES into a fully connected European power system. By applying a modeling approach to long‐term meteorological and load data, we find that a suitable combination of solar and wind capacities permits the cost‐effective integration of very high shares of VRES if complemented with the installation of small, highly efficient storage systems and fully flexible backup capacities. Our simulations also show that the grid is used significantly for approximately 3/4 of the time to balance surpluses and deficits. The results emphasize that the expansion of the European transmission grid is an important option to consider for the reduction of the required balancing measures for integrating very high shares of VRES.

Correlating empirical data and extended topological measures in power grid networks

Power grids are considered complex networks. Their structure and dynamics have been thoroughly studied and many topological measures have been used to classify them, evaluate their behaviour or model their response to malfunctions. Results have been theoretical and correlations between real dynamical behaviour (i.e., major events) and structural measures have not yet been found. New electrically modified topological measures have been recently used to quantify the ability of a network in sustaining its functions. Here, we present a first attempt to correlate these new measures with real malfunction data for some European power transmission grids. Similar behaviour is found, in terms of robustness to selected attacks to buses, between different networks. These behaviours can be correlated with similar probability distributions of major events, identifying similar dynamical response among topologically similar grids. This would raise hopes in finding a more meaningful linkage between structural measures and the real dynamical output of a grid.

Going Green: Transmission Grids as Enablers of the Transition to a Low-Carbon European Economy

The transition to a low-carbon economy will create major challenges for the European energy sector in the 21st century. In this sector, electricity is a very important vector for allowing a lower consumption of fossil fuels while maintaining a competitive European economy. The European transmission grid and European transmission system operators (TSOs) are at the core of the complex European electrical system (see Figure 1). Aging infrastructure, low public acceptance of new overhead power lines, and long permitting processes only increase these challenges. All over Europe, the required investments are very significant, and R&D activities must be performed to allow an optimization of these investments. ENTSO-E, Europe's association of transmission system operators, has defined an R&D roadmap for tackling the most challenging issues. RTE, the French TSO, has participated in the definition of this roadmap and is a major contributor to ongoing European research projects.

Transmission investment problems in Europe: Going beyond standard solutions

The European transmission grid is facing an investment challenge. There is a strong call for more transmission capacity. At the same time, the investment climate is fierce and troubled by public opposition, a complex regulatory framework, etc. Many transmission capacity expansion projects are delayed or canceled. In this paper different technology options suitable for increasing transmission capacity are discussed. The aim is to provide policy-makers with information on technologies without going too much into technical details. The focus is on opportunities and limitations to implement various technological alternatives in practice, including technical solutions that go beyond constructing new connection lines. The criteria used in this technology assessment are based on the obstacles reported in the European Priority Interconnection Plan. This ensures a realistic approach based on problems encountered in real projects. Although AC overhead lines (OHL) will remain the standard solution for grid expansion, it is argued that different technology options can overcome many obstacles that OHL face. Additionally, it is illustrated that the higher investment costs for some solutions can be offset with an increased benefit, e.g. by accomplishing investments with smaller delays due to fewer obstacles encountered.

Regulated cross-border transmission investment in Europe

In a liberalized market, generation and transmission investment decisions are decoupled, so that a more elaborated grid is necessary. The European transmission grid has to ensure security of supply, facilitate the market and integrate renewables. Transmission grid investments are clearly needed, especially to increase the scarcely available cross-border transfer capacities. The regulatory framework in which these investments have to take place is discussed in this paper. It is stated that this framework does not ensure that congestion revenues are used for transmission investments that are in the long-term benefit of the market, because regulators are biased towards a short-term tariff reduction. The authors conclude that more coordination is clearly necessary, either pushed by European regulation or driven by coordinated regulatory actions. Copyright © 2006 John Wiley & Sons, Ltd.