Espacio social: Traslados físicos y sociales

In the REDCRIT project, the vulnerability of the coupled infrastructure of the gas and electricity transmission networks in Spain was also evaluated, considering the expansion plans proposed by network operators to improve the power supply security. The geodesic vulnerability measure was applied to the interconnected systems of electric power and natural gas, calculating the (𝑣̅) indicator in random cascading failures for each new topology resulting from the investment plans of the networks for the years 2018-2020 [30].

In this evaluation, 22 case studies were considered, corresponding to the construction of new 400-kV high-voltage power lines and 80-bar high-pressure gas pipelines between 2018 and 2020. Table I shows the results for different case studies corresponding to the removal of a certain number of nodes in the network (f), the impact on the disconnection of the loads from the system by means of the geodesic vulnerability index (𝑣̅), and the fmax value, where the final disintegration of the system occurs [31].

Table I: Simulation results for random errors based on the fraction of nodes removed (EL: new power

line, GL: new pipeline)

Case Asset 〈𝒇 = 𝟐%〉 〈𝒇 = 𝟒%〉 〈𝒇 = %〉 〈𝒇 = 𝟖%〉 〈𝒇 = 𝟏𝟎%〉 Failure _〈𝒇

𝒎𝒂𝒙〉 Base case 0.1696 0.3924 0.5771 0.7893 0.8762 12.30 Case 1 EL 0.1969 0.3904 0.6129 0.7368 0.8903 14.02 Case 2 EL 0.2063 0.4480 0.6264 0.7917 0.8970 11.36 Case 3 EL 0.1901 0.4017 0.6123 0.7575 0.9292 11.16 Case 4 EL 0.1841 0.3946 0.5898 0.8081 0.9321 13.12 Case 5 EL 0.2008 0.3960 0.6355 0.7826 0.9537 12.22 Case 6 EL 0.1974 0.4101 0.6377 0.7353 0.9069 13.15 Case 7 EL 0.1808 0.3786 0.5944 0.8005 0.9085 14.52 Case 8 EL 0.1959 0.3978 0.6030 0.7780 0.8789 12.21 Case 9 EL 0.1739 0.4354 0.6183 0.7655 0.8992 11.71 Case 10 EL 0.1878 0.4002 0.6095 0.7981 0.8669 11.95 Case 11 EL 0.1833 0.3939 0.5580 0.7904 0.8828 13.32 Case 12 EL 0.1831 0.3779 0.6132 0.7852 0.8823 13.21 Case 13 EL 0.1879 0.3690 0.5883 0.7391 0.8434 13.25 Case 14 EL 0.1889 0.3739 0.5913 0.7904 0.9033 12.90 Case 15 EL 0.1910 0.4202 0.6072 0.8009 0.8978 13.24 Case 16 EL 0.1878 0.3747 0.6007 0.7640 0.9288 12.75 Case 17 EL 0.1935 0.4014 0.6019 0.7592 0.8562 13.86 Case 18 EL 0.1848 0.4400 0.6175 0.7610 0.8299 12.00 Case 19 EL+GL 0.1761 0.3808 0.5808 0.7503 0.8522 11.75 Case 20 EL 0.1900 0.3982 0.6225 0.7718 0.9014 12.38 Case 21 GL 0.2303 0.3856 0.5624 0.7652 0.8418 13.01 Case 22 GL 0.2003 0.3949 0.5667 0.7829 0.8232 11.34

Fig. 3 shows the geodesic vulnerability values (𝑣̅) for all the case studies corresponding to a loss of 10% of the nodes (f=10%). The trend line in Fig. 3 shows that the coupled system only improves when all the investments have been made

(Case 22). The numerical values in Table I for (f=10%) demonstrate a 6%

improvement in structural robustness, decreasing from a geodesic vulnerability value of 0.8762 to 0.8232 for Case 22 (taken from [31]).

Figure 3. Geodesic vulnerability values for f=10% (taken

from [31]).

6.

Conclusions

The REDCRIT project developed a cascading failure methodology for coupled natural gas and electricity systems, remarkably simplifying the assessment of structural vulnerability using complex network theory. This proposal was previously validated in test networks and was applied here to real electricity and natural gas transmission networks in Spain. The results show that the natural gas system is less robust than the electrical system. In addition, the coupled network is more vulnerable than the electrical network to both random and deliberate faults, and the removal of 1% of the nodes is enough to completely collapse the network under intentional attacks on the infrastructure. Finally, the vulnerability of the system was evaluated with the construction of new power lines and gas pipelines between 2018 and 2020, resulting in a potential improvement of 6% in the combined robustness of the infrastructure.

Acknowledgements

This research was supported by the Ministerio de Economia y Competitividad (Ministry of Economy and Competitiveness), Spain, under project ENE2016-77172- R.

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