Incidents associated to vegetation in the Portuguese transmission grid have decreased from one of the major causes to negligible impact in less than a decade. This was due to the cumulative effect of four independent, yet concurrent, programs: 1) routine clearance inspections with LiDAR, extended to the whole grid, provided quantitative measures associated with degrees of severity for each hazardous tree; 2) classification of the right-of-way according to land use, density of vegetation and classification of tree growth rates; 3) targeted actions consisting of tree trimming, pruning and cutting with priorities set by severity and criticality of each Over Head Line [OHL]; 4) public policies to create secondary routes to remove biomass from the forests that mandated the Transmission System Operator [TSO] clear paths around OHL.
The Portuguese TSO (REN – Rede Eléctrica Nacional) operates a grid of 8443km of OHL with three voltage levels and incurs significant investment and operation costs to achieve and maintain vegetation incidents at a very low level. Thus, a program to supersede existing blind systematic actions with probability based approaches leading to risk based management was launched. This combines information from the four programs with environmental, reliability and asset management data with third party information. Given that the outcome (incidents due to vegetation) is already at an optimal level, the current research will try to optimize the process as well