Coordinated security analysis
The main purpose of the CSA service at the Nordic RSC is to identify operational security risks and recommend preventive remedial actions to the individual TSOs.
The possibility to highlight and visualize possible operational security risks in advance, gives the operators additional time during the preparation and planning phase to investigate possibly needed remedial actions and thereby aids the operators in the decision making during real time.
By shifting some of the workload to the planning phase it will be easier to optimize the use of the power system and improve the security, voltage levels, and decrease losses. Additionally, it allows for more time to coordinate with the individual power stations, and for a follow up of the capacity calculations. This will prove especially valuable during the shift to the flow-based capacity calculation method.
Purpose
The CSA service will perform security analysis on CGMs, based on the market results when they are available. The security analysis consists of contingencies from each TSO, simulating a fault situation where one or more elements are connected or disconnected, will be run and the impact on the remaining grid investigated. The focus is to find limit violations and to suggest remedial actions to mitigate the violations.
Limit violations can occur in base case (pre-fault) and in contingency case (post-fault) situations.
Remedial actions are any change in the grid, applied by TSO operators, to mitigate limit violations, and can be categorized as either curative or preventive.
The CGMs in themselves does not contain sufficient information to perform a meaningful security analysis, why additional data is needed, including contingencies, power transfer corridors (PTC) and limits, as well as system protective schemes (SIPS). These have been agreed to be exchanged between the Nordic TSOs and Nordic RSC. When remedial actions are to be suggested, a list of possible remedial action will also need to be shared between the Nordic TSOs and Nordic RSC.
Methodology
The CSA for the Day-Ahead (D1) process is described in the (CSAM): “All TSOs’ proposal for a methodology for coordinating operational security analysis in accordance with Article 75 of Commission Regulation (EU) 2017/1485 of 2 August 2017 establishing a guideline on electricity transmission system operation”.
Additionally, the Nordic SOA group have created a proposal on how the Nordic Capacity Calculation Region (CCR Nordic) shall implement the regional operational security coordination, including the coordinated security analysis for both the D1 and Intra Day (ID) time horizons in the Nordic area: “Nordic TSOs’ common methodology for regional operational security coordination in Nordic capacity calculation region in accordance with Article 76 and Article 77 of the “Commission Regulation (EU) 2017/1485 of 2 August 2017” establishing a guideline on electricity transmission system operation”.
Step wise implementation
The CSA service will be developed in three steps, so-called versions:
- “D1 view and verify the results”
- Version 1.0 + “D1 suggest and accept remedial actions”
- Version 2.0 + “ID view and verify results”
In version 1.0 of the CSA service, remedial actions will not be exchanged electronically (nor in version 2.0). It has been agreed with the Nordic TSOs (22.08.2017) that remedial actions to be considered, in version 2.0 of the CSA service, will be up- and down regulation in sub-geographical regions, as well as changes of HVDC setpoints.
In version 2.0 of the CSA service remedial actions are expected to be found manually by analysing the relevant scenarios (time points) in detail in the security analysis tool.
In version 3.0 of the CSA service, security analysis will be performed in the ID time horizon as well.
Currently Nordic TSOs and Nordic RSC are working on introducing version 1.0 of the CSA service.
Video
See the video below for a basic explanation of the service provided by ENTSO-E and Coreso.