The description and evaluation of technical incident risk on the National Power Grid in the context of power safety growth

In the context of increasing the importance of power safety for national security, the security of power systems within the National Power Grid, must be an objective of major and constant interest for the national transmission and system operator. Evolutions in recent decades have shown the increase in vulnerabilities caused by: failure, destruction and/or disruption of technological infrastructures caused by acts of terrorism, natural disaster, negligence in service, work accidents of technical nature, technical incidents, criminal activities and lack of investment. For the critical analysis of the National Power Grid, 4 (four) possible risk scenarios with effects of instability of the power safety and with major effects on the national security were identified, described and evaluated: Risk Scenario 1 – Technical Incident, Risk Scenario 2 – Damage: Technical Incident Sequence, Risk Scenario 3 – Damage: Natural Disaster, Risk Scenario 4 – Damage: Terrorist Attack. The purpose of the paper is to describe and evaluate the Risc Scenario 1 – Technical Incident (which is most prevalent) on the power substations and to prevent potential disturbances in the safety of the power supply to consumer. 1 National Power Grid Generalities – NPG 1.1 The purpose of NPG The purpose of NPG's existence is to ensure all safety, technical and economic requirements of consumers’s supplying with electrical or thermal energy. In order to do that, NPG must meet the following requirements: safety (security) in consumers`s supplying; the quality of electricity; the economicity; external requirements. * Corresponding author: daniel.fita@yahoo.com , (2019) https://doi.org/10.1051/matecconf /20192 MATEC Web of Conferences 290 901 MSE 2019 120 20 10 10 © The Authors, published by EDP Sciences. This is an open access article distributed under the terms of the Creative Commons Attribution License 4.0 (http://creativecommons.org/licenses/by/4.0/). Fig. 1. The purpose and requirements of NPG


The purpose of NPG
The purpose of NPG's existence is to ensure all safety, technical and economic requirements of consumers's supplying with electrical or thermal energy.
In order to do that, NPG must meet the following requirements: -safety (security) in consumers`s supplying; -the quality of electricity; -the economicity; -external requirements.

NPG statuses
NPG can be functionally found in one of the following status: -normal operation status -N; -exposed status (alarm) -E; -critical status -C; -damage status -D.

NPG interconnection with neighboring power systems
NPG interconnection is one of the main ways to increase its reliability and safety, without affecting power independence. These interconnections provide emergency assistance without the need of installing and maintaining of a strong power reserve.

Faults's typology (threats) in NPG operation
In NPG's, installations and power equipment running (power plants, electrical networks) it may occure different faults (threats) as follows: -current malfunctions; -faults; -incidents:

Identification of possible risk scenarios with NPG instability effects
For the critical analysis of the National Power Grid, 4 (four) possible risk scenarios with effects of instability of the power safety and with major effects on the national security were identified: -Risk Scenario 1 -Technical Incident (Fig. 6, Fig. 7 -the use of non-compliant power subassemblies; -lack of investments; -lack of power substation upgrades; -lack of specialized and/or trained maintenance personnel; -lack of specialized and/or trained operative personnel; -incorrect maneuvers (handling) by power substation personnel; -failure to communicate or poor communication with TED -Territorial Energy Dispatcher or DEN -National Energy Dispatcher; -lack/failure to comply/unawareness of national/european procedures in the event of serious incident or damage. Effects: -work accidents from an explosion that may cause fire (unitary or collective) fatal or incapacitated; -fire accidents at work (unitary or collective) fatal or incapacitated; -explosion reach (fire) to other power equipment in the area; -explosion reach (fire) to other external objectives (forests, houses, blocks, factories, etc.); -the disconnection of the equipment in question; -lack of consumers electric powering; -material damage resulting from lack of electricity; -major material damage happened because of other consumers interdependence. Spatial dimension -territorial area of electricity transport branches within National Power Grid Company Transelectrica SA. Temporal positioning -any time.
Event duration -between 1 hour and 12 hours, depending on the intervention teams.
Evolution of the event -the fire can trigger a series of other fires.
Intervention capacity -it will intervene in the first phase with its own staff with specific attributions; -immediately notify ESI -Emergency Situations Inspectorate for fire insulation.

a) Establishing the probability
To establish the probability of occurrence, the following probability scale was adopted (tabel 2):

Very low
It has a very low probability of happening. Normal measures are required to monitor the evolution of the event.
over 13 years

Low
The event has a low probability of occurrence.
Efforts are required to reduce the probability and/or mitigate the impact produced.

Medium
The event has a significant probability of happening. Significant efforts are required to reduce the probability and/or mitigate the impact.

-9 years X 4. High
The event is likely to happen. Priority efforts are 4 -6 years

DEFINITION OF PROBABILITY PERIODS
required to reduce the probability and mitigate the impact.

Very high
The event is considered imminent. Immediate and extreme measures are required to protect the target, evacuate to a safe location if the impact imposes it.

-3 years b) Determining the gravity of the consequences of the proposed scenario
The gravity of the consequences is given by the worst level of vulnerabilities and levels of impact.
High Very high 8. Technical and human resilience: -the partial or total technical possibility of returning to the initial state; -the partial or total human chance of returning to the original state.

Very low Low Medium High Very high -Impact analysis (tabel 3)
Impact analysis is a management analysis at certain levels that identifies the impact of the loss of resources of a european critical infrastructure (national power substation).
The severity of all scenario impacts will be considered and then the level of severity of the hazard / threat consequences of the scenario considered.
The highest level of severity will be chosen.

Very low
The event produces a minor disturbance in the working process without material damage

Low
The event produces minor material losses and limited activity disturbance

Medium
Personal injury, and/or some loss of equipment, utilities, and delays in service providing.

X 4. High
Serious injury to personnel, significant losses of instalation equipment, delays and/or disruption of service provision.

Very high
Consequences are catastrophic resulting in deaths and serious personal injury, major loss of equipment, instalations and facilities, and the cessation of service provision.

c) Calculation of risk level (Table 6)
In table 6 are presented the probability and gravity of the consequences and the calculated risk level.

-25
The risk is determined by multiplying the probability of producing a hazard with threats and the severity of its consequences. The calculated risk is 16 (probability 4 x gravity 4) therefore there is a high risk of producing the chosen scenario.

d) Risk treatement (table 7)
To reduce the risk,the next steps are required to cover the following vulnerabilities and/or improve the following capabilities:

Very low
The event produces a minor disturbance in the development of activity without material damage.

Low
The event produces minor material damage and limited activity disturbance X

Medium
Personal injury, and / or some loss of equipment, utilities, and delays in providing the service.

High
Serious injury to personnel, significant loss of instalations and facilities equipment , delays and / or disruption of service provision.

Very high
Consequences are catastrophic resulting in deaths and serious injuries to staff, major loss of equipment, instalations and facilities, and cessation of service provision f) Risk level after reduction measures applying (table 10) The risk is given by the product between the probability of producing a hazard and threats and the severity of its consequences. The calculated risk is 12 (probability 4 x gravity 3) therefore there is a medium risk of producing the chosen scenario.  -to establish the probability of the event to happen, it was selected the scale 4 probability (high); -level 4 (high) was selected for the severity of the consequences; -the calculated risk is 16 (high risk); -after the risk reduction measures have been applied, the severity of the consequences has been recalculated and level 3 (medium) has been selected; -the recalculated risk is 12 (medium risk). To reduce the risks, the following measures were selected in order to diminish the vulnerabilities and to improve the next capabilities (table 12): VULNERABILITY AND/OR CAPABILITY PROPOSED MEASURES Degree of specialization and periodic training of the operational staff with attributions to restore the power supply process.
-combined training and retraining courses; -events and incidents analysis etc .; -installations's checking on the operating line and performing preventive maintenance Equipping the power station with fire extinguishing equipment -equipping with individual means of fire extinguishing. Equipment and technological installations related to the electricity transmission process status(lack of investments).
-major investments in high performance equipment.