Johan Setréus

Identifying Critical Components for Transmission System Reliability

This paper presents a method to quantify and rank transmission system components by their importance for system reliability under different load scenarios. Each component is ranked by three separate importance indexes based on its expected outage rate and impact on: 1) system security margin; 2) load supply; and 3) generation units. By studying these three interests individually, a more complete view of the risks to system reliability can be assessed. The method is demonstrated on a detailed power system model (7000 components) of a significant part of the Great Britain transmission system at 400 and 275 kV. The results show how sensitive the component indexes are to the load scenario. The method provides an input for decision-making when planning maintenance and new investment and can be used as a complement to deterministic criteria.

Model of capacity demand under uncertain weather

Load forecasting is important in the operation of power systems. The characteristics of the electrical energy consumption are analyzed and its variation as an effect of several weather parameters is studied. Based on historical weather and consumption data received from a distribution system operator (DSO), numerical models of load forecasting are suggested according to electrical power consumption and on daily peak power respectively. Two linear regression models are presented: simple linear regression (SLR) with one input variable (temperature) and multiple linear regressions (MLR) with several input variables. The models are validated with historical data from other years. For daily peak power demand a MLR model has the lowest error, but for prediction of energy demand a SLR model is more accurate.

Component ranking in Great Britain transmission system based on either equipment failures or sabotage

In the long-term and operational planning of the power transmission system (PTS), one challenge is to identify components critical to system reliability. In this paper, the importance of each component for system reliability and vulnerability are quantified for two scenarios in a model of the Great Britain (GB) PTS. The scenarios are: (1) technical failures based on statistical data and (2) sabotage where the attacker has the ability to immobilize two contiguous components. In a novel method approach, the total importance of each component is based on three separate indices that include the system impact on (i) security margin, (ii) load, and (iii) generation. The final result of the GB system screening, including nearly 7000 components and 50 million outage events, is a ranking list indicating the 30 most critical components for each of the two scenarios. The results show that a component ranking that only includes risks of technical failures cannot be used to describe critical sabotage threats. Based on the results, the system operator can perform further and more detailed analysis on a few components and then make the necessary investments to improve the system reliability for equipment failures and strengthen the system vulnerability against sabotage.