Securing the smart grid

The availability of electricity is fundamental to modern society. It is at the top of the list of critical infrastructures and its interruption can have severe consequences. This highly important system is now evolving to become more reliable, efficient, and clean. This evolving infrastructure has become known as the smart grid; and these future smart grid systems will rely heavily on ICT. This infrastructure will require many servers and due to the nature of the grid, many of these systems will be geographically diverse requiring communication links. At the heart of this ICT infrastructure will be security. At each level of the smart grid from smart metering right through to remote sensing and control networks, security will be a key factor for system design consideration. With an increased number of ICT systems in place the security risk also increases. In this paper the authors discuss the changing nature of security in relation to the smart grid by looking at the move from legacy systems to more modern smart grid systems. The potential planes of attack for future smart grid systems are identified, and the general anatomy of a cyber-attack is presented. The authors then introduce the various threat levels of different types of attack and the mitigation techniques that could be put in place for each. Finally, the authors' introduce a Phasor Measurement Unit (PMU) communication system (operated by the authors) that can be used as a test-bed for some of the proposed future security research.

A smart load appliance application using a single compressor fridge-freezer to support grid operations

This paper describes a fridge-freezer smart load model, which responds to external signals from the wholesale electricity market to support grid operations while switching the fridge-freezer on and off to maintain optimum operations for the owner. The key parameters of the model are the appliance dimensions, thermal mass, the fridge and freezer thermal time constants and the compressor power consumption. The model demonstrates that control strategies help to minimise load at times when the grid is under stress from high demand, and shift some load to a lower wholesale price or when there is excess renewable power. Three control strategies are proposed, based on peak shaving and valley filling, price signals and wind availability.

Python PSS/E Simulation to Test Efficacy of Proposed PMU Based WAMS and Potential WAMPAC Applications

A PSS/E 32 model of a real section of the Northern Ireland electrical grid was dynamically controlled with Python 2.5. In this manner data from a proposed wide area monitoring system was simulated. The area is of interest as it is a weakly coupled distribution grid with significant distributed generation. The data was used to create an optimization and protection metric that reflected reactive power flow, voltage profile, thermal overload and voltage excursions. Step changes in the metric were introduced upon the operation of special protection systems and voltage excursions. A wide variety of grid conditions were simulated while tap changer positions and switched capacitor banks were iterated through; with the most desirable state returning the lowest optimization and protection metric. The optimized metric was compared against the metric generated from the standard system state returned by PSS/E. Various grid scenarios were explored involving an intact network and compromised networks (line loss) under summer maximum, summer minimum and winter maximum conditions. In each instance the output from the installed distributed generation is varied between 0 MW and 80 MW (120% of installed capacity). It is shown that in grid models the triggering of special protection systems is delayed by between 1 MW and 6 MW (1.5% to 9% of capacity), with 3.5 MW being the average. The optimization and protection metric gives a quantitative value for system health and demonstrates the potential efficacy of wide area monitoring for protection and control.

Exhaled breath temperature measurement and asthma control in children prescribed inhaled corticosteroids: A cross sectional study

BACKGROUND: Exhaled breath temperature (EBT) reflects airways (both eosinophilic and neutrophilic) inflammation in asthma and thus may aid the management of children with asthma that are treated with anti-inflammatory drugs. A new EBT monitor has become available that is cheap and easy to use and may be a suitable monitoring device for airways inflammation. Little is known about how EBT relates to asthma treatment decisions, disease control, lung function, or other non-invasive measures of airways inflammation, such as exhaled nitric oxide (ENO).

OBJECTIVE: To determine the relationships between EBT and asthma treatment decision, current control, pulmonary function, and ENO.

METHODS: Cross-sectional prospective study on 159 children aged 5-16 years attending a pediatric respiratory clinic. EBT was compared with the clinician's decision regarding treatment (decrease, no change, increase), asthma control assessment (controlled, partial, uncontrolled), level of current treatment (according to British Thoracic Society guideline, BTS step), ENO, and spirometry.

RESULTS: EBT measurement was feasible in the majority of children (25 of 159 could not perform the test) and correlated weakly with age (R = 0.33, P = <0.01). EBT did not differ significantly between the three clinician decision groups (P = 0.42), the three asthma control assessment groups (P = 0.9), or the current asthma treatment BTS step (P = 0.57).

CONCLUSIONS & CLINICAL IMPLICATIONS: EBT measurement was not related to measures of asthma control determined at the clinic. The routine intermittent monitoring of EBT in children prescribed inhaled corticosteroids who attend asthma clinics cannot be recommended for adjusting anti-inflammatory asthma therapy.