86,694 research outputs found
RISK ASSESSMENT OF MALICIOUS ATTACKS AGAINST POWER SYSTEMS
No full textThe new scenarios of malicious attack prompt for their deeper consideration and mainly when critical systems are at stake. In this framework, infrastructural systems, including power systems, represent a possible target due to the huge impact they can have on society. Malicious attacks are different in their nature from other more traditional cause of threats to power system, since they embed a strategic interaction between the attacker and the defender (characteristics that cannot be found in natural events or systemic failures). This difference has not been systematically analyzed by the existent literature. In this respect, new approaches and tools are needed. This paper presents a mixed-strategy game-theory model able to capture the strategic interactions between malicious agents that may be willing to attack power systems and the system operators, with its related bodies, that are in charge of defending them. At the game equilibrium, the different strategies of the two players, in terms of attacking/protecting the critical elements of the systems, can be obtained. The information about the attack probability to various elements can be used to assess the risk associated with each of them, and the efficiency of defense resource allocation is evidenced in terms of the corresponding risk. Reference defense plans related to the online defense action and the defense action with a time delay can be obtained according to their respective various time constraints. Moreover, risk sensitivity to the defense/attack-resource variation is also analyzed. The model is applied to a standard IEEE RTS-96 test system for illustrative purpose and, on the basis of that system, some peculiar aspects of the malicious attacks are pointed ou
Assessment of primary frequency control through battery energy storage systems
No full textThis article focuses on the impact of the primary frequency control that can be provided by Battery Energy Storage Systems (BESSs) on the transient response of electric grids. A procedure based on the Fourier transform is used for synthesizing a realistic frequency signal based on the variations of load consumption and generation. The impact of BESSs is evaluated with respect to the storage capacity installed and the regulation strategy adopted and then compared with the regulation provided by conventional sources. The impact of a variable-droop strategy on the dynamic response of the grid and the BESSs State of Charges (SoCs) is also evaluated. A novel index to quantify the performance of the BESSs is proposed and discussed. The case study is based on a detailed dynamic model of the all-island Irish transmission system
Improving reliability in MV power distribution systems. The use of algorithms for optimum choice of emergency connections
No full textClassical grid control: Frequency and voltage stability
No full textMaintaining voltage and frequency within their allowed ranges guarantees the stability of the power system. Hence, understanding the causes that affect these two state quantities is very important, because this allows to take the appropriate correction actions to avoid reaching operation points that result dangerous for the power system. This chapter can be successfully used by educators because it includes (i) the essential explanations of the phenomena affecting the frequency and voltage stability, (ii) high quality drawings of the control schemes, and (iii) numerical simulation graphs. Novel measurement results from the Romanian power system are presented as well, which allow to demonstrate the importance of the mechanical inertia for frequency stability
Sustainability Assessment of Flywheel Energy Storage for Grid Applications
No full textFlywheel Energy Storage (FES) Systems could be
exploited to support energy transition maintaining, at the same
time, secure conditions in electricity grids. Among the current
remunerated services, they can be deployed for Frequency Con-
tainment Reserve (FCR) and automatic Frequency Restoration
Reserve (aFRR). However, several aspects have to be addressed,
such as environmental impacts of these systems, and the costs.
Additionally, since the exploitation of scarce raw materials for the
assembling, also risk on supply disruption for these materials has
to be taking into account. Main indicators exploited to evaluate
Flywheels are the Global Warming Potential, the Cumulative
Energy Demand, the Levelized Cost of Storage (LCOS) and
the Supply Risk Indicator for Raw Materials. Most impact-
ing components for Cumulative Energy Demand and Global
Warming Potential are represented by the steel-based Vacuum
Chamber and the Power Conversion System. Investment costs
and charging costs are instead major contributors in LCOS,
whereas replacement costs have a small contribution on it. The
Supply Risk, assessed first for raw materials and then aggregated
for the entire FES, is influenced mostly by Natural Graphite
and Aluminium. Results on risk are almost not affected by
considering the elements contained within the FES instead of
raw materials. Finally, the comparison between greenhouse gases
emitted during the manufacturing stage of alternative Storage
Technologies shows that FES is the highest emitter, due to a low
Energy on Power rati
A graph theory based methodology for optimal PMUs placement and multiarea power system state estimation
No full textThis paper proposes a novel methodology based on the graph theoretical observability analysis for optimal placement of phasor measurement units (PMUs) in a power system. The proposed method identifies the optimal PMUs number, their strategic location and the minimum set of critical measurements aimed at ensuring the complete system observability. Besides, we demonstrated that the identified monitoring asset allows us to decompose the overall power system into a minimum number of decoupled non-overlapping observable islands. Thanks to this feature each island can assess its state by processing only local variables without the need for a central fusion center acquiring and processing all the PMUs measurements. Consequently the state of the entire power system can be estimated according to a distributed and decentralized computing paradigm. Numerical results obtained on several large case studies, including both IEEE test networks and national power systems, confirm the effectiveness of the proposed methodolog
An IPV auction model for strategic bidding analysis under incomplete and asymmetric information
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