Wind turbines are, generally, placed at remote locations and are subject to harsh environmental conditions throughout their lifetimes. Consequently, major failures in wind turbines are expensive to ...repair and cause losses of revenue due to long down times. Asset management using optimal maintenance strategies can aid in improving the reliability and the availability of wind turbines, thereby making them more competitive. Various mathematical optimization models for maintenance scheduling have been developed for application with wind turbines. Typically, these models provide either an age based or a condition based preventive maintenance schedule. This paper proposes a wind turbine maintenance management framework which utilizes operation and maintenance data from different sources to combine the benefits of age based and condition based maintenance scheduling. A mathematical model called Preventive Maintenance Scheduling Problem with Interval Costs (PMSPIC) is presented with modification for the maintenance optimization considering both age based and condition based failure rate models. The application of the maintenance management framework is demonstrated with case studies which illustrate the advantage of the proposed approach.
•A framework which provides tools for utilization of data from various sources for optimal maintenance strategy is presented.•An optimization model is presented and compared to a frequently used simple model and the implications are discussed.•The optimization model is modified for a hybrid maintenance plan, considering age-based and condition-based strategies.•A novel approach for utilizing the proportional hazards model is presented for condition based maintenance scheduling.
Supervisory Control and Data Acquisition (SCADA) systems are the underlying monitoring and control components of critical infrastructures, such as power, telecommunication, transportation, pipelines, ...chemicals and manufacturing plants. Legacy SCADA systems operated on isolated networks, that made them less exposed to Internet threats. However, the increasing connection of SCADA systems to the Internet, as well as corporate networks, introduces severe security issues. Security considerations for SCADA systems are gaining higher attention, as the number of security incidents against these critical infrastructures is increasing. In this survey, we provide an overview of the general SCADA architecture, along with a detailed description of the SCADA communication protocols. Additionally, we discuss certain high-impact security incidents, objectives, and threats. Furthermore, we carry out an extensive review of the security proposals and tactics that aim to secure SCADA systems. We also discuss the state of SCADA system security. Finally, we present the current research trends and future advancements of SCADA security.
Current wind turbine (WT) studies focus on improving their reliability and reducing the cost of energy, particularly when WTs are operated offshore. A supervisory control and data acquisition (SCADA) ...system is a standard installation on larger WTs, monitoring all major WT sub-assemblies and providing important information. Ideally, a WT's health condition or state of the components can be deduced through rigorous analysis of SCADA data. Several programmes have been made for that purposes; however, the resulting cost savings are limited because of the data complexity and relatively low number of failures that can be easily detected in early stages. This study proposes a new method for analysing WT SCADA data by using an a priori knowledge-based adaptive neuro-fuzzy inference system with the aim to achieve automated detection of significant pitch faults. The proposed approach has been applied to the pitch data of two different designs of 26 variable pitch, variable speed and 22 variable pitch, fixed speed WTs, with two different types of SCADA system, demonstrating the adaptability of the approach for application to a variety of techniques. Results are evaluated using confusion matrix analysis and a comparison study of the two tests is addressed to draw conclusions.
Application of computing and communications intelligence effectively improves the quality of monitoring and control of smart grids. However, the dependence on information technology also increases ...vulnerability to malicious attacks. False data injection (FDI), that attack on the integrity of data, is emerging as a severe threat to the supervisory control and data acquisition system. In this paper, we exploit deep learning techniques to recognize the behavior features of FDI attacks with the historical measurement data and employ the captured features to detect the FDI attacks in real-time. By doing so, our proposed detection mechanism effectively relaxes the assumptions on the potential attack scenarios and achieves high accuracy. Furthermore, we propose an optimization model to characterize the behavior of one type of FDI attack that compromises the limited number of state measurements of the power system for electricity theft. We illustrate the performance of the proposed strategy through the simulation by using IEEE 118-bus test system. We also evaluate the scalability of our proposed detection mechanism by using IEEE 300-bus test system.
Detecting Integrity Attacks on SCADA Systems Mo, Yilin; Chabukswar, Rohan; Sinopoli, Bruno
IEEE transactions on control systems technology,
07/2014, Letnik:
22, Številka:
4
Journal Article
Recenzirano
Odprti dostop
Ensuring security of systems based on supervisory control and data acquisition is a major challenge. The goal of this paper is to develop the model-based techniques capable of detecting integrity ...attacks on the sensors of a control system. In this paper, the effect of integrity attacks on the control systems is analyzed and countermeasures capable of exposing such attacks are proposed. The main contributions of this paper, beyond the novelty of the problem formulation, lies in enumerating the conditions of the feasibility of the replay attack, and suggesting countermeasures that optimize the probability of detection by conceding control performance. The methodologies are shown and the theoretical results are validated using several sets of simulations.
Pipeline bursting, production lines shut down, frenzy traffic, trains confrontation, the nuclear reactor shut down, disrupted electric supply, interrupted oxygen supply in ICU – these catastrophic ...events could result because of an erroneous SCADA system/ Industrial Control System (ICS). SCADA systems have become an essential part of automated control and monitoring of Critical Infrastructures (CI). Modern SCADA systems have evolved from standalone systems into sophisticated, complex, open systems connected to the Internet. This geographically distributed modern SCADA system is more vulnerable to threats and cyber attacks than traditional SCADA. Traditional SCADA systems were less exposed to Internet threats as they operated on isolated networks. Over the years, an increase in the number of cyber-attacks against the SCADA systems seeks security researchers’ attention towards their security. In this review paper, we first review the SCADA system architectures and comparative analysis of proposed/implemented communication protocols, followed by attacks on such systems to understand and highlight the evolving security needs for SCADA systems. A short investigation of the current state of intrusion detection techniques in SCADA systems is done, followed by a brief study of testbeds for SCADA systems. The cloud and Internet of things (IoT) based SCADA systems are studied by analyzing modern SCADA systems’ architecture. In the end, the review paper highlights the critical research problems that need to be resolved to close the security gaps in SCADA systems.
Pada penelitian ini diimplementasikan sistem kontrol kecepatan dan posisi sejajar 2 benda pada conveyor yang berbeda. Setiap conveyor memiliki sensor jarak. Selisih data jarak pada masing masing ...conveyor digunakan untuk kontrol posisi sejajar saat conveyor aktif. Selain itu terdapat variasi beban yang perlu dikontrol untuk tetap mencapai kecepatan yang diperlukan. Sistem ini menggunakan hardware (PLC Siemens S7-300), Software (Simatic Manager), dan mekanik berupa motor conveyor untuk sinkronisasi posisi 2 benda. Pada Fuzzy terdapat 4 input dan 1 output berupa setpoint kecepatan motor. Setpoint ini diproses oleh kontrol PID dengan umpan balik yang berasal dari data rotary encoder atas kecepatan motor yang berubah karena variasi beban. Program Fuzzy-PID diimplemetasikan dengan instruksi dasar (tidak menggunakan fitur add-on software atau Function Block) dan ditanam pada 2 buah PLC yang saling berkomunikasi. Hasil pengujian kecepatan motor paling cepat dan stabil pada 50 rpm terhadap variasi beban 2.5 kg sampai 9.5 kg dengan respon waktu kembali menuju steady state sebesar 200ms (pemberian beban) dan sebesar 350 ms (pelepasan beban). Hasil output fuzzy1 mempunyai galat rata-rata sebesar 5% dan output fuzzy 2 sebesar 5.7%.
As information and communication networks are highly interconnected with the power grid, cyber security of the supervisory control and data acquisition (SCADA) system has become a critical issue in ...the electric power sector. By exploiting the vulnerabilities in cyber components and intruding into the local area networks of the control center, corporation, substations, or by injecting false information into communication links, the attackers are able to eavesdrop critical data, reconfigure devices, and send trip commands to the intelligent electronic devices that control the system breakers. Reliability of the power system can thus be impacted by various cyber attacks. In this paper, four attack scenarios for cyber components in networks of the SCADA system are considered, which may trip breakers of physical components. Two Bayesian attack graph models are built to illustrate the attack procedures and to evaluate the probabilities of successful cyber attacks. A mean time-to-compromise model is modified and adopted considering the known and zero-day vulnerabilities on the cyber components, and the frequencies of intrusions through various paths are estimated. With increased breaker trips resulting from the cyber attacks, the loss of load probabilities in the IEEE reliability test system 79 are estimated. The simulation results demonstrate that the power system becomes less reliable as the frequency of successful attacks on the cyber components increases and the skill levels of attackers increase.
This paper presents a new methodology – based on cointegration analysis of Supervisory Control And Data Acquisition (SCADA) data – for condition monitoring and fault diagnosis of wind turbines. ...Analysis of cointegration residuals – obtained from cointegration process of wind turbine data – is used for operational condition monitoring and automated fault and/or abnormal condition detection. The proposed method is validated using the experimental data acquired from a wind turbine drivetrain with a nominal power of 2 MW under varying environmental and operational conditions. A two-stage cointegration-based procedure is performed on six process parameters of the wind turbine, where data trends have nonlinear characteristics. The method is tested using two case studies with known faults. The results demonstrate that the proposed method can effectively analyse nonlinear data trends, continuously monitor the wind turbine and reliably detect abnormal problems.
•New method based on cointegration analysis of SCADA data is proposed for condition monitoring of wind turbines.•The method is illustrated using two experimental case studies from wind turbine data.•The method can effectively analyse nonlinear data trends, continuously monitor the wind turbine and reliably detect abnormal problems.
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