Minimal set of generators of controllability space for singular linear dynamical systems

Due to the significant role played by singular systems in the form E ¿ x ( t ) = Ax ( t ) , on mathematical modeling of science and engineering problems; in the last years recent years its interest in the descriptive analysis of its structural and dynamic properties. However, much less effort has been devoted to studying the exact con- trollability by measuring the minimum set of controls needed to direct the entire system E ¿ x ( t ) = Ax ( t ) to any desired state. In this work, we focus the study on obtaining the set of all matrices B with a minimal number of columns, by making the singular system E ¿ x ( t ) = Ax ( t ) + Bu ( t ) controllable.Postprint (author's final draft

Genetic variability on leaf morpho-anatomical traits in relation to sterility mosaic disease (SMD) resistance in pigeonpea

Abstract Sterility mosaic disease (SMD) is a major biotic constraint in almost all pigeonpea growing areas caused by eriophyid mite transmitted pigeonpea sterility mosaic virus (PPSMV). Direct selection for resistance to SMD is expensive and laborious as it requires dependent of sick plots. Identification of easily assayable and simply inherited morphological traits such as leaf anatomical traits would enable increased efficiency of breeding pigeonpea for SMD resistance. A set of 70 pigeonpea accessions were evaluated for 12 leaf structural features such as leaf thickness (LT), upper epidermal thickness (UEPT), lower epidermal thickness (LEPT), upper cuticle cell wall complex (UCWC), lower cuticle cell wall complex (LCWC), trichome number on upper surface of leaf (TNUS), trichome number on lower surface of leaf (TNLS), trichome length on upper surface of leaf (TLUS) and on lower surface of leaf (TLLS) at experimental plots of Zonal Agricultural Research Station (ZARS), UAS, Bengaluru. The accessions differed significantly for most of the traits except for specific leaf area (SLA) and specific leaf weight (SLW). The accessions were grouped into four clusters, with significant differences in cluster means and variances. Principal component analysis (PCA) showed first three PCs explaining 69.70 % of the total variation and morpho-anatomical traits such as leaf thickness (LT), trichome length on upper (TLUS) and lower (TLLS) surface of leaf were the most important characters for disease incidence. Furthermore, correlation of all the leaf traits in relation to percent incidence (PDI) indicated only TLLS having significant negative correlation (-0.456*) with SMD incidence. While, trichome length also showed higher phenotypic (PCV) and genotypic (GCV) coefficient of variation 34.33 and 34.02, respectively and broad senesce heritability (98.2%) coupled with high genetic advance (69.45). Therefore, breeding for trichome length is very important to impart vector resistance. This may provide broad based resistance to all the isolates of SMD in pigeonpea

On-line power system inertia calculation using wide area measurements

Future developments in power systems, e.g. relatively larger generator sets, the virtual power plant and synthetic inertia concept and connection of generation assets over inverters, will cause the system inertia to vary significantly. During system operation, if the inertia of the system is significantly lower than anticipated at the planning stage, then the existing, deterministic protection and control may fail to ensure system stability. Therefore, the ability to accurately determine the inertia of individual system areas, and the system as a whole, online would be very useful. In this paper, an Inertia Calculation Application (ICA), which could be implemented as part of a Wide Area Monitoring Protection and Control scheme, is presented. The necessary wide area measurements must be processed during large disturbances to the active power balance of the system. The ICA has been validated by using computer simulations, under laboratory conditions and by using real-life data recorded by a transmission system operator

An Input-to-State Stability Approach to Verify Almost Global Stability of a Synchronous-Machine-Infinite-Bus System

Conditions for almost global stability of an operating point of a realistic model of a synchronous generator with constant field current connected to an infinite bus are derived. The analysis is conducted by employing the recently proposed concept of input-to-state stability (ISS)–Leonov functions, which is an extension of the powerful cell structure principle developed by Leonov and Noldus to the ISS framework. Compared with the original ideas of Leonov and Noldus, the ISS–Leonov approach has the advantage of providing additional robustness guarantees. The efficiency of the derived sufficient conditions is illustrated via numerical experiments

High-performance predictor for critical unstable generators based on scalable parallelized neural networks

A high-performance predictor for critical unstable generators (CUGs) of power systems is presented in this paper. The predictor is driven by the MapReduce based parallelized neural networks. Specifically, a group of back propagation neural networks (BPNNs), fed by massive response trajectories data, are efficiently organized and concurrently trained in Hadoop to identify dynamic behaviour of individual generator. Rather than simply classifying global stability of power systems, the presented approach is able to distinguish unstable generators accurately with a few cycles of synchronized trajectories after fault clearing, enabling more in-depth emergency awareness based on wide-area implementation. In addition, the technique is of rich scalability due to Hadoop framework, which can be deployed in the control centers as a high-performance computing infrastructure for real-time instability alert. Numerical examples are studied using NPCC 48 machines test system and a realistic power system of China

Performance of wide-area power system stabilizers during major system upsets: investigation and proposal of solutions

© 2021 Springer Nature Switzerland AG. This is a post-peer-review, pre-copyedit version of Benasla, M., Denaï, M., Liang, J. et al. Performance of wide-area power system stabilizers during major system upsets: investigation and proposal of solutions. Electr Eng (2021). The final authenticated version is available online https://doi.org/10.1007/s00202-020-01168-3Wide-area damping controllers (WADCs) are effective means of improving the damping of inter-area oscillations and thereby ensuring a secure operation of modern highly stressed interconnected power systems; however, their implementation costs are high. Therefore, the controller must be well configured and designed to ensure its cost-effectiveness. Several techniques have been proposed in the literature to design effective controllers and good results have been achieved. However, some important practical aspects that could potentially impact the performance of the designed controller have not been addressed or studied in sufficient detail in these previous works. One such aspect is assessing the performance of the designed controllers under major system upsets resulting in large deviations in the frequency and fluctuations in the power. These may lead to controller saturation which could negatively impact its damping performance or even cause instability. In this paper, the impact of such large upsets is investigated on several test systems via extensive small- and large-signal analyses and it is shown that, during severe transients, controller saturation may occur and persist over a long period of time, posing a potential threat to the power system stability. This paper presents a very effective solution to alleviate this problem and help design more robust WADCs. The simulation results show that the proposed solution works well and leads to improved power system stabilisers performance during transient upsets.Peer reviewedFinal Accepted Versio

An Improved On-line Contingency Screening for Power System Transient Stability Assessment

peer reviewedThis paper presents a contingency screening method and a framework for its on-line implementation. The proposed method carries out contingency screening and on-line stability assessment with respect to first-swing transient stability. For that purpose, it utilizes the single machine equivalent method and aims at improving the prior developed contingency screening approaches. In order to determine vulnerability of the system with respect to a particular contingency, only one time-domain simulation needs to be performed. An early stop criteria is proposed so that in a majority of the cases the simulation can be terminated after a few hundred milliseconds of simulated system response. The method’s outcome is an assessment of the system’s stability and a classification of each considered contingency. The contingencies are categorized by exploiting parameters of an equivalent one machine infinite bus system. A novel island detection approach, appropriate for an on-line application since it utilizes efficient algorithms from graph theory and enables stability assessment of individual islands, is also introduced. The New England and New York system as well as the large-scale model of the Continental-European interconnected system are used to test the proposed method with respect to assessment accuracy and computation time

Die Attraktivität großer Städte - ökonomisch, demografisch, kulturell: Ergebnisse eines Ressortforschungsprojekts des Bundes

In einer Reihe deutscher Großstädte zeichnet sich seit Jahren eine positive Bevölkerungsentwicklung ab, während Suburbanisierungstendenzen rückläufig sind. Diese Entwicklung hat in Fachkreisen eine umfassende Re-Urbanisierungsdebatte ausgelöst. Damit verbunden die Hoffnung, das planerische Ideal von Urbanität, kompakter Stadtentwicklung sowie von weniger Pendlerverkehr und Zersiedelung werde sich nun endlich umsetzen lassen. Wie schätzen die Städte selber diesen Trend, seine Ursachen und Folgen ein? Wer wandert in die Städte und in welche Stadtquartiere? Wie geht die Stadtplanung mit dem Wachstum um, was hat sie dazu beigetragen? In einem Ressortforschungsprojekt des Bundesministeriums für Verkehr, Bau und Stadtentwicklung (BMVBS) hat das Bundesinstitut für Bau-, Stadt- und Raumforschung (BBSR) dieses Thema zusammen mit Vertreterinnen und Vertretern aus der Verwaltung deutscher Großstädte behandelt, die in den letzten Jahren ein kontinuierliches Wachstum ihrer Bevölkerungszahlen zu verzeichnen hatten - darunter München, Bonn, Jena und Ingolstadt. Die Publikation lenkt den Blick ganz konkret auf einige der wachsenden Städte, die an dem Projekt beteiligt waren, auf die Ursachen sowie stadtentwicklungspolitischen Implikationen ihres Wachstums. Expertenbeiträge greifen zudem aktuelle Aspekte der Entwicklung der Städte und des Städtischen auf

Modelling, Simulation and Fuzzy Self-Tuning Control of D-STATCOM in a Single Machine Infinite Bus Power System

© 2019 Bentham Science Publishers. This is the accepted manuscript version of an article which has been published in final form at https://doi.org/10.2174/2352096511666180314141205In recent years, demand for electricity has increased considerably, while the expansion of generation and transmission has been very slow due to limited investment in resources and environmental restrictions. Methods: As a result, the power system becomes vulnerable to disturbances and instability. FACTS (Flexible AC Transmission Systems) technology has now been accepted as a potential solution to this problem. This paper deals with the modelling, simulation and fuzzy self-tuning control of a D-STATCOM to enhance the stability and improve the critical fault clearing time(CCT) in a single machine infinite bus (SMIB).A detailed modelling of the D-STATCOM and comprehensive derivation of the fuzzy logic self-tuning control is presented. Results: The dynamic performance of the power system with the proposed control scheme is validated through in a simulation study carried out under Matlab/Simulink and SimPowerSystems toolbox. Conclusion: The results demonstrate a significant enhancement of the power system stability under the simulated fault conditions considered.Peer reviewe