Vector control of a position sensorless SPMSM drive with RNN based stator flux estimator

A position sensorless Surface Permanent Magnet Synchronous Motor (SPMSM) drive based on single layer Recurrent Neural Network (RNN) is presented in this paper. The motor equations are written in rotor fixed d-q reference frame. A PID controller is used to process the speed error to generate the reference torque current keeping the magnetizing current fixed. The RNN estimator is used to estimate flux components along the stator fixed stationary axes. The flux angle and the reference current phasor angle are used in vector rotator to generate the reference phase currents. Hysteresis current controller block controls the switching of the three phase inverter to apply voltage to the motor stator. Simulation studies on different operating conditions indicate the acceptability of the drive system. The proposed estimator can be used to accurately measure the motor fluxes and rotor angle over a wide speed range. The proposed control scheme is robust under load torque disturbances and motor parameter variations. It is also simple and low cost to implememnt in a practical environment

A comparative study of different power system stabilizers for dynamic stability analysis

Power system stabilizers (PSSs) are extensively used to ensure the dynamic stability of power systems through the modulation of excitation signals supplied to synchronous generators. This paper presents a comparative study of two different PSSs: STAB1 and IEEEST. The stabilizers are designed for the linearized model of a single machine infinite bus (SMIB) system with different loads. Both time-and frequency-domain simulations are carried out to investigate the performance of these stabilizers. For all PSSs, the time-domain simulations are performed by applying a three-phase short-circuit fault at the terminal of the synchronous generator. These simulation results are compared against the open-loop characteristics of the SMIB system where no PSS is implemented. Simulation results demonstrate that the speed-fed PSS provides more damping as compared to frequency- and power-fed stabilizers.

A nonlinear adaptive backstepping approach for coordinated excitation and steam-valving control of synchronous generators

Steam-valving and excitation systems play an important role to maintain the transient stability of power systems with synchronous generators when power systems are subjected to large disturbances and sudden load changes. This paper presents a nonlinear adaptive backstepping approach for controlling excitation and steam-valving systems of synchronous generators. In this paper, the proposed excitation and steam-valving controllers are designed in a coordinated manner so that they can work under several and most severe operating conditions. Both excitation and steam-valving controllers are designed by considering some critical parameters as unknown. The effectiveness of the proposed coordinated control scheme is evaluated on a single machine infinite bus system under different operating conditions such as load changes and three-phase short circuit faults at the generator terminal. Finally, performance of the proposed scheme is compared to that of a similar nonlinear adaptive backstepping excitation controller without any coordination and simulation results demonstrate the superiority of the proposed one.

Nonlinear excitation control of synchronous generators based on adaptive backstepping method

n this paper, the design of a nonlinear excitation control of a synchronous generator is presented where the generator is connected to a single machine infinite bus (SMIB) system. An adaptive backstepping method is used to design the excitation controller with an objective of enhancing the overall dynamic stability of the SMIB system under different contingencies. In this paper, two types of contingencies are considered- i) unknown parameters and physical quantities during the controller design process and ii) controller performance evaluation under different system configurations such as three-phase short circuit faults. The adaption law, which is mainly based on the formulation of Lyapunov function, is used to estimate the unknown parameters which guarantee the convergence of different physical quantities of synchronous generators, e.g., the relative speed, terminal voltage, etc. The effectiveness of the proposed scheme is evaluated under different system configurations as mentioned in the second contingency and compared to that of an existing adaptive backstepping controller and a conventional power system stabilizer (PSS). Simulation results demonstrate the superiority of the proposed control scheme over the existing controllers.

Nonlinear adaptive excitation controller design for multimachine power systems

This paper presents a nonlinear adaptive excitation control scheme to enhance the dynamic stability of multimachine power systems. The proposed controller is designed based on the adaptive backstepping technique where the mechanical power input to the generators and the damping coefficient of each generator are considered as unknown. These unknown quantities are estimated through the adaption laws. The adaption laws are obtained from the formulation of Lyapunov functions which guarantee the convergence of different physical quantities of generators such as the relative speed, terminal voltage, and electrical power output. The proposed scheme is evaluated by applying a three-phase short-circuit fault at one of the key transmission lines in an 11-bus test power system and compared with an existing backstepping controller and conventional power system stabilizer (CPSS). Simulation results show that the proposed scheme is much more effective than existing controllers.

An efficient mapreduce-based parallel clustering algorithm for distributed traffic subarea division

Traffic subarea division is vital for traffic system management and traffic network analysis in intelligent transportation systems (ITSs). Since existing methods may not be suitable for big traffic data processing, this paper presents a MapReduce-based Parallel Three-Phase K -Means (Par3PKM) algorithm for solving traffic subarea division problem on a widely adopted Hadoop distributed computing platform. Specifically, we first modify the distance metric and initialization strategy of K -Means and then employ a MapReduce paradigm to redesign the optimized K -Means algorithm for parallel clustering of large-scale taxi trajectories. Moreover, we propose a boundary identifying method to connect the borders of clustering results for each cluster. Finally, we divide traffic subarea of Beijing based on real-world trajectory data sets generated by 12,000 taxis in a period of one month using the proposed approach. Experimental evaluation results indicate that when compared with K -Means, Par2PK-Means, and ParCLARA, Par3PKM achieves higher efficiency, more accuracy, and better scalability and can effectively divide traffic subarea with big taxi trajectory data.

A review of the game-centred approaches to teaching and coaching literature since 2006

Background: In 2006, Oslin and Mitchell published a review of the game-centred approaches (GCAs) to teaching and coaching literature highlighting a number of core concepts thought to provide justification for the use of GCAs including (a) its potential to enhance participant motivation, (b) potential for tactical transfer, and (c) development of decision-making skills and effective decision-makers. Oslin and Mitchell also suggested recommendations for future GCA research.Purpose: The purpose of this paper was threefold: (a) to present a review of Anglophone research into GCAs building on the previous review of Oslin and Mitchell published in 2006; (b) to identify new trends in research since 2006; and (c) to investigate the extent to which the initial suggestions and future research directions suggested by Oslin and Mitchell have been addressed.Data collection: GCA literature since 2006 was searched systematically using a three-phase approach. Phase 1 included initial searches of the EBSCO database using terms associated with GCAs and their acronyms (e.g. TGfU (teaching games for understanding), GS (Game Sense), etc.). Phase 2 expanded the search adopting more generic terms from keywords located in the recent literature (e.g. teaching games, tactical development, game performance, etc.). Multiple searches through the EBSCO database were conducted, whereby key terms were cross-referenced until a saturation point was reached. Phase 3 involved removing those publications that were not empirical, peer reviewed, intervention studies or published in English.Findings: Forty-four studies on GCA implementation were identified and the methodological and substantive nature of these studies was examined. The review noted two positive trends: (a) the expansion of research which included the growth of research on GCAs in Europe and Southeast Asia and (b) an increased amount of research in the affective domain. The review found, however, that a number of key challenges remain within GCA research, which include (a) the need for improved articulation of GCA verification procedures; (b) further assessment of tactical awareness development; (c) extended inquiry about GCAs in coaching contexts; (d) more research into ‘newer’ GCAs (i.e. PP (play practice), IGCM (invasion game competence model) and TDLM (tactical decision learning model)); (e) use of longitudinal research designs; (f) inadequate length of GCA induction and training for teachers and coaches, and (g) examination of GCAs in terms of fitness and special populations.Conclusions: GCA pedagogies are of significant importance as they have the potential to promote change within current adult-centric cultures of youth sport and encourage engagement in physical activity over the life course. To meet these needs, it is recommended that GCA research undergo continued expansion with the use of research designs and data collection techniques that aid the examination of different philosophical understandings of GCAs (e.g. ethnographic, phenomenological and psycho-phenomenological). These are paramount to the exploration of ‘who the individual is’ and ‘how the learner is motivated to continue to participate’ and further permit the in-depth, contextual and ecological analysis of GCA interventions that Oslin and Mitchell recommended in their previous review.

Using a delphi process to extend a rural mental health workforce recruitment initiative

Purpose – The Gippsland Mental Health Vacation School program has been shown to positively change student participants’ interest and attitudes to living and working in a rural area. A range of factors are impacting on the future viability of the initiative including: limitations on the number of student participants, the reusability of content, staffing, time pressures, a dwindling funding base, and a drop-off in interest in living and working in a rural setting. The paper aims to discuss these issues. Design/methodology/approach – A three-phase Delphi Study was employed to engage with expert knowledge of the program’s key stakeholder groups (student participants and service provider staff) in order to inform the initial steps of shifting the program toward a blended model, distributed across space and time. Findings – The results suggest that: first, the current mode of delivery, a week-long intensive face-to-face format, should be transitioned to a more sustainable blended learning approach that includes both on-line content and an in situ component; and second, trailing the use of social media as a mechanism to maintain student interest in rural mental health work following the vacation school. Originality/value – This study highlights how the transition to a sustainable approach to the delivery of a novel rural mental health workforce recruitment strategy was informed through a three-phase Delphi Study that involved the key stakeholders (groups of student participants and service provider staff). The study has important implications for addressing the shortage of mental health practitioners in rural areas. It will and be of interest to educators, administrators, researchers and bureaucrats.