Firing Angle Research Articles

Traction drive simulations when starting an electric locomotive series ŽS 444 on the railway tracks of Serbia

The manuscript presents and describes the Model in Matlab-simulink, which allows to display the time change of the firing angle of the thyristor of the single-phase rectifier, the mean value of the voltage, the armature current and the speed of the electric motor during the start-up of the electric locomotive ŽS 444 series for different given mechanically loaded and reference speeds of traction electric motors. The model makes it possible to establish the desired reference speed change ramps for different reference speeds and mechanical loads from +250 rpm, i.e., the maximum current of the electric motor armature up to 1250 A.

Enhancing SRM Performance through Multi-Platform Optimization and FPGA-Based Real-Time Simulation

This paper proposes a multi-platform algorithm methodology in order to define firing angles of torque sharing functions (TSFs) for the indirect torque control of switched reluctance motors (SRM) through a hardware-in-the-loop (HIL) system. This proposal is used to achieve optimal levels of torque ripple and losses with accuracy and reliability, while taking advantage of real-time simulation. The analysis is performed assuming steady-state conditions of speed and torque reference for levels below the base speed, aiming to obtain firing angles ensuring optimal tracking performance. A novel methodology is proposed by using a grid search algorithm that handles the communication between Python, Code Composer, and the Typhoon HIL device. For that, an experimental data FPGA-based model with 500~ns of simulation time step is used to ensure highly accurate dynamic responses of current and electromagnetic torque. Moreover, controller-HIL (C-HIL) is used to have a safe and high fidelity testing environment, allowing rapid testing before transitioning to an experimental test bench. The simulation results are experimentally validated, demonstrating that the proposed strategy is effective and ensures optimal performance, taking into account peripheral systems of A/D, signal conditioning, PWM, and sensor emulation.

An Interactive Pedagogical Tool for Simulation of Controlled Rectifiers

Active learning approaches, incorporating student engagement through experimentation and problem solving, effectively foster higher-level thinking abilities and enhance academic performance. Interactive tools like simulators align with these methodologies, but commercially available simulators have limitations; particularly, their high cost and lack of customization features pose significant challenges for many educational institutions. This article presents CORES, a web-based educational application designed to simulate controlled rectifier circuits. CORES eliminates the need for intricate circuit assembly and software installation by providing pre-built circuits so that users can concentrate on analyzing circuit behavior by manipulating the thyristor firing angle and load characteristics, while the application generates output voltage and current waveforms under steady-state conditions, minimizing computation time. CORES has proven to be a valuable pedagogical tool, surpassing commercial simulators in terms of accessibility, ease of use, and enriched learning experiences for power electronics students and educators.

Optimization of an IPMSM for Constant-Angle Square-Wave Control of a BLDC Drive

Interior permanent magnet synchronous machines (IPMSMs) driven with a square-wave control (i.e., six-step, block, or 120° control), known commonly as brushless direct current (BLDC) drives, are used widely due to their high power density and control simplicity. The advance firing (AF) angle is employed to achieve improved operation characteristics of the drive. The AF angle is, in general, applied to compensate for the commutation effects. In the case of an IPMSM, the AF angle can also be adjusted to exploit reluctance torque. In this paper, a detailed study was performed to understand its effect on the drive’s performance in regard to reluctance torque. Furthermore, a multi-objective optimization of the machine’s cross-section using neural network models was conducted to enhance performance at a constant AF angle. The reference and improved machine designs were evaluated in a system-level simulation, where the impact was considered of the commutation of currents. A significant improvement in the machine performance was achieved after optimizing the geometry and implementing a fixed AF angle of 10°.

Real-Time Rotor Ground Fault Protection Based on the Convolution Integral for Synchronous Motors With Static Excitation

The detection of motor failures is a very active research topic within the literature. In particular, ground faults in wound rotors of synchronous motors have a relatively high failure rate since the rotor winding is exposed concomitantly to electrical, mechanical, and thermal stress cycles. Its detection depends on the grounding type of the electrical power system, and, in its early stages, it may present significant resistance. This manuscript provides a new rotor ground fault protection method based on the convolution integral of the neutral voltage that is measured by a single extra sensor. In addition, it is able to fill out the gaps of the current state-of-the-art, such as: provides a larger detection frontier for incipient faults; has low sensitivity for dynamic variances of the firing angle, allowing its utilization in cyclical applications; and can be implemented in power electronic controller systems with limited bandwidth. In this sense, mathematical modeling, simulations and experimental data are presented to support to the proposed method. Furthermore, it was implemented in the controller of static excitation converters for real-time protection and successfully tested with synchronous motors (2.4MW/3.3kV) of a cold rolling mill plant owned by ArcelorMittal Group.

Controlling of Induction Motor

Abstract: This paper describes how to use an Arduino Uno to regulate the speed of an induction motor and create an energyefficient, smooth control system. Due to their affordability and adaptability, induction motors are frequently utilized in industrial drives; nevertheless, the rangeof speed control available with stator control is limited. Controlling the firing angle and utilizing power electrical gadgets can help fix this issue. The goal is to use stator control to regulate the induction motor's speed. This hardware provides a signal to the microprocessor, which manages the power supply to the electronic devices. Through the use of an Arduino Uno to adjust the firing angle of a semiconductor power device, the motor's stator winding's terminal voltage canbe controlled

Examining the Thyristor-Controlled Reactor's (TCR) Performance to minimize Self-Generated Harmonics.

This work discusses the minimizing of self-generated harmonics in a Thyristor Controlled Reactor (TCR) used in a power distribution system. When a nonlinear load is connected to the system, power quality difficulties arise, including reactive power compensation, harmonics, voltage unbalance, poor power factor, and so on. These flaws degrade the power quality of the system. FACTS and electronics devices are most commonly employed for reactive power correction. A conventional Static VAR compensator is the best option for this application. The static VAR compensator consists of either a fixed capacitor-thyristor controlled reactor (FC-TCR) or a thyristor switched capacitor-thyristor controlled reactor (TSC-TCR). The reactive power demand objective can be met by controlling the conduction angle of TCR. However, the switching operation of the thyristor-controlled reactor reduces power quality by adding self-generated harmonics into the system. The proposed topology in this study outlines the usage of a delta-connected TCR to reduce self-generated harmonics rather than a thyristor controlled reactor (SCR).
 The work carried out in this paper has two major sections
 
 Determine (a) the firing angle range for reactive power adjustment, and (b) the mechanism to control inductive susceptibility. 2. A comparison of three presented methods: a) single delta connected TCR; b) Equally stepped delta connected TCR (ESTCR); and c) Binary stepped delta connected TCR (BTCR).

CSA-based harmonic elimination controlled reduced switch multilevel inverter for standalone PV system

A standalone photovoltaic (PV) system has emerged as a clean energy solution for application in remote areas. To establish such a system a suitable converter is required for voltage boosting as well as to produce high-quality output as required by the load. To achieve this, multilevel inverters (MLIs) are the proven substitute in PV systems. A conventional MLI uses multiple sources and switches that increase the cost and complexity. To provide a complete stand-alone system solution that addresses this issue, reduced component switched capacitor (SC) based seven-level MLI is disclosed in this paper. A new crow search algorithm (CSA) based selective harmonic elimination (SHE) method is employed to estimate the switching angles. The dominant harmonic orders are removed from the 7-level SC-MLI output while the desired firing angles for the switches are evaluated. Using only seven switches, the circuit boosts the voltage to 1.5 times with the aid of self-balanced capacitors. Therefore, the circuit does not require an additional control circuit for voltage balancing. The overall system is designed in MATLAB/Simulink environment to test under different operating conditions. An experimental prototype of the 7-level SCMLI is also designed to validate the CSA-based SHE control and MLI performance in real time.

Automatic Star Delta Starter with an Arduino and Relays for Three Phase Induction Motor

Abstract: The most popular low voltage starters for 50 Hz industrial motors are either star or delta starters. Their purpose is to minimize the starting current that is supplied to the motor at the beginning of operation. Three contactors, a timer, and a thermal overload are typically used in the manufacturing of Star/Delta starters, which are used to run three-phase motors at 440 volts and 50 Hz AC mains supply. But in our project, we've used the same to run a\ 3-phase motor at 440-volt AC mains supply 50 Hz with a series of 12-volt DC relays, an Arduino-provided electronically adjustable timer, and a series of tiny circuit breakers. While maintaining its application for a 3-phase motor starting with a single phasing prevention, the interlocking arrangement of the relay coils and the electronic Arduino is all wired in low voltage DC of 12 Volt fed from an inbuilt DC power supply for safe handling of the starter during the study. The timer consists of an Arduino, whose output is sent to a relay to switch the mains supply from a three-phase star to a delta. Since the 3-phase motors could burn if one of the phases disappears while they are operating, the project additionally includes single-phase protection. In the case of a phase failure, the lamps' output will be switched off. In addition, the project can be improved by utilizing thyristors in a firing angle control principle to soft start the induction motor, which would eliminate all of the star delta starter's shortcomings.

Evaluation of FACTS Contributions Using Branch Flow Model and Newton–Raphson Algorithm

Flexible alternating current transmission systems (FACTSs) have been widely incorporated in electric power systems in order to control system parameters. This paper proposes the modeling of four FACTS devices, using the Branch Flow Model (BF) as an optimization problem to reduce the complexity of the Newton–Raphson (NR) load flow code with FACTS devices. The devices are represented as variable impedances, as a function of a firing angle, and as voltage source converters (VSCs) located on the buses and transmission lines. This proposed model solves the problem associated with the selection of appropriate initial conditions of the parameters of each device that guarantee convergence. The model is validated by evaluating its percentage deviation with respect to the NR method, using the standard test systems, IEEE 5-bus, IEEE 14-bus, IEEE 30-bus, and IEEE 57-bus systems.

INTERCONNECTION OF A PHOTOVOLTAIC GENERATOR (PVG) TO A MAIN SUPPLY: A PRACTICAL STUDY

This paper presents a technique for interconnecting a photovoltaic generator (PVG) to a main supply of AC nature. The technique has been implemented practically in one of the laboratories of the author’s work place. The technique uses a single phase full wave bridge rectifier. Such bridge rectifier is operated in an inverter mode of operation and that is to guaranty its contribution of real power to a main AC supply. The bridge rectifier is controlled by a practical firing angle controller developed in LABVIEW software environment. The firing angle controller is interfaced to the power bridge rectifier through the use of simple optocoupler and pulse transformer elements. The practical results show that under a certain insolation/irradiation level (taken randomly) and for a resistive load requiring presumably130 W power , the PVG source was contributing 90 W power to such power load and the AC grid was contributing 40 W to such power load The technique of interconnection alleviates the problem of synchronization encountered often when using the traditional way of interconnecting the DC grid (made of conventional renewable energy resources) to the AC grid system.

The study of self-organised behaviours and movement pattern of pedestrians during fire evacuations: virtual experiments and survey

In this study, Minecraft was adopted to investigate pedestrian behaviours and evacuation processes in non-fire (normal) and fire conditions involving multiple simultaneous players. We built a PaddlePaddle-based deep learning platform for the automatic recognition of pedestrian coordinates from the Minecraft background database. To verify the virtual experiments in Minecraft, we conducted a series of experiments under identical conditions in a real (physical) room and virtual environment on the Minecraft platform. The pedestrian behaviour, flow patterns and evacuation time in the Minecraft experiments fit well with the results of the real-life experiments, indicating the potential of Minecraft for realistically simulating evacuation processes. To further demonstrate the feasibility of using Minecraft for evacuation studies, we conducted a series of virtual evacuation experiments with different fire configurations and room geometries in Minecraft. The pedestrians were found to keep higher distance towards fire and greater detour angle during the fire emergency in a square room. Furthermore, in the scenario of a fire in a corridor, in addition to the aforementioned fire avoidance behaviours, the pedestrians exhibited orderly queuing and exited the room one by one, resulting in increased walking speeds and thus a faster evacuation for most pedestrians. Finally, one post-experiment survey was designed to assess participants' perceptions of the Minecraft environment and the pedestrian behaviours and related psychological factors. The results show that the Minecraft can generate considerate realistic real-life situations, and pedestrians chose self-organised behaviours including away from fire, along the wall and detour towards fire in both survey and evacuation experiments.

Phase-Controlled Multibank Resistive Heating With Optimized Current Harmonics

This paper proposes an SCR phase controlled 3-phase 3-wire industrial heating system using multiple Delta Banks of resistors. In the proposed scheme, out of two similar groups denoted as ‘Set’, each has two resistance banks with a finite ratio of maximum power dissipation between them and operating with same controlled firing angle. Each bank of resistance is ‘Delta’ connected, one with SCRs in phase while the other with SCRs in line. This proposed configuration eliminates triplen besides some major characteristic harmonics in the line current. ‘Delta’ connection permits use of same voltage rating of all resistors. In the proposed scheme, two such Sets are operated with a fixed firing angle difference to substantially reduce residual harmonics without any additional filters. An offline-optimization process determines the operating conditions of the sets. The proposed scheme with simple construction & operation, wide power range, low THD makes it a practical and cost-effective solution. The modeling, analysis and performance of the proposed scheme are presented, with supporting simulation and experimental results.

Performance Prediction of D.C. Motor Fed From Half-Controlled Bridge Rectifier

Controlled rectification is the process of obtaining a controlled output DC voltage from a constant AC voltage. This can be used in the speed control of the DC motor to provide rapid torque control and a quick starting response. In this work, a three-phase half-controlled bridge rectifier has been used. The average output DC voltage varies smoothly by varying the firing angle (α). Different methods of analysis such as state-space and Fourier-series, are used to obtain the performance of the DC motor fed from the bridge-rectifier supply. However, these methods do not deal with the prediction of the discontinuous conduction phenomenon which occurs during the operation of the DC motor with a variation of delay angle. This paper deals with the prediction of performance characteristics during the operation of the DC motor fed by a 3-phase half-controlled bridge rectifier, including the transient as well as steady-state operation with a variation of delay angle as well as application of load torque at starting.

Modeling and exergy analysis of an integrated cryogenic refrigeration system and superconducting magnetic energy storage

Superconducting magnetic energy storage (SMES) systems widely used in various fields of power grids over the last two decades. In this study, a thyristor-based power conditioning system (PCS) that utilizes a six-pulse converter is modeled for an SMES system. The main subject of this research is the generation of required helium for an SMES because for the coil to be at superconducting temperature, it needs to always be immersed in liquid helium. In the conducted simulation, the helium production system provided, in which primarily the gaseous helium temperature was reduced by heat transfer in LNG heat exchangers, and then after the sudden pressure drop, it turned into a liquid. The effect of the various firing angles is investigated, and it is found that at angles lower than 90°, at a specific angle, the output current enhances with time. In the 90°, this current remains constant, and at degrees greater than 90°, the output current reduces with time. The percentage of input flows to the expanders is investigated to find the rate of the maximum liquid helium production amount to the inlet gaseous helium. The diverted ratio of mass flow via expander 1 and expander 2 was 0.46 and 0.35, respectively. The system's work utilization of network, and liquid helium production is 67.18 MW and 12.7 kg/h. Also, the exergy analysis is done and the results show 35.7 % exergy efficiency. The efficiency of helium production has a direct relation to liquid nitrogen mass flow. However, due to the required high power for producing liquid nitrogen, with mass flow rate increment, the total system's efficiency is reduced. The results are evaluated with Aspen HYSYS, Aspen Energy Analyzer, and MATLAB. Specific work obtained from the analysis is 290,097 kW.s/kg which indicates that uses lower power in comparison with the other helium production methods which saves power and electrical costs.

Characterization of four heat-treated reciprocating instruments: Design, metallurgy, mechanical performance, and irrigation flow patterns.

To compare the design, metallurgy, and mechanical properties of four heat-treated reciprocating instruments coupled with the evaluation of the irrigation flow using an in silico model. New EdgeOne Fire Primary, Easy-File Flex Regular 25, WaveOne Gold Primary and Reciproc Blue R25 instruments (n = 124) were initially evaluated regarding their design through stereomicroscopy, scanning electron microscopy and 3D surface scanning. In addition, energy-dispersive X-ray spectroscopy was utilized to determine their elemental composition, and differential scanning calorimetry tests to evaluate their phase transformation temperatures. Their mechanical performance was further assessed through torsional and bending tests. Using scans obtained from a real tooth and the instruments, a computational fluid dynamics assessment was conducted to determine the irrigation flow pattern, apical pressure, and wall shear stress in simulated canal preparation. Mood's median and One-way anova post hoc Tukey tests were used for statistical comparisons (α = 5%). Reciproc Blue exhibited a superior number of blades (n = 8), whereas EdgeOne Fire had the highest overall volume (4.38 mm3 ) and surface area (32.32 mm2 ). At the 3-mm axial level, EdgeOne Fire displayed the lowest core diameter (0.13 mm), while Reciproc Blue had the highest (0.16 mm). All blades were symmetrical, and the tips of the instruments were non-active but differed from each other. The most irregular surfaces were observed in EdgeOne Fire and Easy-File Flex. All instruments were manufactured from nickel-titanium alloys and exhibited distinct phase transformation temperatures. WaveOne Gold and Reciproc Blue demonstrated the highest maximum torque values (1.87 and 1.62 N cm, respectively), while the lowest was observed on EdgeOne Fire (1.21 N cm) (p < .05). The most flexible (p < .05) were EdgeOne Fire (angle of rotation: 602.6°; maximum bending load: 251.4 g.f) and Reciproc Blue (533.2° and 235.6 g.f). There were no significant differences observed in the irrigation flow among the four domains generated by the tested instruments. Despite observing variations in the design, phase transformation temperatures, and in the torsional and bending test outcomes among the four heat-treated reciprocating instruments, no significant differences were found in the irrigation flow pattern among the different groups in the simulated root canal preparations.

A Novel Methodology for Fault Sensing in Presence of Power Swing for Transmission Line with Thyristor Controlled Series Compensator

Digital distance relaying is implemented in extra high voltage (EHV) transmission network for speedy and reliable fault detection. But it should not activate in case of slow transients known as power swings. However, for occurrence of any type of fault during power swing, the relay should sense the faulty condition and send trip command to concerned circuit breaker. The detection of fault in a transmission line network with TCSC during the power swing condition has become further complex due to transients generated by series capacitor and the metal–oxide varistor (MOV) protecting it. This paper firstly presents effect of TCSC on distance relay operation for varied TCSC degree of compensation and firing angle values. Further, a discrete wavelet transform-based fast acting fault and swing classification algorithm is proposed which can sense all types of faults during slow as well as fast power swing in first decomposition level and within 0.001 sec. The proposed utilizes optimized threshold values both for swing and fault sensing by using Honey Bee Optimization Algorithm (HBOA). The proposed novel algorithm is coded in MATLAB software and the test system comprising of 400kV, 50Hz parallel transmission line network along with TCSC is built using MATLAB Simulink environment with sim power systems toolbox. It is tested for high/low resistance faults, symmetrical/asymmetrical faults and close-in/far end faults by changing TCSC compensation level and firing angle value. The simulation results prove the accuracy of proposed methodology for swing and fault classification.

An Automatable Approach for Small-Signal Stability Analysis of Power Electronic-Based Power Systems Using EMT Companion Circuits

The increasing presence of power electronic (PE) controlled devices in power systems has widened the bandwidth of transients to be studied for grid stability. While these transients are normally studied using time-domain simulation (TDS), wide bandwidth linear time-invariant (LTI) state-space models are a useful complement to TDS for diagnostics, controller design and parametric analysis. A general automatable method to compute an LTI sampled-data model of a PE-based circuit is presented in this paper. The proposed method is based on the techniques employed in electro-magnetic-transient (EMT) programs to perform TDS of PE-based circuits. The method uses the building blocks of EMT nodal formulation such as conductance matrix of companion circuit and its LU factors computed during TDS, interpolation and chatter elimination corrections, and EMT model of the firing angle control system. The method yields a small-signal LTI sampled-data model which is amenable to eigenanalysis and is illustrated using simple PE-based circuits such as a buck converter and a grid-connected STATCOM with closed-loop control.

Faulty phase identification and ground detection in TCSC compensated lines integrated with wind farms

Nowadays there is a trend for offshore wind farms to be connected with power grids through a TCSC series controlled compensating device employed in transmission lines for the improvement of large power flows. In such transmission lines, faulty phase identification and ground detection create a challenge for conventional distance relaying schemes because of non-linear output power fluctuation due to variations in wind speed and different firing angle operations of TCSC. Therefore, to overcome the problem of such transmission lines relaying, a novel time-frequency analysis-based intrinsic time scale decomposition (ITD) method is proposed in this paper. The proposed intrinsic time scale decomposition method uses only a three-phase grid side current from relaying end for faulty phase and ground detection and ITD supported random forest classifier for fault classification accuracy approach. The evaluation of the proposed scheme is tested on several fault cases with varying system parameters and non-fault transient events through the EMTDC/PSCAD platform during different wind speeds and varying firing angle operations of TCSC. The performance of the proposed scheme is also verified through a real-time interface dSPACE DS 1104 control prototype hardware. Finally, a comparison analysis with existing techniques demonstrated the effectiveness of the presented method to assess the mentioned problem of the conventional protective relaying schemes. The proposed method demonstrated a 100% accuracy for faulty phase selection and a 99.99% accuracy for fault classification.

Influence of sidewall restriction on flame characteristics of double fires in a channel

In this paper, the influences of sidewall restriction on flame characteristics of double fires in a channel were studied. Two typical fire scenarios (center fire and wall fire), different heat release rates and burner separation distances were considered. The results show that ΔT = 300 K can be used as the boundary temperature of the flame. Further, the merging phenomenon is more likely to occur for wall fires, and the critical flame merging separation distances (Sc) of center and wall fires are around 0.13∼0.16 and 0.21, respectively. The flame tilt angle decreases with the increasing fire separation distance, and it is not sensitive to HRR for both center and wall fires. The flame tilt angle of wall fire is slightly larger than that of center fire under a given fire separation distance. Finally, two prediction models are proposed to estimate the normalized effective flame lengths of impinging and non-impinging flames for the center and wall fires in a channel. This study will provide a basis for exploring the interaction mechanisms of double fires under restricted boundary conditions.