Daily Archives: 8 January 2020

Contributions Regarding the Modernization of the Anti-Hail Rocket Launcher Monitoring System

8 January 2020Fără categoriecburada

Abstract

The University of Craiova – Center for Innovation and Technology Transfer carried out systematic research on the complementary equipment for the anti-hail system. One of the research topics covered the anti-hail rocket launcher monitoring system. At present, the monitoring system for the launching ramps is composed of slave modules mounted on ramps and a central master module provided with a small display for viewing the parameters of the launching ramps. To view all the parameters, operators must perform several maneuvers at the master module buttons. The paper presents one of the adaptations made this year to take into account the experience gained by those who manage the Romanian national anti-hail system. The optimization of the rocket launcher monitoring system structure is based on the practice of using it and consists of the use of a single piece of equipment for simultaneous display of information in a sug-gestive form, easily used by human operators under stress in real condition of shooting with rockets. The proposed solu-tion allows displaying all the parameters on the monitor screen and helps the operators in the activity of combating the hail by reducing the number of operations they have to perform. This reduces the intervention time and the stress to which the operators are exposed. The software part of the monitoring system ensures its flexibility and competitive-ness.

Tuning the PID Controller to the Model of Object with Inertia Second Order According to the Maximum Stability Degree Method with Iteration

8 January 2020Fără categoriecburada

Abstract

In this paper there was elaborate the procedure for tuning the PID controller to the object with inertia of the second order according to the maximum degree of stability method with iterations. The characteristic equation of the closed system is determined. By derivative operations on the unknown variable of the maximum degree, analytical expressions of the parameters of the PID controller are obtained as functions of the parameters of the object and the degree of stability. By graph-analytical procedures these functions are constructed by varying the argument. By procedures with iterations on these curves for the same value of the argument, sets of values of the parameters controller are chosen. The synthesized system is simulated and the system performances are evaluated. Two examples of objects with inertia less and greater than one according to the proposed method and the pole-zero allocation method by simulating on the computer system were examined. The parameters of the objects were varied and the robustness of the system at the unit step reference action was verified. The advantages of the proposed method are highlighted by reduced calculations and minimal time, which lead to the simplification of the procedure for tuning the controller for these objects.

Achievement of Current Pulses of High Amplitude Using a Voltage Pulse Generator

8 January 2020Fără categoriecburada

Abstract

This paper presents a comprehensive project aim-ing to achieve high amplitude current impulses using a high voltage generator (GIT) as a power supply. To obtain im-pulse currents with GIT, a wide range of simulations has been carried out to obtain the optimal parameters of the current impulse. LC delay cells were introduced in the test system circuit in order to increase the duration of the cur-rent impulse. A current impulse generator (GIC) circuit has been developed to meet the standards in force. This system has enabled new test methods to be developed and improved equipment developed. The development of this project al-lowed current impulses to be obtained with minimum costs. The methods and procedures used can be used to expand research fields by using current impulses to determine the dynamic and thermal stability of electrotechnical and elec-tro-energetic equipment as well as the functional stability of electronic devices in electromagnetic disturbed environ-ments.

Modified Petri Nets for Hybrid Systems Modeling - a Case Study

8 January 2020Fără categoriecburada

Abstract

In this paper we deal with the problem of modeling and simulation a DC electric drive system using a Hybrid Petri Net formalism, considering that the electric drive is a hybrid system which switches between its states under the occurrence of generic and non-generic external events. The synthesized topology is called a Modified Hybrid Petri Net and is a hybrid model that combines both differentials and discrete Petri Nets dynamic and enables us to simulate and to analyzing the behavior of DC electrical drives in different operating regimes due to the particularities imposed by the load of electrical motor. A real application case was finally considered; different scenarios were analyzed, depending on the nature of the engine load and the specific working conditions. The correctness of the initial model was verified by simulation and, also, by comparison of the results with those obtained experimentally, on a physical model. The modified Petri Nets model is carried out with an available software Visual Object Net ++, which allowed at the same time the synthesis of a hierarchical Object Petri Net structure. All models obtained through this method had been synthesized through an ascendant technique, around a central core, by adding new elements according to the studied processes.

Rehabilitation of Wastewater Treatment Plant Gardabani

8 January 2020Fără categoriecburada

Abstract

In this project, the problem was the realization of a SCADA (Supervisory Control and Data Acquisition) system and automation system that will reduce the costs of maintenance, will increase energy efficiency and will help to improve the quality of wastewater that drains into the river and which comes directly from the sewerage system of Tbilisi and Gardabani cities. The automated station will work non-stop, with high efficiency in water quality and cleaning. The warranty of this station is 25 years without mechanical defects, from which comes the decrease on the maintenance expenses towards a non-automated station.

Operational Aspects of an Auxiliary Converter Used in Railway Applications

8 January 2020Fără categoriecburada

Abstract

This paper presents operational aspects of an auxiliary converter for rail traction which was designed, simulated and realized by authors under the frame of an academia-industry project based partnership. The general technical and functional characteristics of the equipment are described. Data representing electrical waveforms ac-quired from the realized converter’s key test points are pre-sented. High harmonic orders (exceeding the 70-th rank) had to be removed through original programs in order to reveal the significant low harmonic order components. The instantaneous values representing the pollution with har-monic orders were evaluated, along with the components oscillating at the fundamental frequency. Highly variable levels of noise were revealed. Unlike the current waveforms from the analyzed converter’s output, the phase voltages preserved a significant content of harmonic distortions after the removal of harmonics higher than 70. Therefore an analysis based on the Fast Fourier Transform was per-formed. Most significant power quality indices were com-puted for cutoff frequencies corresponding to the harmonics from the set {40, 70 and 80}. Harmonic spectra for phase currents, voltages, active and reactive powers were also rep-resented, along with the phasor diagram. Filtering of all frequencies over the 40-th harmonic was revealed to be a good solution for electromagnetic compatibility compliance.

Harmonics Based Clustering Patterns Featured by the Final Nodes of a WPT tree

8 January 2020Fără categoriecburada

Abstract

Decompositions1 of electric waveforms relying on the Wavelet Package Transform (WPT) provide numerous advantages but require a significant amount of computa-tional resources (runtime and memory). A tree topology with 7 levels, relying on a wavelet mother from Daubechies family with a filter of 28 components was studied. Studies on artificial waveforms polluted with a single harmonic were made firstly, revealing interesting aspects relative to clusters of nodes affected by the same group of harmonic orders. Different pairing patterns of odd and even harmonics were revealed, along with decisions on nodes being more relevant for certain harmonics. Nodes clustering patterns with re-spect to the most significant odd harmonic orders were de-duced as well. These patterns consist in sequences of 4, 8 and 32 nodes. Similarities in harmonic weights associated to node clustering patterns based on the most significant har-monic orders were also derived and discussed. The harmon-ics-nodes clustering properties were afterward tested with respect to capabilities related to time-frequency identifica-tion of most common harmonic orders magnitudes modifi-cation. Multi-harmonic artificial test signals, similar to those from power applications were used to validate the original WPT based algorithms relying on the special clustering and patterns-related properties derived by authors. The results were commented and conclusions were drawn.

Sensorless Adaptive and Predictive Control of PMSM Based

8 January 2020Fără categoriecburada

Abstract

This article presents a sensorless control structure for a PMSM (Permanent Magnet Synchronous Motor), with a MRAC (Model Reference Adaptive Controller) type speed controller, FOC (Field Oriented Control) type overall con-trol strategy, and d-q axis type reference system, for which the Id current reference set to zero is selected for reasons of torque maximization, and the current reference is supplied by the MRAC adaptive controller output. The numerical simulations results obtained in the case of parameter varia-tion and rapidly varying load torque with a random compo-nent, plus an adjustment mechanism described by first-order differential equations recommend the implementation of this structure in an embedded system in real time. Also, presents a sensorless MPC (Model Predictive Control) for a PMSM in which the rotor speed is provided by a MRAS (Model Reference Adaptive System) observer. The results of the numerical simulations show the superiority of the MPC control system compared to FOC type control system in the case of parameter variation and rapidly varying torque load with a random component. The relatively low complexity of the number of arithmetic operations required to implement the estimation and control algorithms recommends the im-plementation of an embedded system in real time in future works.

Deploying Renewable Energy Sources and Energy Storage Systems to Achieve Energy Security in the R. of Moldova

8 January 2020Fără categoriecburada

Abstract

100% RES scenario to improve energy security of R. Moldova is analyzed. Economic simulations are used. The paper shows that only about 70% of the demand could be covered directly from wind farms (WF) and photovoltaic (PV) energy sources (WPES). The remained 30% of energy (RE) – by energy storage system (ESS) with a capacity (kWh) of 32% from RE and a power (MW) of 87% from maximum power demand. As country doesn’t have its own hydro reserves, Li-ion batteries are considered for ESS. The investment in such SSE would exceed 3-52 times national GDP and that makes unrealistic 100% RES scenario for R. Moldova. As analysis showed, there are more than 1400 episodes within the year when energy to cover daily demand cannot be accumulated during 1 to 4 days. By reducing SSE capacity to a value equal to the daily energy demand and maintaining ESS power, it was found that the levelised tariff of WPES+ESS scenario exceeds, however, those of traditional scenarios. Only 5% of energy produced by WPES can be accumulated in such ESS, the remaining 25% – by importing night electricity, at negligible price in the calculations.

On the Thermographic Analysis and Thermal Re-sistance Estimation of the Capacitor-Run Single-Phase Induction Motors

8 January 2020Fără categoriecburada

Abstract

The real-time estimations of heating of the elec-tromechanical converters are important for both overheat-ing prevention and overall efficiency optimization during operation. The two-phased induction motors with capacitor-run capacitors onto the auxiliary phase are sensitive to the capacitance variations of the capacitor. In this respect, the optimization of the two-phased induction motors with elec-tronically-switched, capacitor-run, supplied from frequency inverters may be achieved if the elliptical magnetic motion field into the machine is controlled such as the ratio between the maximum and the minimum of its amplitude is reduced to unity. Observations of the heat of the machine’s body and an appropriate thermal model may provide information about the eccentricity of the magnetic motion field in the machine. In this work, the authors investigated the impact of the capacitor-run capacitance onto the characteristics of the thermal field of the machine. In this perspective, the authors implemented a method based on the image analysis techniques that allows estimating: (a) the geometric features of the machine from the boundaries of the thermal field, and (b) the temperature distribution onto the cross-section of the body in correlation with the main components of the ma-chine and (c) the thermal resistance of the machine’s body.