Nameplate Values Research Articles

Experience of application of chemical cleaning of oil heat exchanger in conditions of Turkmenistan

This paper presents the results of research on the application of chemical cleaning for oil/oil heat exchangers. The aim of the research is to develop a safe and effective chemical cleaning method for these exchangers, using the model HJ2300-H/1.6-Q (H-2001A) as the object of the research. The results showed that after 48 hours of chemical cleaning, all oil fouling and scale were completely removed. Additionally, the pressure drop across the oil/oil heat exchanger decreased to 1.85 kgf/cm² after 12 hours, 1.38 kgf/cm² after 24 hours, 0.75 kgf/cm² after 36 hours, and finally reached the nameplate value of 0.3 kgf/cm² after 48 hours.

Analysis of various degradations of five years aged mono c-Si, poly c-Si, and thin-film photovoltaic modules from rooftop solar installations in Dhaka’s tropical wet and dry climate conditions

This study evaluates the degradation of mono, poly, and thin-film silicon solar photovoltaic (PV) modules through visual and electrical measurements in Dhaka’s tropical wet and dry climate conditions. For this, several sites of rooftop solar PV installations in Dhaka, aged at least 5 years, were selected for field investigation. A visible inspection for visual degradation followed by experimental testing on various electrical characteristics of the PV modules installed on the rooftop using a portable Seaward I–V Tracer for measuring the electrical degradation was done. The electrical data were used to evaluate the degradation of short circuit current, open circuit voltage, fill factor, and maximum power in the field as compared to the nameplate values. Experimental results showed the varying types of visual degradation types such as visible cracks, snail trails, moisture intrusion, front glass, and discoloration for the investigated PV modules. The degradation of PV modules in terms of short circuit current was 0.7%/year for 85Wp mono c-Si, 7.6%/year for 150Wp poly c-Si, and 9.7%/year for 105Wp silicon thin-film, respectively. We believe this study would guide the maintenance of the solar PV systems installed on Dhaka city’s rooftop buildings.

Study on main characteristics of HANWHA solar panels

In this article a Korean-made HANWHA solar panel is considered. Scientific research has been carried out in the first photovoltaic plant since this type of solar panels was installed at this plant. The scientific research based on the measurement, observation and monitoring methods were carried out in October 2022. It turned out that the characteristics of this solar panels are acceptable and can be used in the natural climate conditions of our country. But, in recent years the parameters of the characteristics of this panel have decreased. The average short circuit current value of this panel during the study was 3.5 Amps, which is about 60.18 % less than the nameplate value and the average power on the first and sixth day of the study was 99.60 and 91 Watt respectively, which differ by 8.63 %. After that the authors suggest that is necessary to increase the parameters of characteristics of this panels by applying new cleaning system.

A NEW COOLING APPROACH TO INCREASE EFFICIENCY FOR THE INDUCTION MOTOR: VORTEX TUBE

With the rising demand for energy, concepts such as energy efficiency, energy-efficient devices, and efficiency have grown in importance in recent years. It is well known that a substantial amount of energy produced around the world is consumed in industry, with electric motors accounting for the majority of this consumption. As a result, it is critical to conduct research to improve the efficiency of newly manufactured electric motors in the high efficiency class, as well as electric motors that are still in use because they have not reached the end of their economic lives. The advantages of the proposed system over the conventional fan-cooled system were investigated in this study, which proposed a vortex tube-supported cooling system for cooling the squirrel-caged asynchronous electric motor of the IE3 efficiency class. In this context, an Ansys motor-CAD model of the test engine was created, and a vortex tube-supported experimental setup was built based on the data. As a result of the simulation and experimental studies, the experimental motor's stator winding temperature improved by 68.64%, and its efficiency improved by 1.79% according to the motor nameplate value. The proposed method increased efficiency without requiring any structural changes to the existing electric motor.

Верификация расчетной модели трансформатора напряжения для исследования феррорезонансных процессов в распределительных электрических сетях

Methodology for parameterization of voltage transformer model was developed. Verification of the model is carried out by comparing the nameplate data of the transformer with the results of computer calculations. The magnetization branch parameters are determined by the nameplate values, such as magnetization current and the residual magnetization of the voltage transformer’s magnetic circuit. In conclusion voltage error and the angular error are estimated in terms of the amplitude values and the root-mean-square values of voltage curve for transformer type «NOL-SECH-20». Calculations were carried out with the help of EMTP-RV software.

Analysis of long-term performance and reliability of PV modules under tropical climatic conditions in sub-Saharan

Reliability assessment of Photovoltaic (PV) modules is very crucial to increase the service lifetime of PV systems. This study assesses the degradation rate and reliability of PV modules operated for twelve years under the tropical climatic condition in sub-Saharan. For this purpose, various characterization techniques, namely visual inspection, infrared (IR) thermography assessment, and current-voltage (I-V) characterization, have been employed to evaluate the performance of PV modules. Moreover, the functioning of bypass diodes has been tested under partial shading situations. The results demonstrate that after twelve years of outdoor operation, the short-circuit current (Isc) of modules have been degraded up to 16.4% with an average decrease of 11.7% compared to the nameplate values. The open-circuit voltages (Voc) were reduced from 11.4% to 17.1% with a mean of 14.8%. The decline in Fill Factor (FF) of the modules ranges from 11.3% to 24.2%, and the losses of power output were between 34.5% and 41.4%. Moreover, the visual and thermography assessment reveals that the PV modules are severely affected by various failures such as EVA browning, cell interconnects ribbons browning and the corrosion of solder bonds. The results show that averagely, the FF is the most significant factor influencing the loss in the power output of the modules.

Corrosion growth of solar cells in modules after 15 years of operation

This paper is to study the deterioration of PV modules after 15 years of operation in Thailand. All 16 modules of a string were annually measured in the standard testing laboratory, then taken back to the same position of string since the 7th year after operation. The results and data analysis can be divided into 3 parts consisting of electrical performance evaluation, physical deterioration observation, and corrosion growth on cell ribbons. From the electrical results of performance at STC, it was found that power of modules were less than 80% of the nameplate value in the 15th year for 75% of total modules. The average degradation rates, based on nameplate, was 1.47%/year. The degradation rates of modules since the 10th year after operation were in the range of 2.5 to 3.0%. From the visual failures on the front and rear side of modules were appeared in all modules. During the 12th – 15th year, the corrosion area growth on cell ribbons, calculated by ImageJ program, was around 10–17%/3 years of ribbons area, especially for cells beside junction box. The colors of corrosion products were also observed in both color appearance and color change on each cell of selected modules. For these modules, we intend to continue operation until end-of-life of the system. Another similar module was destructed and taken to investigate. The corrosion products and color of corrosion products can be justified by EDS and referred to ASTM D130 standard. Sn and Pb corrosion products were confirmed by SEM and EDS.

Robust and Cost-Effective Synchronization Scheme for a Multicell Grid Emulator

Steadily increasing requirements for grid-connected converters, their growing unit power, and output voltage call for flexible high-power medium-voltage grid emulators. Four-quadrant cascaded H-bridge topology features high output voltage resolution and high effective switching frequency, which enable high-dynamic high-fidelity grid emulation. This article shows that despite nonidealities (turn ratios, phase-shift angles, and different stray inductances) in a typical phase-shifting multiwinding transformer, active front-ends of the cells can be effectively synchronized to their respective supply voltages using transformer primary-side voltage measurements and nameplate values. Consequently, cell input filters can be omitted, making the grid emulator more compact, cheaper, faster, and exhibiting more robust grid synchronization. Theoretical developments and designs are verified by means of high-fidelity time-domain simulations.

A New Simplified Five-Parameter Estimation Method for Single-Diode Model of Photovoltaic Panels

This work proposes a new simplified five-parameter estimation method for a single-diode model of photovoltaic panels. The method, based on an iterative algorithm, is able to estimate the parameter of the electrical single-diode model from the panel’s datasheet. Two iterative steps are used to estimate the five parameters starting from data provided by the manufacturer (nameplate values or I–V curves). The first step permits finding the optimal value of the diode ideality factor A, and the second step allows the calculation of the Rp value to improve the accuracy. A model that takes into account variations in temperature and solar irradiance has been used to validate the behavior of the output parameters. Compared to other estimation work, the proposed method shows the best result in the standard test condition (STC) and with a variable solar irradiance. Indeed, the optimization of the A, Rs, and Rp parameters allows guaranteeing the minimum error between I–V curves obtained from method and datasheet.

Investigation of PV yield differences in a desert climate

PV modules which are less sensitive to temperature (i.e. have lower power temperature coefficient, PTC) are expected to produce more energy in hot environments. Yet a year-long study of 26 PV technologies in Doha, Qatar, found that their daily Specific Yield (Wh/day/Wp) only weakly correlated with their PTC. To investigate possible explanations, we examined in detail the field data from one multi-Si and one CdTe string, and calculated their energy losses attributable to module temperature, low-light conditions, and “Wp discrepancy” (difference in Wp between manufacturers’ flash tests and field measurements). We found that although the CdTe system had lower PTC than multi-Si, it had larger Wp discrepancy, which largely accounted for its lower Specific Yield. Further, PTC values derived from field measurements were significantly different from the modules’ nameplate values, for both the multi-Si and CdTe systems. The results indicate that modules’ nameplate PTC values did not strongly predict their relative Specific Yields in desert climates, largely because of discrepancy between nominal and field values of PTC and Wp.

Detection of Generalized-Roughness and Single-Point Bearing Faults Using Linear Prediction-Based Current Noise Cancellation

The dominant components in the stator current of a typical induction motor contain a substantial amount of information that is not related to bearing faults and can be considered as “ noise ” to bearing fault detection. The presence of the noise in the current signal creates the possibility of missed and false alarms. This paper develops a current noise cancellation method. When noise cancellation is used for recovering a desired signal, the distinguishing characteristics of both the desired signal and the noise need to be considered. Contrary to conventional current noise cancellation methods, “predictability” is considered as the distinguishing characteristic. Linear prediction theory with an optimum prediction order is applied to efficiently model the predictable components as noise. The developed method is able to efficiently cancel out the noise from the current signal. The information about the mechanical load level, the faulty part of the bearing, machine parameters, nameplate values, the current spectrum distribution, and the current data associated with the healthy bearing is not required in this method. Simulation and experimental results confirm the merits and effectiveness of the developed method to detect the bearing fault types through kurtosis and spectral analysis.

Оценка пульсаций тока в режиме поддерживающего заряда аккумуляторных батарей

Failures of storage batteries (SBs) and reduction of their service life due to current ripple in the supporting charge mode are observed in the control DC power supply systems at power plants and substations. For checking whether an SB is in compliance with the current ripple level permitted by the relevant regulations, it is necessary to have a procedure for calculating the ripple level in selecting the SB charging devices. The article proposes a model most suitable for estimating the current ripple level in the supporting charge mode. The effect of different factors on the SB parameters and the influence of the SB equivalent circuit on the current ripple are considered. It is shown that in calculating the current ripple it is possible to neglect the SB inner inductance and use the nameplate value of the SB inner resistance.

Short‐term performance variations of different photovoltaic system technologies under the humid subtropical climate of Kanpur in India

The study discusses the short-term performance variations of grid-connected photovoltaic (PV) systems installed in Kanpur, India. The analysis presents a holistic view of the performance variations of three PV array technologies [multi-crystalline (multi-Si), copper indium gallium diselenide and amorphous silicon] and two inverter types (high-frequency transformer and low-frequency transformer). The analysis considers the DC–AC conversion efficiency of the inverter, system performance through performance ratio (PR) calculations, energy variations between fixed and tracking systems and the comparison between calculated and simulated data for the examined period. The energy output difference between the tracking and fixed systems of the same PV technology show that these are dependent on differences in temperature coefficient, shading and other system related issues. The PR analysis shows the effect of temperature on the multi-Si system. The difference between the simulated and measured values of the systems was mostly attributed to the irradiance differences. Regarding the inverter evaluation, the results showed that both inverter types underperformed in terms of the conversion efficiency compared with nameplate values.

Incipient Bearing Fault Detection via Motor Stator Current Noise Cancellation Using Wiener Filter

Current-based monitoring can offer significant economic savings and implementation advantages over traditional vibration monitoring for bearing fault detection. The key issue in current-based bearing fault detection is to extract bearing fault signatures from the motor stator current. Since the bearing fault signature in the stator current is typically very subtle, particularly when the fault is at an incipient stage, it is difficult to detect the fault signature directly. Therefore, in this paper, the bearing fault signature is detected alternatively by estimating and removing nonbearing fault components via a noise cancellation method. In this method, all the components of the stator current that are not related to bearing faults are regarded as noise and are estimated by a Wiener filter. Then, all these noise components are cancelled out by their estimates in a real-time fashion, and a fault indicator is established based on the remaining components which are mainly caused by bearing faults. Machine parameters, bearing dimensions, nameplate values, and the stator current spectrum distribution are not required in the method. The results of online experiments with a 20-hp induction motor under multiple load levels have confirmed the effectiveness of this method.

Experimental modeling and control design of shunt active power filters

One of the main issues when designing a control strategy for a power electronic system is the development of a reliable model of the real system. However, the evaluation of the actual plant parameters is difficult due to the mismatch between nameplate and actual values of components, and the presence of unmodeled dynamics and non-linearities. This paper presents a novel technique for both model parameters identification and optimized control design of a shunt active power filter system using genetic algorithms (GAs). Experimental results demonstrate that the proposed modeling and control design approach greatly improve the system performance.

Transient tolerance analysis of power cables thermal dynamic by interval mathematic

The safeguard of power equipments is assuming a major role in the deregulated electricity market, where a malfunctioning power system could be responsible for serious damages to a large number of system operators having access to the shared energy resource. In this context thermal monitoring of power cables represents a key issue in evaluating the risks associated with a given load management policy especially during emergency conditions. In particular this demands for reliable assessment models that should be able to predict the transient thermal behaviour when the load exceeds the nameplate value. In this connection the application of both simplified and detailed power cable thermal models is often complicated by the presence of uncertainties affecting the tolerances of the input data. The effect of these uncertainties could influence the final solution to a considerable extent. A comprehensive tolerance analysis is therefore required in order to incorporate the effect of data uncertainties into the thermal modelling process. To address this problem, in the paper the employment of interval mathematic is proposed. Several numerical results are presented and discussed in order to assess the effectiveness of the proposed methodology which offer a rough qualitative insight of the solution in a very short time, comparable to the time required for a deterministic numerical simulation.

The Role of Learning Methods in the Dynamic Assessment of Power Components Loading Capability

The need for dynamic loading of power components in the deregulated electricity market demands reliable assessment models that should be able to predict the thermal behavior when the load exceeds the nameplate value. When assessing network load capability, the hot-spot temperature of the components is known to be the most critical factor. The knowledge of the evolution of the hot-spot temperature during overload conditions is essential to evaluate the loss of insulation life and to evaluate the consequent risks of both technical and economical nature. This paper discusses an innovative grey-box architecture for integrating physical knowledge modeling (a.k.a. white-box) with machine learning techniques (a.k.a. black-box). In particular, we focus on the problem of forecasting the hot-spot temperature of a mineral-oil-immersed transformer. We perform a set of experiments and we compare the predictions obtained by the grey-, white-, and black-box approaches.

A first step towards unmanned intelligent process management: A procedure for the diagnostics and prognostics of energy conversion plants

This paper describes the conceptual development and the prototype implementation of an Expert System that deals with the prognosis and diagnosis of a significant subset of the operative faults of a cogeneration power plant. The expert system receives both raw and organised real-time information on the “instantaneous” (actually, averaged over 60-seconds intervals) plant operating conditions from a non-intelligent “plant interface” consisting of a standard plant data acquisition system and of a specific plant simulation software. This solution was adopted in view of possible future applications to industrial plants, where a low number of intrusive sensors is desirable: in this case, the simulator provides the missing data. The Inference Engine operates on the basis of a set of pre-defined rules that seek possible “faults chains” expressed as combinations of a pre-assigned number of continuously calculated performance indicators, like the air filter output pressure drop, the relative compressor, combustion and turbine efficiency decay with respect to their respective nameplate values, the compressor enthalpy gain and surge conditions, the pollutants concentration in flue gases, the relative pressure losses in both the primary and secondary water circuit, the TTD of the Heat Recovery Boiler, etc.: the complete list includes 29 indices. The rules establish whether a component’s behaviour is degraded by examining both the individual indicators and all of their relevant combinations. A graphic window displays a series of icons, one for each indicator, with a refresh rate of one real-time minute. The Expert System enables the user to determine in detail the instantaneous performance conditions. If performance deterioration is detected, it sends a message to the operator and provides some decision support via a customised graphic interface. The structure of the code is Object Oriented, and each component as well as each flux are represented as the instance of a class. Both the reasoning and the controlling actions are taken in the same O-O environment. The present paper presents the organization of an ES whose prototype version has been nicknamed PROMISE, from the Italian acronym for PROgnostic and Intelligent Monitoring Expert System, defines its goals and discusses both the results of the tests conducted so far and the implications for future applied research in this field.

Influence of single-phase excitation and magnetizing reactance on transformer leakage reactance measurement

Low voltage and single-phase excitation are often used to measure leakage reactance or short-circuit impedance of transformers. Winding distortion may be detected by comparing field results with factory nameplate values measured at 25-100% of the rated current using three-phase excitation. The results of single- and three-phase excitation will not always correlate. If the voltage applied in the field is not properly selected then the data may be influenced by the magnetizing reactance. The resulting difference between the nameplate value and the field data might then lead to erroneous analysis of test results and could be interpreted as an indication of winding distortion. The intent of this paper is to analyze the physics of the process and gain insight on test circuit selection and analysis of the results. Methods for avoiding erroneous test results are suggested.

Thermal Test Performance of a Modern Apparatus Bushing

As part of an overall program for establishing thermal loading capability of substation electrical equipment, it was necessary to investigate the inherent thermal capabilities of typical oil impregnated paper bushings used in power transformers and circuit breakers. The investigation described in this paper included developing and implementing a test program to determine actual bushing temperature levels for load currents over rated nameplate value, tabulating and analyzing test results, performing an accelerated thermal life test, and finally, evaluating the physical condition of the bushing insulation to determine the effect of elevated temperatures on its integrity.