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Structure of the analog digital converter AD7569 type. 1-range network; 2-unit of tracking/holding; 3-analog digital converter (ADC); 4-ADC latch; 5-DAC register; 6-digital analog converter (DAC); 7-the amplifier; 8-range network; 9-synchronizing clock; 10-reference power supply.
Source publication
Microprocessor-based protection devices (MPDs) are supplied with switchmode power supplies in which the input voltage acts on the rectifier and the filter then interrupts with the high frequency with the help of a powerful switching transistor, which turns the supply into high-frequency AC. This high-frequency voltage is transformed by the high-fre...
Contexts in source publication
Context 1
... device transforms an input analog signal from CTs and VTs in binary code transmitted through special filters to processing in the microprocessor. All ADC work by sample of input values through the fixed intervals of time and thus will transform a sine wave signal to a set of the fixed amplitudes. As can be seen from Fig. 3, this is a rather complex device carrying out a complex algorithm and containing a sizable set of internal units. 4 -ADC latch; 5 -DAC register; 6 -digital analog converter (DAC); 7 -the amplifier; 8 -range network; 9 -synchronizing clock; 10 -reference power ...
Context 2
... nonlinearity of the transfer characteristic, an aperture error, aliasing, etc. How it is possible to supervise the proper functioning of such complex devices during the continuously change of input values when there is only a single element storing a constant level of a signal during ADC functioning as the reference voltage source 10 (see Fig. 3). The so-called "self-diagnostics" ADC is based on this reference voltage monitoring [21]. The efficiency and usefulness of such "self-diagnostics" the reader can estimate ...
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Citations
... The comprehensive availability of PCS-9XX high-voltage series and PCS-96XX low-voltage series relay protection devices for the next ten years were calculated respectively as shown in Table 9. The change in comprehensive availability and the average comprehensive availability [21,22] (98.5%) are shown in Fig. 4. The comprehensive availability of PCS-9XX high-voltage series and PCS-96XX low-voltage series devices after ten years is 99.016% and 98.866% respectively, which is in line with the average comprehensive availability (98.5%) of the relay protection device system during the maintenance cycle stage, indicating that the prediction results are reasonable. The comprehensive availability of the two-layer state space system of relay protection devices developed in this paper is verified to be credible for predicting the quality and reliability of future relay protection device operation in the field. ...
As a critical component of the present day power system, a few studies have been conducted on the optimization and future prediction for quality reliability of relay protection devices during their production stage of intelligent testing. Therefore, in this study, a Markov model of multimodal hierarchical spatial states is proposed (1) to calculate the stationary probability and comprehensive availability of different spatial state transfers (2) to predict the quality reliability of the device during production intelligence testing and (3) to infer and calculated the integrated availability of the relay protection device for its future operation during testing. Statistical results from the theoretical findings of this study are highly relevant when compared to the actual operation of relay protection device systems. The correctness of the model calculation method proposed in this study is verified, which provides a feasible method for reliability assessment of relay protection device intelligence tests. In addition, it was also found that the failure rate of the device internal module CPU has a relatively large impact on the comprehensive availability. It is therefore recommended to focus on CPU module detection and timely replacement during the maintenance cycle of on-site operations and maintenance. Finally, the CPU module failure rate threshold for production intelligence testing was amended, which is a valuable indicator for the evolutionary optimization of quality problems in actual smart manufacturing and testing.
... Microprocessor based relays have many advantages over conventional relays [1]. However the basic protection principles have remained principally unchanged throughout in advanced microprocessor based relays [3]. ...
This paper proposes a novel approach to determine symmetrical components of power system by applying method of least squares in time domain. For the modern power system stability, clearance of faults on high voltage transmission lines in zero response time is crucial and important. Symmetrical components have a great attention since last century. They have been found an effective tool for the analysis of symmetrical and unsymmetrical faults in power system. Moreover, magnitude of symmetrical components are also used as a caution about faults in system. With rapid changes in technology, Microprocessor assumed to be fastest machine of the modern era. Hence microprocessor based techniques were developed and implemented for last few decades. The proposed technique apply least square method in the computation of symmetrical components which is suitable as an application in microprocessor based monitoring and controlling power system in order to avoid cascading failures. Simulation of proposed model is carried out in MATLAB/SIMULINK and all results exploit the validity of model.
... This device transforms an input analog signal from current sensors and voltage sensors in binary code transmitted through special filters to processing in the microcontroller [9]. The resolution of the converter indicates the number of discrete values it can produce over the range of analog values. ...
... It requires only simple wiring, has small footprint, and boasts a faster processing speed, which makes it ideal for guidance purposes [8]. What needs to be discussed is how to burn Basic programming onto 8051 chip, and making it the main factor in controlling movements, making optical analysis, and accommodate with stepping motor [9][10][11][12][13]. Stepping motor is a device that transforms input pulse frequency into mechanical energy. ...
Automated Guiding Vehicle (AGV) is widely used in factories, hospitals, warehouses, and offices. It can also be controlled remotely to operate under hazardous environments that are unsuitable for human presence. On the other hand, medical advancement and the decrease of birth rate are pushing the world into population aging. For elderly or the physically/mentally-challenged patient, some of the common foot problem includes diabetic foot, myotenositis, having calluses in the soles of the foot, foot deformities, etc. This research is aimed at the design and the implementation of an automated guiding vehicle, which is controlled by PC. Once the input is received from optical sensors, it will pass the information to chip, which will process the information and output the decision to stepping motor to finish the process. The research includes understanding the mechanical design, optical sensor input, defining the control units, and initiating stepping motor. Using BASIC programming, the program is burned onto a chip, which works as the central of the AGV. The result can be applied in barrier-free facilities. This research analyzes the pros and cons of AGV based on its behavior under different scenarios.
... Generally, the disturbances produced by lightning conduct to the permanent faults (insulation breakdown) in a half of cases and the switching operations produces temporary failures of numerical protective relays. Critical considerations about the use of microprocessors based protective relays are done in [10]. ...
The good performance of secondary circuits in a substation is conditioned by the accurate, undisturbed signals provided mainly by instrument transformers as well as by other components of primary circuits. The connections between primary and secondary circuits are subjected to aggressions originated from the electromagnetic environment of the substation: high level of power frequency electric and magnetic field, transient electromagnetic fields produced by lightning, switching, insulation faults, transient ground potential rise, the last being a result of the previous described events. Consequently, the signals in the secondary circuits must be adequately protected in order to preserve the good operation of protection, monitoring, measuring or automation functions. Nowadays, in the secondary circuits of Romanian substations coexist several generations of equipments, from electromechanical relays to numerical ones having different immunity levels, and also different types of signal cables, shielded or unshielded. The paper analyses the effects of disturbances generated in the primary circuits on the signals in the secondary circuits, considering different coupling mechanisms. The intrinsic features of signal cables are presented. Consequences of possible misuse or bad mounting practice are discussed.
... However, as any sensible professional should know, an ideal technical device does not exist and even the MPD has many technical problems and shortcomings that have already led to a significant reduction in the hardware reliability of relay protection [1][2][3][4] and increased its cost. Since there is no alternative to MPD today, we face a challenge to counterbalance the negative impact that MPDs introduced into relay protection. ...
... Answer: throw the old MPD into garbage, even if there is only one faulty module (printed circuit boards of modern MPDs are developed in such a way that they cannot be repaired), and fork up another sum of money for purchasing a new unit. Therefore, insufficient hardware reliability of MPD [1][2][3][4] results in a serious economic problem since built-in self-diagnostic features, so much advertised by manufacturers, do not help to reduce failures and breakdowns. ...
Transition from electromechanical to digital protective relays is accompanied with serious technical problems. The author offers a new approach in designing the digital relays capable of solving these problems. It is proposed to construct digital relays in the form of standard modules from which it would be possible to assemble the digital relay in the same way as now a personal computer.
... In other words it means that reliability of EM correlates with MPD's. But does it mean that the switch from EM to MPD will not reduce the reliability of relay protection as it is indicated in [7][8][9]? Can we see it from comparison of left and right diagrams in figure 1? Absolutely not! As these dia-grams do not consider the number of relays for which they show the values of failures, the left and right diagrams can not be compared. ...
In the paper observed estimation of reliability of relay protection (RP). It is shown, that an exist-ing method, both Russian, and foreign, do not allow to evaluate RP reliability correctly. The new method of RP reliability estimation is offered.
... One of the widely widespread fables [3,4] justifying the inevitability of transition to Digital Protective Relays (DPR) is the myth that electromechanical protective relays do not provide for the performance of the technical requirements for relay protection and the continuing existence of electric power industry of today is not possible without DPR Actually, no new functions in relaying DPR have been introduced. The parameters and facilities of the high-quality electromechanical and semiconductor, that is, the static analog devices con-structed on the basis of discrete solid-state elements and integrated microcircuits, completely provide all relay protection requirements. ...
Transition from electromechanical to digital protective relays is accompanied with serious technical problems. The author offers the new approach in designing the digital relays, capable to solve these problems. This approach is based on similarity of functional units of digital relays and personal computers. It is offered to carry out digital relays in the form of standard modules from which it would be possible to assemble the digital relay in the same way as now a personal com-puter. Key words: digital protective relays, electromechanical relays, reliability of relay protection. Massive power grid failures (blackouts), leading to huge losses and often to death (USA: 1965,: 2003, Sweden: 1983, 2003). Malfunction pro-tective relays is one of the main causes of the heavy failures that periodically occur in power sys-tems all over the world. According to the North American Electric Reliability Council in 74 % cases the reason of heavy failures in power systems was the incorrect actions of relay protection in trying to avoid the failure. Thus the reliability of a power system depends on the reliability of relay protec-tion in many respects. In previous publications the author has already analyzed the transition from electromechanical to a microprocessor-based protective relays, and con-sidered the prospects and problems of microproc-essor relays applications [1, 2]. The rather sharp reaction of the readers, often arising after these publication, on the one hand, and the author's de-tailed answers to the criticism of opponents on the other show that among the specialists in this area there is no common opinion about the prospects of microprocessor protection, there is no unequivocal understanding that, as any other complex device, the microprocessor protection not only possesses obvious advantages, but also has serious weak-nesses. One of the widely widespread fables [3, 4] justi-fying the inevitability of transition to Digital Protec-tive Relays (DPR) is the myth that electromechani-cal protective relays do not provide for the per-formance of the technical requirements for relay protection and the continuing existence of electric power industry of today is not possible without DPR Actually, no new functions in relaying DPR have been introduced. The parameters and facilities of the high-quality electromechanical and semi-conductor, that is, the static analog devices con-structed on the basis of discrete solid-state ele-ments and integrated microcircuits, completely provide all relay protection requirements. In relay-ing there are no actual problems that could not be solved by means of electromechanical or static relays (note: recording emergency modes is not relay protection function). Confirmation of this is the fact that branched and complex electrical net-works and systems exist and successfully function all over the world, and have for more than hundred years; whereas microprocessor-based relay pro-tection has appeared in use in not very appreciable numbers just 10-15 years ago. Thus, with the be-ginning of the use of DPR the functioning logic of an electric power system has not changed, the number of operations that are carried out by an electric power system has not increased, the quan-tity of the produced electric power has not changed, principles of transmission and distribu-tion of the electric power have not changed.
... Systems reliability depends largely on economical problems requiring more investment to achieve better reliability. At present, the only approach to improve the equipment reliability without adding a new capacity is either through time reduction by hiring more personnel for repairs, or increasing inservice time (up time) through more sophisticated monitoring and maintenance techniques [1][2][3]. These alternatives are now in common practice since the combination of capital scarcity, uncertainties in demand and fuel costs is higher for new equipment. ...
A high-voltage generator PowerformerTM is a new generation of the AC generators. The most significant advantages of these PowerformerTM are their direct connection to high-voltage grid, higher availability, and more reactive power margin, short term overloading capacity and removing the power transformer from the structure of the power plant. In this paper, the installation effect of these generators on the power system reliability is investigated. The amount of the effects depends on the type and location of the power plant, location of the PowerformerTM, the size of load and network topology. For this purpose, in the 6-bus IEEE RBTS system, the conventional generators are replaced by these new PowerformerTM and then, the reliability indices are evaluated. The simulation results show that the reliability indices such as the expected duration of load curtailment (EDLC) and the expected energy not served (EENS) are improved. .
... In previous publications the author has already analyzed the transition from electromechanical to a microprocessor-based protective relays, and considered the prospects and problems of microprocessor relays applications [1][2][3][4]. The rather sharp reaction of the readers, often arising after these publication, on the one hand, and the author's detailed answers to the criticism of opponents on the other show that among the specialists in this area there is no common opinion about the prospects of microprocessor protection, there is no unequivocal understanding that, as any other complex device, the microprocessor protection not only possesses obvious advantages but also has serious weaknesses. ...
... One gets the feeling that there is a certain taboo imposed on discussion on this theme. If an author happens to break by chance through this "Iron Curtain" [1][2][3][4], there is a squall of criticism including personal attacks and even charges of attempts to bring to a stop the technical progress. ...
... In [4] we already considered, in detail, problems with the reliability of each of the basic functional units of MPD and have shown, through concrete examples, that the so-called "self-diagnosis" by which 80 % of MPD units are captured ostensibly, is, by and large, an advertising gimmick and a widespread myth. While it is true that self-diagnosis in MPD can reveal some internal damages, for example, such as failure of the internal power supply or the central processor unit (CPU), how it is possible to speak seriously about this as about a great "advantage" of MPD against of electromechanical relays if in the electromechanical relays there are no internal power supplies and CPUs, that is, there is simply nothing to "self-diagnose"?! ...
The article is a continuation of a set of the author's previous publications about the reliability of the microprocessor- based protective devices. The statistical data introduced by the author coincide with data of other authors and confirm higher reliability of electromechanical relays in comparison with microprocessor-based. The inadequacy of the criterion for estimating the reliability of the protective relay is noted and a new normalized criterion for such estimation is offered by author. K e y w o r d s: microprocessor-based protective devices, reliability, relay protection, life expectancy, intensity of failures, failure rate
