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Condition monitoring and fault diagnosis is the groundwork of condition-based maintenance, and much research has been done about diagnostic algorithm and monitoring manufactures, but less research about diagnostics strategy and management. Plenary diagnostics based on event driven threads of data propagated through successive diagnostic levels is an improving attempt about it. In this approach, abnormities...
The need for improved performance of power systems in terms of reliability and higher productivity has necessitated more and more application of condition monitoring techniques, which can provide early warning of potential failure with the opportunity of organizing avoidance strategies to minimize loss of time and unexpected costs. Periodic condition monitoring tests have limitations such as continuous...
Power companies arrange regular training sessions to keep their operators ready to face blackout events, and expert systems play an important role in achieving this goal. Expert systems [1] have been proven to be an effective platform for diagnostic and control applications in power industry. Conventional expert systems are PC based and are not of much use where the expertise is required over a large...
Distribution management system has been implemented and utilized by utilities around the world to support the system operators in their decision making process especially when emergencies occur in the distribution system. The system can vary from utility to utility due to the complexity of each system. This inevitably leads to the importance of the Distribution Management System design in order to...
This paper represents the VHF/UHFpartial discharge measurement technique compared with conventional partial discharge measurement method, IEC 60270. The artificial partial discharge objects which represent corona discharge, internal discharge, and surface discharge, were set up and tested with the mention techniques. The test results show that three kinds of partial discharge give obviously different...
The vibration test system for the gearbox of wind turbine , the wavelet denoising method , the artificial neural networkpsilas essential principles and its features, BP network structures model in the gearbox fault diagnosis are discussed. Tested vibration signals are disposed by the method of wavelet denoising and than as the inputs of BP neural network. By using classical BP neural network, four...
An enhanced K-NN algorithm is proposed in this paper to improve the conventional K-NN algorithm. The enhanced K-NN algorithm proposed uses information gain and extension relativity. The weight coefficient is got through computing the information gain of attributes. In this approach, the anti-jamming ability and accuracy of the K-NN algorithm is improved highly, and the computing time is reduced and...
This paper describes the GHz order electromagnetic (EM) wave generator we have developed that simulates UHF band aerial noise occasionally measured in HV substation. Using this generator and the model GIS, we investigated the invasion properties of such UHF band aerial noise into the model GIS by changing the location of the generator, i.e. partial discharge (PD) source. As a result, PD-induced EM...
In the UHF detection of power transformers, the main method is detecting the UHF signals through UHF sensor in the transformer. The sensibility of this method is high but mounting way is trouble. Field detection and lab testing show that the UHF signals can diffract from the transformerpsilas joint. Some PD detector using external detection has used in field. But, the difference of signals in transformer...
This paper introduces an evaluation code, which can numerically express the noise possessing degree of signals. By using this code, the best kind and setting of noise suppressing techniques can be chosen automatically. This code is applied to three kinds of specific denoising techniques; those are simple noise removing method in the count versus phase distribution, fuzzy logic method based on noise...
A test system with UHF and UWB detection technologies developed to measure PD under DC voltage is introduced in this paper. According to the typical defects in oil-paper insulation of converter transformer, six corresponding PD models are designed. The test results of PD UWB detection under DC voltage show that the PD current pulses have a very short rise-time, which are capable of radiating UHF signals...
On the basis of life-cycle cost evaluation on periodical diagnosis, a modified calculation method is put forward to evaluate the economic feasibility of the diagnosis rule suggesting an attention value of the measurement parameter above which the apparatus should be diagnosed more frequently. The calculation results show that this diagnosis rule is of more economic merit than the one with a simple...
Electric power equipment must be operated in the state of high reliability with its responsibility in the seamless power supply. Therefore, persistent maintenance is very important. There are many maintenance methods well known in industrial business. Among them, the reliability-centered maintenance (RCM) is a state of the art maintenance technique. This paper shows a RCM method for electric power...
The current technical condition of an equipment is best evaluated beginning with the analysis of its components. Some of the methods used for this type of diagnose are the mathematical methods implemented in the NOVA Predict software application. This paper briefly describes the main issues which led to the designing of the NOVA Predict software application, the architecture, the function, the features...
This paper presents a fault detection and service restoration method for distribution automation system(DAS) in ungrounded distribution system. Fault detection and service restoration is principal function to supply high reliability power continuously in distribution system. The proposed method utilizes the turning point of fault information between connected feeders in the process of shifting the...
A novel deterioration evaluation method of class 1E cable insulation, Polyetheretherketone (PEEK), are proposed by using dielectric relaxation characteristic in order to evaluate the deterioration process for the accelerated aged PEEK. The procedure of accelerated ageing consists of 3 steps, 60Co gamma-ray irradiation, thermal ageing, and loss of coolant accident (LOCA) simulation. Also, the proposed...
In this paper, experimental studies were carried out to investigate the contamination characteristics of porcelain insulators in natural high altitude areas (1970 m). The experimental results indicate that the DC arcs have a significant effect on the flashover performance at high altitudes. The insulator profiles, suspension patterns and contamination distribution have a strong effect on the arc behaviors...
We introduce in this paper the sensitivity of two UHF couplers, disc-type measuring electrode and loop-type measuring electrode embedded in an epoxy insulator, for detecting partial discharge (PD) and diagnosing GIS. Each of the couplers has sufficient performance for detecting the electromagnetic waves up to 8 GHz. The attenuation characteristic of electromagnetic waves is changed depending upon...
This paper describes important aspects of PD diagnostics of distribution power cables. PD parameter were discussed under consideration of attenuation and dispersive effects of cable characteristics. Field experiences with PD diagnosis on PILC and XLPE cables by energizing with Damped AC Voltage demonstrate relevant demands and the effective outcome for asset management decision support. The main difficulty...
Knowledge rules for paper/oil insulated high voltage (HV) power cables are necessary to support asset management decision processes. For development of these knowledge rules investigation has been done into a diagnostic method, for integral condition assessment of paper/oil insulation to DC voltage charging. This method is called the recovery voltage measurement and is based on the dielectric response...
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