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سایت اطلاع رسانی صنعت برق ایران - 6

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Advanced Substation Data Collecting and Processing for State Estimation Enhancement

Abstract

Many functions within a substation can be performed more efficiently if all the substation data is collected from and shared among Intelligent Electronic Devices (IEDs). Gathered measurements and apparatus statuses can be processed by (local) substation computer(s). Processing includes data consistency checking, switching sequence monitoring, predicting switching outcomes, etc. Processed data may be used locally and/or communicated to remote sites (neighboring substations and/or control centers). Substation data integration is facilitated by existence and appropriate connection of IEDs. The paper presents an approach to implementation of substation data integration and information exchange. The emphasis is on the utilization of local data redundancy to enhance power system state estimation, especially topology error detection.

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حجم: 140 KB
رمز: www.power2.ir
تعداد صفحات: 6
نوع فایل: pdf

 

درباره : انتقال , توزیع ,
بازدید : 187
تاریخ : پنجشنبه 15 بهمن 1394 زمان : 12:28 | نویسنده : admin | لینک ثابت | نظرات ()

DISTANCE DIGITAL RELAY MODEL DEVELOPED IN ATP“FOREIGN MODEL”AND C++

 This paper presents a new approach in the problem of digital relay development. An interactive model in the simulation program of power system, eg, ATP-EMTP, could properly contribute to the improvement of digital relays. This model is not available and the code for this model has to be created in ATP. There is an internal programming language MODELS in ATP which allows creation of programs themselves but because of its simplicity it is not sufficient for developing sophisticated models as in object oriented programming language. This deficit is compensated for by allowing a suitable interconnection between the ATP computing core and external model developed in another programming language. For this reason, the object oriented programming language C++ was chosen for relay model development. The paper describes the way of linking and compiling of the relay model with ATP. Next, a multifunctional digital relay developed model is introduced with its functional elements, used algorithms and tripping characteristics. Simulation results are presented and correct tripping action is verified at the end.

 
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حجم: 1.62 MB
رمز: www.power2.ir
تعداد صفحات: 8
نوع فایل: pdf

 

 
 
 
درباره : نیروگاه , تولید ,
بازدید : 164
تاریخ : دوشنبه 12 بهمن 1394 زمان : 12:27 | نویسنده : admin | لینک ثابت | نظرات ()

Current Differential Line Protection Setting Considerations

Abstract

 The most common pilot line protection today is directional comparison by use of distance relays. However, the increased availability of digital communications channels has renewed the interest in line differential relaying. Current-only relays have many advantages. One of the most significant advantages is the simplicity of the scheme with regards to settings.

The percentage differential principle originally developed for transformer and generator protection was extended for use on short transmission lines already in the 1930s, and is still widely in use. These Pilot Wire Relays typically use a telephone type pilot wire channel to exchange analog information between the line terminals. The electromechanical pilot wire relays were very easy to set; they either came with factory default fixed sensitivity or had a few tap settings. What tap to use was determined by estimated fault current on the line, making sure that the relay sensitivity was sufficient for the relays to dependably trip for all types of fault on the line. Three phase sensitivity was often limited to current above load levels in order not to trip for open pilot wires.

For digital current differential line relays, the sound and simple setting principles utilized for pilot wire relays seem to have been forgotten. Commonly, the most sensitive setting (10 – 20 % of nominal current) is applied and even recommended without any consideration of actual fault current levels for the application. This practice contradicts fundamental relaying principles that balance security, sensitivity, dependability and operating speed of the protection scheme. For sensitivity, the requirement is to set the relay to detect all faults on the line with a sufficient margin, seldom does this require the most sensitive setting. Higher sensitivity will increase dependability, but decrease security. Too high sensitivity may cause false trips due to ct errors at external faults with high fault currents, or even false trips on load for channel delay measurement errors due to unequal transmit and receive delays.

This paper reviews the basic setting criteria for current differential line protection, and the charge comparison relay in particular. While setting parameters will differ depending on the type of current differential relay, the setting principles and system conditions to consider remain largely the same. Operating time, sensitivity, dependability and security requirements are examined for typical applications. Considerations for weak feed conditions, ct errors and ct saturation, and charging current are discussed. In addition, the effect of channel delay compensation errors and asymmetrical channel delays possible on digital communications networks with regards to setting considerations is examined.

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حجم: 666.57 KB
رمز: www.power2.ir
تعداد صفحات: 28
نوع فایل: pdf

 

درباره : تولید , انتقال , توزیع ,
بازدید : 286
تاریخ : جمعه 09 بهمن 1394 زمان : 12:26 | نویسنده : admin | لینک ثابت | نظرات ()

Detection of inrush current in distribution transformer using wavelet transform

 Abstract

 Inrush currents in transformers are non-sinusoidal, high magnitude currents generated due to flux saturation in the core during energization. For protection purpose, in this paper an efficient method for detection of inrush current in distribution transformer based on wavelet transform is presented. Using this method inrush current can be discriminated from the other switching transients such as: load switching, capacitor switching and single phase to ground fault. Inrush current and other events for feature extraction and discrimination are simulated using Electro Magnetic Transient Program (EMTP). Results in all cases show the effectiveness of proposed procedure in identifying inrush current from other transients.

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حجم: 350 KB
رمز: www.power2.ir
تعداد صفحات: 10
نوع فایل: pdf

 

 

درباره : تولید , توزیع ,
بازدید : 178
تاریخ : سه شنبه 06 بهمن 1394 زمان : 12:25 | نویسنده : admin | لینک ثابت | نظرات ()

MatLab Simulation -Modeling of the Siemens 7UT6 Differential Protection Relay

Abstract

 In today’s demanding business environment, modeling the power system has become necessary in order for utilities to make the right decision when it embarks on any form of asset expansion. Modeling allows the proposed system to be checked for any potential problems, such as mal-operation and incompatibility. The Siemens 7UT6 differential protection relay is used for power transformer differential protection and is capable of protecting transformers of any vector group. This paper covers the steps of modeling the 7UT6 relay and the application of the modeled relay in testing a protection system. A demonstration tripping of vector group D11 will be shown and the fault currents discussed. Graphs showing the phase voltages and currents will be inspected.

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حجم: 118 KB
رمز: www.power2.ir
تعداد صفحات: 9
نوع فایل: pdf

 

درباره : نیروگاه , توزیع , مصوبات جدید ,
بازدید : 206
تاریخ : شنبه 03 بهمن 1394 زمان : 12:25 | نویسنده : admin | لینک ثابت | نظرات ()

TRANSFORMER MODELING AS APPLIED TO DIFFERENTIAL PROTECTION

 ABSTRACT

This paper presents a power transformer model to evaluate differential element performance. The paper analyzes transformer energization, overexcitation, external fault, and internal fault conditions with this model. Test results with an actual transformer validate the model. The paper includes a guide for properly selecting current transformers for differential protection applications. Accurate power transformer modeling and proper current transformer selection lead us to improved transformer protection.

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حجم: 135.27 KB
رمز: www.power2.ir
تعداد صفحات: 21
نوع فایل: pdf

 

درباره : توزیع , مصوبات جدید ,
بازدید : 182
تاریخ : چهارشنبه 30 دي 1394 زمان : 12:24 | نویسنده : admin | لینک ثابت | نظرات ()

Wavelet based ANN Approach for Transformer Protection

Abstract

 This paper presents the development of a wavelet based algorithm, for distinguishing between magnetizing inrush currents and power system fault currents, which is quite adequate, reliable, fast and computationally efficient tool. The proposed technique consists of a preprocessing unit based on discrete wavelet transform (DWT) in combination with an artificial neural network (ANN) for detecting and classifying fault currents. The DWT acts as an extractor of distinctive features in the input signals at the relay location. This information is then fed into an ANN for classifying fault and magnetizing inrush conditions. A 220/55/55 V, 50Hz laboratory transformer connected to a 380 V power system were simulated using ATP-EMTP. The DWT was implemented by using Matlab and Coiflet mother wavelet was used to analyze primary currents and generate training data. The simulated results presented clearly show that the proposed technique can accurately discriminate between magnetizing inrush and fault currents in transformer protection.

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حجم:  490 KB
رمز: www.power2.ir
تعداد صفحات: 8
نوع فایل: pdf

 

درباره : توزیع , وزارت نیرو ,
بازدید : 193
تاریخ : یکشنبه 27 دي 1394 زمان : 12:24 | نویسنده : admin | لینک ثابت | نظرات ()

Prediction of CT Saturation Period for Differential Relay Adaptation Purposes

Abstract

 A new approach to CT saturation assessment is presented in the paper. Detailed algorithms for decaying DC component measurement and CT saturation prediction are proposed and their accuracy is discussed. The information on CT saturation period is further used for adaptation of the generator / transformer differential protection. Improved stabilization for external faults is achieved by appropriate temporal adjustment of the differential curve for the time period of CT saturation. The protection developed was tested with both EMTP-generated and real world registered current signals.

 

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حجم: 115 KB
رمز: www.power2.ir
تعداد صفحات: 6
نوع فایل: pdf

 

درباره : نیروگاه , تولید ,
بازدید : 175
تاریخ : پنجشنبه 24 دي 1394 زمان : 12:23 | نویسنده : admin | لینک ثابت | نظرات ()

A Novel Digital Relay Model Based on SIMULINK and Its Validation Based on Expert System

Abstract

This paper presents the development of a novel digital relay model and its validation by a digital relay data analysis application. The model is developed as a SIMULINK Sfunction block. MATLAB file I/O functions are employed to generate an oscillography file and an event report. The expert system based digital relay data analysis application validates the relay model and generates diagnosis information for refining the model. An example is used to demonstrate the procedure of simulation, validation, and refining.

 

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حجم: 156.5 KB
رمز: www.power2.ir
تعداد صفحات: 6
نوع فایل: pdf

 

درباره : توزیع , وزارت نیرو ,
بازدید : 171
تاریخ : دوشنبه 21 دي 1394 زمان : 12:23 | نویسنده : admin | لینک ثابت | نظرات ()

PERFORMANCE ANALYSIS OF TRADITIONAL AND IMPROVED TRANSFORMER DIFFERENTIAL PROTECTIVE RELAYS

ABSTRACT

 This paper describes a new approach for transformer differential protection that ensures security for external faults, inrush, and overexcitation conditions and provides dependability for internal faults. This approach combines harmonic restraint and blocking methods with a wave shape recognition technique. First, we review the concept of transformer differential protection. We then analyze magnetizing inrush, overexcitation, and current transformer (CT) saturation phenomena as possible causes of relay misoperation. After summarizing the existing methods for discriminating internal faults from inrush and overexcitation conditions, we propose a new approach for transformer differential protection and describe the relay that is based on this approach. Finally, we compare the behavior of some of these methods for real cases of magnetizing inrush conditions.

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حجم: 415 KB
رمز: www.power2.ir
تعداد صفحات: 34
نوع فایل: pdf

 

درباره : نیروگاه , انتقال ,
بازدید : 201
تاریخ : جمعه 18 دي 1394 زمان : 12:22 | نویسنده : admin | لینک ثابت | نظرات ()
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