Fault Location in Transmission Systems Using Synchronized Measurements

Compared with conventional measurements from supervisory control and data acquisition (SCADA) system, phasor measurement units (PMUs) provide time-synchronized and direct measurements of phasors. The availability of synchronized phasor measurements can significantly improve power system protection and analysis. This dissertation is specifically committed to using synchronized measurements for estimation of fault locations in transmission systems. Transmission lines are prone to various short-circuit faults. Accurate fault location is critical for rapid power recovery. Chapter 2 proposes a new fault location method based on sparse wide area measurements. One distinguishing feature of this method is its applicability to both transposed and untransposed transmission lines. In addition, the method is developed based on sparse-wide area measurement that may be taken far away from the faulted line. Shunt capacitances of transmission lines are also fully considered by the algorithm. Moreover, when synchronized measurements from multiple buses are available, an optimal estimator can be used to make the most use of measurements, and to detect and identify potential bad measurements. Most of the existing fault location literatures discuss common shunt faults, including single line-to-ground faults, line-to-line faults, line-to-line-to-ground faults, and three-phase faults. However, in addition to common shunt faults, some complex faults may also occur in power systems. Among these complex faults, evolving fault and inter-circuit fault are two typical examples. Chapter 3 extends the method developed in Chapter 2 to deal with evolving faults. The proposed wide-area fault location methods are immune to fault type evolution, and are applicable to both transposed and untransposed lines. Chapter 4 discusses location of inter-circuit faults. Inter-circuit fault is a type of simultaneous fault, and it is the most common simultaneous fault type. Inter-circuit faults between each circuit in a double-circuit line is the most common inter-circuit fault. A fault location method for inter-circuit faults on double-circuit lines are developed and evaluated in Chapter 4. Chapter 5 puts forward a fault location algorithm, which does not require line parameters information, for series-compensated transmission lines. Two-end synchronized voltage and current measurements are utilized. The proposed method is independent of source impedance and fully considers shunt capacitances of transmission lines

Cause Identification of Electromagnetic Transient Events using Spatiotemporal Feature Learning

This paper presents a spatiotemporal unsupervised feature learning method for cause identification of electromagnetic transient events (EMTE) in power grids. The proposed method is formulated based on the availability of time-synchronized high-frequency measurement, and using the convolutional neural network (CNN) as the spatiotemporal feature representation along with softmax function. Despite the existing threshold-based, or energy-based events analysis methods, such as support vector machine (SVM), autoencoder, and tapered multi-layer perception (t-MLP) neural network, the proposed feature learning is carried out with respect to both time and space. The effectiveness of the proposed feature learning and the subsequent cause identification is validated through the EMTP simulation of different events such as line energization, capacitor bank energization, lightning, fault, and high-impedance fault in the IEEE 30-bus, and the real-time digital simulation (RTDS) of the WSCC 9-bus system.Comment: 9 pages, 7 figure

A Review of Fault Diagnosing Methods in Power Transmission Systems

Transient stability is important in power systems. Disturbances like faults need to be segregated to restore transient stability. A comprehensive review of fault diagnosing methods in the power transmission system is presented in this paper. Typically, voltage and current samples are deployed for analysis. Three tasks/topics; fault detection, classification, and location are presented separately to convey a more logical and comprehensive understanding of the concepts. Feature extractions, transformations with dimensionality reduction methods are discussed. Fault classification and location techniques largely use artificial intelligence (AI) and signal processing methods. After the discussion of overall methods and concepts, advancements and future aspects are discussed. Generalized strengths and weaknesses of different AI and machine learning-based algorithms are assessed. A comparison of different fault detection, classification, and location methods is also presented considering features, inputs, complexity, system used and results. This paper may serve as a guideline for the researchers to understand different methods and techniques in this field

Tarkan ja luotettavan ajan siirto kantaverkossa

This master’s thesis is about time distribution that supports substation applications needed for power transmission. The work was done for the Telecommunication department of Finland’s power transmission system operator Fingrid Oyj. This thesis answers to the following question: What is the need for accurate and synchronized time in power substations and how it will be delivered? Fingrid’s telecommunication network supports the power transmission grid and its operation. Telecommunication network can distribute time to power substations for the applications that need synchronized and accurate time. Current telecommunication equipment used in Fingrid is getting old and new techniques are planned to be implemented. When Fingrid is acquiring new communication equipment, they need to set requirements on the capability to distribute time. This thesis is an initial effort to investigate time distribution requirements for Fingrid’s needs. This thesis aids Fingrid Telecommunication department to define requirements for time distribution. For this thesis, I met with multiple Fingrid professionals, telecommunication device suppliers and time distribution researchers. This thesis answers to its research questions by means of a literature review and interviews.Tämä diplomityö käsittelee ajansiirron vaikutusta sähköasemasovellusten toimintaan. Työ tehtiin Suomen kantaverkkoyhtiö Fingrid Oyj:n tietoliikenneyksikölle. Fingridin tietoliikenneverkko on osa kantaverkkoa ja mahdollistaa sähköjärjestelmän toiminteita. Tietoliikenneverkon yksi palvelu on synkronoidun ajan siirtäminen sähköasemille. Nykyinen tietoliikennetekniikka on vanhenemassa ja uutta laitteistoa suunnitellaan hankittavaksi ja testattavaksi. Tämän diplomityön tarkoitus on selvittää mikä on järkevä tapa toteuttaa ajan siirto ja kuinka tarkkaa sen pitää olla. Työ auttaa tietoliikenneyksikköä hankinnan vaatimusmäärittelyssä ajansiirron osalta. Työtä varten on tavattu monia Fingridin asiantuntijoita, tietoliikennelaitetoimittajia sekä ajansiirron asiantuntijoita. Työ vastaa tutkimuskysymykseen kirjallisuuskatsauksen ja haastattelujen perusteella

PMU-voltage drop based fault locator for transmission backup protection

Local protection elements such as fuses and relays are the first protective mechanism to clear the fault and isolate the affected part of the power grid. Although the selectivity, speed, and sensitivity of these primary protection devices are relatively high, they cannot be considered flawless. There is a small percentage of events for which relays experience blinding effects. For these scenarios, a redundant arrangement can be made through backup protection. This paper proposes a centralized remote backup protection method based on two techniques, the delta algorithm and the least-squares technique. The proposed method successfully detects the faulted transmission line, fault type, and the distance to the fault. Besides, it makes use of phasor measurement unit data and it is non-iterative. The grid is split in a user-determined number of subareas based on the phasor mesurement unit locations, in order to accurately determine the fault location. Firstly, the faulty area is located and thereafter an in-depth search is carried out on the faulted area to determine the faulted line. Finally, the fault distance is determined based on the distributed parameter model of the transmission line. The method is demonstrated and validated in an RTDS-Matlab co-simulation platform. Extensive simulation studies are carried out on the IEEE 39-bus system to validate the proposed method

Detection and Location of Faults in Wide Area Systems based on Error-Dependent Communication Strategy

Transmission system serves as a crucial link between generating stations and consumers. Early detection and accurate location of faults on transmission lines are essential to prevent the occurrence of blackouts. Also real time monitoring of power system states during faults will enhance the situational awareness for power system operators. Wide Area Measurement and Protection Systems (WAMPS) based on Phasor Measurement Unit (PMU) are a promising solution for dynamic real time monitoring and protection of power system.;This thesis deals with detection and location of faults on a transmission system based on synchrophasor technology. Performance of WAMPS is largely dependent on the performance of its information and communication technologies infrastructure. Error-dependent communication strategy is employed in this work for communication of real time data from PMU to the centralized controller. As PMUs are expensive, they cannot be placed at every bus. Hence linear state estimator based on synchronized measurements is employed for estimating the state of the entire system. The estimated states of the system are then compared to a certain threshold and if any abnormality is found, fault is detected. Once the faulted bus is detected, two-terminal algorithm is employed to identify the exact location of fault. The proposed methodology is implemented on IEEE 9 bus system developed in MATLAB/SIMULINK environment

Permanent Fault Location in Distribution System Using Phasor Measurement Units (PMU) in Phase Domain

This paper proposes a new method for locating high impedance fault in distribution systems using phasor measurement units (PMUs) installed at certain locations of the system. To implement this algorithm, at first a new method is suggested for the placement of PMUs. Taking information from the units, voltage and current of the entire distribution system are calculated. Then, the two buses in which the fault has been occurred is determined, and location and type of the fault are identified. The main characteristics of the proposed method are: the use of distributed parameter line model in phase domain, considering the presence of literals, and high precision in calculating the high impedance fault location. The results obtained from simulations in EMTP-RV and MATLAB software indicate high accuracy and independence of the proposed method from the fault type, fault location and fault resistance compared to previous methods, so that the maximum observed error was less than 0.15