• Energy Research

In this paper, the performance of the phase comparison (PC) transmission line protection is evaluated, considering fault scenarios which are not readily analyzed in the literature on the subject. In order to do so, several faults in a 500 kV/60 Hz transmission line 200 km long were simulated using the Alternative Transients Program (ATP). Different values of power system loading, fault parameters and system-to-line impedance ratio (SIR) were taken into account. In each case, both phase and sequence elements, with and without charging current effect removal, were analyzed. The obtained results reveal the sensitivity limits of the studied PC protection algorithms, highlighting the differences on their performances when the line capacitive effect is removed from the measured currents.

Abstract In this paper, the effects of stray capacitances that may appear on the coupling capacitor voltage transformer (CCVT) during field operation are addressed. Those stray capacitances are usually ignored in the existing limited frequency bandwidth CCVT digital models reported in the literature. A sensitivity analysis is carried out to evaluate how the equipment magnitude and phase frequency responses can be affected when such capacitances are taken into account. Besides, the feasibility of classical CCVT transient response compensators is analyzed in these scenarios. The impact of these features is investigated on the performance of one- and two-ended traveling wave (TW)-based fault location techniques. The obtained results attest that the presence of the stray capacitances improve the performance of two-ended TW-based fault locators, but the classical CCVT compensator may not accurately reproduce the voltage TWs.

Abstract This paper presents a steady-state electromagnetic interference study between a 500 kV overhead transmission line and a neighboring pipeline, based on data from a real project with a complex geometry and with emphasis on how the soil structure affects the inductive coupling mechanism, as well as the effectivity of grounding devices to reduce potentially hazardous pipeline induced voltages. Soil parameters are determined from actual field measurements, which results in a soil model composed of three layers. Conductor impedances are computed using a modification of the original Carson equation, in which the term describing the soil resistivity is replaced by an equivalent uniform of the multilayered structure, and then a circuit model is built using the Alternative Transients Program (ATP) to predict the resulting induced voltages. Results show an excellent agreement between the proposed approach and the reference values, with a comprehensible evaluation of the risks to which the interfered pipeline is exposed and how to mitigate them.

This paper highlights the evolution of wind power sources in the modern energy scenario, emphasizing the impacts of inverter-based generators, namely Full-Converter and DFIG (Doubly-Fed Induction Generator), on fault currents and fault voltages in transmission systems. The studies were carried out through computer simulations, with an EMTP (Electromagnetic Transients Program) type software. A power system with high penetration of such renewable generations was modeled and several contingency scenarios were simulated in a transmission line that performs the connection of the wind power plant to the grid. The scenarios included the variation of parameters such as fault type, inception instant angles, resistance, and distance, to explore the main differences between the contributions to the fault of a wind power plant and conventional generation. Among the atypical analyzed characteristics, the following can be highlighted: the absence of the DC (Direct Current) component for Full-Converter generation, independent of fault inception instant angle and distance variation; low levels of the fault contributions at the wind power plant terminal; low levels of voltages at the wind power plant terminal, evidencing the high SIR (Source Impedance Ratio) characteristic of these generations; atypical relations between the fault resistance and measured currents; and others. The obtained results show the importance of further studies on the impacts of inverter-based generations on fault currents and voltages, allowing developments that are able to improve control and protection systems for grids with high penetration of this wind generation topologies

This work describes the modeling of busbar differential protection function by using the MODELS language available in the software Alternative Transients Program (ATP). This type of modeling includes data acquisition and signal conditioning modules for suitably implementing the commercially used 1-out-of-1 and 2-out-of-2 logics. This algorithm is based on instantaneous values of currents and considers an additional zone selection logic to keep up with the dynamic reconfiguration of flexible busbar arrangements. The results show that this type of modeling is a powerful tool for assessments of protection relays for any substation configuration in operational conditions, not readily available in actual records.

Cet article présente une analyse approfondie des effets de la fréquence d'échantillonnage sur les performances de la méthode classique de localisation des pannes de ligne de transmission à ondes progressives à deux terminaux, démontrant que ces effets peuvent être représentés par des régions bien définies (au format de losanges) dans un plan espace-temps. Ainsi, il est démontré que le procédé classique estime la localisation des défauts en des points prédéfinis en raison de la résolution temporelle associée à la fréquence d'échantillonnage. En outre, les défauts au même emplacement peuvent être estimés de manière aléatoire dans différents emplacements prédéfinis en fonction de l'heure de début du défaut, ce qui entraîne des incertitudes d'emplacement. Néanmoins, les losanges spatio-temporels proposés soutiennent une analyse probabiliste afin de considérer les effets de fréquence d'échantillonnage en ajoutant une composante de champ de recherche probabiliste à la formulation classique de localisation de défaut qui indique la région dans laquelle le défaut a eu lieu avec 100% de certitude concernant les effets de fréquence d'échantillonnage. Par conséquent, cet article propose également une amélioration de la méthode classique en considérant les effets de la fréquence d'échantillonnage. L'approche proposée a été évaluée au moyen de simulations numériques et validée expérimentalement en laboratoire par l'application de failles le long d'un câble de 1 km de long. Este documento presenta un análisis profundo de los efectos de la frecuencia de muestreo en el rendimiento clásico del método de ubicación de fallas de la línea de transmisión basada en ondas viajeras de dos terminales, lo que demuestra que estos efectos pueden representarse mediante regiones bien definidas (en el formato de pastillas) en un plano de tiempo-espacio. De este modo, se demuestra que el método clásico estima la ubicación de la falla en puntos predefinidos debido a la resolución de tiempo asociada a la frecuencia de muestreo. Además, las fallas en la misma ubicación se pueden estimar aleatoriamente en diferentes ubicaciones predefinidas dependiendo del tiempo de inicio de la falla, lo que resulta en incertidumbres de ubicación. Sin embargo, las pastillas de tiempo-espacio propuestas respaldan un análisis probabilístico para considerar los efectos de la frecuencia de muestreo al agregar un componente de campo de búsqueda probabilístico a la formulación clásica de ubicación de fallas que indica la región en la que tuvo lugar la falla con el 100% de certeza con respecto a los efectos de la frecuencia de muestreo. Por lo tanto, este artículo también propone una mejora en el método clásico al considerar los efectos de la frecuencia de muestreo. El enfoque propuesto se evaluó mediante simulaciones digitales y se validó experimentalmente en laboratorio mediante la aplicación de fallas a lo largo de un cable de 1 km de longitud. This paper presents a deep analysis of sampling frequency effects on the classical two-terminal traveling wave-based transmission line fault location method performance, demonstrating that these effects can be represented by well-defined regions (in the format of lozenges) in a time-space plane. Thereby, it is demonstrated that the classical method estimates the fault location in predefined points due to sampling frequency-associated time resolution. Furthermore, faults at the same location can be randomly estimated in different predefined locations depending on the fault inception time, resulting in location uncertainties. Nevertheless, the proposed time-space lozenges support a probabilistic analysis in order to consider the sampling frequency effects by adding a probabilistic search field component to the classical fault location formulation which indicates the region in which the fault took place with 100% of certainty regarding the sampling frequency effects. Therefore, this paper also proposes an improvement on the classical method by considering the effects of the sampling frequency. The proposed approach was evaluated by means of digital simulations and validated experimentally in laboratory by the application of faults along a 1 km long cable. تقدم هذه الورقة تحليلًا عميقًا لتأثيرات تردد أخذ العينات على أداء طريقة تحديد موقع خطأ خط الإرسال الكلاسيكي القائم على الموجة المتنقلة ثنائية الطرف، مما يدل على أن هذه التأثيرات يمكن تمثيلها بمناطق محددة جيدًا (في شكل معينات) في مستوى الزمان والمكان. وبالتالي، يتضح أن الطريقة الكلاسيكية تقدر موقع الخطأ في نقاط محددة مسبقًا بسبب تحليل الوقت المرتبط بتكرار أخذ العينات. علاوة على ذلك، يمكن تقدير الأخطاء في نفس الموقع بشكل عشوائي في مواقع مختلفة محددة مسبقًا اعتمادًا على وقت بدء الخطأ، مما يؤدي إلى عدم اليقين في الموقع. ومع ذلك، فإن معينات الزمان والمكان المقترحة تدعم التحليل الاحتمالي من أجل النظر في تأثيرات تكرار أخذ العينات عن طريق إضافة مكون حقل بحث احتمالي إلى تركيبة موقع الصدع الكلاسيكية التي تشير إلى المنطقة التي حدث فيها الصدع بنسبة 100 ٪ من اليقين فيما يتعلق بتأثيرات تكرار أخذ العينات. لذلك، تقترح هذه الورقة أيضًا تحسين الطريقة الكلاسيكية من خلال النظر في آثار تكرار أخذ العينات. تم تقييم النهج المقترح عن طريق المحاكاة الرقمية والتحقق من صحته تجريبياً في المختبر من خلال تطبيق الأعطال على طول كابل طوله 1 كم.

The integration of distributed generation in distribution networks have grown over the years due to many advantages. However, in order to integrate this kind of energy generation, technical challenges in protection schemes must be overcome. The goal of this paper is to list impacts and concerns that may arise due to the interconnection of distributed generation in the grid, pointing out feasible solutions and trends.

Abstract In this paper, a new single-ended travelling wave-based protection scheme for double-circuit lines is proposed. It is developed to operate in parallel with traditional phasor-based protective relays and is able to accelerate the tripping time in most fault scenarios. The proposed method considers the propagation of travelling waves in a loop formed by the faulted and healthy line circuits. Disturbances within a given protected zone can be reliably detected according to the amplitude, polarity and time difference between the arrival instants of travelling waves that reach the monitored terminal. Also, the accumulative cross-differential current deviation is used to confirm internal faults, distinguishing them from other non-fault events. From the analysis of massive digital fault simulations and actual field records, it is attested that the proposed protection is feasible and effective.

Abstract This paper presents a new time domain busbar protection algorithm which uses current samples and their half-cycle incremental quantities to implement a fast and reliable tripping logic. The sign of incremental quantities is used to determine the fault direction and to distinguish internal from external busbar faults. Also, a differential incremental current is calculated for properly selecting the circuit breakers that must be opened to clear the fault. In order to test the proposed technique, a double-bus single-breaker busbar configuration was modeled in ATP/ATPDraw software and several types of internal, external and evolving faults are simulated. The results reveal the proposed function quickly operates for internal faults and ensures security for external faults. Moreover, the proposed approach allows a fast detection of internal faults during an external fault. Hence, although the proposed function is based on well-known fundamentals, it achieves the principal requirements for a busbar protection scheme with a high degree of adaptability and reliability for severe cases.