Partial operating current characteristics to discriminate internal and external faults of differential protection zones during CT saturation
01 Jan 2018-Iet Generation Transmission & Distribution (The Institution of Engineering and Technology)-Vol. 12, Iss: 2, pp 379-387
TL;DR: The results documented encompasses various possible short-circuit (fault) scenarios and indicate the capability of the proposed algorithm in discriminating internal and external faults under CT saturation conditions.
Abstract: To protect transformers, transmission lines and busbar systems, low impedance current differential protection schemes based on percentage restraint characteristics are widely used in power systems. The main application issue of these schemes is mis-operation due to current transformer (CT) saturation during close-in external faults. A comprehensive fault discrimination algorithm is highly required for current differential protection schemes to overcome the CT saturation issue. The purpose of this study is to introduce a methodology based on partial operating current (POC) characteristics which discriminate internal and external faults of differential protection zones. The study includes the mathematical model of POC characteristics, a fault discriminating algorithm using POC features, and bus differential protection zone results. The results documented encompasses various possible short-circuit (fault) scenarios and indicate the capability of the proposed algorithm in discriminating internal and external faults under CT saturation conditions.
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TL;DR: The theoretical analysis and experimental simulation results show that the protection performance is sensitive and reliable, with a quick response and simple criterion, and is essentially not susceptible to the impacts of the initial fault angle, fault type, and fault resistance.
Abstract: To avoid the impact of the transient saturation of a current transformer, a fast busbar protection method based on the initial traveling wave integrated active power differential principle is proposed in this paper. The Peterson equivalent model is applied to analyze the initial traveling wave distribution characteristics of the internal and external faults of the busbar. The initial traveling wave active powers of each sampling point on each transmission line connected to the busbar are calculated with the implementation of an S-transform. By introducing the integrated active power actuating quantity and active power braking quantity, a protection criterion with a characteristic braking ratio is proposed. The theoretical analysis and experimental simulation results show that the protection performance is sensitive and reliable, with a quick response and simple criterion, and is essentially not susceptible to the impacts of the initial fault angle, fault type, and fault resistance.
13 citations
Cites background from "Partial operating current character..."
...To prevent these serious consequences caused by a busbar fault, special busbar protection should be set up to interrupt the short circuit current of the fault busbar both in a timely manner and correctly, creating higher requirements for the performance of the busbar protection [1]–[3]....
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TL;DR: A novel bus differential protection scheme that provides enhanced immunity against mis-operation resulted from current transformer (CT) saturation during close-in external faults and better sensitivity for internal faults is presented.
Abstract: This paper presents a novel bus differential protection scheme that provides enhanced immunity against mis-operation resulted from current transformer (CT) saturation during close-in external faults and better sensitivity for internal faults. The proposed scheme incorporates a fault discrimination algorithm based on partial operating current (POC) characteristic making the scheme capable of discriminating high current internal and external faults even with CT saturation. A supervision technique based on CT saturation detection is also included in the scheme design to increase the sensitivity of the proposed relaying scheme for very high impedance internal faults. A relay model is built in Matlab platform based on the proposed scheme and the performance is validated using a transmission network simulated in Electromagnetic Transients Program (EMTP) for various fault scenarios. Documented results show the proposed scheme improves the performance in terms of reliability, sensitivity, and selectivity over traditional bus differential schemes.
8 citations
TL;DR: These results proved the ability of the proposed algorithm to differentiate between in-zone and out-of-zone faults relating to CT saturation conditions and the noticeable adaptability and performance of the algorithm since it is not affected by such fault parameters as fault type, fault resistance, and fault inception time.
Abstract: One area of the major concern of busbar differential schemes is misoperation due to current transformer saturation through close-in out-of-zone faults. A comprehensive fault discrimination scheme is extremely needed for differential protection algorithms to overcome the CT saturation problem. This paper attempts to introduce a method based on innovative Cos–Sin characteristics that is capable of distinguishing between in-zone and out-of-zone faults of busbar protection. The results covered a wide variety of fault scenarios; these results proved the ability of the proposed algorithm to differentiate between in-zone and out-of-zone faults relating to CT saturation conditions. They further demonstrated the noticeable adaptability and performance of the algorithm since it is not affected by such fault parameters as fault type, fault resistance, and fault inception time. Experimental implementation of the devised Cos–Sin signal was conducted and manifested the capability and simplicity of its experimental constructability.
6 citations
01 Dec 2019
TL;DR: A new advanced protection algorithm based on a correlation technique to protect a busbar station consist of two voltage levels (220kV and 66 kV) will be presented in this paper.
Abstract: A new advanced protection algorithm based on a correlation technique to protect a busbar station consist of two voltage levels (220kV and 66 kV) will be presented in this paper. The proposed technique is developed for Busbar protection against all faults types, which may occurs in busbar zone. The technique uses the existing current transformers of all feeders in the station to measure the current signals and not need any extra equipment’s, while the technique depends only on the existing currents transformers at all feeders which connected to the protected zone. The proposed methodology is applied for a part of 220 KV Egyptian network. There are two program packages are used to implement the proposed technique (ATP) and MATLAB program. Large numbers of operation and fault cases are simulated to fulfill the requirements of busbar protection high speed and sensitivity for internal faults, and stability during normal and external faults with and without CT saturation effect. They further demonstrated the noticeable adaptability and performance of the algorithm since it is not affected by such fault parameters as fault type, fault resistance, and fault inception time.
3 citations
01 Mar 2018
TL;DR: In this article, the authors examined the performance of the current fault detection algorithm, the Alienation Coefficient Algorithm (ACA), and proposed an alternative fault detection technique for ACA and presented a simulation study to validate the performance.
Abstract: One of the latest fault discrimination algorithms used to supervise bus differential protection schemes, is Alienation Coefficient Algorithm (ACA). ACA uses alienation coefficient of current signals during first one-eighth cycle after fault inception to discriminate between internal and external faults. Therefore, the performance of ACA highly depends on fault detection speed. This paper examines the performance of ACA for currently used fault detection technique and the results reveal that ACA fails to detect external fault in case of fast current transformer (CT) saturation. This paper also proposes an alternative fault detection technique for ACA and presents a simulation study to validate the performance. Documented results show that ACA with the new fault detection technique performs better for fast CT saturation during close-in external faults.
2 citations
Cites background from "Partial operating current character..."
...Numerous fault discrimination techniques [4-13] were proposed by exploring various aspects of busbar faults....
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References
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TL;DR: In this paper, the authors describe an EPRI study of current transformer (CT) digital models intended for protective relay transient performance analysis, implemented using the Electromagnetic Transient Program (EMTP).
Abstract: This paper describes an EPRI study of current transformer (CT) digital models intended for protective relay transient performance analysis. Experimental evaluation of CT models implemented using the Electromagnetic Transient Program (EMTP) was carried out. Two relaying CTs with 600/5 and 2000/5 ratios were used in the study. Experiments in a high power laboratory were performed to obtain transient responses. Simulation of the CT response to the same transient events was set up using three different CT models. They were implemented based on the saturable transformer and nonlinear reactor models available in an EMTP. Comparison of laboratory and simulation results indicates that CT models developed based on the EMTP program give satisfactory results for most of the cases. It has also been discovered that in some instances EMTP models need further improvements. >
141 citations
11 Apr 2011
TL;DR: In this paper, the authors examine several common methods for defining restraint and slope characteristics and provide guidance on selection of the correct slope setting, and examine a multirestraint transformer differential application with steady-state, proportional, and transient sources of mismatch in the zone of protection.
Abstract: Percentage restrained differential protection is one of the oldest forms of adaptive protection algorithms. The slope characteristic provides high sensitivity when low levels of current are flowing in the zone of protection but has less sensitivity when high levels of current are flowing and false differential current due to current transformer (CT) saturation is more likely. The percentage restraint characteristic operates on the ratio of operate-to-restraint current in the zone of protection. The operate quantity is universally defined as the magnitude of the differential current in the zone of protection. However, several different methods have been developed to quantify the restraint quantity, which is a measure of the through current in the zone of protection. The definition of the restraint magnitude will have an impact on the effective sensitivity and security of a given percentage slope characteristic. This paper examines several common methods for defining restraint and slope characteristics and provides guidance on selection of the correct slope setting. Examples are used to examine a multirestraint transformer differential application with steady-state, proportional, and transient sources of mismatch in the zone of protection.
58 citations
20 May 2010
TL;DR: In this article, two drastically different types of differential relays, one with a single set of very high-impedance inputs and another with multiple sets of low-impingance inputs, are available for bus differential protection.
Abstract: Two drastically different types of differential relays, one with a single set of very high-impedance inputs and another with multiple sets of low-impedance inputs, are available for bus differential protection. Protection engineers often question which type to choose for their bus protection applications. This paper discusses for each type of relay the concepts used, the pros and cons, and the importance that current transformer selection plays in applications.
32 citations
01 Jul 2000
TL;DR: The design, implementation and testing of a microprocessor-based busbar protection system that uses the positive- and negative-sequence models of the power system and is composed of delta-impedance relays which implement a fault-detection algorithm, based on the developed technique.
Abstract: The design, implementation and testing of a microprocessor-based busbar protection system is presented. The proposed system employs a protection technique that uses the positive- and negative-sequence models of the power system. The system is composed of delta-impedance relays which implement a fault-detection algorithm, based on the developed technique. The algorithm, hardware and software of the relays are described. Performance of the proposed system was checked in the laboratory; the testing procedure and test results are presented.
22 citations
TL;DR: In this article, an adaptive differential relay with adaptive relay characteristics for avoiding current transformer (CT) saturation effects has been proposed, which uses the alienation and differential protection principles to make adaptive logic; if no CT saturation is detected, the differential principle alone is capable of tripping the busbar.
Abstract: This study presents an advanced technique provided with adaptive differential relay characteristics for avoiding current transformer (CT) saturation effects. The proposed technique uses the alienation and differential protection principles to make adaptive logic; if no CT saturation is detected, the differential principle alone is capable of tripping the busbar. If CT saturation is detected, both the alienation and differential principles must pickup in order to trip. The alienation coefficient is useful in CT saturation detection, evaluation of CT saturation degree and adapting the differential relay characteristics during saturation period of CTs to avoid false operation in the event of external faults. The differential current and alienation coefficient are calculated from two terminal currents of the busbar. The proposed protective scheme has several attractive features, including the simplicity of on-line implementation, not affected by the remanent flux in the CT core, and it is independent of the CT parameters/characteristics and secondary burden. A real 19.57 kV busbar is simulated using Alternate Transients Program/Electro-Magnetic Transient Program and MATLAB packages to examine the suggested scheme under different types of faults. Under normal operating conditions and external faults, the scheme remains stable and it operates only for the case of internal faults. Moreover, it is unaffected by CT saturation.
20 citations