Wide-area Backup Protection Research Articles

Research on a Distance Relay-Based Wide-Area Backup Protection Algorithm for Transmission Lines

In this paper, a distance relay-based wide-area backup protection (WABP) algorithm for transmission lines is presented. The proposed WABP collects the statuses of zone 2 and zone 3 distance relays in local substation and immediate neighboring substations. When a fault has occurred, the WABP decides whether the fault is on the protected transmission line or somewhere else. Then, it determines the appropriate time delay of tripping and acts in coordination with conventional distance relays. With the proposed WABP equipped, the setting of conventional distance relays can be simplified. The requirement of coordination between the conventional relays can be loosened and the difficulty of setting calculation can be reduced. Simulation results show that the proposed WABP can coordinate with conventional distance relays set by different methods, and it can correctly detect faults and help to reduce blackout area with fault tolerance.

A Survey on Wide-Area Backup Protection in Energy Internet

能源互联网的建设为继电保护领域的发展提供了机遇，然而传统继电保护系统在复杂互联的电网保护中已凸显能力的不足。以广域测量技术、通信技术、计算机技术为基础，能源互联网继电保护发展为着眼于全局角度的广域保护。本文通过对能源互联网继电保护与传统继电保护的对比，介绍了能源互联网继电保护的功能、结构，以纵联差动保护为例阐述了能源互联网继电保护的主要特征，并对其未来发展进行了展望。 The construction of energy Internet provides an opportunity for the development of relay pro-tection. However, the traditional relay protection system is inadequate in the complex inter-connected power grid protection. Based on wide area measurement technology, communication technology and computer technology, the energy internet relay protection has developed into a global perspective of the wide-area protection. Through comparison of the energy internet relay protection and traditional protection, the function and structure of energy internet relay protection are introduced, and the main features of the energy internet relay protection are described in the case of the differential protection. Besides, the future development is prospected in this paper.

A Wide-Area Backup Protection Algorithm Based on Distance Protection Fitting Factor

In view of the time delay and potential information loss problem in wide-area data acquisition, a wide-area backup protection algorithm based on the distance protection fitting factor is proposed in this paper. First, the contribution of the distance protection operating information to fault identification is defined as the distance protection contribution degree. Second, the protection fitness function and protection fitness expectation function are constructed using the distance protection contribution degree as the weight. And then, the distance protection fitting factor is gained by calculating the division of the protection fitness function by the protection fitness expectation function. Thus, the fault line can be identified. Finally, simulation tests on the IEEE 10-machine 39-bus system and Guizhou Duyun real-time digital simulator verify that the proposed method is not affected by the time delay in wide-area data acquisition and is able to identify the fault line correctly even when a large amount of distance protection operating information is lost or in error. Meanwhile, the uncertainty problem in traditional weight setting due to reliance on subjective experience is avoided. Besides, being small in computation amount, the proposed method is easy to implement in engineering practice.

Wide area backup protection algorithm for transmission lines based on fault component complex power

In this paper a new wide area backup protection algorithm based on the fault component complex power is proposed to overcome the problem of maloperation of conventional backup protection in highly stressed conditions of power system operation. Firstly, suspected faulty lines are detected using measured values of fault component voltages known as faulted area identification (FAI) criteria. Then, the fault component voltages and currents provided by phasor measurement units (PMUs) are applied to calculate the injected complex power to both terminals of the suspected faulty lines. The ratio between sum and difference of injected complex power to the both terminals of the suspected faulty lines is used as faulted line identification (FLI) criteria. The simulation studies performed on the IEEE 10 generator 39-bus system verify effectiveness of the proposed algorithm under various conditions and fault types.

An Advanced Fault Locating Technique with WAMS based Backup Protection Scheme for Power System with Simultaneous Faults

Protection of power systems is important for stable and uninterrupted operation of power network. Maloperation of traditional back up protection schemes (e.g-Zone3 maloperation) causes many catastrophic phenomenon like cascaded tripping in power systems. So, some defensive mechanism are needed for taking care of such failures in power systems and to increase their security and reliability. Due to hugeness and complexity of Modern power systems, they are controlled, monitored and protected by Wide Area Measurement systems (WAMS). WAMS increases the efficiency and reliability of power networks and prevent the chance of blackouts and cascading failures in tandem. A synchronized phasor measurement-based wide-area backup protection scheme is presented in the paper where the magnitude of sequence voltages of buses at a system protection centre are used to identify the faulted area, bus closest to the fault and faulted line. The proposed method is tested for several faults including simultaneous faults in power systems with interconnections also. This technique is found to be Reliable, accurate and fast with contemporary synchronized measurement based technology. It is expected that numerous disastrous blackouts, cascaded tripping of power networks can be avoided and reliability and security of the power systems can be improved by the scheme. The study of new and improved back up protection scheme is done on a WSCC-3 machine-9 bus system. The data is simulated through EMTDC/PSCAD and MATLAB /SIMULINK software.

A Model Checking Approach to Testing the Reliability of Smart Grid Protection Systems

As distributed, communication-based protection systems become more prevalent in the emerging smart grid, the task of critically assessing their reliability has become increasingly challenging due to the complexity of their underlying software designs. This paper demonstrates that the discipline of software model checking can be applied to smart grid protection software designs to rigorously assess their fault tolerance. In this paper, the SPIN model checker is applied to a published wide-area backup protection system (WABPS). The WABPS was specifically architected to be highly reliable under various kinds of common failure scenarios, including mechanical malfunctions, erroneous sensor readings, and communication failures. However, because of its built-in redundancy and decentralized peer-to-peer design, calculating its precise fault tolerance is nontrivial. This paper shows how SPIN can be applied to the WABPS's design to brute-force prove the limits of the number and types of failures that can occur while the system remains able to successfully perform its function. This same technique is applicable to a wide variety of smart grid protection software designs, and the information it provides is invaluable to protection engineers during the development of new systems, for assessing the quality of competing designs, and for risk management purposes.

Association Analysis of System Failure in Wide Area Backup Protection System

Abstract Wide area backup protection algorithm based on fault component identification is the heart of the whole wide area backup protection system, its validity and reliability is a problem which needs to be first considered in the engineering practice applications of wide area backup protection system. Wide are backup protection algorithm mainly use two kinds of wide area information to realize protection criterion, one is electrical quantity information, such as voltage, current, etc. Another one is protection action and circuit breaker information. The wide area backup protection algorithm based on electrical quantity information is mainly utilizing the significant change of electrical quantity to search fault component, and the primary means include current differential method of wide area multi-measuring points, the comparison method of calculation and measurement, the multiple statistics method. In this paper, a novel and effective association analysis of system failure in wide area backup protection system will be discussed carefully, and the analytical results are successful and reliable.

Synchrophasor-Based Wide-Area Backup Protection Scheme with Data Requirement Analysis

This paper presents a fast and robust wide-area backup protection scheme to detect the faulty condition and to identify the faulted line in a large power network. The proposed methodology uses positive-sequence synchrophasor data captured by either digital relays with synchronization capability or phasor measurement units dispersed over the network. The basic idea behind the new protection scheme is the comparison of bus voltage values calculated through dissimilar paths. Upon occurrence of a fault, the faulty condition is first detected and the bus(es) connected to the faulted line is(are) determined. Among transmission lines connected to the suspected bus(es), the faulted one is thereafter identified. In addition to two-terminal transmission lines, multiterminal lines are also incorporated. The performance of the proposed method is validated on the IEEE 57-bus test system in different fault conditions (fault type, fault location, and fault resistance). Discrimination of faulty and normal conditions is simulated by examining various stressed conditions, for example, load encroachment, generator outage, and power swing. The data requirement of the proposed technique is analyzed as well. To do so, a mathematical model for the optimal placement of measurement devices is developed and applied to different IEEE standard test systems.

Directional weighting based wide area backup protection tripping strategy

Summary The development of large inter-connected power grid poses an urgent need for better adaptability of the backup protection. In this paper, a wide area backup protection tripping strategy based on directional weighting is proposed, on the premise that the fault component has been identified by the limited wide area centralized backup protection. First, according to the network topology and the positive sequence current phasor information of the switches in local area, the node–branch correlation matrix based on directional weighting is formed. And then, based on the fault identification result and the positive sequence current phasor information of the switches, the component–breaker correlation degree vector is constructed, and the correlated breakers are identified and tripped. Simulation results verify that, with the proposed method, the backup protection coordination is simplified and fault clearance could be limited to the minimum range in various cases. Meanwhile, the proposed method is applicable and reliable even when part of the information is missing, and the requirement on information synchronization is not strict. Copyright © 2015 John Wiley & Sons, Ltd.

Communication-Constrained Regionalization of Power Systems for Synchrophasor-Based Wide-Area Backup Protection Scheme

The evolving wide-area measurement system technology offers new opportunities for backup protection of transmission lines to avert the misoperation of conventional relays against system disturbances and prevent system instability. Since wide-area backup protection (WABP) is to operate at the range of a few hundred milliseconds, the delays associated with data and command communications and algorithm execution can be a troublesome issue in a large-scale power system. This paper briefly reviews a WABP scheme based on positive-sequence voltage phasor direct and indirect measurements. To overcome the problem of WABP delays, an integer linear programming (ILP) model is proposed to divide the power system into several protection regions. This process is accomplished in three stages in which the number and location of measurement devices (MDs), the number and boundary of protection regions, and the location of protection rooms, as well as the total number of communication links between MDs and protection rooms are optimized. The proposed WABP scheme is implemented in each region and individually protects the associated transmission lines. Execution of the proposed ILP model on different test systems reveals that with regionalization of the systems, WABP schemes can reliably be used in practice.

An Adaptive PMU-Based Wide Area Backup Protection Scheme for Power Transmission Lines

This paper proposes a novel adaptive wide area backup protection scheme for transmission lines. In the proposed scheme, both the faulted line and fault location are determined by a limited number of synchronized phasor measurements. Based on phasor measurement unit placement and network topology, subsets of lines and buses called backup protection zones (BPZs) are formed. After a fault occurs in the transmission network, the sum of zero- and/or positive-sequence currents entering the faulted BPZ highly increases, and hence, the faulted BPZ can be determined. The linear least squares method is then used to determine the faulted line, as well as the fault location by voltage and current phasors of the faulted BPZ. Accordingly, the proposed scheme provides a closed-form and noniterative solution for the faulted line and fault location identification problem. On the other hand, it readily determines the faulted line regardless of the fault type, fault resistance, and measurement errors. To show the effectiveness of the method, it is applied to the WSCC 9-bus and IEEE 118-bus test systems. Simulation results verify successful identification of the faulted BPZ as well as the faulted line within the faulted BPZ with limited measurement points.

Wide-Area Measurement-Based Backup Protection for Power Network With Series Compensation

This paper presents a synchronized phasor measurement-based wide-area backup protection scheme which compares the magnitude of sequence voltages of buses at a system protection center to identify the bus closest to the fault. Then, the sign of cosine of the angle between voltage and current at both ends of all lines connected to this bus are compared to identify the faulted branch. The technique is tested for various faults resulting in voltage/current inversion in a series-compensated line and during load encroachment and power swing conditions using data simulated through EMTDC/PSCAD for a nine-bus, three-machine power system. The scheme is found to be accurate and fast. With today's synchronized phasor measurement technology and communication system, the proposed scheme can overcome the limitations of the conventional backup protection scheme.

A Wide-Area Backup Protection Algorithm for Multi-Fault Location in Complex Large Power Grid

This paper presents a fitting degree-based multi-fault location algorithm for complex large power grid utilizing wide-area information. Firstly, fault injection current of the equivalent fault points is used in the equivalent model. Then the correlation matrix is formed by the network topology and associated nodal injection current and a network is formed to determine the location of faults. When multiple faults occur, the addition of the current of each two fault lines is calculated and the real-time current is measured. Then by calculating the minimum of fitting degree between two current values, fault line and virtual fault location can be determined. The simulation results of 10-generator 39-bus system verify the validity and feasibility of this algorithm.

Wide-Area Backup Protection Algorithm Based on Earth Impedance Comparison Principle

A novel algorithm is proposed for the purpose of improving the reliability and sensibility of fault component identification of wide area backup protection. The algorithm, called earth impedance comparison protection (EICP), is realized by comparing the ratios of different nodes, and the ratio is obtained by the bus voltage to the differential current. The advantages of EICP are verified in this paper using the measurement function of wide-area measurement system. The results of case studies show that EICP is superior to the current differential protection in terms of the sensitivity and to the directional pilot protection in terms of the dependability. The satisfactory results can be obtained when the EICP method is applied in the event of abnormal operations of protective relays and circuit breakers, measurement error scenarios or substation DC failure.

A novel wide-area backup protection based on fault component current distribution and improved evidence theory.

In order to solve the problems of the existing wide-area backup protection (WABP) algorithms, the paper proposes a novel WABP algorithm based on the distribution characteristics of fault component current and improved Dempster/Shafer (D-S) evidence theory. When a fault occurs, slave substations transmit to master station the amplitudes of fault component currents of transmission lines which are the closest to fault element. Then master substation identifies suspicious faulty lines according to the distribution characteristics of fault component current. After that, the master substation will identify the actual faulty line with improved D-S evidence theory based on the action states of traditional protections and direction components of these suspicious faulty lines. The simulation examples based on IEEE 10-generator-39-bus system show that the proposed WABP algorithm has an excellent performance. The algorithm has low requirement of sampling synchronization, small wide-area communication flow, and high fault tolerance.

Fault Location Method Based on Wide-Area Voltage

Backup protection chain tripping caused by flow transferring is one of the most concerned issues in power system. The introduction of wide area backup protection is an effective way to solve the problem. However, in wide area protection system, an effective fault location puts forward a high demand for the location algorithm. This paper presented a method which combined effective mathematical methods with fault location calculation in power system together: firstly used fuzzy clustering analysis method for fast classification of voltage, locked the fault area, and prevented the occurrence of even jump accident at the first time. Then determined the fault location by calculating additional nodal current ratio in the fault area. The method avoids the repeated modification of network structure after fault. It lock the fault to the component quickly and improves the efficiency of fault location greatly.

The Study of a Regional Decentralized Peer-to-Peer Negotiation-Based Wide-Area Backup Protection Multi-Agent System

Conventional protection relays, which use local signals to locate faults, are a poor fit to modern power grids when compared to communication-based alternatives. This article presents a novel Wide-Area Backup Protection (WABP) algorithm that uses information shared across wide-area communication networks. The WABP algorithm fuses and integrates information in a regional decentralized peer-to-peer negotiation architecture for enhanced effectiveness. Line decision-making agents (LDAs), focused on line-fault detection, collect distance and directional protection information on both sides of a line. If LDAs cannot detect a fault locally, wide-area information that includes directional protection and line-fault states from neighboring lines is collected to locate the fault. The LDA considers the possible presence of relay misoperations, protection failures, and/or communication failures. Regional decision-making agents (RDAs) that reside in a regional decision-making device (RDD) in the monitoring layer of a substation can negotiate in a peer-to-peer manner without a control center. The RDA serves as the manager, coordinator, and message transponder for the LDAs. The design of the WABP is described including its architecture, workflow, and its agents' functions. Simulation scenarios illustrate the correctness of the WABP multi-agent system and the higher fault-tolerance of its response to misoperations, protection failures, and communication failures.

A New Approach to Fault Location in the Random Disturbance of Wind Power

The development and utilization of renewable energy resources is the future development direction. Wide area backup protection needs to locate fault element and fault section before backup protection action, and prepare for modifying fixed value of backup protection. The researches in this paper are mainly serving wide area adaptive backup protection system. Considering the development of new energy resources power system, especially the random disturbances of wind power, based on Bayes posterior decision principle, we will explore a new fault location technology. According to different types of faults, extensive simulation experiments have amply demonstrated the reliability of this fault location technology

Bayes-Based Fault Discrimination in Wide Area Backup Protection

Multivariate statistical analysis is an effective tool to finish the fault location for electric power system. In Bayesian discriminant analysis as a subbranch, by the research of seve ...

Correction to “Wide-Area Backup Protection Algorithm Based on Fault Component Voltage Distribution” [Oct 11 2752-2760

In the above titled paper (ibid., vol. 26, no. 4, pp. 2752-2760, Oct. 2011), Figs. 1 and 2 appear incorrectly. The correct figures are presented here.