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The new IEC 61850 standard for communication networks and systems in substations has a significant impact on the development of a new generation protection solutions that offer significant benefits to the user. The paper analyzes conventional centralized and distributed bus differential protection schemes and compares them with IEC 61850 station and process bus based solutions. It describes their...
Several pilot projects related to the Process Bus are being executed with the main goal to certify the reliability of the network as the mean to transmit information which is critical to the integrity of the protection system. This paper presents a methodology to evaluate the process bus reliability based on the model of reliability for different network topologies. Considering the MTBF of the elements...
Generator protection has traditionally only measured stator AC currents and voltages. Measurement of rotor DC current was typically more difficult and required special measurement equipment (e.g. resistive shunt) in the rotor DC circuit. With advance of numerical technology it is now actually feasible for modern Intelligent Electronic Devises (i.e. IEDs) to measure the rotor winding DC current by...
A multi-converter network, either radial or meshed, requires not only a means of clearing faults on the DC network but also means of detecting and locating these faults. The characteristics of these DC side faults are fundamentally different to those in AC systems and therefore a DC network protection system requires special consideration. This paper explores the types of fault currents and fault...
This paper focuses on the protection challenges associated with multi-terminal high voltage direct current (HVDC) offshore transmission networks. The applicability of fibre optic communications based differential protection to such networks is explored using a dynamic model of a five-terminal North Sea “supergrid”. Short circuit fault transients are simulated and used to define the protection requirements...
The shunt large capacitor, on both sides of voltage source converter based HVDC (VSC-HVDC) transmission lines, will rapidly discharge to the fault point when a fault occurs. The system side can be equivalent to the shunt large capacitance in the fault component model. According to this characteristic of the VSC-HVDC system, a novel pilot protection scheme for VSC-HVDC transmission lines based on parameter...
Packet/frame-based communication services have been in general use for utility communications for a number of years with the exception of communications for protection and in particular line current differential protection. Recently, a number of utilities have begun to investigate the possibility of applying packet/frame-based communication supported by Ethernet Layer 2 (L2) for protection signaling...
A trend was recognized that utilities worldwide outsource manpower or experts for testing and commissioning. Service providers accept such challenges for utilities' newly established substations. Although the engineers from service providers are usually very experienced with relay testing, some time-consuming tasks during the commissioning remains unchanged, e.g. the reasoning process on relay testing...
This paper describes a novel algorithm for feeder earth-fault protection applicable in compensated and unearthed mediumvoltage networks. The suggested algorithm provides good protection sensitivity and very secure discrimination between faulty and healthy feeders even in the most challenging faults with highly distorted signals such as restriking earth faults. The operation of the novel method is...
The different protocols offered by IEC 61850 can be transmitted over a common communication network for transporting traffic of different kinds from multiple senders to multiple receivers instead of using multiple point-to-point connections. There have been always concerns what might happen if high traffic load occurs on such a network, especially when many components of a power utility automation...
A new technique to detect the fault direction of single-phase-to-earth fault for Petersen's Coil compensated earthed power system is presented in this paper. The proposed technique can make a precise decision on detecting the single-phase-to-earth fault, not requiring higher frequency sampling rates, higher accuracy measurements. It can be implemented in traditional feeder relay with low sampling...
Conventional instrument voltage transformers are currently used as the essential instrument for harmonic measurement in power network. However, their frequency bandwidths are limited. As a result, they are not suitable for high frequency harmonic measurement unless their frequency responses in a concerned frequency range (e.g. 50Hz to 5 kHz) are clarified. Hence, this paper presents the test and analysis...
Creating a common protection testing-template is very intricate because of the high flexibility of digital protection devices. In such a testing-template all main protection functions need to be considered. The Substation Configuration Language (SCL) referring to IEC 61850 defines a consistent representation format. This representation format for example describes the configuration of the protection...
This work proposes a software tool for fault diagnosis in power systems. The solution was developed to monitoring real-time SCADA data of the transmission and generation network of a Brazilian electric utility in order to assist operators of control centres to analyse the occurrence and to decide the best procedures to re-establish the service in order to enhance the service reliability and reduce...
Dynamic state estimation is a useful tool for bad data detection and identification. However so far no dynamic state estimator considers the state constraints like zeros injection constraints in power system. In this paper, a new dynamic state estimator based on the projected unscented Kalman filter (PUKF) is presented. It is based on the application of unscented transformation and estimate-projection...
In order to maintain the power system stability for more serious disturbance, some stability control devices have been installed, and the stability control system is developed. Angle stability problem is one important stability problem of power system and the control strategy is computed ahead of time by offline simulation. The power flow of data used in the offline simulation usually is very serious...
This paper outlines the effects of frequency deviations on modern memory polarised distance protection relays. During such conditions the behaviour of the relay characteristics may be cause undesirable mal-operations, which can be avoided by the use of appropriate load blinders and protection starters.
It is well known that line switching operations like reclosing are able to cause transient power oscillations which can stress or damage turbine generators. This paper presents a reclosing scheme to reduce the shaft torsional torques of turbine generators by inserting an additional reactor. In this paper, the turbine generator shaft is represented by a multi-mass model to measure torsional torques...
This article presents a brief description of closed-loop tests and tools for their implementation. The main emphasis in article is on the principle of operation of closed-loop simulation for protective relays and the particular construction of built real-time simulator. Selected test results of distance relay (made with built simulator) have also been shown. The hardware part of the simulator using...
For many years now, the accuracy of data used for thermal evaluation of insulating materials and systems has been grossly impaired by systematic errors inherent in the degradation process itself. The most significant of these are the errors due to temperature variation within the oven chamber used for thermal ageing experiments. It is important to be able to declare within acceptable tolerances that...
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