Protection System Coordination Research Articles

The Economic and Social Impact of Coordination

In this article the economic and social impacts of the coordination of pensions and pension policy in the EU are analysed. Three different aspects are discussed: the coordination of the individual social security rights of migrant workers; the coordination of national social protection systems; and the coordination of economic and employment policies as far as they affect social security. With respect to the coordination of the individual social security rights of migrant workers, it is argued that this is a prerequisite for the free movement of workers in the EU. The article discusses the impacts of this coordination, such as impacts on pension payments arising from EC Regulation 883/2004 (formerly EC Regulation 1408/71), and the provision of international counselling events. It is noted that the Regulation covers not only old age pensions but also pensions in cases of reduced earning capacity and benefits for rehabilitation. The second area of coordination is implemented through the Open Method of Coordination (OMC). It is argued that, on the one hand, the OMC provides support to national governments to deal with the challenges of social security systems. On the other hand, the OMC also directly influences national social security policies, even though they are actually the responsibility of national authorities. Implications for national pension policy can also be found in the third area of coordination. Both Broad Economic Policy Guidelines and Employment Guidelines are used, which set targets which are relevant for pension policy, such as placing limits on public expenditure and the prolongation of working life. Finally it is argued that in the growing field of second- and third- pillar pension systems there is a need for further coordination.

Distribution Network Reconfiguration Considering Protection Coordination Constraints

The issue of protection system coordination in reconfigurable distribution systems is dealt with in this article. The protection coordination requirement restricts the changes in the power-flow direction through the distribution lines and drastically reduces the search space to be explored by the network reconfiguration algorithms. Moreover, the protection system for the reconfigurable distribution network has to be designed considering all permissible configurations of the network. This article illustrates the protection design procedure through a test network and presents a network reconfiguration algorithm incorporating the protection coordination constraints.

Application of support vector machines for fault diagnosis in power transmission system

Post-fault studies of recent major power failures around the world reveal that mal-operation and/or improper co-ordination of protection system were responsible to some extent. When a major power disturbance occurs, protection and control action are required to stop the power system degradation, restore the system to a normal state and minimise the impact of the disturbance. However, this has indicated the need for improving protection co-ordination by additional post-fault and corrective studies using intelligent/knowledge-based systems. A process to obtain knowledge-base using support vector machines (SVMs) is presented for ready post-fault diagnosis purpose. SVMs are used as Intelligence tool to identify the faulted line that is emanating and finding the distance from the substation. Also, SVMs are compared with radial basis function neural networks in datasets corresponding to different fault on transmission system. Classification and regression accuracies are is reported for both strategies. The approach is particularly important for post-fault diagnosis of any mal-operation of relays following a disturbance in the neighbouring line connected to the same substation. This may help to improve the fault monitoring/diagnosis process, thus assuring secure operation of the power systems. To validate the proposed approach, results on IEEE 39-Bus New England system are presented for illustration purpose.

배전계통의 보호협조측면에서 본 분산전원 연계용량 검토

정부의 신ㆍ재생 에너지 관련 정책으로 인해 앞으로 국내에서 신ㆍ재생에너지원은 보급은 증가할 것으로 예상된다. 신ㆍ재생에너지원은 전원의 특성상 전력계통에 연계되어 운전하는 것이 일반적이지만 이러한 연계 운전은 전력 계통 계획 및 운영상에 상당한 영향을 미치게 된다. 기존 배전계동의 전력조류는 변전소에서 수용가를 향한 단방향이며 이를 기반으로 계통운영이 이루어지고 있으나, 신ㆍ재생에너지원의 연계로 배전계통에 양방향의 전력조류가 형성되므로 기존의 보호시스템의 신뢰성 및 전력품질이 저하될 수 있다. 따라서 신ㆍ재생에너지원의 연계평가에 대한 기술적 평가절차가 필요하다. 본 논문에서는 국내 배전계통의 전형적인 보호기기인 자동 재폐로 차단기와 구분 개폐기의 특성을 살펴보고, 현재의 자동재폐로 차단기-구분개폐기 보호시스템에서 분산전원의 연계용량을 검토하는 방안을 제시하고자 한다.

Fault Current Contribution From Synchronous Machine and Inverter Based Distributed Generators

There are advantages of installing distributed generation (DG) in distribution systems: for example, improving reliability, mitigating voltage sags, unloading subtransmission and transmission system, and sometimes utilizing renewables. All of these factors have resulted in an increase in the use of DGs. However, the increase of fault currents in power systems is a consequence of the appearance of new generation sources. Some operating and planning limitations may be imposed by the resulting fault currents. This paper discusses a model of inverter based DGs which can be used to analyze the dynamic performance of power systems in the presence of DGs. In a style similar to protective relaying analysis, three-dimensional plots are used to depict the behavior of system reactance (X) and resistance (R) versus time. These plots depict operating parameters in relation to zones of protection, and this information is useful for the coordination of protection systems in the presence of DG

Electric Power Supply Options for FIRE

The FIRE experiment1 will present a net electric power demand approaching 1000MW for 10's of seconds, repeated once every 2 hours, delivered to the load via thyristor AC/DC converters which exhibit a widely varying power factor. The issues associated with the supply of such a load from the utility grid can be divided into two categories:Technical▪ transmission line power flow vs. capacity▪ voltage deviation within the grid vs. limits▪ frequency deviation within the grid vs. limits▪ loading of electrical equipment (e.g. generators)▪ control of power generation (e.g. steam turbines)Operational▪ control and monitoring of grid power flow▪ coordination of protection systems▪ repetitive cycling of power system equipment▪ allowance for contingency on tie line power flows▪ power flow reversal▪ harmonic content of load▪ power and energy monitoring, billing rate structure

Systems analysis of protection system coordination: a strategic problem for transmission and distribution reliability

A discussion is presented of the various aspects that combine to make coordination the strategic problem that it is. These aspects include: topological contingencies of a network, periodic coordination reviews, power system modification, protective device optimization, protective device outages, loss of system-knowledge base, restoration, and adaptive relaying of networks.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The state of the art of numerical relaying

The present state of the art of numerical relaying (commonly known as computer relaying) and its expected advantages, is outlined. This paper commences with a brief overview of computer and microprocessor-based relaying developments. Computers have brought two developments to protective relaying: more sophisticated traditional relaying, and the ability to adapt the protective system to changing system conditions. Numerical relays have already been put into operation at several utilities and they have contributed greatly to the improvement of power supply reliability. Typical examples of the developed equipment are described. Owing to the introduction of numerical techniques, the coordination of protection and station control systems has been an important issue during the recent years. Finally, expected trends in the area of algorithm and communication development which permit the development of a concept of adaptive relaying and coordinated protection and control for power system network are briefly mentioned.

The Concept of Figure of Merit Applied to Protection System Coordination

The Concept of Figure of Merit Applied to Protection System Coordination

The Concept of Figure of Merit Applied to Protection System Coordination

Clearly there is a need for further development and discussion of the Figure of Merit concept. This paper has presented three alternative Figures of Merit with numerical examples for a sample power system. The need for these measuring parameters is certainly clear to anyone who has performed a system-wide protection analysis using a digital computer program. The FOMs provide a means of comparison between alternative protective system designs just a system losses provide a means of comparison between different operating strategies. There is little doubt that the definitions of the Figures of Merit presented here will change or be replaced as practical experience is gained in their application. It is the author's intent that this paper will provoke serious consideration of an area requiring further study.

Distribution System Protection with Decentralized Generation Introduced into the System

Cogeneration from renewable energy sources has been universally proposed as a partial alternative to the solution of our nation's energy problems. New technical, safety, and operational problems are introduced when this generation is placed into a distribution grid. Addressed is the problem of distribution system protection with the introduction of cogeneration sources and the changes and modifications which may be required in the application of present-day protection devices. A sample system is considered, and system protection and coordination with and without cogeneration has been calculated through a digital fault and system protection coordination program. The results indicate through the study of several systems that additional coordination and protection considerations will be required when sizable cogeneration sources are introduced to maintain a high degree of reliability and service continuity.