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Power grid intellectualization is an important method to promote the development of renewable energy source and implement energy conservation and emission reduction. Along with the increasing development of power electronics, IT and communication technologies, the construction of smart grid is becoming an important development direction of electric power industry. Smart distribution grid is a critical...
The MV compensated Networks in Czech Republic are operated as nonsymmetrical, that means as networks with non-transposed lines. In these networks the fault currents depend on the affected phase because the Petersen coil is tuned only for one value of earth current. The paper deals with influence of fault type on size of fault current and on the length of its transient phenomena. There are described...
This paper discusses the topic of Control Systems within the Electricity industry. Distributed, Centralised, Regional are a small example of the varied types discussed. The purpose is to define the solution for a specific problem/requirement utilising the appropriate architecture of a 'Control System', rather than proposing a control system and tailoring the requirement accordingly.
Due to the increase in penetration of Distributed Generation (DG), the performance of power system protection at the distribution level is becoming increasingly critical to the reliable operation and stability of the whole system. This paper presents a critical assessment of the practice and performance of Loss-Of-Mains (LOM) protection (also referred to as anti-islanding protection), underpinned...
Multi-terminal lines are more often used in modern power systems than before. They are becoming particularly popular in sub-transmission networks (i.e. in networks with rated voltages between 60kV – 160kV) but also in HV networks [3, 4]. Practical experience with such protection from a commercial installation in Sweden will be presented.
LV networks have always their own difficulties regarding fault detection and location methods as compared with either MV or LV ones. Among these problems, detecting and locating high impedance faults still represent the most challenging problem. Load types as well as load variations may play a remarkable role for profiling the harmonic contents of voltage and current signals during faulty and non-faulty...
To date, synchronized phasor measurements have been used mainly for power system model validation, post-event analysis, real-time display, and other similar activities. However, synchrophasors have a greater potential than monitoring and visualization. Synchrophasors will increasingly contribute to the reliable and economical operation of power systems as real-time control and protection schemes become...
During the last decade, the needs for exploitation of distributed generation (DG), including renewable energy such as photovoltaic, wind turbine, fuel cells, etc., has been growing. In spite of many economic and technical advantages of DG, high penetration of DG in distribution systems would cause some negative impacts on distribution network operation such as increase of fault current level, false...
Saudi Electricity Company (SEC) had adapted the intensive Protection Relay Approval Process for the protection devices to be used on their network. This process had coincided with the advent of numerical relays in SEC network in 1999.
Increasingly, communications has become a significant component in modern power systems. The recently introduced standard IEC61850, describes the concepts for sub-station communications covering protection, control and metering functions. Not only is this is going to have a major impact on the power systems communications but it will also influence the design of future protection systems. The concepts...
In view of large power transformer, a novel composite criterion of transformer protection based on power frequency variation is proposed in this paper. The new scheme makes full use of the advantages that microprocessor-based protection can extract power frequency variation easily. According to the different phase characteristics of fault current and different polarity of the power frequency current(voltage)...
It has always been a challenge to perform extensive functional tests on protection and control panels, encompassing both most likely and unlikely scenarios that could happen in a substation environment.
The protection system design in common MV and LV distribution networks is determined by a passive paradigm, i.e. no generation is expected in the network. With distributed sources, the networks get active and conventional protection turns out to be unsuitable. In most cases, the issue is investigated with synchronous generators, while other generator types like Doubly Fed Induction Generators (DFIG)...
Multiterminal lines can be protected by distance protection and/or unit protection schemes. A well known fact of multiterminal lines, equipped with distance protection, is the inherent complexity for current in-feed and backup zone coverage. Prior to this millennium most relays (for this particular application) were unable to achieve the desired backup coverage due to limitations in zoned technologies...
Due to the advancement of technologies, Intelligent Electronic Devices, (IED's) can handle multiple protection and control function. IEC61850 standard allows high levels of data that can be exchanged between IED's from different product suppliers. These developments will enable innovative re-design of the secondary substation protection systems compared with current industry practices, where different...
Start from Beijing-Tianjin intercity dedicated passenger line, a new 2 × 25 kV autotransformer feeding is applied to China high-speed railway. The traction power supply system is different from China common-speed electrified railway. In this paper, the traction power supply system, the course of fault isolation and supply recovery are introduced. According to normal operation and emergency operation,...
Numerical phase comparison protection overcomes the problems faced on the long EHV transmission system by providing dynamic compensation of charging current at all times thus providing stability during external fault conditions. With the implementation of impedance starters complimenting current and voltage starters, enhances the sensitivity thus enabling the gap detection algorithm, which is based...
The complexity of future power networks and the expected high level of uncertainties in these networks might radically affect the required security and reliability of their operation. Wide-Area Monitoring, Protection and Control (WAMPAC) involves the use of system-wide information and the communication of selected local information to a remote location to counteract the propagation of large disturbances...
Standard communication protocols have been used for substation automation for many years. The applications are mainly on the station level communication to indicate alarms and events within a substation and make them visible to the operator. However the configuration and implementation of the protocols have differed widely between manufacturers leading to difficulties when attempting to support product...
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