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Real-time Dynamics Monitoring System(RDMS) is applicable to monitor the dynamic behaviors of large region grid, such as low-frequency oscillation, short-circuit, frequency fluctuation, etc. For the perturbation in power systems occurs incidentally, it's difficult to collect enough cases for an complete test on RDMS, which may lead to potential risks of outage. So it's necessary to study more efficient...
For decades, various versions of the Takagi algorithm have been used by microprocessor-based relays for fault location. This system provides accurate fault location, limited by nonhomogeneous infeed, load flow, fault resistance, and series-compensated or parallel lines. With the emphasis placed on reliability in today's power system, the need for improved accuracy in fault location has increased....
Since IEC 61850 became the widely used standard for substation communication with a lot of implementations. Testing is an important issue. The standard in its current version covers some possibilities and approaches for testing in general and for measures of performance. Nevertheless some issues came out which needed to be clarified with the new edition of the standard. Edition 2 will be available...
Traction transformer is often on short-time overload state to meet the needs of traction load. In order to prevent the damage to the traction transformer caused by overthermal which is produced by load current, inverse time overcurrent protection is often used in China. Firstly, this paper introduces inverse time overcurrent protection and three standard characteristic equations of inverse time overcurrent...
Pantograph of an en-energized train may never run through n neutral section. As it does so, the arc generated across the pantograph will likely short the two feeding lines together at both sides of the neutral section where two phases are separated, The fault is called out-of-phase short-circuit fault for which short two out-of-phase feeding lines. Traditional feeder distance protection and current...
Although there has been a practice of transposition of transmission lines, most of the real life EHV/UHV lines are untransposed. The distance protection of such lines becomes very complicated. With the advent of Global Positioning System (GPS) and Fiber optics technology, current differential protection can be a better choice for such lines. This paper proposes current differential protection scheme...
This paper proposed a new power grid fault diagnosis model combining Petri nets and grid computing. It includes the power grid computing system's structure, software service and algorithm. The model can use the high performance computing method and distributed environment of grid computing. At the same time, Data grid system can offer table, efficient and unified information resources for the power...
The paper describes a Transient Bias technique designed to overcome the effects of Current Transformer (CT) saturation, which might severely affect the behaviour of a protection system. This Transient Biasing, as the name implies, is only active during transient conditions in the power system, and it decays quickly once the transients disappear. A complementary algorithm for fast detection of external...
The quest for intelligent, so called Smart Grid technology is seen by many as the key to future exploitation of renewable energy sources and the inclusion on the Grid of home grown generation from micro CHP systems. But, as Keith Hamilton, Group Managing Director of PBSI Group Limited explains, the prerequisite for the establishment of Smart Grids relies on a significant investment in equipment as...
In this paper wide-area protection is discussed in smart microgrids. Smart grids inherently propose opportunities to enhance the protection of the lines due to the communication capabilities that present. Smart distribution microgrids would have a communication infrastructure that promotes the performance of their protection decisions. The paper considers a sample microgrid with the required communication...
In this paper, the capability of the numerical relays within the microgrid is sophisticatedly used to adapt the settings of the relays to the status of the microgrid. Different settings for the overcurrent relays are calculated off-line and saved in the relays. Whenever the microgrid is disconnected from the grid, the settings are automatically changed to the associated group of settings. This would...
Distance relays used for transmission line protection can mal-operate on power swing. This paper presents protection schemes for out of step detection based on synchronized phasor measurement. Voltages and currents at both the ends of a transmission line are used to derive the parameters required for designing these schemes. The proposed schemes can distinguish stable and unstable power swing and...
At present, gas protection and current differential protection are generally used as the main protection for traction transformer in China high-speed railway. Overcurrent protection with busbar low-voltage start-up is used as the backup protection installed at HV side and LV side of transformer. This paper introduces the principle of overcurrent protection with busbar low-voltage start-up, and then...
Transmission line parameter is important for obtaining power network structure, generating power system node admittance matrix or impedance matrix to calculate power flow, calculating short-circuit current, and setting relaying protection devices. But actually, transmission line parameters applied in power system are mostly experience values or offline measuring values provided by manufacturers, they...
Because of the fluctuation and intermittence of solar light, output generation of photovoltaic power system keeps continuous change. This determines it can not to be used as main source of frequency regulation like traditional thermal and hydro units. The output generation will be fluctuated rapidly in a large scale when sunlight intensity changes quickly. To make photovoltaic generation better utilized,...
This paper presents a network-based simulator for protective relaying algorithms. The simulator is based on the client-server paradigm. The simulator which consists of server-side relaying algorithm modules and the user interface provides the network-based environment to simulate a variety of protective relaying algorithms. It is developed by using open-source development tools and model-based design...
The increase of the electric power demand is at the level 2–3% per year, and in some regions of the world may become much higher. In the same time the infrastructure of power systems develop much slower. The smart grid technology is to use modern telecommunication and informatics to bridge the gap. The aim is to integrate generation, transmission, distribution and consumption of the electrical energy...
Protection of power systems requires a high degree of reliability. Whenever a protection is called upon to operate, it must do so. Failure to do so may result in costly damage to plant, loss of supply to many consumers, and potentially, danger to life. Protection relays are designed in such a way as to ensure reliability of operation. Very often, the main threat to reliable operation is the circuit...
This paper discusses the behaviour of both current- and voltage transformers under low-burden conditions. It is shown that this behaviour is basically linear under steady-state conditions. Moreover, there is a duality between the equations for VT and CT. Recommendations and possible mitigation strategies in case of low burden on the secondary side of measurement transformers are discussed.
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