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Due to its current limitation, Inverter-interfaced Distributed Generation (IIDG) is supposed to have little impact on protection system of distribution networks. However, in case of high power IIDG, the situation could be changed. This paper aims to show situations in which IIDG could provoke false tripping to overcurrent protections along distribution feeders. Proposed solution is to provide directional...
Recently the importance of Wide-Area Situational Awareness (WASA) has increased as it can form the basis for power system stabilisation systems or be part of a smart grid. The standardisation of communication interfaces with the ability to integrate many kinds of sub systems becomes increasingly important in enabling the build of a standard WASA system. In Japan, Wide Area Monitoring, Protection and...
Wide-area Situational Awareness (WASA) is of key importance in power system operators' decision-making. Lack of WASA can set in motion cascading failures, or contribute to the development of a blackout. Inadequate WASA was actually identified as one of the major causes of several blackouts in the last decade. A variety of factors in a power system control centre can affect the formation of WASA, especially...
Testing of Phasor Measurement Units (PMU devices) is necessary for any PMU application, be it a simple visualization and archiving system or a more complex set of real-time system operations tools. PMUs are available from virtually every manufacturer of protection and monitoring equipment. They are often implemented as embedded functions within relays or disturbance recorders. This paper describes...
Future power systems face several challenges; one of them is the use of high power converters that decouple new energy sources from the AC power grid. This decreases the total system inertia affecting its ability to overcome system frequency's disturbances. The wind power industry has created a controller to enable inertial response on wind turbines generators: Artificial, Emulated, Simulated, or...
Transformer differential protection schemes normally use multi slope characteristics to provide stability during CT saturation with 2nd harmonic restraint or blocking for inrush conditions. This paper presents new algorithms that have been developed to improve the performance of the differential protection. Extensive testing has been used to demonstrate that the transient bias algorithm can reduce...
This paper builds upon the earlier research which proposed the use of satellite communication media to achieve improved performance of the Loss-Of-Mains (LOM) protection by eliminating nuisance tripping and ensuring reliable islanding detection. The focus of this paper is the practical development of the laboratory based trial of the satellite based LOM protection and the experimental assessment of...
Effective voltage control is essential for the satisfactory operation of distribution networks. The increased connection of distributed generation to existing distribution networks challenges the current methods of controlling network voltages. Network voltage is primarily controlled by changing tap position of the primary transformers. The transformer secondary voltage will be automatically increased...
Transformers are critical to the successful operation of the electrical power systems. Their reliability and availability is therefore key to flawless and optimum power generation and transmission. Effective condition monitoring is essential to evaluate transformer performance and safe operating conditions. Over the past few years many stand-alone devices have been developed for transformer condition...
In the last two decades there has been a continuous increase in the amount of Distributed Generation (DG) connected to the power network. This has resulted in a number of technical challenges for network protection including: sympathetic tripping of DG interface protection; blinding of feeder over-current (OC) protection; and deterioration of feeder OC protection grading. While the available literature...
This paper discusses potential extreme scenarios which could result in unstable conditions on the main interconnected electricity transmission system of Oman. Case studies on loss-of-stability scenarios between different parts of the network are examined. The objectives of the study are to identify possible locations of the electrical centre of swing and to develop an approach for controllable system...
This paper aims to present the modeling and simulation of numerical differential protection of power transformers using the software ATP/ATPDraw and its MODELS environment. In order to validate the relay model, simulations were carried out using a simplified electrical power system whose parameters were obtained from a real system. The results reveal the advantages of using this type of modeling,...
Injection-based 100% stator earth-fault protection has been used for many years. However traditionally signals with frequency between 10Hz and 25Hz have been injected into the stator winding. To inject such a signal, either a dedicated grounding transformer with secondary grounding resistor or injection on primary side of the grounding circuit, is normally used. This paper will present a novel approach...
IEC 61850 is the new standard for communications in substations that defines a new generation of protection applications based on high speed peer-to-peer communications between different substation devices. Accelerated protection schemes use permissive or blocking signals exchanged between relays at the two or more ends of the protected transmission line in order to provide fast fault clearing for...
This paper proposes a Multi-agent System (MAS) approach to coordinate overcurrent relays, aiming to protect distribution systems with distributed generators. The connection of distributed generation (DG) units causes a reduction in the efficacy of protection systems coordination and, in some cases, an increase of operating times. Coordination studies aim to guarantee the protection selectivity in...
Due to the distributed capacitance, the conventional current differential protection has unsatisfying performance. Considering matrix pencil algorithm can accurately analyze the composition of fault transient currents, a novel pilot protection principle using only current data is proposed in this paper to solve the above problem. This principle adopts model recognition concept. Firstly, the theoretical...
This paper addresses three aspects of testing relay protection systems using a real time simulator: (1) simplify the setup by using low level analog signals to the relay; (2) use a ‘threading’ process when a hybrid setup (commercial relays and simulated relay models) is chosen; (3) test substation protection system together with control and communication systems.
Power transformers are traditionally protected by differential protection schemes that use voltages and currents to detect abnormalities in the differential zone of protection. For this type of scheme, a short circuit or high magnitude current must be present to initiate a trip. However, this scheme might not be ideal when transformers need to be overloaded to mitigate contingency conditions. Using...
Many countries are accepting the Kyoto Protocol to the United Nations Framework Convention on Climate Change (UNFCCC) in other to reduce the emission of carbon dioxide and other greenhouse gases. Renewable distributed generation (RDG) has become one of the most effective ways to reach this goal. It has been recognized as an alternative way of generating clean energy around the globe today. There has...
This paper presents an accurate fault location algorithm for double-circuit transmission lines with series capacitor compensation at both ends. It has been considered that a fault locator utilizes a communication channel of differential protective relays through it phasors of currents at both line ends are exchanged. Besides the phasors of two-end currents, three-phase voltage measured at a local...
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