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Based on the basic voltage and flux equations of the Doubly Fed Induction Generator, this paper derived expressions of short-circuit current of wind turbines, which are expressed by transient equations of stator and rotor flux. The transient equations of stator and rotor flux were functions of initial values of stator and rotor flux and transient time constants of stator and rotor windings. The initial...
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...
With the development and expansion of modern power system, the double circuit lines on the same tower are used widely as an important electric power transmission mode, but it is particularly complex to determine the failure of the double circuit lines. This paper judge whether the fault occurs in the double circuit lines or not using the topology model according to the information of the fault at...
Fault Processing is the most important part of dispatchers routine monitoring work, which is significant to improving processing efficiency, shorten the processing time and prevent further deterioration of the accident when enhance its intelligent level. From the features of dispatchers fault processing, this paper presents a general framework of large grid online decision-making support for accident...
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...
Adaptive power system protection can be used to improve the performance of existing protection schemes under certain network conditions. However, their deployment in the field is impeded by their perceived inferior reliability compared to existing protection arrangements. Moreover, their validation can be problematic due to the perceived high likelihood of the occurrence of failure modes or incorrect...
Loss-Of-Excitation (LOE) condition of a generator may cause severe damages on both generator and the interconnected systems. This paper analyses the behaviours of different LOE protection schemes, such as R-X, G-B, P-Q and U-I schemes, for a hydro generator, which is connected to an infinite bus. Based on the simulation results, the reliability and stability of existing LOE protection schemes are...
This paper reviews the characteristics of inrush current and analyses its causes. The development of digital substation and the concept of integrated protection are also outlined. The paper studies different models to simulate several kinds of inrush and internal short-circuit fault. Through these models, the new composite algorithm is analysed in order to verify the reliability and sensitivity of...
Integrating Distributed Generation (DG) in distribution systems will have an impact on the fault current magnitudes. This could have an impact on the coordination of the protective devices. In this paper, the optimal DG locations are determined in order to minimize the overall relay operating times for a meshed distribution system. The problem is formulated as a Non-Linear Programming (NLP) problem...
This paper provides a discussion on future direct current (DC) network development in terms of system protection under DC-side fault scenarios. The argument between appropriate DC circuit breaker and new DC fault-tolerant converters is discussed after a review on DC technology development and bottleneck issues that require proper solutions. The overcurrent/cost curve of power-electronic DC circuit...
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....
The new generation of current sensors has performance characteristics that can improve design and operation of modern power systems. This paper presents novel solutions for protection of capacitor banks using Rogowski coils as currents sensors.
Transmission level protection functions are increasingly being looked at for Distribution systems. This can be attributed mainly to the enhancements being planned for by the Operating Companies, to increase the system efficiency, and also to ensure reliable power supply to the end Consumers. Slowly, the catch word "Smart Grid" is being consciously and progressively transformed to practical...
The advent of IEC61850 Standard has ushered a new age for substation automation. This standard has gained a very strong footing in Europe and its application is spreading across the world. In USA the progress towards IEC61850 implementation is relatively slower. IEC61850 holds great promises for substation automation and protection. There are many advantages that this standard brings to the area of...
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