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A dispatch-oriented risk perception and fault disposal decision support technique for online monitoring and control is proposed in this paper. It helps to improve the sensitivity and accuracy of risk perception by multi-source information mining based on data from SCADA, relay, WAMS and other measurement systems. And it provides a direct means to grasp the whole process of incident handling by online...
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...
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...
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.
The presence of supplementary controllers for thyristor controlled series compensators (TCSC), to damp the Inter-area power system oscillations makes the resultant transmission line (T.L), reactance varying during the damping process. This variation causes an undesirable effect on the distance relay DR, as its setting depends on the physical impedance of the T.L. In this paper, a novel algorithm is...
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,...
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...
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...
In a power system network, an unbalanced voltage condition can occur due to various reasons. Excessive voltage unbalance has become an issue of concern in power quality at network level, leading to numerous problems. This calls for a stringent management of unbalanced. There are several codes of practice to advise and to enforce network operating conditions to keep system unbalance within specific...
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...
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...
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...
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...
In the traditional domain of teleprotection signalling, there is a recognised triangle of performance. This triangle depends upon the required speed of communication, the expected dependability of the command, and the security of receipt. These three aspects are interlinked, and the correct balance of each is required in order to offer the traditional functionality such as permissive signalling, blocking...
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.
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 discusses real world examples of utility initiatives to address the issue of substation cyber security in the context of both industry best practices and the global standards organizations seeking to provide a blueprint for security implantation. The authors provide an overview of existing technologies for securing IP and Ethernet communications networks and end devices. One of the aspects...
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