The transient pressure process, which determined the gas blasting in the interrupter of SF6 circuit breaker, have attracted the attention of designer and developer for long time. In this investigation, a onload SF6 in...
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ISBN:
(纸本)9781457712739
The transient pressure process, which determined the gas blasting in the interrupter of SF6 circuit breaker, have attracted the attention of designer and developer for long time. In this investigation, a onload SF6 interrupter pressure measurement method was established with piezoresistive pressure transducer and insulating-tube. The pressures in the puffer cylinder, at the upstream, throat and downstream of nozzle have been measured. The difference of gas blowing characteristics between N2 and SF6 has been pointed out. The insulating-tube can effectively protect the pressure transducer from the high voltage and high temperature during on-load interrupting. It was found that the arc process can cause high frequency oscillations to superimpose upon the pressure waveforms during on-load interrupting.
Huge interconnected power grids are formed in AC and DC powersystems in China. The nanoseconds, microseconds, milliseconds electromagnetic transient due to AC and DC system operation and fault, the DC converter valve...
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Huge interconnected power grids are formed in AC and DC powersystems in China. The nanoseconds, microseconds, milliseconds electromagnetic transient due to AC and DC system operation and fault, the DC converter valve movement, the load generated by changes interact in the AC and DC interconnected system, impairing AC and DC powersystems, especially leading to the commutation of DC system failures and atresia such serious incidents. Consequently, a theoretical analysis was combined with a test method to establish an over ground network, considering DC electrical networks, controlsystems and underground grounding system of the full-wave process of the UHV system, Finally, converter transformer was modeled with UMEC model, and transmission line was modeled with J-Marti frequency dependent model;moreover, valve was modeled with transistor, RLC circuit, and other units including DC controller, and DC filter and AC filter were modeled with RLC circuit. The broadband characteristics of electromagnetic transient models of key units in DC sides for the analysis of AC and DC interconnected system were also analyzed.
China AC-DC powersystems are interconnected to form a huge power grid. The nanoseconds, microseconds, milliseconds electromagnetic transient were generated due to AC-DC system operation and fault, the DC converter va...
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China AC-DC powersystems are interconnected to form a huge power grid. The nanoseconds, microseconds, milliseconds electromagnetic transient were generated due to AC-DC system operation and fault, the DC converter valve movement, the load generated by changes in the interaction of AC-DC interconnected system electromagnetic transient, which can pose a hazard on AC and DC powersystems, in particular, can lead to the commutation of DC system failures and atresia such serious incidents. Based on the broadband characteristics model which can accurately reflect the existing AC-DC interconnected system electromagnetic transient characteristics of the key components, we applied the PSCAD/EMTDC platform to establish a computational model, and revealed DC side electromagnetic transient interaction on AC side. The results show that the DC system has little effect on AC system electromagnetic transient, In various types of failures, the overvoltage produced at side of 750 kV, 330 kV lines and bus are in the allowable range.
The Common Spatial Patterns (CSP) algorithm is useful for calculating spatial filters for detecting event-related desynchronization (ERD) for use in ERD-based brain-computer interfaces (BCIs). However, basic CSP is a ...
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The amplitude of switching overvoltages is a key factor for designing the insulation of UHV equipment. The effect of different arresters needs to be studied, since installing arresters is an important way to suppress ...
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The amplitude of switching overvoltages is a key factor for designing the insulation of UHV equipment. The effect of different arresters needs to be studied, since installing arresters is an important way to suppress switching overvoltages in UHV transmission lines. Switching overvoltages on the 1000 kV Huainan-Huxi double-circuit transmission line were simulated for different operating modes and different arrester designs using the electromagnetic transient program PSCAD/EMTDC. With parallel resistors, the switching overvoltages are less than 1.70 p.u. (1.0 p.u.=1100×√ 2 /√3 kV). If the arrestors are better, the switching overvoltages can be reduced even lower to 1.55 p.u. Without parallel resistors, the arresters can reduce three-phase energizing overvoltages to 1.70 p.u, while the single-phase reclosing overvoltages still exceed the limit. The results show that the parallel resistors cannot be eliminated if the arresters are only installed at each end of the transmission line. Also, better quality arresters significantly lower the switching overvoltages.
A fundamental difference between simple and complex systems is how the research objects are subdivided to support different study purposes. Based on a comparison between two urban energy system models – one with 5 an...
A fundamental difference between simple and complex systems is how the research objects are subdivided to support different study purposes. Based on a comparison between two urban energy system models – one with 5 and the other with 17 sectors – we concluded that the two models were most similar in terms of their description of the overall system structure and most different in terms of their description of specific intra-system relationships. The smaller number of system components and relationships in the 5-sector model facilitated judgments of the system's overall situation, thereby revealing where the key problems were found. In contrast, the 17-sector model provided enough details about the system to assist in the formulation of concrete operational measures to solve specific problems. Our results indicate that the division of a model into sectors should depend on the explicit problem to be solved and the context for that problem; different goals will require different numbers of system components. The results also demonstrate how simple and complex models can be used in tandem to examine a system from different perspectives.
The implementation of non-communication protection of double circuit line systems based on two independent relays has disadvantages like information shareless,complex connection and lack of economic. This paper resear...
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The implementation of non-communication protection of double circuit line systems based on two independent relays has disadvantages like information shareless,complex connection and lack of economic. This paper researched the implementation of non-communication protection of double circuit line systems based on one relay - the integrated protection platform. Hardware structure of the integrated protection platform is described, and software flow of non-communication protection of double circuit line systems which implemented on the integrated protection platform is also described. Large number of RTDS experiments proved that, according to various asymmetrical fault and symmetrical fault, this protection scheme has reliable and sensitive action performance. It is proved that the implement non-communication protection of double circuit line systems based on the intergrated protection platform is feasible.
The paper proposes faulted feeder selector in power distribution system with neutral non-effectively grounded. At first, the paper presents basic principle of single-phase-to-ground fault feeder selection based on tra...
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The paper proposes faulted feeder selector in power distribution system with neutral non-effectively grounded. At first, the paper presents basic principle of single-phase-to-ground fault feeder selection based on traveling waves, which compares amplitude and polarity of the initial current traveling waves in all feeders. Then the implementation scheme, including hardware design and software flowchart is presented. At last field application of faulted feeder selector is introduced. The field operation results validated the correctness of faulted feeder selector based on transient traveling wave.
In the annular power distribution system, short-circuit fault of bus-bars will do fatal harm to aircraft, and it is necessary to protect the ring-net bus-bars. Protecting bus-bars has to meet the requirements that pro...
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In the annular power distribution system, short-circuit fault of bus-bars will do fatal harm to aircraft, and it is necessary to protect the ring-net bus-bars. Protecting bus-bars has to meet the requirements that protection devices do not refuse to operate and backup protection devices do not act incorrectly. This paper builds a model about the annular power distribution system and stimulates the fault system based on MATLAB. According to the fault features, directional blocking pilot protection is put forward. The results prove that the new method can achieve automatic isolation of the bus-bar at fault, ensures the safety of aircraft power distribution system, and it is of great importance to improve the reliability of aircraft power distributing.
The interaction of nanoseconds, microseconds, milliseconds electromagnetic transients due to AC-DC system operation and fault, the DC converter valve movement, the load generated by changes in the interaction of AC-DC...
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The interaction of nanoseconds, microseconds, milliseconds electromagnetic transients due to AC-DC system operation and fault, the DC converter valve movement, the load generated by changes in the interaction of AC-DC interconnected system electromagnetic transient, can pose a hazard on AC and DC powersystems, in particular, lead to the commutation of DC system failures and artesian such serious incidents. Combining theoretical analysis with test, we can establish the analysis method of electromagnetic transient of the full-wave process of the UHV system based on AC-DC interconnected system, controlsystems, and underground grounding system, and focus on the equivalence circuit of AC side network with the Ward method of equivalency under many operation modes and steady-state debugging for the analysis of AC-DC interconnected system, so as to lay the foundation for the interaction of electromagnetic transient.
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