With the continuous advancement of the construction of new powersystems, the data information of the power system is increasing exponentially, and the spatiotemporal distribution of the use of smart terminals and ele...
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A novel protection scheme for two-phase faults in power distribution system with neutral ungrounded is presented. The feasibility of tripping single-phase circuit when a phase-tophase or two-phase-to-ground fault occu...
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ISBN:
(纸本)9781849198349
A novel protection scheme for two-phase faults in power distribution system with neutral ungrounded is presented. The feasibility of tripping single-phase circuit when a phase-tophase or two-phase-to-ground fault occurs is studied with induction motor loads as the focus. The paper at first analyses the effect of a induction motor runs with one phase cut off theoretically. And then a real power distribution system model with 110kV, 35kV and 6kV voltage levels is built in PSCAD/EMTDC. Three feasibility criteria are proposed for motors in continuous operation with single-phase opened. At last, the novel protection scheme is testified in simulation with protection time and reclosing time as variables respectively. The results verify that the scheme is feasible and power supply reliability is improved.
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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Travelling-wave starting element is an integral part of the ultra high-speed protection. Existing design method depends on engineering experience, low accuracy in travelling-wave signal recognition, easy to trip frequ...
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Travelling-wave starting element is an integral part of the ultra high-speed protection. Existing design method depends on engineering experience, low accuracy in travelling-wave signal recognition, easy to trip frequently or refuse to trip. To solve these problems, through mass of starting signal simulation and analysis under different fault conditions, this paper focuses on the travelling-wave starting element and figures out the travelling-wave identification method. This paper summarizes the frequency and voltage characteristics of travelling-wave head, puts forward a new method in real-time travelling-wave fault identification. In addition, the analysis course included in this paper is a useful attempt that can be used in similar fault travelling-wave analysis.
This paper presents a new control strategy for three-level neutral point clamped (NPC) pulse width modulated (PWM) rectifier without power source voltage sensors. The relationship between instantaneous power and volta...
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Online partial discharge monitoring for powerequipments is useful to improve the capacity of the power supply. Main technology for PD testing is introduced in this paper. Advantages and disadvantages of pulse current...
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ISBN:
(纸本)9789881532329
Online partial discharge monitoring for powerequipments is useful to improve the capacity of the power supply. Main technology for PD testing is introduced in this paper. Advantages and disadvantages of pulse current, UHF, ultrasonic and TEV method are present. The status quo of online PD monitoring is analyzed, and the detection effect of online PD monitoring is not good. Opinions to improve the effect are given. They include built-in sensors, increasing sensitivity and sample rate. Analysis of the state quo indicates that the relevant technical standards and specifications must be revised to improve the normalization and standardization.
Arc fault occurs easily when circuit breakers (CB) cut the AC filters circuits in HVDC substation frequently. A transient arc model and online detection method are proposed in this paper. The proposed arc model is bas...
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Performance of a power system security early warning and control system depends on accuracy of power grid parameter to a great extent. It is important to develop a practical branch parameter estimation method. From th...
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Performance of a power system security early warning and control system depends on accuracy of power grid parameter to a great extent. It is important to develop a practical branch parameter estimation method. From the results of expanded state estimation application, which is a representative parameter estimation method proposed before, it often happened that the parameters could not be estimated or estimated imprecisely. Focusing on IEEE 9 and a real-life area power grid in China, deep research on expanded state estimation method is carried out. As a result, these numerical instability and local optimization problems existing in the method were found here. A novel parameter estimation method based on Tabu search strategy is proposed to overcome these problems existing in the expanded state estimation method. Its good behavior in numerical stability and global optimization is verified by numerical tests on IEEE 9 and the real-life area power grid in China.
In the deregulated retail market, consumers should have more right of choice for paying for their energy demand. This paper focuses on the design of electricity price package mechanism in retail market considering the...
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For PD pattern recognition, six kinds of typical cable fault models are made and tested. Characteristics are calculated from test data. Multiple statistical characteristics of PD distribution map are calculated and pa...
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