The problem of high resistance grounding fault detection in resonant grounding system is always the pain point and difficulty in the field of powersystem research. To solve the problem, based on PSCAD software, this ...
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ISBN:
(数字)9781728117225
ISBN:
(纸本)9781728117232
The problem of high resistance grounding fault detection in resonant grounding system is always the pain point and difficulty in the field of powersystem research. To solve the problem, based on PSCAD software, this paper firstly establishes a typical distribution system model, and analyzes the relationship between the transient component, traveling wave component and the fault initial angle, transition resistance value and arc. Secondly, this paper analyzes the effect of the main fault detection methods such as transient methods and travelling wave method, and gives the effective domain of different detection methods. Above analysis establishes a complete systematic test scheme for the high resistance grounding fault detection, and provides an effective test support for the subsequent effectual fault detection method for high resistance grounding fault.
The CLLC converter is widely used in bidirectional power conversion systems. The conventional control method for CLLC converter is pulse frequency modulation (PFM) method. However, PFM method can not realize smooth bi...
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ISBN:
(数字)9781728153018
ISBN:
(纸本)9781728153025
The CLLC converter is widely used in bidirectional power conversion systems. The conventional control method for CLLC converter is pulse frequency modulation (PFM) method. However, PFM method can not realize smooth bidirectional power switching, because the driver signals for the primary and the secondary side switches are asymmetric. This paper proposed a voltage-fed control method for CLLC and Synchronous Rectified (SR) Buck two stage converters, which can realize the automatic and smooth bidirectional power switching for CLLC stage. In the proposed control method, the PWM signals for both the primary and the secondary switches are the same. The effectiveness of the proposed voltage-fed control method is verified by experiments.
With the implementation of the "coal to electricity" project, the heat pump load in the distribution network increases significantly. Standing in the point of heat pump users, cooperative game mode is used f...
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Wind power ultra-short-term prediction plays a key role in day scheduling of powersystems and cross-provincial power trading. However, the randomness and non-stationary nature of wind power, and the mismatch between ...
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Wind power ultra-short-term prediction plays a key role in day scheduling of powersystems and cross-provincial power trading. However, the randomness and non-stationary nature of wind power, and the mismatch between the training data and the predicted data have become the main obstacles for the improvement of prediction accuracy. This paper proposes a prediction algorithm based on variational mode decomposition(VMD) and clustering. Firstly, the original non-stationary sequence is transformed into several relatively stationary modes utilizing VMD. Secondly, key features can be conveniently selected for each mode, which has a central frequency. Then the k-means clustering method is used to cluster each mode into several typical patterns based on correlation coefficient based distance definition. Finally, the method of "offline training, online matching" is adopted to perform training and prediction process. The actual data of a wind farm in Jilin Province was used to verify the results. The results show that the proposed method can improve the accuracy of ultra-short-term in multi-step prediction of wind power.
The non-inverting buck boost (NIBB) converter has attracted significant attention in recent years, as it shares ground between input and output, and the voltage stress of switches is lower. In order to investigate the...
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Vulnerability assessment is the key to the security and stability analysis of powersystem. During the operation of power grid, the fault risk of electrical equipment is not fixed because of the influence of system op...
Vulnerability assessment is the key to the security and stability analysis of powersystem. During the operation of power grid, the fault risk of electrical equipment is not fixed because of the influence of system operating conditions, operating environment and equipment itself, so the vulnerability of powersystem will also be changeable. Based on the existing research results of complex network theory, a vulnerability assessment method considering operational reliability is proposed in this paper. Firstly, the basic idea of reliability weighted vulnerability assessment is introduced. Then HITS algorithm and PageRank algorithm will be used to analyze the basic vulnerability of power grid topology. Moreover, the vulnerability index of power grid considering reliability weighted is calculated. Finally, numerical analysis focusing on the difference between basic and improved assessment method is tested in IEEE RTS-79 system, and the preventive planning suggestions will be given based on the vulnerability assessment results.
The cumulative installed capacity of wind power worldwide has grown rapidly in recent years. Fixed reactive powercontrol is adopted by wind turbines (WTs) to receive cycle instruction of wind farm (WF) automatic volt...
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We constructed a frequently updated, near-real-time global powergeneration dataset: Carbon Monitor-power since January, 2016 at national levels with near-global coverage and hourly-to-daily time resolution. The data ...
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Traveling wave method has been proved to be effective in fault line selection of power distribution system with the neutral non-effectively grounded. However, it can be easily disturbed by non-faulty traveling wave wh...
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ISBN:
(数字)9781728117225
ISBN:
(纸本)9781728117232
Traveling wave method has been proved to be effective in fault line selection of power distribution system with the neutral non-effectively grounded. However, it can be easily disturbed by non-faulty traveling wave when selecting the line. For this reason, this paper proposes a new traveling wave line selection method based on sparse representation, in which current traveling wave signals are measured for the selection task. The algorithm of selection is based on the idea that all non-zero terms in the sparse coefficients of the measured signal are found to be associated with training samples from a single class, and the test samples can be easily assigned to the class. This makes it possible to distinguish between the non-faulty traveling wave and the real fault traveling wave.
In recent years, human electric shock accident caused by line fault of distribution system has happened all over the world. This kind of problem of high resistance grounding fault safety is becoming more and more the ...
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ISBN:
(数字)9781728117225
ISBN:
(纸本)9781728117232
In recent years, human electric shock accident caused by line fault of distribution system has happened all over the world. This kind of problem of high resistance grounding fault safety is becoming more and more the attention of the researchers. In this paper, typical arc high resistance grounding fault model is established to simulate the human electric shock accident and the line fell to the ground condition. The transient- state and steady-state fault characteristics of high resistance grounding fault are analyzed in the neutral point grounded through a small resistance grounding system and the resonant grounding system. The above analysis has laid a good foundation for the establishment of an effective fault detection method for high resistance grounding and the realization of human electric shock protection.
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