A new ultra high-speed protection scheme is proposed in this paper. Using wavelet transform with multiresolution analysis, the current signals is decomposed into a series of detailed wavelet components. The spectral e...
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ISBN:
(纸本)9810557027
A new ultra high-speed protection scheme is proposed in this paper. Using wavelet transform with multiresolution analysis, the current signals is decomposed into a series of detailed wavelet components. The spectral energies of the wavelet components are calculated and then employed to detect the faults. Characteristics of the proposed ultra high-speed protection algorithm are analyzed and results of simulation studies are given. The results show that the proposed algorithm is promising and easy to implement for computer relaying application
A new non-unit voltage protection algorithm for extra high voltage (EHV) transmission lines is presented in this paper. The singularity of fault transient voltage signals in one terminal is utilized to discriminate cl...
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ISBN:
(纸本)9810557027
A new non-unit voltage protection algorithm for extra high voltage (EHV) transmission lines is presented in this paper. The singularity of fault transient voltage signals in one terminal is utilized to discriminate clearly between internal and external faults. Lipschitz exponent (LE) is obtained from wavelet modulus maximum to detect singularity of signals. A typical 500 kV EHV transmission system has been simulated by ATP to evaluate the scheme. The simulation results show that this scheme is capable of providing correct responses under various system configurations and fault conditions
作者:
F.F. SongT.S. BiQ.X. YangSi Fang Research Institute
Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University Beijing China
In this paper, the state of the arts of powersystems in China and some applications in transient stability control based on wide area measurement system (WAMS) are introduced briefly. With the development of power gr...
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In this paper, the state of the arts of powersystems in China and some applications in transient stability control based on wide area measurement system (WAMS) are introduced briefly. With the development of power grid interconnection and transmission utility deregulation, the operation of electric powersystem become more and more complex, which challenges the security and transient stability control of powersystems. The advent of WAMS opens a new path to the system trajectory prediction and real time closed-loop stability control to prevent powersystem outage. The defects of current transient stability controlsystem are analyzed, then a possible scheme of transient stability control based on WAMS is proposed, and the corresponding future work is put forward as well. Finally, a new way of solving cascading events is discussed
The paper studies a practical project of 2 MVA dynamic voltage restorer on the basis of transformer-less cascade multilevel topology, it discusses each part working principle of DVR, but also provides a practical volt...
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The paper studies a practical project of 2 MVA dynamic voltage restorer on the basis of transformer-less cascade multilevel topology, it discusses each part working principle of DVR, but also provides a practical voltage sag problem solving scheme for a 6 kV feed line based on proposed cascade structure. EMTDC/PSCAD based simulation results verify the validity of proposed scheme
This paper presents an integrated framework for the optimal management of electricity purchase allocation and risk for load service entities (LSEs). To the practice of China power Markets, we propose the framework of ...
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This paper presents an integrated framework for the optimal management of electricity purchase allocation and risk for load service entities (LSEs). To the practice of China power Markets, we propose the framework of power portfolio of combined physical forward contract and spot market. The framework suggests that the forward contracts should have different prices on-peak and off-peak in accord with sale prices distinguish on-peak and off-peak. The optimal purchase problem is described by the utility maximum integrated the rate of return and risk tolerance level, and risk is evaluated by Value at Risk (VaR). The analytical solution is also conducted. The numerical results are reasonable with higher rate of return and better risk hedging compared with the corresponding results from the existing portfolio selection approach. The presented framework gives one possible and effective method for the optimal power portfolio and risk management in incomplete power markets.
Based on mathematical morphology and grille fractal, a novel approach on power quality disturbance detection and location is presented in this paper. At first a parallel composite morphological filter with multiple-st...
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Based on mathematical morphology and grille fractal, a novel approach on power quality disturbance detection and location is presented in this paper. At first a parallel composite morphological filter with multiple-structure elements is designed to filter the random noise and impulse noise in power quality disturbance signals. Then to the filtered curves, an easy implementation criterion for singularity detection based on the change regularity of grille fractal is proposed to locate the start and end time that disturbance occurs. The voltage sag, swell, harmonic and their combined disturbances are used to verify the validity of the proposed filter-location approach. Numerical results show that the proposed approach is valid and effective
On-site partial discharge detection on XLPE cables accessories is very difficult because of pulse noise interference, such as pulse interference created by automobile ignition coils on the street, etc. A suitable solu...
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On-site partial discharge detection on XLPE cables accessories is very difficult because of pulse noise interference, such as pulse interference created by automobile ignition coils on the street, etc. A suitable solution for the monitoring of cable accessories during operation is a sensitive on-site PD detection method. This can be realized in an advantageous way with combinatorial sensors, an antenna sensor, a UHF sensor, and two VHF split-core PD sensors. These sensors are not connected to the high voltage directly, a UHF sensor can be placed near the cable joint and two split-core sensors can be installed on both sides of the cable joint easily and safely. The detection making several windows in the time domain towards multiple wide-band pulse signals can achieve reliable discrimination of real internal PD and external noise under noisy on site conditions. More than twenty cases of on-site PD detection for HV XLPE cables have been proven this way. This method has high detection sensitivity and high noise recognition ability
The magnetic storm results in the transmission lines with geomagnetically induced current (GIC). And GIC happening in random has the frequency between 0.001 Hz~0.1 Hz, and continues from several minutes to several hou...
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The magnetic storm results in the transmission lines with geomagnetically induced current (GIC). And GIC happening in random has the frequency between 0.001 Hz~0.1 Hz, and continues from several minutes to several hours. Based on elaborating mechanism and characteristic of GIC in grids and the influence on China power grids, the article has conducted the research work of GIC monitoring technology, and has investigated the method of sampling data of GIC, the survey algorithm and the new monitoring device. The simulated test shows, the monitoring device can effectively measure GIC which is signal of quasi direct current and randomness, has advantages of having few data to be handled and needing little memory space, etc
This paper presents a new approach for environmental/economic transaction planning model of the electricity market. The environmental/economic transaction planning problem is formulated as a multi-objective optimal po...
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This paper presents a new approach for environmental/economic transaction planning model of the electricity market. The environmental/economic transaction planning problem is formulated as a multi-objective optimal power flow (MOPF) problem. A novel algorithm using multiobjective particle swarm optimization (MOPSO) and non-stationary multi-stage assignment penalty function is proposed to solve this problem. PSO is modified by using dynamic neighborhood strategy, new particle memory updating, and one-dimension optimization to deal with multiple objectives. Incorporating of non-stationary multistage assignment penalty function in solving OPF problem can improve the convergence. The proposed method is demonstrated on the IEEE 30-bus system. The results show that the proposed approach can efficiently gain multiple pareto optimal transaction planning that match with the sustainable development strategy
Short-term load forecasting of powersystem is not only the basis of scheduling of generating sets, but also the basis of working out the transaction schedule in electricity market. This paper proposes a short-term lo...
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Short-term load forecasting of powersystem is not only the basis of scheduling of generating sets, but also the basis of working out the transaction schedule in electricity market. This paper proposes a short-term load forecasting method based on combination of radial basis function (RBF) neural network and fuzzy control, uses on-line self-modify factor fuzzy control to eliminate forecast error on the basis of RBF neural network forecasting. The practical examples show that the accuracy of short-term load forecasting and training speed can be improved and gains the very satisfactory results by the proposed method
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