In the electricity market environment, the quantified description from power quality synthetic evaluation is a vital basis for power quality evaluation (PQE) and electricity pricing. This paper presents a synthetic ev...
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In the electricity market environment, the quantified description from power quality synthetic evaluation is a vital basis for power quality evaluation (PQE) and electricity pricing. This paper presents a synthetic evaluation method for power quality based on fuzzy cluster analysis (FCA). First of all, with the membership function, the degree of membership of the different indices for different monitoring places was obtained and the fuzzy similar matrix was established. After a series of conversions for fuzzy similar matrix and operations, different clustering of power quality can be obtained. With the dynamic clustering diagram, the power qualities of different monitoring places were sorted and evaluated. Some typical example analysis shows that the FCA is practicable for the synthetic evaluation of power quality, and it is also a new idea. As a matter of fact, the FCA overcomes evaluation standard limitation too definitely on evaluation results, takes into the effect of general elements on power quality and ensures objective and precision. The FCA offers a scientific basis for customers to select power suppliers and price according to power quality.
A criterion is proposed to distinguish between temporary and permanent faults of shunt compensated EHV/UHV transmission lines. Its compensation criterion is established. In order to improve its sensitivity when resona...
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A criterion is proposed to distinguish between temporary and permanent faults of shunt compensated EHV/UHV transmission lines. Its compensation criterion is established. In order to improve its sensitivity when resonant frequency is high. The performance of the criterion and its compensation criterion is hardly influenced by fault distance, fault earth resistance and the currents of healthy phases. The criterion and its compensation criterion can distinguish between temporary and permanent faults effectively and quickly. Simulation tests show that the conclusions in this paper are correct
In this paper, a novel model of opportunity cost of spinning reserve capacity is proposed based on sequential dispatching. A model of strategic behaviors of generation firms based on conjectural variation is proposed ...
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In this paper, a novel model of opportunity cost of spinning reserve capacity is proposed based on sequential dispatching. A model of strategic behaviors of generation firms based on conjectural variation is proposed to apply in monopoly spinning reserve capacity markets with incomplete information. According to the conjectural variation model, each firm rationally maximizes its profits while considering reactions of their competitors. The advantage of this method over others is that it is a real reflection of actual power markets without the need to know all firms' actual costs. Examples are used to illustrate that the proposed model is logical and practical.
This paper presents an integrated framework for evaluating impacts of demand side management (DSM) on composite generation and transmission system reliability. A set of load management models for peak clipping/shiftin...
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This paper presents an integrated framework for evaluating impacts of demand side management (DSM) on composite generation and transmission system reliability. A set of load management models for peak clipping/shifting and valley filling, strategic conservation and strategic load growth are presented. Composite DSM actions in the power system's diverse areas are also modeled. Composite system reliability evaluation procedure incorporated with DSM resources is given in Monte Carlo simulation approach. The DC power-flow-based optimal load curtailment objective and multiple level load curves are employed to calculate composite reliability indices. The IEEE reliability test system is used to illustrate the proposed approach and implement comparisons of impacts with and without DSM activity on reliability indices
power quality (PQ) is an issue that is becoming increasingly important to electricity consumption. How to design a market mechanism for power quality exchange becomes acute more and more. Due to its systematic propert...
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power quality (PQ) is an issue that is becoming increasingly important to electricity consumption. How to design a market mechanism for power quality exchange becomes acute more and more. Due to its systematic property, a managed power quality market (PQM) should be organized. In this paper, a novel competing model involving two-price bidding of demand side and marginal cost bidding of supply side is presented to optimize the allocation of emission right (ER) among the consumers in a managed PQM. The uniform price for the basic emission capacity can help to reduce the risks in markets, and the ultimate allocation can maximize the total system utility because the trading between suppliers and consumers occurs at the point of market equilibrium. An example is given to illustrate the rationality and feasibility of the proposed model.
A new ultra-high-speed protection scheme based on multi-resolution morphological gradient (MMG) transformation is proposed in this paper. The transient current generated by the internal and external faults in extremel...
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A new ultra-high-speed protection scheme based on multi-resolution morphological gradient (MMG) transformation is proposed in this paper. The transient current generated by the internal and external faults in extremely high voltage (EHV) transmission line contains different high frequencies because of the line traps and bus-bar stray capacitance. So there are differences in singularity degree of transient current wave forms at sudden change point between internal and external fault. The differences are extracted and amplified by multi-resolution morphological gradient (MMG). By detecting the singularity of fault transient current signals in one terminal using MMG, the proposed ultra-high-speed protection scheme can discriminate between internal and external faults rapidly and securely. A typical 500 kV EHV transmission system has been simulated by ATP/EMTP to evaluate the scheme. A large of simulation results show that the proposed scheme is effective and capable of providing correct responses under conditions of different fault types, positions, path resistances, and inception angles.
The trading model consisting of day-ahead market and real-time market exists in most of power markets. The power purchaser must consider how to allocate the specified power energy between the two markets to minimize t...
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The trading model consisting of day-ahead market and real-time market exists in most of power markets. The power purchaser must consider how to allocate the specified power energy between the two markets to minimize the purchasing cost and to limit the market risk. This paper firstly analyzes the features of separate clearing energy in day-ahead market and real-time market, then points out this kind of separate clearing mechanism not the most economical. Regarding the load demand as random process, this paper puts forward an optimal model considering risk factors that incorporates day-ahead energy scheduling with real-time energy scheduling to find an optimal day-ahead scheduling scheme so as to achieve the total purchase cost minimum. Monte Carlo simulation algorithm and Hooke and Jeeves pattern search are developed to solve the proposed model. Numerical testing based on a 5-unit system shows that the proposed model with higher economy than the conventional separate energy dispatching approach, and it can consider the market risk.
This paper addresses a new relaying scheme for identifying the inrush current and short circuit current caused by internal fault on the basis of sudden changes detection using novel morphological gradient (NMG), trans...
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This paper addresses a new relaying scheme for identifying the inrush current and short circuit current caused by internal fault on the basis of sudden changes detection using novel morphological gradient (NMG), transient current signals are then extracted by use of morphological opening and closing transform. Based on different characteristics of transient signals between the short circuit current and the inrush current, the transformer protection method is proposed. This method can avoid the symmetrical inrush current and saturation of current transformer (CTs). The results of Electrical powerdynamiclaboratory (EPDL) indicate that the proposed technique can also deal with the sampled data contaminated with various kinds of noises and DC components and is stable during internal faults with external shunt capacitance in a long EHV transmission line
A novel technique for treating electrically thin dispersive layers with the finite-difference time-domain (FDTD) method based on Z transforms is introduced. The proposed model is based on the subcell technique, where ...
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A novel technique for treating electrically thin dispersive layers with the finite-difference time-domain (FDTD) method based on Z transforms is introduced. The proposed model is based on the subcell technique, where the constitutive relations are locally averaged in the FDTD grid. The most significant feature of the proposed model is its ability to model rather complicated dispersive layers having multiple pole pairs. The model is validated with several numerical examples making comparison with the exact results
Considering the displacement current in the multi-layer soil, the formulas of the ground return impedance and the Fresnel reflection coefficients are derived in frequency domain. These expressions are valid for discre...
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ISBN:
(纸本)142440293X
Considering the displacement current in the multi-layer soil, the formulas of the ground return impedance and the Fresnel reflection coefficients are derived in frequency domain. These expressions are valid for discretional soil conductivities and the whole range of frequencies. For the convenience of transient analysis, the vector fitting method is adopted to expand the time-domain forms of the ground return impedance and the Fresnel reflection coefficients into the sum of finite exponential functions which are easy to be treated. Based on the recursive algorithm for the time-domain convolution, the finite difference time-domain (FDTD) method improved by the authors is used for the transient analysis of the external excited overhead line. Compared with the existing method applicable for homogeneous soil, the proposed method is demonstrated to be correct.
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