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
Available transmission capability (ATC) is the transfer capability remaining in physical transmission network for further commercial activity above existing transmission commitments. ATC is an important reference for ...
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Available transmission capability (ATC) is the transfer capability remaining in physical transmission network for further commercial activity above existing transmission commitments. ATC is an important reference for market participators to make decisions, as well as a judgment for system operators to alleviate transmission congestion, and a reference for system planning and expansion. Most of the existing ATC calculation methods are mainly based on deterministic techniques. In practical powersystems, there are large amount of uncertainties, and powersystem is dynamic and time-varying. A novel approach is proposed to analyze relevant features of ATC and calculate ATC based on sequential Monte Carlo simulation and linear programming considering uncertainties and time variation of the system. Through long-time simulation and analysis, the distribution features of ATC can be obtained. The algorithm based on MATLAB 6.5 is developed. IEEE 14-bus test system is used to verify the presented approach.
An equivalent continuous-time state-space model for VSC-HVDC in the synchronous dq reference frame has been established in the paper. Based on the model, relevant control strategies have been developed for the cases o...
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An equivalent continuous-time state-space model for VSC-HVDC in the synchronous dq reference frame has been established in the paper. Based on the model, relevant control strategies have been developed for the cases of supplying active and passive systems. The multi-input multi-output (MIMO) control schemes are emphasized in designing powercontroller and voltage controller. The scheme features feed forward compensation to decouple the d- and q-axis of the voltage source converter (VSC) model, which ensures the independent control of active and reactive power, DC voltage and reactive power as well. Simulations have been performed on PSCAD/EMTDC, a visual design environment for powersystem studies. The validity of the mathematic model and the feasibility of the control strategies have been proved by the simulation results
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.
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 Super Capacitor Energy Storage (SCES) system applied to distributed generation system and distribution network is presented. Application studies of the SCES system for active power supply, voltage control and harmon...
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A Super Capacitor Energy Storage (SCES) system applied to distributed generation system and distribution network is presented. Application studies of the SCES system for active power supply, voltage control and harmonic elimination are described. With inverter control, both active and reactive power pumped into the utility grid can be controlled. The proposed approach combines a dual-loop voltage and current control and a powercontrol which does not require knowledge of the equivalent impedance of the utility grid the SCES unit is connected to. Furthermore, the proposed powercontrol has superiorities as strong P and Q regulation capability, fast enough response, and purely sinusoidal line current. Finally, experiments are performed to verify the proposed theory which shows its well performances.
VSC-HVDC technology based on voltage source converter (VSC) and isolated gate bipolar transistor is a kind of novel HVDC technology for low power and long distance with flexible control and operation modes. In this pa...
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VSC-HVDC technology based on voltage source converter (VSC) and isolated gate bipolar transistor is a kind of novel HVDC technology for low power and long distance with flexible control and operation modes. In this paper, the dynamic mathematic model of VSC-HVDC with SPWM control is founded based on analyzing the fundamental principle of VSC-HVDC system. Its switch characteristic and dynamic operation mechanism are analyzed. Simulation results of dynamic operation characteristics for VSC-HVDC system with a rapid power change or a short time fault show that the theoretical analysis is correct. This is a basement to do more dynamic analysis for VSC-HVDC
This paper put forward to an interactive flexible SCADA system in which information shared, on the basis of analyzing and summarizing the defections of former SCADA. It not only solves the interaction of data and func...
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This paper put forward to an interactive flexible SCADA system in which information shared, on the basis of analyzing and summarizing the defections of former SCADA. It not only solves the interaction of data and function in the information islands, but also solves functions coordination and data exchange of distributed application system in different location. The paper proposes the concept of general data acquisition, discusses the structure and the ways of technology support, and describes the application of flexible SCADA based on the example of fault decision support system (FDSS). This proposal flexible SCADA extends and develops the data source of traditional SCADA and enriches the data foundation for powersystem advanced analysis software
Against the stability of the multi-infeed HVDC (MIDC) transmission system, voltage source converter based HVDC (VSC-HVDC) is applied to MIDC systems. The new systems can reduce probability of commutation failure and i...
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Against the stability of the multi-infeed HVDC (MIDC) transmission system, voltage source converter based HVDC (VSC-HVDC) is applied to MIDC systems. The new systems can reduce probability of commutation failure and improve the stability of the MIDC systems. A physical model of a multi-infeed HVDC and VSC-HVDC system is developed, and its mathematical model is analyzed. The rectangular coordinate form of VSC's power transmission equations is deduced through coordinate conversion. Based on the inverse system method for multivariable nonlinear control, the nonlinear controllers of the multi-infeed HVDC and VSC-HVDC system are designed. Simulation results by PSCAD/EMTDC show that the designed nonlinear controllers improve effectively the voltage stability of the multi-infeed HVDC and VSC-HVDC systemunder small or large disturbances, such as short circuit fault, reduce the probability of commutation failure in the inverter of HVDC systems and increase the operation reliability of HVDC systems
It is a trend to construct unattended substation in powersystem *** paper systematically analyses the superiority and limitation of MATLAB and Visual C++ and illustrates how to compile m-files to cpp-files by MATLAB ...
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ISBN:
(纸本)0863416381
It is a trend to construct unattended substation in powersystem *** paper systematically analyses the superiority and limitation of MATLAB and Visual C++ and illustrates how to compile m-files to cpp-files by MATLAB engines and integrate cpp-files code into existing C++ projects by Visual C++ to realize intelligent function on image recognition used for unattended *** intelligent function can effectively test illegal intrusion and fires through the detection and recognition of moving goals by three-image difference method and self-adapting threshold value segmentation algorithm and detect situations of disconnection link by use of image crop and image index processing and give warnings to alarm system. Because of lacking of brightness of image or nonlinear brightness and being influenced by kinds of noise,this paper determines to adopt contrast enhanced algorithm and high-frequency enhanced algorithm to repair grey-scale distribution and uses median filtering to remove noise of image. In the end,this paper brings forward the expectation about the image recognition of the unattended substation. When non-uniform of image illumination distribution, grey-scale of background changes largely and image segmentation has not the fittest threshold, so the paper uses self-adapting threshold segmentation algorithm to gain the image segmentation.
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