In this paper, the Chebyshev wavelet method, constructed from the Chebyshev polynomial of the first kind is proposed to numerically simulate the single-phase flow of fluid in a reservoir. The method was used together ...In this paper, the Chebyshev wavelet method, constructed from the Chebyshev polynomial of the first kind is proposed to numerically simulate the single-phase flow of fluid in a reservoir. The method was used together with the operational matrices of integration which resulted in an algebraic system of equations. The system of equation was solved for the wavelet coefficient and used to construct the solutions. The efficiency and accuracy of the method were demonstrated through error measurements. Both the root mean square and the maximum absolute error analysis used in the study were within significantly close range. The Chebyshev wavelet collocation method subsequently was observed to closely approximate the analytic solution to the single phase flow model quite well.展开更多
An islanding detection method in ungrounded power distribution system based on single-phase operating mechanisms of the circuit breaker(CB)is proposed in this paper.When CB opens three phase circuits to form an island...An islanding detection method in ungrounded power distribution system based on single-phase operating mechanisms of the circuit breaker(CB)is proposed in this paper.When CB opens three phase circuits to form an island,one phase circuit is opened firstly and the other two phase circuits are opened secondly after certain duration.During the period when only one phase circuit is opened,negative sequence voltage with certain duration is obtained at DG side because of the asymmetric operation of the system.After all three phase circuits are opened,the voltage variation direction of the two phases that are secondly disconnected from the grid follows the voltage variation direction of the firstly disconnected phase.Based on the above voltage characteristics,an islanding detection scheme is proposed to identify genuine islanding from system disturbances.The performance of the proposed scheme is tested in PSCAD/EMTDC using a 10 kV distribution network with synchronous DG interconnection.Simulation results demonstrate the proposed method is effective and reliable to detect islanding formation.展开更多
文摘In this paper, the Chebyshev wavelet method, constructed from the Chebyshev polynomial of the first kind is proposed to numerically simulate the single-phase flow of fluid in a reservoir. The method was used together with the operational matrices of integration which resulted in an algebraic system of equations. The system of equation was solved for the wavelet coefficient and used to construct the solutions. The efficiency and accuracy of the method were demonstrated through error measurements. Both the root mean square and the maximum absolute error analysis used in the study were within significantly close range. The Chebyshev wavelet collocation method subsequently was observed to closely approximate the analytic solution to the single phase flow model quite well.
文摘An islanding detection method in ungrounded power distribution system based on single-phase operating mechanisms of the circuit breaker(CB)is proposed in this paper.When CB opens three phase circuits to form an island,one phase circuit is opened firstly and the other two phase circuits are opened secondly after certain duration.During the period when only one phase circuit is opened,negative sequence voltage with certain duration is obtained at DG side because of the asymmetric operation of the system.After all three phase circuits are opened,the voltage variation direction of the two phases that are secondly disconnected from the grid follows the voltage variation direction of the firstly disconnected phase.Based on the above voltage characteristics,an islanding detection scheme is proposed to identify genuine islanding from system disturbances.The performance of the proposed scheme is tested in PSCAD/EMTDC using a 10 kV distribution network with synchronous DG interconnection.Simulation results demonstrate the proposed method is effective and reliable to detect islanding formation.
