In this paper a practical but sufficiently accurate method of calculating transient components in short circuit currents and voltages is proposed. It enables to find the roots of the chara...In this paper a practical but sufficiently accurate method of calculating transient components in short circuit currents and voltages is proposed. It enables to find the roots of the characteristic equation of high order without forming and solving it. This method is convenient to use especially in case of complicated expansionary power systems.展开更多
Current phase comparison based pilot protection had been generally utilized as primary protection of the transmission lines in China from the 1950＇s to the 1980＇ s, Comentional phase comparison pilot protection has ...Current phase comparison based pilot protection had been generally utilized as primary protection of the transmission lines in China from the 1950＇s to the 1980＇ s, Comentional phase comparison pilot protection has a long phase comparison time, which results in a longer fault-clearing time. This paper proposes a new current phase comparison, pilot protection scheme that is based on non-power frequency fauh eun＇ent component. The phase of the fourth harmonic eun＇ent of each end of the protected line has heen abstracted hy utilizing complex wavelet transformation and then compared in order to determine whether the inner fauh occurs or not. This way can greatly deerease fauh-elearing time and improve performances of this pilot protection when fault occurs under the heavy-load current and asymmetrical operation eonditions, Many EMTP simulations have verified the proposed scheme＇s correctness and effectiveness.展开更多
This series of papers report on relay protection strategies that satisfy the demands of a strong smart grid.These strategies include ultra-high-speed transient-based fault discrimination,new co-ordination principles o...This series of papers report on relay protection strategies that satisfy the demands of a strong smart grid.These strategies include ultra-high-speed transient-based fault discrimination,new co-ordination principles of main and back-up protection to suit the diversification of the power network,optimal co-ordination between relay protection and auto-reclosure to enhance robustness of the power network.There are also new development in protection early warning and tripping functions of protection based on wide area information.In this paper the principles,algorithms and techniques of single-ended,transient-based and ultra-high-speed protection for EHV transmission lines,buses,DC transmission lines and faulty line selection for non-solid earthed networks are presented.Tests show that the methods presented can determine fault characteristics with ultra-high-speed(5 ms)and that the new principles of fault discrimination can satisfy the demand of EHV systems within a smart grid.展开更多
文摘In this paper a practical but sufficiently accurate method of calculating transient components in short circuit currents and voltages is proposed. It enables to find the roots of the characteristic equation of high order without forming and solving it. This method is convenient to use especially in case of complicated expansionary power systems.
基金Sponsored by the Power Electrical Science and Technology Foundation of XJ Group and the Shanghai University Foundation for Excellent Young Teacher.
文摘Current phase comparison based pilot protection had been generally utilized as primary protection of the transmission lines in China from the 1950＇s to the 1980＇ s, Comentional phase comparison pilot protection has a long phase comparison time, which results in a longer fault-clearing time. This paper proposes a new current phase comparison, pilot protection scheme that is based on non-power frequency fauh eun＇ent component. The phase of the fourth harmonic eun＇ent of each end of the protected line has heen abstracted hy utilizing complex wavelet transformation and then compared in order to determine whether the inner fauh occurs or not. This way can greatly deerease fauh-elearing time and improve performances of this pilot protection when fault occurs under the heavy-load current and asymmetrical operation eonditions, Many EMTP simulations have verified the proposed scheme＇s correctness and effectiveness.
文摘This series of papers report on relay protection strategies that satisfy the demands of a strong smart grid.These strategies include ultra-high-speed transient-based fault discrimination,new co-ordination principles of main and back-up protection to suit the diversification of the power network,optimal co-ordination between relay protection and auto-reclosure to enhance robustness of the power network.There are also new development in protection early warning and tripping functions of protection based on wide area information.In this paper the principles,algorithms and techniques of single-ended,transient-based and ultra-high-speed protection for EHV transmission lines,buses,DC transmission lines and faulty line selection for non-solid earthed networks are presented.Tests show that the methods presented can determine fault characteristics with ultra-high-speed(5 ms)and that the new principles of fault discrimination can satisfy the demand of EHV systems within a smart grid.
