The operation mode of power grids with intermittent distributed generations(DGs)changes frequently due to the bidirectional power flow.In comparison with the conventional grids,the protection relays in power grids wit...The operation mode of power grids with intermittent distributed generations(DGs)changes frequently due to the bidirectional power flow.In comparison with the conventional grids,the protection relays in power grids with micro-sources are more difficult to set.To tackle this problem,this paper proposes an extended bus differential protection(EBDP)strategy based on the limited wide area(LWA).In this method,the micro-grids are divided into several protection areas at the core of the bus.The whole protection areas are protected by the wide area current differential relays,which are also configured to protect each component in this protection area.Moreover,the protection areas can be changed adaptively according to the power flow direction.Finally,a micro-grid model with multiple DGs is developed using the PSCAD/EMTDC platform.The simulation results indicate that the proposed adaptive limited wide area differential protection(LWADP)has better performance than the traditional relaying protection in detecting the faulty area in micro-grids and isolating the fault,and can be widely utilized in larger micro-grids.展开更多
Decimeter-level service is provided by the BeiDou satellite navigation system wide area differential service(BDS WADS)for users who collect carrier phase measurements.However,the fluctuations in Geostationary Earth Or...Decimeter-level service is provided by the BeiDou satellite navigation system wide area differential service(BDS WADS)for users who collect carrier phase measurements.However,the fluctuations in Geostationary Earth Orbit(GEO)satellite orbit errors reduce the spatial correlation of orbit errors.These fluctuations not only decrease the accuracy and stability of zone correction service provided by BDS WADS,but also shorten its effective range.In this paper,we proposed an algorithm to weaken the influence of GEO satellite orbit error fluctuations and verified the method using data from eight sparsely distributed zones.The results show that orbit errors can be stabilized using orbit fluctuation corrections,and the positioning precision and stability of the BDS WADS can be improved simultaneously.Under normal circumstances,the horizontal and vertical positioning accuracy of users within 1000 km from the center of the zone can reach 0.19 m and 0.34 m.Furthermore,the effective range is increased.The positioning performance within 1800 km could reach 0.24 m and 0.38 m for the horizontal and vertical components,respectively.展开更多
文摘The operation mode of power grids with intermittent distributed generations(DGs)changes frequently due to the bidirectional power flow.In comparison with the conventional grids,the protection relays in power grids with micro-sources are more difficult to set.To tackle this problem,this paper proposes an extended bus differential protection(EBDP)strategy based on the limited wide area(LWA).In this method,the micro-grids are divided into several protection areas at the core of the bus.The whole protection areas are protected by the wide area current differential relays,which are also configured to protect each component in this protection area.Moreover,the protection areas can be changed adaptively according to the power flow direction.Finally,a micro-grid model with multiple DGs is developed using the PSCAD/EMTDC platform.The simulation results indicate that the proposed adaptive limited wide area differential protection(LWADP)has better performance than the traditional relaying protection in detecting the faulty area in micro-grids and isolating the fault,and can be widely utilized in larger micro-grids.
基金the National Natural Science Funds of China(Grant No.41604032).
文摘Decimeter-level service is provided by the BeiDou satellite navigation system wide area differential service(BDS WADS)for users who collect carrier phase measurements.However,the fluctuations in Geostationary Earth Orbit(GEO)satellite orbit errors reduce the spatial correlation of orbit errors.These fluctuations not only decrease the accuracy and stability of zone correction service provided by BDS WADS,but also shorten its effective range.In this paper,we proposed an algorithm to weaken the influence of GEO satellite orbit error fluctuations and verified the method using data from eight sparsely distributed zones.The results show that orbit errors can be stabilized using orbit fluctuation corrections,and the positioning precision and stability of the BDS WADS can be improved simultaneously.Under normal circumstances,the horizontal and vertical positioning accuracy of users within 1000 km from the center of the zone can reach 0.19 m and 0.34 m.Furthermore,the effective range is increased.The positioning performance within 1800 km could reach 0.24 m and 0.38 m for the horizontal and vertical components,respectively.