Bank erosion of rivers, e.g. Bagmati, Burhi Gandak, Kosi and Kamla-Balan, all originating in the Himalayan hills of Nepal and flowing throughthe alluvial plains of North Bihar, is a chronic and common phenomenon.Cutti...Bank erosion of rivers, e.g. Bagmati, Burhi Gandak, Kosi and Kamla-Balan, all originating in the Himalayan hills of Nepal and flowing throughthe alluvial plains of North Bihar, is a chronic and common phenomenon.Cutting and deposition result in shifting or meandering of the riverendangering the embankment, road, bridge, barrage, and countryside.Anti-erosion and maintenance require huge investment. The river Kamla-Balan faces bank erosion throughout its embanked length, but stretchesat km 37 and 62 are highly unstable and vulnerable. This paper dealswith the problem, presents the hydrological details responsible for thehazard, and demonstrates the effectiveness of supplementary geo-textilewith conventional sand filter pitching to protect the soil and slope of theriverbank. Estimated flood discharge and velocity at 100 years of returnperiod is nearly 2100 cumecs and 0.9 m/sec, respectively. Riverbed andbank material is represented by silt with d50 of 0.018 to 0.05 mm while0.02 mm of silt may get eroded and transported by flow above 0.15 m/s. Launching apron is also required due to local scour. Model study testshows its suitability under various hydraulic conditions. Study reveals theeffectiveness of woven type geo-textile reinforced revetment irrespective ofcost and environmental consideration.展开更多
As photovoltaic （PV） capacity in power system increases, the capacity of synchronous generator needs to be reduced relatively. This leads to the lower system inertia and the higher generator reactance, and hence the...As photovoltaic （PV） capacity in power system increases, the capacity of synchronous generator needs to be reduced relatively. This leads to the lower system inertia and the higher generator reactance, and hence the generator transient stability may negatively be affected. In particular, the impact on the transient stability may become more serious when the considerable amounts of PV systems are disconnected simultaneously during voltage sag. In this work, the generator transient stability in the power system with significant PV penetration is assessed by a numerical simulation. In order to assess the impact from various angles, simulation parameters such as levels of PV penetration, variety of power sources （inverter or rotational machine）, and existence of LVRT capability are considered. The simulation is performed by using PSCAD/EMTDC software.展开更多
In the previous paper [1], the transient stability of synchronous generator in power system with high-penetration PV （photovoltaic） was assessed by simulation analysis of a single-machine infinite-bus system model. ...In the previous paper [1], the transient stability of synchronous generator in power system with high-penetration PV （photovoltaic） was assessed by simulation analysis of a single-machine infinite-bus system model. Through the simulation analysis, we have obtained some conclusions in terms of the impact of high-penetration PV on the stability. However, for more accurate assessment of the transient stability, it is necessary to analyze various simulation models considering many other power system conditions. This paper presents the results of the analysis for the transient stability simulation performed for IEEE 9-bus system model, in which the effects of various conditions, such as variety of power sources （inverter or rotational machine）, load characteristics, existence of LVRT （low-voltage ride-through） capability and fault locations, on the transient stability are investigated.展开更多
文摘Bank erosion of rivers, e.g. Bagmati, Burhi Gandak, Kosi and Kamla-Balan, all originating in the Himalayan hills of Nepal and flowing throughthe alluvial plains of North Bihar, is a chronic and common phenomenon.Cutting and deposition result in shifting or meandering of the riverendangering the embankment, road, bridge, barrage, and countryside.Anti-erosion and maintenance require huge investment. The river Kamla-Balan faces bank erosion throughout its embanked length, but stretchesat km 37 and 62 are highly unstable and vulnerable. This paper dealswith the problem, presents the hydrological details responsible for thehazard, and demonstrates the effectiveness of supplementary geo-textilewith conventional sand filter pitching to protect the soil and slope of theriverbank. Estimated flood discharge and velocity at 100 years of returnperiod is nearly 2100 cumecs and 0.9 m/sec, respectively. Riverbed andbank material is represented by silt with d50 of 0.018 to 0.05 mm while0.02 mm of silt may get eroded and transported by flow above 0.15 m/s. Launching apron is also required due to local scour. Model study testshows its suitability under various hydraulic conditions. Study reveals theeffectiveness of woven type geo-textile reinforced revetment irrespective ofcost and environmental consideration.
文摘As photovoltaic （PV） capacity in power system increases, the capacity of synchronous generator needs to be reduced relatively. This leads to the lower system inertia and the higher generator reactance, and hence the generator transient stability may negatively be affected. In particular, the impact on the transient stability may become more serious when the considerable amounts of PV systems are disconnected simultaneously during voltage sag. In this work, the generator transient stability in the power system with significant PV penetration is assessed by a numerical simulation. In order to assess the impact from various angles, simulation parameters such as levels of PV penetration, variety of power sources （inverter or rotational machine）, and existence of LVRT capability are considered. The simulation is performed by using PSCAD/EMTDC software.
文摘In the previous paper [1], the transient stability of synchronous generator in power system with high-penetration PV （photovoltaic） was assessed by simulation analysis of a single-machine infinite-bus system model. Through the simulation analysis, we have obtained some conclusions in terms of the impact of high-penetration PV on the stability. However, for more accurate assessment of the transient stability, it is necessary to analyze various simulation models considering many other power system conditions. This paper presents the results of the analysis for the transient stability simulation performed for IEEE 9-bus system model, in which the effects of various conditions, such as variety of power sources （inverter or rotational machine）, load characteristics, existence of LVRT （low-voltage ride-through） capability and fault locations, on the transient stability are investigated.
