The paper takes a new campus project site of Shanxi university town for example, tests the influence of dynamic com- paction vibration and vibration isolation effect of isolation trench on this ground, and compares th...The paper takes a new campus project site of Shanxi university town for example, tests the influence of dynamic com- paction vibration and vibration isolation effect of isolation trench on this ground, and compares the influences of the dynamic compaction vibration on surrounding buildings with isolation trench and without it. Furthermore, the attenuation law of dy- namic compaction vibration in fill foundation of the loess area under different tamping energy and how to determine safe distance of dynamic compaction construction are studied. And then the quantitative relationship between acceleration and vibration source in new campus project site is presented. We derive the evaluation method that dynamic compaction construction affects adjacent buildings by contrasting with the existing standards and norms. The monitoring results show that isolation trench makes the amplitude attenuation of the horizontal velocity of dynamic compaction vibration reach above 75%, and the safe dis- tance be 30 m under the tamping energy of 6 000 kN · m. Therefore, isolation trench is better for vibration reduction under dynamic compaction construction.展开更多
We propose a novel series transformer based diode-bridge-type solid state fault current limiter （SSFCL）. To control the fault current, a series RLC branch is connected to the secondary side of an isolation series tr...We propose a novel series transformer based diode-bridge-type solid state fault current limiter （SSFCL）. To control the fault current, a series RLC branch is connected to the secondary side of an isolation series transformer. Based on this RLC branch, two current limiting modes are created. In the first mode, R and C are bypassed via a paralleled power electronic switch （insulated-gate bipolar transistor, IGBT） and L remains connected to the secondary side of the transformer as a DC reactor. In the second mode, the series reactor impedance is not enough to limit the fault current. In this case, the fault current can be con- trolled by selecting a proper on-off duration of the parallel IGBT, across the series damping resistor （R） and capacitor, which inserts high impedance into the line to limit the fault current. Then, by controlling the magnitude of the DC reactor current, the fault current is reduced and the voltage of the point of common coupling （PCC） is kept at an acceptable level. In addition, in the new SSFCL, the series RC branch, connected in parallel with the IGBT, serves as a snubber circuit for decreasing the transient recovery voltage （TRV） of the IGBT during on-off states. Therefore, the power quality indices can be improved. The measure- ment results of a built prototype are presented to support the simulation and theoretical studies. The proposed SSFCL can limit the fault current without any delay and successfully smooth the fault current waveform.展开更多
基金Project of National Natural Science Fund for the Youth,China(No.51208473)The Key Project for Science and Technology of Shanxi,China(No.20130313010-3)
文摘The paper takes a new campus project site of Shanxi university town for example, tests the influence of dynamic com- paction vibration and vibration isolation effect of isolation trench on this ground, and compares the influences of the dynamic compaction vibration on surrounding buildings with isolation trench and without it. Furthermore, the attenuation law of dy- namic compaction vibration in fill foundation of the loess area under different tamping energy and how to determine safe distance of dynamic compaction construction are studied. And then the quantitative relationship between acceleration and vibration source in new campus project site is presented. We derive the evaluation method that dynamic compaction construction affects adjacent buildings by contrasting with the existing standards and norms. The monitoring results show that isolation trench makes the amplitude attenuation of the horizontal velocity of dynamic compaction vibration reach above 75%, and the safe dis- tance be 30 m under the tamping energy of 6 000 kN · m. Therefore, isolation trench is better for vibration reduction under dynamic compaction construction.
文摘We propose a novel series transformer based diode-bridge-type solid state fault current limiter （SSFCL）. To control the fault current, a series RLC branch is connected to the secondary side of an isolation series transformer. Based on this RLC branch, two current limiting modes are created. In the first mode, R and C are bypassed via a paralleled power electronic switch （insulated-gate bipolar transistor, IGBT） and L remains connected to the secondary side of the transformer as a DC reactor. In the second mode, the series reactor impedance is not enough to limit the fault current. In this case, the fault current can be con- trolled by selecting a proper on-off duration of the parallel IGBT, across the series damping resistor （R） and capacitor, which inserts high impedance into the line to limit the fault current. Then, by controlling the magnitude of the DC reactor current, the fault current is reduced and the voltage of the point of common coupling （PCC） is kept at an acceptable level. In addition, in the new SSFCL, the series RC branch, connected in parallel with the IGBT, serves as a snubber circuit for decreasing the transient recovery voltage （TRV） of the IGBT during on-off states. Therefore, the power quality indices can be improved. The measure- ment results of a built prototype are presented to support the simulation and theoretical studies. The proposed SSFCL can limit the fault current without any delay and successfully smooth the fault current waveform.
