Based on real-time digital simulations(RTDS),a laboratory environment similar to the real-time operation situation of the Three Gorges Hydropower Station is established.Then,the causes for the power fluctuation of the...Based on real-time digital simulations(RTDS),a laboratory environment similar to the real-time operation situation of the Three Gorges Hydropower Station is established.Then,the causes for the power fluctuation of the second generator by errors in the rotor rotating speed calculation are found,and the tuning method of the speed related parameters are given.The damping and reverse tuning characteristics of power system stabilizers(PSSs)in the digital automatic voltage regulator(AVR)are compared and investigated in the frequency range of 0.18-1.1 Hz.The efficiency of the proposed tuning method for ensuring power system stability is verified by RTDS.Finally,field tests show the validity of the laboratory test results.展开更多
1运行状况冷水塔风机电机为YDT315M-4/8W型双速电动机（110 k W/30 k W）,额定电压380 V,夏季生产用110 k W、4极运行,冬季采用30 k W、8极运行。我厂有8座冷水塔,共26台冷水塔风机,冷却后的水温要求控制在17~22℃之间。一般风机运行在...1运行状况冷水塔风机电机为YDT315M-4/8W型双速电动机（110 k W/30 k W）,额定电压380 V,夏季生产用110 k W、4极运行,冬季采用30 k W、8极运行。我厂有8座冷水塔,共26台冷水塔风机,冷却后的水温要求控制在17~22℃之间。一般风机运行在额定电流的80%左右,可计算得知风机在春、夏、秋季每天的用电量为110×26×24×80%=54912（kWh），冬季每天的用电量为30×26×24×80％=14976（kwh）。电动机功耗大。展开更多
The performance of multi-antenna multi-relay cooperative system is investigated in this paper. Two relaying strategies, i.e., reactive and proactive strategies are analyzed with the Amplifyand-Forward (AF) and Decode-...The performance of multi-antenna multi-relay cooperative system is investigated in this paper. Two relaying strategies, i.e., reactive and proactive strategies are analyzed with the Amplifyand-Forward (AF) and Decode-and-Forward (DF) protocols. We derive the Cumulative Distribution Function (CDF) of the received Signal-to-Noise Ratio (SNR) at the destination, which is used to calculate the exact outage probability, for both AF and DF protocols. According to these results, we conclude that a cooperative network which composes K relays each equipped with nr antennas can achieve maximal order-(2nrK+1) diversity gain, by proper processing at relays and destination. Furthermore, the performance comparison is given, in terms of outage probability. These two strategies outperform each other in different scenarios in AF protocol, whilst proactive strategy is always better than its counterpart in DF protocol. According to these results, the optimal power allocation schemes among relay nodes are also presented, with reasonable power constraint.展开更多
Technical process and pressure control system of coke furnace were introduced.The mathematical model based on experimental method of gas-collector pressure wasproposed.To a certain extent, it is more reliable and depe...Technical process and pressure control system of coke furnace were introduced.The mathematical model based on experimental method of gas-collector pressure wasproposed.To a certain extent, it is more reliable and dependable than mechanism method.Manufacturing process and experimental modeling can be finished at the same time, andfurthermore, the mathematical model can be established automatically.The realization algorithmof the total decoupling and on the line's modification for model value plays an importantrole in improving regulating quality.Finally, the DCS network structure to realizethe process was introduced.The control results show that the regulator can get reliableand robust performance.展开更多
XY table automated assembly machines ensure time saving and quality improving in the electronics industry. Recently, due to the need of higher operation speeds and lighter machines in PCB （Printed Circuit Board） ass...XY table automated assembly machines ensure time saving and quality improving in the electronics industry. Recently, due to the need of higher operation speeds and lighter machines in PCB （Printed Circuit Board） assembly, a challenging problem has arisen which is the table positioning vibration. The high speed with the machine flexibility, make the positioning vibration inevitable although the inner control. The positioning vibration is to be reduced otherwise the machine becomes useless. Firstly, the machine is modeled, the positioning vibration is formulated, and then analyzed. Secondly, using the analysis, three direct control methods are identified to decrease the positioning vibration, they are based on the kinematics, dynamics, and operation of the machine. Thirdly, the methods are examined numerically to evaluate their efficiency. Lastly, the identified methods are discussed to conclude on their application. The results are a real contribution in the vibration control of XY table automated assembly machines, which is classified as industrial knowhow.展开更多
文摘Based on real-time digital simulations(RTDS),a laboratory environment similar to the real-time operation situation of the Three Gorges Hydropower Station is established.Then,the causes for the power fluctuation of the second generator by errors in the rotor rotating speed calculation are found,and the tuning method of the speed related parameters are given.The damping and reverse tuning characteristics of power system stabilizers(PSSs)in the digital automatic voltage regulator(AVR)are compared and investigated in the frequency range of 0.18-1.1 Hz.The efficiency of the proposed tuning method for ensuring power system stability is verified by RTDS.Finally,field tests show the validity of the laboratory test results.
文摘1运行状况冷水塔风机电机为YDT315M-4/8W型双速电动机（110 k W/30 k W）,额定电压380 V,夏季生产用110 k W、4极运行,冬季采用30 k W、8极运行。我厂有8座冷水塔,共26台冷水塔风机,冷却后的水温要求控制在17~22℃之间。一般风机运行在额定电流的80%左右,可计算得知风机在春、夏、秋季每天的用电量为110×26×24×80%=54912（kWh），冬季每天的用电量为30×26×24×80％=14976（kwh）。电动机功耗大。
基金supported by the National Natural Science Foundation of China (Grant No. 60932003)the National Hightech R&D Program of China (863 Program, Grant No. 2007AA01Z452, No. 2009AA01Z118)the Shanghai Municipal Natural Science Foundation (Grant No. 09ZR1414900)
文摘The performance of multi-antenna multi-relay cooperative system is investigated in this paper. Two relaying strategies, i.e., reactive and proactive strategies are analyzed with the Amplifyand-Forward (AF) and Decode-and-Forward (DF) protocols. We derive the Cumulative Distribution Function (CDF) of the received Signal-to-Noise Ratio (SNR) at the destination, which is used to calculate the exact outage probability, for both AF and DF protocols. According to these results, we conclude that a cooperative network which composes K relays each equipped with nr antennas can achieve maximal order-(2nrK+1) diversity gain, by proper processing at relays and destination. Furthermore, the performance comparison is given, in terms of outage probability. These two strategies outperform each other in different scenarios in AF protocol, whilst proactive strategy is always better than its counterpart in DF protocol. According to these results, the optimal power allocation schemes among relay nodes are also presented, with reasonable power constraint.
文摘Technical process and pressure control system of coke furnace were introduced.The mathematical model based on experimental method of gas-collector pressure wasproposed.To a certain extent, it is more reliable and dependable than mechanism method.Manufacturing process and experimental modeling can be finished at the same time, andfurthermore, the mathematical model can be established automatically.The realization algorithmof the total decoupling and on the line's modification for model value plays an importantrole in improving regulating quality.Finally, the DCS network structure to realizethe process was introduced.The control results show that the regulator can get reliableand robust performance.
文摘XY table automated assembly machines ensure time saving and quality improving in the electronics industry. Recently, due to the need of higher operation speeds and lighter machines in PCB （Printed Circuit Board） assembly, a challenging problem has arisen which is the table positioning vibration. The high speed with the machine flexibility, make the positioning vibration inevitable although the inner control. The positioning vibration is to be reduced otherwise the machine becomes useless. Firstly, the machine is modeled, the positioning vibration is formulated, and then analyzed. Secondly, using the analysis, three direct control methods are identified to decrease the positioning vibration, they are based on the kinematics, dynamics, and operation of the machine. Thirdly, the methods are examined numerically to evaluate their efficiency. Lastly, the identified methods are discussed to conclude on their application. The results are a real contribution in the vibration control of XY table automated assembly machines, which is classified as industrial knowhow.
