This paper focuses on the direct current-alternating current （DC-AC） interfaced microsource based H∞ robust control strategies in microgrids. It presents detail of a DC-AC interfaced microsource model which is conn...This paper focuses on the direct current-alternating current （DC-AC） interfaced microsource based H∞ robust control strategies in microgrids. It presents detail of a DC-AC interfaced microsource model which is connected to the power grid through a controllable switch. A double loop current-regulated voltage control scheme for the DC-AC interface is designed. In the case of the load disturbance and the model uncertainties, the inner voltage and current loop are produced based on the H∞ robust control strategies. The outer power loop uses the droop characteristic controller. Finally, the scheme is simulated using the Matlab/Simulink. The simulation results demonstrate that DC-AC interfaced microsource system can supply high quality power. Also, the proposed control scheme can make the system switch smoothly between the isolated mode and grid-connected mode. 更多展开更多
With rapid growth of power demand, transmission capacity is also in urgent need of upgrading. In some cases, converting existing AC transmission lines to DC lines can Improve the transmission capacity and reduce the c...With rapid growth of power demand, transmission capacity is also in urgent need of upgrading. In some cases, converting existing AC transmission lines to DC lines can Improve the transmission capacity and reduce the construction investment. In this paper, the upstream finite element method was expanded to calculate the total electric field of same tower multi-circuit DC lines converted from double-circuit AC lines, and the validity of the algorithm was confirmed by experiments. Taking a DC line converted from a typical same tower 500 kV double-circuit AC transmission line as an example, the surface electric field and the ground total electric field in different pole conductor arrangement schemes were calculated and analyzed, and the critical height of pole conductors for DC lines in residential and non-residential area were determined. Then, the corridor width of DC and AC lines at critical height in residential and non-residential areas before and after AC-DC line transformation were compared. The results indicate that for DC lines converted from common 500 kV double-circuit AC lines, the ground total electric field can meet the requirements of corresponding standard with appropriate pole conductor arrangement schemes.展开更多
为在实验室环境下实现40 k W容量的船舶中压电力模拟试验系统,需要将380 V发电机组输出的交流电经电力变换得到稳定的4 k V直流输出。系统采用两级变换,前级AC/DC变换采用无桥boost型PFC(Power Factor Correction)电路,后级DC/DC变换采...为在实验室环境下实现40 k W容量的船舶中压电力模拟试验系统,需要将380 V发电机组输出的交流电经电力变换得到稳定的4 k V直流输出。系统采用两级变换,前级AC/DC变换采用无桥boost型PFC(Power Factor Correction)电路,后级DC/DC变换采用四路全桥PWM(Pulse Width Modulation)变换器级联进行升压,其中一路为移相全桥完成调压控制输出,三路为普通全桥得到固定电压输出。在MATLAB/Simulink环境下对该AC/DC变换器系统进行了系统建模,仿真结果表明,该方案能输出稳定的4 k V电压,效率94.8%,纹波2.08%。展开更多
基金supported by National Natural Science Foundation of China(No. 51177142)China Postdoctoral Science Foundation(Nos.2012T50019 and 20110490210)Hebei Provincial Natural Science Foundation of China(No.F2012203063)
文摘This paper focuses on the direct current-alternating current （DC-AC） interfaced microsource based H∞ robust control strategies in microgrids. It presents detail of a DC-AC interfaced microsource model which is connected to the power grid through a controllable switch. A double loop current-regulated voltage control scheme for the DC-AC interface is designed. In the case of the load disturbance and the model uncertainties, the inner voltage and current loop are produced based on the H∞ robust control strategies. The outer power loop uses the droop characteristic controller. Finally, the scheme is simulated using the Matlab/Simulink. The simulation results demonstrate that DC-AC interfaced microsource system can supply high quality power. Also, the proposed control scheme can make the system switch smoothly between the isolated mode and grid-connected mode. 更多
文摘With rapid growth of power demand, transmission capacity is also in urgent need of upgrading. In some cases, converting existing AC transmission lines to DC lines can Improve the transmission capacity and reduce the construction investment. In this paper, the upstream finite element method was expanded to calculate the total electric field of same tower multi-circuit DC lines converted from double-circuit AC lines, and the validity of the algorithm was confirmed by experiments. Taking a DC line converted from a typical same tower 500 kV double-circuit AC transmission line as an example, the surface electric field and the ground total electric field in different pole conductor arrangement schemes were calculated and analyzed, and the critical height of pole conductors for DC lines in residential and non-residential area were determined. Then, the corridor width of DC and AC lines at critical height in residential and non-residential areas before and after AC-DC line transformation were compared. The results indicate that for DC lines converted from common 500 kV double-circuit AC lines, the ground total electric field can meet the requirements of corresponding standard with appropriate pole conductor arrangement schemes.
文摘为在实验室环境下实现40 k W容量的船舶中压电力模拟试验系统,需要将380 V发电机组输出的交流电经电力变换得到稳定的4 k V直流输出。系统采用两级变换,前级AC/DC变换采用无桥boost型PFC(Power Factor Correction)电路,后级DC/DC变换采用四路全桥PWM(Pulse Width Modulation)变换器级联进行升压,其中一路为移相全桥完成调压控制输出,三路为普通全桥得到固定电压输出。在MATLAB/Simulink环境下对该AC/DC变换器系统进行了系统建模,仿真结果表明,该方案能输出稳定的4 k V电压,效率94.8%,纹波2.08%。
