For multiple grid-connected inverters with active filter function,it makes sense to regulate every unit to output maximum active power from photovoltaic arrays,as well as eliminate the harmonic due to the non-linear l...For multiple grid-connected inverters with active filter function,it makes sense to regulate every unit to output maximum active power from photovoltaic arrays,as well as eliminate the harmonic due to the non-linear loads connected to the electric networks.Naturally,a centralized control coordination strategy was proposed for the purpose of high facility utilization,good harmonic compensation ability and unwanted overcompensation condition.Based on a vector decoupling control scheme and generalized instantaneous reactive power theory,the solution was to allocate the harmonic eliminating task for every inverter according to the instantaneous power margin of each.The grid current always keeps sinusoidal in spite of non-linear load change and output active power change for any inverter.The simulation results validate the efficacy of the proposed coordination strategy.展开更多
In order to reduce the switching frequency harmonics caused by the grid-connected converter,the LCL filter is adopted.However the third-order LCL filter,as an undamped system,is not stable.In order to overcome this pr...In order to reduce the switching frequency harmonics caused by the grid-connected converter,the LCL filter is adopted.However the third-order LCL filter,as an undamped system,is not stable.In order to overcome this problem,a damping resistor and the active damping method are often used;but the damping resistor will result in the power consumption,and the method of active damping needs more sensors compared to the standard control.展开更多
Modeling method for the current control loop of a grid-connected PWM inverter with the LCL output filter was discussed.Firstly,the current control loop with the LCL inverter-side current as feedback was established.Th...Modeling method for the current control loop of a grid-connected PWM inverter with the LCL output filter was discussed.Firstly,the current control loop with the LCL inverter-side current as feedback was established.Then,parameters of PI controller were calculated on the basis of an equivalent controlled object.Finally,Norton equivalent circuit for the current control loop of grid-connected system was derived by integrating one control equation,which connected the PWM inverter output voltage and the LCL inverter-side current,with two circuit equations,separately using the LCL inverter-side current and the injected current as loop currents.With the induced Norton equivalent circuit,system-level resonant and unstable issues on real grid-connected system applied in weak distributed power systems can be easily analyzed.The validity of substituting Norton equivalent circuit for grid-connected system is verified by simulation and experiment.展开更多
基金Project(51107111)supported by the National Natural Science Foundation of China
文摘For multiple grid-connected inverters with active filter function,it makes sense to regulate every unit to output maximum active power from photovoltaic arrays,as well as eliminate the harmonic due to the non-linear loads connected to the electric networks.Naturally,a centralized control coordination strategy was proposed for the purpose of high facility utilization,good harmonic compensation ability and unwanted overcompensation condition.Based on a vector decoupling control scheme and generalized instantaneous reactive power theory,the solution was to allocate the harmonic eliminating task for every inverter according to the instantaneous power margin of each.The grid current always keeps sinusoidal in spite of non-linear load change and output active power change for any inverter.The simulation results validate the efficacy of the proposed coordination strategy.
文摘In order to reduce the switching frequency harmonics caused by the grid-connected converter,the LCL filter is adopted.However the third-order LCL filter,as an undamped system,is not stable.In order to overcome this problem,a damping resistor and the active damping method are often used;but the damping resistor will result in the power consumption,and the method of active damping needs more sensors compared to the standard control.
基金Project(51307009)supported by the National Natural Science Foundation of ChinaProject(12JJ4045)supported by Hunan Provincial Natural Science Foundation,China+2 种基金Project(2011KFJJ003)supported by the Key Laboratory for Power Technology of Renewable Energy Sources of Hunan Province,ChinaProject(2011kfj14)supported by the Fund of Key Laboratory of Hunan Province about Power System Operation and Control,ChinaProject(454.13S-20)supported by the Enterprises’Postdoctoral Funds of Pudong Area of Shanghai,China
文摘Modeling method for the current control loop of a grid-connected PWM inverter with the LCL output filter was discussed.Firstly,the current control loop with the LCL inverter-side current as feedback was established.Then,parameters of PI controller were calculated on the basis of an equivalent controlled object.Finally,Norton equivalent circuit for the current control loop of grid-connected system was derived by integrating one control equation,which connected the PWM inverter output voltage and the LCL inverter-side current,with two circuit equations,separately using the LCL inverter-side current and the injected current as loop currents.With the induced Norton equivalent circuit,system-level resonant and unstable issues on real grid-connected system applied in weak distributed power systems can be easily analyzed.The validity of substituting Norton equivalent circuit for grid-connected system is verified by simulation and experiment.
