Transformerless grid-connected inverters offer greater efficiencies when transferring power from renewable energy sources to the electrical grid.If the grid-inverter connection is done with an LCL filter,high attenuat...Transformerless grid-connected inverters offer greater efficiencies when transferring power from renewable energy sources to the electrical grid.If the grid-inverter connection is done with an LCL filter,high attenuation of switching harmonics is achieved while preserving a small-size output filter.However,damping must be included in the controller to assure closed-loop stability.This paper proposes a reference computation methodology for the inverter-side current feedback in a photovoltaic(PV)generation system connected to the grid through an LCL filter.Theoretical analysis of the closed-loop system stability and of the steady-state performance are presented as well as experimental validation of the closed-loop performance.The feedback controller includes active damping and relies on a resonant control structure which improves the ability of dealing with grid harmonic distortion.The controller uses a reduced set of measurements,which requires the inverter-side current and grid voltage only,and assures a power factor close to unity.展开更多
This paper addresses the control design and the experimental validation of a current mode control for a three phase voltage source rectifier. The proposed control law is able to fulfill the voltage regulation and the ...This paper addresses the control design and the experimental validation of a current mode control for a three phase voltage source rectifier. The proposed control law is able to fulfill the voltage regulation and the current tracking control objectives despite of unbalanced and distorted grid voltages. The proposed control law consists of two loops, which are referred as inner tracking loop and the outer voltage regulation loop. The inner loop is designed to provide damping to the system, which also includes and adaptive mechanism. The construction of the current reference is based on the positive component detection of thegrid voltage. Therefore, the current produced by the power rectifier is proportional to the fundamental component of the grid voltage, despite of the presence of unbalanced grid voltages. The voltage regulation loop is designed as a proportional-integral controller, which is aimed to regulate the DC output voltage to a desired level. Finally, experimental results are obtained in an experimental prototype of2 kW to evaluate the performance of the proposed controller.展开更多
文摘Transformerless grid-connected inverters offer greater efficiencies when transferring power from renewable energy sources to the electrical grid.If the grid-inverter connection is done with an LCL filter,high attenuation of switching harmonics is achieved while preserving a small-size output filter.However,damping must be included in the controller to assure closed-loop stability.This paper proposes a reference computation methodology for the inverter-side current feedback in a photovoltaic(PV)generation system connected to the grid through an LCL filter.Theoretical analysis of the closed-loop system stability and of the steady-state performance are presented as well as experimental validation of the closed-loop performance.The feedback controller includes active damping and relies on a resonant control structure which improves the ability of dealing with grid harmonic distortion.The controller uses a reduced set of measurements,which requires the inverter-side current and grid voltage only,and assures a power factor close to unity.
文摘This paper addresses the control design and the experimental validation of a current mode control for a three phase voltage source rectifier. The proposed control law is able to fulfill the voltage regulation and the current tracking control objectives despite of unbalanced and distorted grid voltages. The proposed control law consists of two loops, which are referred as inner tracking loop and the outer voltage regulation loop. The inner loop is designed to provide damping to the system, which also includes and adaptive mechanism. The construction of the current reference is based on the positive component detection of thegrid voltage. Therefore, the current produced by the power rectifier is proportional to the fundamental component of the grid voltage, despite of the presence of unbalanced grid voltages. The voltage regulation loop is designed as a proportional-integral controller, which is aimed to regulate the DC output voltage to a desired level. Finally, experimental results are obtained in an experimental prototype of2 kW to evaluate the performance of the proposed controller.
