一种无延时的单相光伏并网功率控制方法

针对分布于电网末梢的单相光伏并网发电系统,提出一种无延时的兼具无功补偿功能的并网功率控制方法,使系统在向电网和本地负载快速提供有功电能的同时,也能提供负载所需的无功电能。该方法由无功电流检测、电压电流双环控制、功率前馈及电网电压前馈构成。提出的无延时单相无功电流检测方法,解决了传统单相无功电流检测存在较大延时的不足;电压外环采用比例积分(proportion integration,PI)控制实现逆变器直流侧稳压;电流内环采用准谐振PR控制实现并网电流的零稳态误差控制,并降低电网频率偏移对电流的影响;引入功率前馈加快系统响应;引入电网电压前馈降低电压畸变或扰动造成的电流畸变。给出了并网功率控制系统的设计,分析了准谐振PR控制中不同控制参数对系统性能的影响,并选取了合适的设计参数。仿真与实验结果验证了所提方法的有效性。

A Single-phase Photovoltaic Grid-connected Power Control Method Without Delay

For the single-phase photovoltaic grid-connected generation system installed at the end of the grid,a power control method with reactive power compensation without delay was proposed.By this way,the system could quickly provide the grid and the local loads with not only active power but also the required reactive power.The proposed method included functions like reactive current detection,voltage and current dual loop control,power feed-forward and grid voltage feed-forward.A single-phase reactive current detection method without delay was presented to solve the shortcoming of the long delay in conventional reactive current detection.In the outer voltage loop,the PI controller was used to stabilize DC link voltage.In the inner current loop,the quasi-PR controller was applied to realize the current zero steady error control and to reduce the influence on the current due to the grid frequency offset.Power feed-forward was introduced to speed up the system response.Grid voltage feed-forward was introduced to reduce the current distortion due to the distortion and disturbance of the grid voltage.The grid-connected power control system was designed.The effects on the system performance were analyzed under the different control parameters of the quasi-PR controller,and the proper parameters were selected.Simulation and experimental results verified the validity of the proposed control methods.