基于三相光伏并网系统的DVR模糊PID控制应用研究

Application of DVR Fuzzy PID Control Based on Three-Phase Grid-Connected Photovoltaic System

光伏发电系统极易受外界条件的影响而出现电压波动及谐波,由于其时变、非线性、多变量的特性,仅由常规PID控制或是模糊控制调节器进行控制,存在对于跟踪指令值与抑制扰动的需求之间、稳态与动态性能之间、控制性能和鲁棒性之间的矛盾。利用动态电压补偿器消除光伏阵列的电压波动、跌落、闪变,以及电压的三相不平衡问题,并在常规PID控制的基础上,以被控对象的指令值与实际值的误差及其变化率作为输入,用模糊推理对PID的3个参数K_p、K_i、K_d进行在线自整定,以满足指令值与反馈值不断变化时误差及其变化率对控制器的不同要求。最后通过仿真证明了系统控制效果理想,动态响应速度更快,稳态误差更小,被控对象具备良好的动、静态性能。

The photovoltaic(PV) power generation system,vulnerable to the external influence,would generate the voltage fluctuation and harmonic and can not be controlled only by the conventional PID and the fuzzy controller due to its time-varying,nonlinear,multi variable characteristics,resulting in the contradiction problems between the tracking and disturbance rejection requirement,steady and dynamic performance,and the control performance and the robustness.In this paper,the dynamic voltage restorer(DVR) is used to eliminate the problem of the voltage sag,fluctuation,flicker,and the three-phase unbalance voltage of the PV array.Based on conventional PID control,the error and variation rate between the instruction value of the controlled object and the actual value are employed as input.Fuzzy reasoning is used for PID's three parameters K_p,K_i,K_d online self-tuning,in order to meet the requirements for the controller varying with the error and variation rate between the instruction value and feedback value.Finally,the simulation proves the system ideal control effects;faster dynamic response,smaller steady-state error,and better dynamic and static performance of the controlled object.