matlab_simulink_单相光伏并网发电系统电压前馈控制和有源频率偏移（AFD）孤岛检测法_并网电流与电网电压的同频同相

function [sys,x0,str,ts] = afd(t,x,u,flag) switch flag, case 0, [sys,x0,str,ts]=mdlInitializeSizes; case 1, sys=[]; case 2, sys=[]; case 3, sys=mdlOutputs(t,x,u); case 4, sys=[]; case 9, sys=[]; otherwise error(['Unhandled flag = ',num2str(flag)]); end %============================================================================= % mdlInitializeSizes function [sys,x0,str,ts]=mdlInitializeSizes global f_i f_vo theta_i theta_vo isIslanding f_i=50; f_vo=50; theta_i=0; theta_vo=0; isIslanding=0; sizes = simsizes; sizes.NumContStates = 0; sizes.NumDiscStates = 0; sizes.NumOutputs = 2; sizes.NumInputs = 2; sizes.DirFeedthrough = 1; sizes.NumSampleTimes = 1; % at least one sample time is needed sys = simsizes(sizes); x0 = []; str = []; ts = [1e-4 0]; %============================================================================= % mdlOutputs function sys=mdlOutputs(t,x,u) global f_i f_vo theta_i theta_vo isIslanding theta_vo=u(2); if abs(theta_vo)<0.04 % 电压相位为0时更新频率 f_vo=u(1); end if(isIslanding==0) if abs(theta_vo)<0.04 if (f_vo>50.5) || (f_vo<49.5) %判断频率是否越界 sys=[0 0]; isIslanding=1; else f_i=f_vo+2.5; theta_i=theta_vo; end else if(pi-theta_i<0.03) && (pi-theta_vo>0.03) theta_i=pi; elseif(2*pi-theta_i<0.03) && (2*pi-theta_vo>0.03) theta_i=2*pi; elseif (pi-theta_vo<0.03) && (pi-theta_i>0.03) theta_i=pi; elseif (2*pi-theta_vo<0.03) && (2*pi-theta_i>0.03) theta_i=2*pi; else theta_i=theta_i+2*pi*f_i*1e-4; end end sys(1)=sin(theta_i); else sys(1)=0; end sys(2)=f_vo;