function?[sysx0strts]?=?afd（txuflag）
switch?flag
??case?0
????[sysx0strts]=mdlInitializeSizes;
??case?1
????sys=[];
??case?2
????sys=[];
??case?3
????sys=mdlOutputs（txu）;
??case?4
????sys=[];
??case?9
????sys=[];
???otherwise
????error（[‘Unhandled?flag?=?‘num2str（flag）]）;
end

%=============================================================================
%?mdlInitializeSizes
function?[sysx0strts]=mdlInitializeSizes??%初始化
global??f_vo?theta_i?theta_vo?isIslanding?cf?%并網(wǎng)電流電壓及其相位和孤島標(biāo)志
f_vo=50;????????%50Hz
theta_i=0;??????%I
theta_vo=0;?????%V
isIslanding=0;??%Island
cf=0;
sizes?=?simsizes;
sizes.NumContStates??=?0;
sizes.NumDiscStates??=?0;
sizes.NumOutputs?????=?3;
sizes.NumInputs??????=?3;
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（txu）
global??f_vo?theta_i?theta_vo?isIslanding?cf
theta_vo=u（2）;?%數(shù)字鎖相環(huán)輸出的電壓頻率

if?abs（theta_vo）<0.04??%?電壓相位為0時(shí)更新頻率
????????f_vo=u（1）;
????????cf=u（2）+0.2*（f_vo-50）;
????????if?（f_vo>50.5?||?f_vo<49.5）	%判斷頻率是否越界
????????????sys=[0?0?cf];
????????????isIslanding=1;%頻率越界則輸出為0，置孤島標(biāo)志?
????????end
end

if（isIslanding==0）	?%判斷是否孤島效應(yīng)
???if?cf>=0
????????if?（theta_vo>=0）&&（theta_vo<=0.5*pi*cf）
????????????theta_i=0;
????????elseif?（abs（pi-theta_vo））<=0.5*pi*cf
????????????theta_i=pi;??
????????elseif?（theta_vo>=pi*（2-0.5*cf））&&（theta_vo<=2*pi）
?????????theta_i=2*pi;
????????elseif（theta_vo>0.5*pi*cf）&&（theta_vo<（pi-0.5*pi*cf））
????????theta_i=（theta_vo-0.5*pi*cf）/（1-cf）;
????????elseif（theta_vo>=pi+0.5*pi*cf）&&（theta_vo<=pi*（2-0.5*cf））
???????????theta_i=（theta_vo-1.5*pi*cf）/（1-cf）;
????????end
?????elseif?cf<0
??????if?（theta_vo>0）&&（theta_vo?????????theta_i=（theta_vo-0.5*pi*cf）/（1-cf）;
??????elseif（theta_vo>pi）&&（theta_vo<2*pi）
????????theta_i=（theta_vo-1.5*pi*cf）/（1-cf）;
???????end
???end
???sys（1）=sin（theta_i）;?
else
???sys（1）=0;
end
???sys（2）=f_vo;
???sys（3）=cf;??
??
??????????????

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