微機(jī)繼電保護(hù)算法仿真電控學(xué)院兩點(diǎn)乘積算法仿真matlab中編寫(xiě)的程序N=12;t=(0:0.02/N:0.02)';m=size(t);y=sin(2*pi*50*t);y1=[zeros(N/4,1);y(1:m-N/4)];ym=sqrt(y.^2+y1.^2);subplot(3,2,1)plot(t,y,'r.',t,y1,'xb');legend('y(k)','y(k-T/4)');title('兩點(diǎn)乘積算法N=12');subplot(3,2,2)holdon;plot(t,ym,'-r');axis([0,0.02,0,1.2]);xlabel('t/s');ylabel('ym');title('兩點(diǎn)乘積算法算的有效值N=12');text(0.01,0.6,'N=12');N=16;t=(0:0.02/N:0.02)';m=size(t);y=sin(2*pi*50*t);y1=[zeros(N/4,1);y(1:m-N/4)];ym=sqrt(y.^2+y1.^2);subplot(3,2,3)plot(t,y,'r.',t,y1,'xb');legend('y(k)','y(k-T/4)');title('兩點(diǎn)乘積算法N=16');subplot(3,2,4)holdon;plot(t,ym,'-r');axis([0,0.02,0,1.2]);xlabel('t/s');ylabel('ym');title('兩點(diǎn)乘積算法算的有效值N=16');text(0.01,0.6,'N=16');N=24;t=(0:0.02/N:0.02)';m=size(t);y=sin(2*pi*50*t);y1=[zeros(N/4,1);y(1:m-N/4)];ym=sqrt(y.^2+y1.^2);subplot(3,2,5)plot(t,y,'r.',t,y1,'xb');legend('y(k)','y(k-T/4)');title('兩點(diǎn)乘積算法N=24');subplot(3,2,6)holdon;plot(t,ym,'-r');title('兩點(diǎn)乘積算法算的有效值N=24');axis([0,0.02,0,1.2]);xlabel('t/s');ylabel('ym');text(0.01,0.6,'N=24');〔2〕仿真出的波形輸出ym=sqrt(y.^2+y1.^2)m=size(t)；得到離散的兩點(diǎn)y1=[zeros(N/4,1);y(1:m-N/4)]N=12，即采樣頻率f=600HZ輸出ym=sqrt(y.^2+y1.^2)m=size(t)；得到離散的兩點(diǎn)y1=[zeros(N/4,1);y(1:m-N/4)]N=12，即采樣頻率f=600HZ，原始信號(hào)離散化輸入信號(hào)y=sin(2*pi*50*t)流程圖傅里葉算法仿真〔1〕matlab中編寫(xiě)的程序T=0.02;t1=0.02;N=12;Ts=T/N;t=0:Ts:4*T;y=(exp(-t/t1)-cos(2*pi*50*t));subplot(3,2,1);plot(t,y,'.r');xlabel('t/ms');ylabel('y(t)');title('輸入信號(hào)N=12');a=1;i=1:N;bs=sin(2*pi*i/N);bc=cos(2*pi*i/N);ys=filter(bs,a,y);yc=filter(bc,a,y);ym=2*abs(complex(ys,yc))/N;subplot(3,2,2);holdonplot(t,ym)xlabel('t/ms');ylabel('ym');title('傅里葉算法計(jì)算的有效值N=12');holdonT=0.02;t1=0.02;N=16;Ts=T/N;t=0:Ts:4*T;y=(exp(-t/t1)-cos(2*pi*50*t));subplot(3,2,3);plot(t,y,'.r');xlabel('t/ms');ylabel('y(t)');title('輸入信號(hào)N=16');a=1;i=1:N;bs=sin(2*pi*i/N);bc=cos(2*pi*i/N);ys=filter(bs,a,y);yc=filter(bc,a,y);ym=2*abs(complex(ys,yc))/N;subplot(3,2,4);plot(t,ym)xlabel('t/ms');ylabel('ym');title('傅里葉算法計(jì)算的有效值N=16');T=0.02;t1=0.02;holdonN=24;Ts=T/N;t=0:Ts:4*T;y=(exp(-t/t1)-cos(2*pi*50*t));subplot(3,2,5);plot(t,y,'.r');xlabel('t/ms');ylabel('y(t)');title('輸入信號(hào)N=24');a=1;i=1:N;bs=sin(2*pi*i/N);bc=cos(2*pi*i/N);ys=filter(bs,a,y);yc=filter(bc,a,y);ym=2*abs(complex(ys,yc))/N;subplot(3,2,6);plot(t,ym)xlabel('t/ms');ylabel('ym');title('傅里葉算法計(jì)算的有效值N=24');〔2〕仿真出的波形流ys=filter(bs,a,y);yc=filter(bc,a,y);bs=sin(2*pi*i/N);bc=cos(2*pi*i/N);輸入信號(hào)y=(exp(-t/t1)-cos(2*pi*50*t))N即每周波的采樣點(diǎn)數(shù)，原始信號(hào)離散化ys=filter(bs,a,y);