a)b)c)“ZPJH”UFLSUnderFrequencyLoadShedding123456()eTfffffte−∞∞−+=3-46f∞Tf∗LK410TfTf“ZPJH”3-2415'3'oft23456t1∆t2∆f)1(∞fef1f)2(∞f)0(∞f2f0∆f1f2fn12f1t1∆33-43-43-3'4f2ZPJHt2∆55-656f)2(∞123fhf4PJHPqe%%/)(/)(*fPfPfffPPPKfhffhfeefhefhefhfL∆∆∆∆==−−=∗∗∗∗∗=−=−−hfLehfeLJHxJHqefKfffKPPPP∆∗∗∗∗−−=hflhfxlqeJHfKfPKPP∆∆1fhf*∆fffehfehff−=∆*xP3-3MWPfhe2800=MWPqe900=2=∗LKHzfhf48=JHP04.0504850*=−=∆hff3-47MWPJH73404.021280004.02900=×−××−=MW900∗P∆∗f∆fz48Hz50H2=∗LKfhePPP3-253-3149Hz24646.5Hz31)fihf⋅⋅maxfihf⋅⋅min2)fihf⋅⋅maxfihf⋅⋅minZPJHi3)ZPJHZPJH4)fhfmin⋅ftsdz⋅5)fihf⋅⋅maxZPJHZPJHfhf1max⋅⋅=fhf2max⋅⋅==fnhf⋅⋅max=fhf06)fhf0ifdziiPi∆fihf⋅⋅maxabfdzifhf0feffhf0∆fi∆%/P%Pbi∆%Pi∆%Pbhf∆3-26i1ifihf⋅⋅min1+i2min⋅=hfdztsff3Tf231525s41n1nfdznnfhfmin⋅()()minmin11%100%⋅∗⋅∗−=−−−⎟⎠⎞⎜⎝⎛∑−≥hfeLedznhfLnkktsffKfffKPP∆∆2ifdztsfhf0()()0011%100%hfeLedztshfLnkktsffKfffKPP−−−⎟⎠⎞⎜⎝⎛∑−≥∗∗−=∆∆3-53%Pts∆3-523-52%Pts∆ZPJHa)ZPJHb)0.20.3sc)5s45Hz