I-DPES-WLD9901 Primary Frequency Regulation Device iyisixhobo esibalulekile emandleni esistimu, esisetshenziselwa ukusabela ngokushesha ekushintsheni kwe-frequency yenethiwekhi, nokugcina ibhalansi phakathi kokukhiqizwa kwamandla nomthwalo. Ngokulawula ukuphuma kwezikhungo zamandla, ingakwazi ukubhekana nezingqinamba zesikhashana zomthwalo emasekhondini ambalwa kuya emashumini ambalwa emasekhondini, futhi iyisixhobo esibalulekile ekuqinisekiseni ukuzinza kwe-frequency yenethiwekhi.