According to the technical requirements of Hebei Electric Power Research Institute, Suzhou Huadian technicians completed the large-capacity three-phase/single-phase relay protection vector simulation system installation. The device is composed of voltage regulating transformer, intermediate transformer, capacitor cabinet and other equipment. This system is used in the relay protection test of 500kV and below voltage grade substations. Through the output of high voltage and high current to the primary equipment of the substation, the secondary voltage and current value converted by the current and voltage transformer can meet the requirements of the computer The relay protection device can display the added parameters reliably, stably and accurately. It can simulate various three-phase symmetric and asymmetric vectors, so as to achieve the purpose of confirming the correctness of the relay protection vector by testing the simulation load method before the substation is put into operation.