Abstract: The dielectric loss angle and power factor angle are common characteristic parameters used in online monitoring technology of capacitive equipment, zinc oxide arresters and dry-type air-core reactors. Its measurement accuracy is mainly controlled by the time difference of synchronous acquisition. Firstly, the principle of on-line monitoring technology of HV electrical equipment based on phase measurement is analyzed, and the time difference requirement for synchronous acquisition trigger is checked. Then, based on the existing intelligent substation online monitoring systems, a study is made on the design schemes and implementation methods of four synchronous acquisition triggering technologies, namely satellite timing, short-range radio broadcast communication, station control layer IRIG-B code timing, and power supply voltage assisted measurement. The experimental results show that the satellite timing has the highest synchronous acquisition accuracy; the short-distance radio trigger mode is simple in structure and easy to expand; the IRIG-B code is good in stability but complex in wiring; the power voltage auxiliary measurement is susceptible to the frequency fluctuation of the power grid. These results can provide a technical support for the online monitoring design of intelligent substations.

Key words: on-line monitoring technology, dielectric loss, synchronous acquisition, capacitive equipment, dry-type air-core reactor