Full Cycle Anti-aliasing Synchronized Sampling Algorithm of Phasor Measurement Units in WAMS
WANG Ke-ying , JI Kun , CAI Ze-xiang South China University of Technology, Guangzhou 510640, China Hefei Power Supply Company, Hefei 230022, China
GPS-based synchronized phasor measurement units (PMUs) are important components in wide area measurement systems (WAMS). A new PMU design scheme and sampling algorithm with digital signal processor (DSP) and high speed AVR MCU are presented. The 1 PPS (pulse per second) of GPS is measured by one input capture unit of the DSP, and the 32-bit Timer of the DSP is synchronized by the 1 PPS to control the first sampling of a wave cycle. The frequency of the wave is measured by another input capture unit of the DSP, and the period register of 16-bit Timer of the DSP is loaded with the sampling period derived from the frequency. The measurement precision and the sampling synchronization are improved by using the full cycle anti-aliasing synchronized sampling method. The high-precision clock of DSP is incorporated with the GPS clock to improve the reliability of synchronous clock.