Harmonic measurement system via synchronized measurements

Waveform distortion monitoring in high voltage transmission systems is a challenging task because of the large geographical extent of the system and the possibility of high Q resonance. Synchronized measurements provide the means to develop meaningful harmonic monitoring systems. The New York Power Authority (NYPA), and the other Empire State Electric Energy Research Corporation (ESEERCO) member utilities, initiated the development of the harmonic measurement system (HMS) in 1992. The HMS hardware consists of GPS synchronized digital event recorders linked to onsite computers, and a master station computer. The present installation includes instrumentation for a total of 150 measurements of which 138 are three phase quantities (voltages or currents) resulting in 46 phasors. The system performs synchronized waveform data acquisition every 15 minutes. The captured data are processed at the onsite computers to correct for error from the nonideal characteristics of the instrumentation and to compute the harmonics. The computed harmonic (magnitude and phase) are transmitted to the master station computer when the system wide harmonic flow is constructed, using a harmonic state estimation technique. The harmonic estimation techniques are based on synchronized measurements. The paper discusses applications of this system.