Reliability Analysis of Phasor Measurement Unit Using Hierarchical Markov Modeling

Abstract

The consequence of a phasor measurement unit failure is very severe and may cause a blackout as it is a primary part of a wide-area measurement system. This article presents a hierarchical Markov modeling technique for reliability evaluation of phasor measurement unit. A phasor measurement unit is divided into seven modules for reliability modeling in terms of the functionalities of phasor measurement unit elements. Each module is hierarchically represented using Markov state space models and equivalently converted into two-state Markov representations, such that the reliability of the entire phasor measurement unit can be easily evaluated. The numerical results and sensitivity analyses indicate that the global positioning system module is the most unreliable source of phasor measurement unit, followed by the central processor unit module. The failure rate of the global positioning system receiver (λ_A) is the most crucial parameter to the phasor measurement unit reliability, followed by the failure rate (λ_hw) of the hardware in the central processor unit module. Improving the time precision of the crystal oscillator is an effective means to enhance the phasor measurement unit reliability if improving the two key parameters is confined in a manufacturing process.

Keywords:

• global positioning system
• Markov modeling
• phasor measurement unit
• reliability analysis
• wide-area measurement system

Acknowledgment

The authors are grateful for the partial support from the National Research and Development Fund of China (2004CB217908).