Synchrophasor PMU Time Synchronization for Wide-Area Grid Analysis
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Solution Overview
Problem
Existing synchrophasor systems face challenges in achieving precise time synchronization and efficient data transmission for wide-area electrical grid analysis, particularly in the context of electrical power systems, where high-accuracy time synchronization and faster data rates are required for accurate phasor measurements.
Innovation Solution
The implementation of phasor measurement units (PMUs) that include voltage and current sensors, analog-to-digital converters, processors for mathematical computations, and communication devices for time-stamped data transmission, utilizing IRIG-B and PTP sources for synchronization, and supporting multicast, broadcast, and unicast modes for data dissemination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If synchrophasor systems use traditional time synchronization methods, then system complexity is reduced, but measurement precision and time synchronization accuracy deteriorate
Solution Approach 1:
The patent introduces GPS satellites as an intermediary time source that provides highly accurate time signals to multiple PMUs across the electrical grid. This external time reference mediator enables precise synchronization without requiring complex inter-PMU coordination mechanisms, thus improving measurement precision while keeping system complexity manageable.
Solution Approach 2:
The patent replaces traditional mechanical or electrical synchronization methods with satellite-based atomic clock time signals. This substitution introduces a more accurate time reference source that operates independently of the electrical grid's mechanical and electrical constraints, significantly improving time synchronization accuracy for phasor measurements.
2Productivity
If synchrophasor systems increase data transmission rates, then productivity and analysis speed improve, but loss of information and data integrity may worsen
Solution Approach 1:
The patent implements a feedback mechanism where PMUs continuously transmit time-stamped phasor measurements with associated quality indicators and status information. This feedback loop allows the system to monitor data integrity in real-time, detect transmission issues, and request retransmission or correction when necessary, thus maintaining data integrity despite high transmission rates.
Solution Approach 2:
The patent applies preliminary error detection and correction coding to phasor data before transmission. By pre-processing the data with redundancy information and integrity checks, the system prepares for potential transmission errors in advance, enabling faster recovery and reducing the risk of information loss during high-speed data transmission.
Data Source
AI summary
A phasor measurement unit (PMU) of the present disclosure measures phasor, i.e., magnitude and phase angle of voltage and current, and related data from a specific location on the electrical gird synchronized to a common time source. The time-synchronized phasor is called a synchrophasor. In a system of the present disclosure, a plurality of PMUs transmit the synchrophasors and related data to a phasor data concentrator (PDC), which aggregates and time-aligns the data for real time and post analysis. The PMU of the present disclosure further functions as a power quality meter determining at least one of symmetrical components' phasor, frequency, rate of change of frequency, high-speed digital inputs, analog fundamental power and/or displacement power factor.