Synchrophasor PMU Timing Using GPS and PDC Data Alignment
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Solution Overview
Problem
Existing synchrophasor technologies 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, which is crucial for accurate protection and control functions.
Innovation Solution
The implementation of phasor measurement units (PMUs) that include voltage and current sensors, analog-to-digital converters, processors for mathematical computations, and time-stamped data transmission using IRIG-B or PTP sources, enabling synchronized phasor measurements and data aggregation through phasor data concentrators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If synchrophasor measurements are implemented across wide-area electrical grids, then grid analysis capability is improved, but time synchronization precision deteriorates due to distance and signal transmission delays
Solution Approach 1:
The patent introduces GPS satellite signals as an intermediary time reference source. Multiple PMUs across the electrical grid simultaneously receive and synchronize to the same GPS time signals, which act as a common mediator. This allows wide-area measurements while maintaining precise time synchronization, as all measurements are referenced to the same GPS time base despite physical distance between measurement points.
Solution Approach 2:
The system implements time synchronization feedback by continuously comparing local PMU clock time with GPS reference time and adjusting the local clock accordingly. This feedback mechanism ensures that even as the grid expands over wider areas, the time synchronization precision is maintained through continuous correction based on the GPS time reference.
2Quantity of substance
If multiple PMUs transmit synchrophasor data across the grid, then data coverage is improved, but data transmission complexity increases
Solution Approach 1:
The patent employs universal communication protocols (IEEE 1364, DNP3, IEC 61850) that enable multiple PMUs to transmit data through standardized interfaces. This multi-functionality allows the same communication infrastructure to handle data from any number of PMUs across the grid, expanding data coverage without proportionally increasing transmission complexity, as the standardized protocols provide a common framework for all data exchanges.
3Measurement precision
If high-speed sampling is implemented in PMUs, then measurement accuracy is improved, but processing requirements and device complexity increase
Solution Approach 1:
The patent replaces complex mechanical signal processing with digital signal processing implemented in FPGA or DSP circuits within the PMU. The high-speed sampling data is processed through digital algorithms (such as Fast Fourier Transform) to compute phasor measurements. This substitution of digital processing for mechanical/analog processing achieves high measurement accuracy while containing device complexity through integrated electronic processing units.
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.